Aging and Physical Performance
There are two approaches to the relationship of aging and physical performance. Most athletes are concerned with the effects of aging on their own abilities to perform and compete. But for the nonathlete, the question is often whether physical activity can counteract or blunt the aging process itself. From that perspective, the answer is yes it can, and it has been estimated that 30% of all deaths from heart disease, diabetes, and colon cancer are related to inadequate physical activity. One study indicated that no more than 20% (and more likely less than 10%) of adults in the US obtain sufficient regular physical activity to have a measurable impact on their health and fitness levels.
Is it safe to exercise as you age? If one uses common sense, the long term health benefits far outweigh any potential cardiac complications. One should avoid the extremes such as exercising above and beyond the level you have trained for, environmental extremes of temperature and humidity, and exercising when not feeling well. But even orthopedic injuries, which might be expected to be more common in the older athlete, do not appear to be increased with activities of moderate intensity and duration.
EFFECTS OF AGING ON PHYSIOLOGIC FUNCTION
Physiologic and performance measures peak in the late teens and 20s, and then decline with age. However they do not all decline at the same rate, and the rates of deterioration vary according to lifestyle (the old use it or lose it philosophy).
Muscular strength
Strength levels for men and women are at their peak between the ages of 20 and 30. Without a regular exercise program, there is then a decrease in muscle mass from muscle fiber atrophy hat becomes particularly apparent at age 60 . However, this is a combination of aging effects on the muscle/ nerve unit AND a decrease in daily muscle loading. One study of men between the ages of 60 and 72 years, training with standard muscle resistance exercises, demonstrated an improvement rate equal to young adults. Another group of 70 year olds, who had regularly trained from age 50, had a muscle cross sectional area equivalent to a group of 28-year-old students.
Neural function
Reflexes do slow with age, but as with muscular strength, activity minimizes the effects. Active men in their 70s had reaction times equivalent to inactive men in their 20s.
Pulmonary function
Once again, there is a decrease in lung function with age that can be blunted with regular activity. These studies indicate that a lifetime of regular physical activity may retard the decline in pulmonary function associated with aging.
Cardiovascular function 
DEVELOPING A TRAINING PROGRAM
(Background)
Designing a training program for any particular activity needs to be tailored to the duration and intensity (power, sprint, endurance) as well as the specific muscle groups being used (running, cycling, lifting, etc.) in the event. A general aerobic training program, for example, will not maximize your performance for that time trial coming up in a few weeks.
Brief power activities lasting for 30 to 60 seconds or repetitive sprint events rely on energy stored in the muscles as ATP and creatine phosphate (CP). Weight lifters and sprinters will gear their training towards improving those energy systems. As duration extends beyond one minute, energy is provided by anaerobic glycogen dependent pathways which produce lactic acid as a byproduct. And finally, after several minutes, aerobic pathways take on increasing significance with well over 90% of the energy in endurance events coming from these oxygen dependent metabolic systems. A successful training program focuses on developing the energy system specific for your particular event.
The muscle groups needed for your event should also be factored into training program development. When 60 college aged men, equal as far as their level of aerobic conditioning, were divided into three groups - one training on a treadmill, one on a bicycle trainer at an equivalent %VO2max, and a third used as a non training control, the exercise specific benefits of training were clearly demonstrated. Both training groups improved their VO2max equally when tested on their training device, however, while the treadmill group improved 7% in VO2max when tested on either the treadmill or bicycle ergometer, the group training on the bicycle trainer improved 8% when tested on the bicycle ergometer, but only 3% when tested on the treadmill - proof of the failure of crosstraining to maximize performance across all aerobic events. The investigators speculated that changes in metabolic and circulatory factors in the muscles being trained, or adaptations related to the total muscle mass used during training, were responsible for these differences. Thus a successful training program also needs to focus on the specific activity and muscle groups to be used in the event.
PRINCIPLES OF TRAINING
All training programs adhere to basic, common principles. They include:
I. EXERCISE OVERLOAD - the training event must increase the frequency, intensity, or duration of the specific exercise activity being trained for to be able to promote physiologic improvement and achieve a training response.
II. SPECIFICITY OF TRAINING - adaptations in metabolic pathways and muscle fibers are dependent on applying the types of metabolic stress (aerobic versus anaerobic) to be used in the final event to the specific muscle groups to be used for that activity.
III. SPECIFICITY OF VO2MAX - To achieve the optimum improvement in VO2max for any activity, the cardiovascular system needs to be stressed by that specific activity. As demonstrated above, there are general benefits to the heart and vascular system from any aerobic exercise, but if one wants to maximize VO2max, one needs to use the specific activity in training (a bicycle trainer will not maximize performance on a treadmill).
IV. SPECIFICITY OF LOCAL MUSCLE CHANGES - there are local improvements in the muscle trained for a specific activity that will not generalize to other muscle fibers in that limb, or to the same muscle used in other exercises. Changes in ATP levels and other metabolic parameters in the vastus lateralis (a thigh muscle) are greater in cyclists (who use this muscle to a greater degree) than in runners training at the same VO2max).
V. INDIVIDUAL DIFFERENCES - Not all individuals will respond to an equivalent training stimulus to the same degree or at the same rate. We are all different genetically and training programs need to be individualized.
VI. REVERSIBILITY OF TRAINING - Deconditioning can occur rapidly when training ceases. At bed rest for 20 days, there is a decrease in VO2max of about 1% per day. Maintaining some level of conditioning during the off season minimizes deconditioning. And a reconditioning program should be part of every athletes schedule before the next season’s competition begins.
PHYSIOLOGIC CHANGES OF TRAINING
Anaerobic pathway changes (sprint and power activities) -
• increases in ATP and creatine phosphate
• increase in enzymes involved in anaerobic glycogen breakdown
• increase in lactic acid levels - probably secondary to increased production and an increase in tolerance to the discomfort produced from lactic acid in the muscles
• increase in fast twitch fiber size
Aerobic pathway changes -
• mitochondria (where aerobic metabolism occurs) are larger and
• increases in number
• increased enzyme levels that generate ATP aerobically (without producing lactic acid)
• increase in enzymes that facilitate lipid metabolism (an alternative route of energy production)
• greater capacity to metabolize glycogen (partly related to increase in mitochondria and intracellular enzyme levels
• increase in slow twitch muscle fiber size
Cardiovascular changes -
• increase in heart size
• increase in blood volume (plasma)
• decrease in heart rate
• increase in volume of blood pumped per heart beat (stroke volume)
• increase in amount of blood pumped per minute (cardiac output = rate x stroke volume)
• increase in oxygen extraction at the muscle capillary interface
• less blood flow needed to the muscle for a set level of exercise (from increased efficiency of oxygen extraction)
• reduction in systolic and diastolic blood pressure
• increase in volume of respirations (each breath, tidal volume) and breathing frequency with exercise
TECHNICAL MONITORS
With all the gizmos and gadgets that are available, it is tempting to focus on the technical aspects of training at the expense of the basics. It is important to listen to your body and be patient waiting for results, Avoid the temptation of constantly measuring yourself against data produced by other athletes. As it is difficult to know HOW to use comparative data from others, you should focus on comparing your current performance to previous efforts as the best measure of progress, leaving the data of others out of the mix. It's basically hard, repetitive work, and there are no short cuts to your personal best. 
 EXERCISE INDUCED MUSCLE PAIN, SORENESS, AND CRAMPS
There are three types of muscle pain related to exercise.
• pain occurring during or immediately after exercise
• delayed onset muscle pain
• muscle cramps
MUSCLE PAIN DURING EXERCISE
Exercise requiring significant effort, either from high energy demands (low resistance, rapid contraction rate) or substantial muscle effort (high resistance, low contraction rate) is often associated with muscle pain or discomfort. No study has identified a single cause for this discomfort, although the fact that it occurs more quickly in a muscle with a limited blood supply suggests that the culprit is a product of muscle metabolism. In addition, as the ingestion of sodium bicarbonate will delay the onset of pain for any level of exercise, it is thought that the substance is acidic in character.
Lactic acid is considered the likeliest candidate although other metabolites such as pyruvic acid and ammonia have also been suggested. Based on the differing results in vaious papers in the literature, it is most likely that pain in the actively contracting muscle is multifactorial (ie related to a combination of substances) including the build up of acidic intermediate metabolites, ionic shifts at the cell membrane level (K, magnesium), and actual changes in the muscle cell proteins themselves. The fact that training will increase the level of activity at which discomfort first occurs indicates that the muscle cell can adapt to these factors.
It is interesting that the body also has a mechanism to deal with this discomfort. Endorphins, opiate like substances produced internally, are secreted into the central nervous system during endurance exercise and will alter the perception of pain during prolonged high intensity exercise. Thus we have a mechanism to warn of muscle overuse, and also one to suppress pain during prolonged exercise which may be beneficial in fleeing from dangerous situations.
Although conventional wisdom holds that taking aspirin before a ride will cut down on muscle pain during exercise, a study at the University of Georgia recently concluded that even at large doses (20 mg per kg or 4 standard aspirin for the average rider), aspirin did not delay the onset of muscle pain during exercise or reduce the perceived intensity when it occured.
DELAYED ONSET MUSCLE SORENESS (DOMS)
This is the soreness (stiffness) that begins 24 to 48 hours after exercise and peaking by 48 to 72 hours. It is most evident after "eccentric" muscle actions which involve actively resisting lengthening of the muscle as occurs in raising or lowering a weight, and indicate a high tension on muscle fibers and connective tissue as opposed to isometric or static tension activity. It is accompanied by a decrease in muscle strength, a reduced range of motion, and leakage of muscle cell proteins (creatine kinase, myoglobin) into the blood. These three findings indicate muscle damage (most likely related to minute tears and physical damage) as opposed to the buildup of metabolic byproducts during exercise, and muscle biopsies demonstrate muscle contractile fiber damage and an inflammatory response.
Generally DOMS is noted after unaccustomed eccentric exercise. And it does not appear that soreness from previous exercise increases the chance of further muscle damage. In fact the adaptive process of healing, even from microscopic injury with minimal pain, appears to have a significant protective effect on the development of muscle damage and soreness from subsequent exercise - the reason one should use a gradually progressive exercise training program.
MUSCLE CRAMPS
It's not unusual to hear the following story:
"I entered my first mountain bike race (18 miles) and at mile 14, my thighs and right calve cramped up. This has happened before on long rides. I thought I trained enough, hydrated enough, and ate enough bananas, but I still cramped up and had to go real slow for the last 4 miles. It was sooooo frustrating. I have another race coming up next month but its only 12 miles but has steeper hills. What should I do? Do tights help reduce cramps? When I get them (cramps) should I massage the cramped area? Should I train the amount of miles of the race?"
Cramps are most common when you use your muscles beyond their accustomed limit (either for a longer than normal duration or at a higher than normal level of activity) - which explains why cramps are more common at the end of a long or particularly strenuous ride or after a particularly vigorous sprint. In fact cramps are among the most frequent complaint in marathon participants (18% in one study). In another study of cyclists competing in a 100 mile race, 70% of male participants experienced cramps (women, interestingly, had a rate less than half as frequent at 30%).
The pain is brought on by an intense, active contraction of the muscle cells themselves. Although cramps may occasionally be the result of fluid and electrolyte (sodium) imbalance from sweating, that is not universally the case as individuals involved in activities requiring chronic use of a muscle without sweating (musicians for example) will also experience cramps.
In one study of marathon runners, there were no differences in sodium or hydration levels between the 15 participants who developed cramps and the 67 who didn't. And although a low magnesium level can cause severe muscle cramping, another study of magnesium supplements in triathletes failed to show any benefits as far as cramping.
As with the two other forms of activity related muscle pain, training to the level of the anticipated activity will decrease the possibility of cramps. If one is going to be exercising in excessively hot or humid conditions, most trainers would suggest paying close attention to salt intake and even adding 1/2 tsp of salt (1150 mg of sodium) per day to your food at these times. Don't worry about elevating your blood pressure as we are talking about a short term supplement and the sodium effect on blood pressure happens over months to years. A sports drink might help, but it is probably maintaining adequate hydration that is more important than the small amount of electrolytes they contain, and water is still a lot less expensive. The role of adequate glycogen reserves in preventing muscle cramps is speculative and requires further investigtion.
If cramps do occur, gently stretching the affected muscle will give relief, and some authorities feel that stretching used prophyllactically will prevent cramps. Calf cramps can be relieved by standing on the bike and dropping your heel, while anterior thigh cramps can be stretched out by unclipping and moving your thigh backwards towards your buttocks. Although a number of medications have been suggested as treatments for muscle cramps (vitamin E, verapamil, and nifedipine to name a few) only quinine has been shown to be effective in scientifically controlled studies. But the high incidence of side effects limit its usefulness as a routine treatment.
My recommendations for those suffering from frequent muscle cramps? An adequate training program designed for the event being considered, maintaining good hydration, a sports drink containing electrolytes for severe conditions of heat and humidity, and a regular program of stetching before, during, and after exercise.I suspect you were pushing beyond your training and that's a sure fire way to get them. Remember to "train to the ride" i.e. push yourself to the level of your competitive ride once a week.

HEART RATE MONITORS
CONTENTS
• Basic cardiovascular physiology
• Pros and cons of using a heart rate monitor
• Definitions
• Calculating your maximum heart rate
• Heart rate training zones
• Training tips using a heart rate monitor
• Resting heart rate
• An opposing opinion
Many cyclists and trainers tout the Heart Rate Monitor (HRM) as the most significant training advance in the last ten years. Although many coaches refuse to work with an athlete without the physiologic training information it provides, HRMs have their detractors. And that small backlash is slowly growing. An alternative to a HRM, not quite as technical and rigid, uses perceived effort as a measure of your level of exertion.
BASIC CARDIOVASCULAR PHYSIOLOGY
First, let's review the basic physiology of the circulatory system asking ourselves the question "What does the heart rate really indicate?" The components of the cardiovascular system are:
• the heart (the pump)
• the arteries (a distribution system)
• the capillaries (the exchange system where gases, nutrients, and other chemical compounds move to and from surrounding tissue
• the veins (which are the return circuit)
With every heart beat (contraction of the heart pump), a certain amount of blood (stroke volume) is pushed through the system. The contraction frequency of the heart is the heart rate (HR). The amount of blood moved to the cells of the body every minute is the product of the heart rate and stroke volume (HR x strove volume).
With physical activity (exercise) more oxygen is required by the muscle cells, and the circulatory system responds by increasing the heart rate (and the cardiac output). With aerobic training, the actual amount of blood pumped per heart beat (stroke volume) increases and the efficiency of the exchange process at the capillary level improves. The result is a lower heart rate for any level of physical activity in the trained versus the untrained individual. Thus aerobic training benefits include:
• a lower resting heart rate
• a lower heart rate for any specific level of exertion
• as well as an increased exercise capacity for an individual's maximum heart rate.
The training effect results when the heart muscle is "stressed" by an increase in cardiac output (just as muscles in the arms and legs respond to the stress of lifting free weights). As the cardiac output is directly proportional to the heart rate, a heart rate monitor (HRM) can be used to structure and monitor an aerobic training program. (For additional background see Basic Exercise Physiology - the cardiac system.)
Let's look at the pros and cons on the use of a HRM.
PROS AND CONS
The ADVANTAGES of a HRM include its use:
• as a motivational tool - like a coach ; brings objectivity to a training program.
• to teach beginners to read their bodies and avoid anaerobic overtraining.
• to aid in doling out energy during time trialing or climbing, saving some for the final effort.
• to analyze race efforts and design a personalized training program.
• to spot overtraining (heart rate 10% higher than normal on awakening for several consecutive days).
The DISADVANTAGES of a HRM are:
• its inconsistency - at the same heart rate you're not always putting out the same effort day to day.
• the lack of scientific support - there is no evidence training with a HRM improve competitive performance.
• too much data, esp with elaborate HRMs, with little agreement on how to use this information to improve training or performance.
• the lag time in heart rate response to a change in exertion - 15 to 30 sec lag with 2 to 3 min to stabilize at the new level of exertion.
• its incompatibility with group training.
• it distracts from dangerous road hazards.
DEFINITIONS
Here are some definitions you'll encounter in the literature on heart rate monitors:
• bpm - beats per minute
• Max HR (MHR) - maximum heart rate (expressed in beats per minute)
• target heart rate - the training heart rate (usually a range of values)
• anaerobic threshold (AT)* (synonomous with lactate threshold). Lactate production occurs with muscle cell activity and increases as activity becomes more vigorous. Lactic acid is metabolized by the muscle cells, but at some point they cannot eliminate (or oxidize) the lactate as fast as it is being produced and the blood lactate level begins to increase. In trained athletes, this threshold for lactate buildup occurs at a higher activity level or percentage of the athlete's MHR or aerobic capacity. For all practical purposes, the AT is the highest heart rate you can maintain for a race or hard ride lasting up to an hour. As the AT increases with aerobic conditioning, it is considered one of the standard measurements to track training. The AT is usually reached at 80-90% of your maximum heart rate, but in elite riders rises to 90-93% of their maximum heart rate.(See also Basic Exercise Physiology - measures of cardiovascular fitness.)
• lactate threshold (LT). See anaerobic threshold.
* Determining your actual Anaerobic Threshold (synonyms are lactate threshold, AT, LT, Concini test). Accurate laboratory determination of your anaerobic threshold requires frequent blood draws while pedaling an ergometer at steadily increasing workloads. But for training purposes, the following approach is an alternative. Using a single gear, start cycling at 35 kph. Slowly increase speed on a flat course by 1km/hr every 300 meters (1/5 mile). Chart heart rate vs speed. Anaerobic Threshold is the "breakpoint" where heart rate levels off relative to speed.
Let's assume you have decided to use a heart rate monitor in your training program. The first step is calculating your MHR or maximum heart rate.
CALCULATING YOUR MAXIMUM HEART RATE (MHR):
Just as we all vary in height and body habitus, everyone has their own personal maximum heart rate genetically "hardwired". Our maximum heart rate also decreases approximately one bpm (beat per minute) per year. The average MHR of a teenager is 220 beats per minute, but this may vary +/- 11 beats from the average (209-231 bpm). For example, a 40 year old who would be expected to have a MHR of 180 (220-40) could vary from 169 to 191 for his or her own personal MHR.
Another key point is maximum heart rates are "sport specific" i.e. they vary from one sport to another. For a given rate of oxygen consumption, weight bearing activities such as running raise the heart rate more than cycling (part of your weight is supported by the bike). So you cannot use your maximum heart rate from running to plan a cycling training program without risking overtraining.
One of the following two approaches can be used to determine your MHR for cycling. The first is more accurate and the one I prefer. There can be marked discrepancies between the estimated MHR and real life results (up to 5% of the population can have heart rates 20 beats above or below the ESTIMATED figure). And if you are in shape, the typical decline of one beat per minute per year doesn't always hold.
• Warm up thoroughly. On a long, steady hill increase effort every minute for at least 5 minutes until you can't go any faster. Then sprint for 15 seconds. Check your heart rate at its maximum for a full 30 seconds and double the number. Similar results can be obtained on a stationary trainer.
• 220 minus your age in years. A rough figure and much less accurate than the on bike approach.
The only limit to the length of time one can ride at 100% of their MHR is personal discomfort. This level of activity does not "strain" the heart muscle or have other harmful effects on the heart itself. Although this level of activity might be considered in a competitive race or event for a short sprint, maximizing the benefits of a training program is the result of a mixture of recovery and hard days (see below). As the time you can hold 100% MHR is considerably shorter than the time you can ride at 84-90% MHR, the art of racing is finding the right mix to get you to the finish line first. Most competitive athletes train at their lactate threshhold (84-90% of their MHR).
HEART RATE TRAINING ZONES
There are 5 training "zones" or heart rate ranges. These are arbitrary divisions and can differ from article to article or coach to coach. They are based on the increase in heart rate (and cardiac output) as the oxygen consumption of the exercising muscle increases, and the concept of the benefits of variable stress in developing the exercising muscle (heart or skeletal). As one moves up the hierarchy of training zones, exercise intensity increases and there is a shift from the use of fat as an energy source for the muscle cell to carbohydrate (below 70% MHR fat is burned preferentially). And as the MHR is reached, there is a shift in the muscle cell towards anaerobic (without oxygen) metabolism with increased lactic acid production.
The Heart Rate Intensity Zones are divided as follows:
• Zone 1 65% of MHR (recovery rides)
• Zone 2 65-72% of MHR (endurance events)
• Zone 3 73-80% of MHR (high level aerobic activity)
• Zone 4 84-90% of MHR (lactate threshold(LT,AT); time trialing)
• Zone 5 91-100% of MHR (sprints and anaerobic training)
If you always train at low heart rates, you will develop endurance with no top end speed. Conversely if you train hard most of the time, you'll never recover completely and chronic fatigue will poison your performance. The solution is to mix hard training with easy pedaling in the proper proportions.
The best approach is to stay below 80% of maximum heart rate (zones 1 to 3) on your easy days to build an aerobic base while allowing day to day recovery, and then push above 85% when it's time to go hard to improve your high level performance. But avoid training in the no man's land or mediocre middle at 80-85% of MHR where it's too difficult to maintain the pace for the long rides needed to build endurance and allow some recovery time, but not hard enough to significantly improve your aerobic performance and increase your lactate threshold.
Training programs should be individualized, but once a good base is developed early in the season with Zones 1 and 2 exertion, most programs contain the following elements.
TRAINING TIPS USING A HEART RATE MONITOR
Tips for a training week: (see also mileage tips and training options)
• one long recovery ride - zone 1 or 2
• one long day (event distance + 10 to 20%) - maxhr = to that planned for the event
• three high intensity days - zone 4
• one or two interval workout days which are counted as one of the three zone 4 days. For example:
o warm up - zone 1
o 20 min - zone 3
o 5 min - zone 4
o 7 intervals - hit 90% max, recover to 60 - 65% max
o 5 min - zone 4
o 20 min - zone 3
o warm down - zone 1
• the sixth and seventh days of the week can be rest days off the bike or slow recovery rides at zone 1 or 2 exertion to stretch out your muscles.
RESTING HEART RATE
Your resting heart rate (RHR) can also be used as an indicator of your degree of training. As you train, your resting heart rate will fall. This is a result of the increased efficiency of the circulatory system. The heart will increase the volume of blood pumped per beat, and the peripheral muscle cells will become more effective at extracting oxygen from the blood passing through their capillary networks. The RHR for an untrained individual is 60 to 80 beats per minute. With training, it is not uncommon to see the RHR fall into the high 40s or low 50s. And as mentioned above, regular monitoring of your resting heart rate in the mornings (before getting up and beginning your daily activities) can be used as a monitor for over training (heart rate on awakening and before getting out of bed 10% higher than your personal normal for several consecutive days).
AN OPPOSING OPINION
But there are differences of opinion on the usefulness of a heart rate monitor for training and competing. So keep an open mind and don't consider the HRM as the only real key to success. The following is from an Aussie coach, Graham Fowler:
"I have observed a number of different %max heart rates during time trials. My nephew once rode a junior nationals ITT at 100%MHR. He didnt win it needless to say however didnt crack either. Obviously he was very fit or his MHR was inaccurate. I advise riders to ride just above (1 to 5 beats per min) what they consider threshold. This is around 92%mhr. This mark needs to be derived in training. I am aware of race day anxiety causing the heart rate to elevate somewhat so the hr is not such a good measure with an anxious rider. I am more inclined in the future the train with heart rate to establish a perceived effort (pe), and then remove the heart rate meter during racing and ride on pe alone. The speedo is then the govener (sic)."
OVERTRAINING (OT)
CONTENTS
• background/physiology
• four types of fatigue
• who is prone to overtraining
• clues to overtraining
• what can you do
The feeling of fatigue that follows a good ride or workout tells us that we are pushing our physical limits, and is a necessary part of improving our personal performance. However, in certain circumstances, fatigue may also be our only warning that we are pushing too hard and indicating a need to back off or risk a deterioration in our abilities. This is a common dilemma in a personal training program: Hard work makes us faster, but how much is too much?
BACKGROUND/PHYSIOLOGY
Fiercer competition between athletes and a wider knowledge of optimal training regimens have dramatically influenced current training methods. A single training bout per day was previously considered sufficient, whereas today’s athletes regularly train twice a day or more. Consequently, the number of athletes who are overtraining and have insufficient rest is increasing.
The positive result of training in any sport is adaptation and improved performance: the supercompensation principle - which includes the breakdown process (training) followed by the recovery process (rest). Overtraining results from an imbalance between training and recovery, exercise and exercise capacity, stress and stress tolerance.
Elite sports require large numbers of training hours per week. It is assumed that the relationship between training and improved performance is an inverted U-shape. Overreaching (or short term overtraining) is most likely associated with insufficient recovery in the muscle with a decline in ATP levels. Overtraining (OT) or staleness is a more generalized physiologic problem, perhaps related to failure of the hypothalamus to cope with the total amount of stress.
Short term OT (overreaching, peripheral or muscle related overtraining) lasts a few days to 2 weeks and is associated with fatigue, reduction of maximum performance capacity, and a brief interval of decreased personal performance. Recovery is achieved within 72 hours. Long term OT (overtraining syndrome, staleness, systemic overtraining) is the result of many weeks of exceeding the athlete’s physiologic limits and can result in weeks or months of diminished performance - symptoms normally resolve in 6-12 weeks but may continue much longer or recur if athletes return to hard training too soon. It involves mood disturbances, muscle soreness/stiffness, and changes in blood chemistry values, hormone levels, and nocturnal urinary catecholamine excretion.
Stress factors such as the monotony of a training program, and an acute increase in training program intensity lasting more than 3 weeks increase the risk of development of an overtraining syndrome. On the other hand, heavy training loads appear to be tolerated for extensive periods of time if athletes take a rest day every week and use alternating hard and easy days of training.
For those of you interested in the basic physiology of the OT syndrome, the underlying pathology is felt to be an autonomic or neuroendocrine imbalance. Several findings support this thesis. During heavy endurance training or overreaching periods, the majority of studies indicate a reduced adrenal responsiveness to ACTH which is compensated by an increased pituitary ACTH release. In early OT syndrome, despite increased pituitary ACTH release, the decreased adrenal responsiveness is no longer compensated and serum cortisol levels fall. In advanced stages of overtraining syndrome, pituitary ACTH release also decreases. In this stage, there is additional evidence of decreased intrinsic sympathetic activity and sensitivity of target organs to catecholamines - indicated by decreased catecholamine excretion during night rest, decreased beta-adrenoreceptor density, decreased beta-adrenoreceptor-mediated responses, and increased resting and exercise induced plasma norepinephrine levels.
There is also a psychological toll from overtraining. For the most part, the competitive athlete is a well-adjusted individual who demonstrates considerable vigor and well-being, as well as less depression, anxiety, and fatigue than nonathletic counterparts. The well-trained athlete, however, may also have a personality that is somewhat rigid, strongly goal oriented, and perfectionist. It is not unrealistic to expect that when confronted with diminished performance or success, such an athlete may be compelled to drive himself or herself harder to succeed. Such behavior can express itself in the form of chronic fatigue and depression.
Listed below are some of the physiologic and performance changes that have been documented with OT. A common thread is the inability to attain maximum energy output in whatever sport you are attempting (aerobically and anaerobically) and the psychological consequences that go along with failing to do your best.
• a decrease in scores on a self assessment of well-being; mood swings noted by others
• sustained fatigue
• a failure to progress in a training program
• a decrease in the level of personal performance following a several day recovery period
• an increase in mild illnesses recorded in a training diary
• increased sleeping heart rate
• a decrease in maximal physical performance
• a decrease in maximal exercise induced heart rate
• a decrease in the ratio of blood lactate concentration to ratings of perceived exertion at maximal work loads
• a decrease in the clearance of blood lactic acid from min. 3 to min. 12 post maximal anaerobic activity
• a decreased intramuscular utilization of carbohydrates at maximal exercise levels
• a decrease in blood glucose, lactate, ammonia, glycerol, free fatty acids, albumin, LDL, VLDL cholesterol, hemoglobin level (transient), leukocytes
• absence of an increase of serum cortisol normally induced by 30 min. of acute exercise
• lowering of VO2max
• nocturnal catecholamine excretion decreased markedly contrary to exercise-related plasma catecholamine responses which increased more than expected.
• resting and exercise-related cortisol and aldosterone levels decreased.
And several studies have suggested that OT may be associated with other health issues above and beyond a deterioration in physical performance. One study of Harvard alumni found a lower death rate (mortality) among men expending as few as 200 Calories per week in exercise versus those leading sedentary lifestyles, but when they routinely spent over 4000 Calories on exercise per week the death rate began to rise again. And two different studies have suggested a decrease in immune system competence with intense training (cycling 300 miles per week for 6 months or 2 intensive sessions of running per day for 6 days). But before you give up exercising completely, there is plenty of evidence that a moderate cycling program will actually stimulate and improve your immune system. The key is planning your own personal training program to occasionally overreach but not overtrain.
To review, there are four levels of fatigue are experienced by the regular cyclist.
• The fatigue (or bonk) which accompanies muscle glycogen depletion develops 1 to 2 hours into a ride unless glucose supplements are used to extend internal muscle glycogen stores.
• The normal post exercise fatigue which tells us we are pushing our normal training limits and will lead to improved performance the next time out.
• The fatigue we feel at the end of a particularly hard week of riding (really a more extreme form of post exercise fatigue) that, with recovery, will also make us faster and stronger. Exercise physiologists refer to this as "overreaching".
• The debilitating and long term (often lasting weeks and months) fatigue which degrades performance and is the real OT syndrome.
The challenge for your personal training program is in finding your own limits, and avoiding that transition from overreaching to overtraining.
WHO IS PRONE TO THE RISKS OF OVERTRAINING?
Cyclists are one of the few groups of athletes capable of reaching the over trained level associated with prolonged fatigue. It has been speculated that this is due to the way cycling stresses the body with muscle activity concentrated in a single muscle group - the quadriceps. And it isn't necessary to undertake an extensive training program to be at risk. In fact those working out sporadically and with light training schedules are at risk. While a professional cyclist might consider a 50 mile ride as part of a light recovery week, your 20 mile ride could produce all the symptoms of OT.

CLUES TO OVERTRAINING
How do YOU know when you are in danger of OT? The following are clues which might suggest that an extra day or two of rest is in order.
Personality/Disposition - While your personal demeanor is difficult to quantify, it appears to be the most sensitive and earliest indicator of overtraining. Anger, depression, and a decrease in your sense of well being and vigor have all been reported as signs of OT. You won't need a psychologist to help you with this one. Your family and significant others are usually the first to point these symptoms out to you.
Resting heart rate - A resting pulse rate is taken on awakening in the morning before getting out of bed. An increase of 10% or 10 beats per minute for several days in a row is accepted by most coaches as a sign to slow down. Remember, it is the trend of your resting heart rate, taken over a period of days, that is important, not a single day's reading.
Performance - A short, standardized time trial every week is another helpful monitoring tool, and the changes will usually be in minutes, not seconds. If you see a deterioration, take some time off or consider switching to another aerobic activity (being careful to keep your exercising heart rate below 70% of maximum). A drop of 10 beats per minute in your time trial maximum heart rate has also been used as an indicator of overtraining.
General fatigue - Ongoing daily lethargy is a clue that it's time to slow down.
General physical complaints - Sore throat, sore muscles, and chronic diarrhea all may indicate the chronic stress of overtraining. An increase in minor illnesses has been reported as well.
Disruption of the normal sleep cycle - Falling asleep easily, awakening abruptly, and then feeling like you need a nap at 10 AM can reflect a change in your normal sleep cycle associated with overtraining.
Biochemical parameters - And of course there are a myriad of biochemical parameters that have been used by coaches to identify early overtraining. These include resting and exercise cortisol levels, norepinephrine levels, and lactic acid clearing after maximal exercise.
But when it comes right down to it, you are how you feel, so to speak. Your sense of well being, sense of fatigue throughout the day, and sense of perceived effort as you take that weekly ride over your regular route all appear to be more sensitive than the most sophisticated laboratory study in identifying early overtraining.
WHAT CAN YOU DO?
The most important aspect of preventing OT is realizing you are almost there. And a good training diary is the single most important tool you have at your immediate disposal to alert you to the risk. In addition to the usual training facts such as mileage and times, it should include a daily notation on:
• resting heart rate before getting out of bed
• mood self assessment
• self assessment of level of fatigue throughout the prior day
• recording minor illnesses - i.e. GI upset, diarrhea, sore throat, and runny nose
• performance on a weekly standardized ride done at your maximum
For professional coaches, there are some intriguing additional tools available. J C Puffer and J M Shane in Clin Sports Med 1992 Apr.11(2):327-38 reviewed the issue of chronic fatigue as it related to OT versus other medical diagnoses, and presented a diagnostic framework to assist in the assessment of the athlete who presents with such complaints. G Kenatta and P Hassmen in Sports Med 1998 Jul 26(1):1-16 describe a methodology they call refer to as the total quality recovery (TQR) process. By using a TQR scale, structured around the scale developed for ratings of perceived exertion (RPE), they suggest that the recovery process can be monitored and matched against the breakdown (training) process (TQR versus RPE). The TQR scale emphasizes both the athlete's perception of recovery and the importance of active measures to improve the recovery process. Directing attention to psychophysiological cues serves the same purpose as in RPE, i.e. increasing self-awareness. They suggest that using this tool (i) differentiates between the types of stress affecting an athlete's performance, (ii) identifies factors influencing an athlete's ability to adapt to physical training, and (iii) structures the recovery process.
From the laboratory or biochemical perspective, A C Snyder et al in Int J Sports Med 1993 Jan 14(1):29-32 proposed monitoring the ratio of blood lactate concentration to ratings of perceived exertion. They performed an incremental exercise test to maximal effort monitoring blood lactate concentration (HLa) and ratings of perceived exertion (RPE) for each workload. They found that at maximal workload all seven subjects had HLa:RPE ratios of less than 100 when over-reached and concluded that the ease and speed at which the HLa:RPE ratio can be determined may make it useful for coaches and athletes in monitoring intensive exercise training and recovery. P Pelayo et al in Eur J Appl Physiol 1996;74(1-2):107-13 reviewed measurements of blood lactate concentration both during and after a maximal anaerobic lactic test (MANLT). The percentage of mean blood lactate decrease (% [La-]recovery) between min. 3 and min. 12 of the passive recovery post-MANLT increased from week 2 to 10 with aerobic training and decreased from week 10 to 21. The lowest % [La-]recovery coincided with signs of OT, such as bad temper and increased sleeping heart rate. They concluded that the % [La-]recovery could be an efficient marker for avoiding OT in elite athletes.
In addition, you can structure your training program to decrease the risk of OT. It should include at least one (and sometimes two) rest days per week as well as a day or two of easy spinning. This reflects the practical experience of coaches who have had to deal with the results of pushing too hard for too long. Increasing variation (decreasing monotony) both in your training routine from week to week (long rides, intervals) as well within individual rides has been proven to minimize training stress and decrease the risk of OT.
IN SUMMARY
Overtraining refers to prolonged fatigue and reduced performance despite increased training. Its roots include muscle damage, cytokine actions, the acute phase response, improper nutrition, mood disturbances, and diverse consequences of stress hormone responses. The clinical features are varied, non-specific, anecdotal and legion. No single test is diagnostic. The best treatment is prevention, which means (1) balancing training and rest, (2) monitoring mood, fatigue, symptoms and performance, (3) reducing distress and (4) ensuring optimal nutrition, especially total energy and carbohydrate intake.
Over reaching is a normal part of the training/recovery cycle, but if your performance is not improving after a few days of recovery, it's time to switch to other aerobic activities which will keep you at 70% of your maximum heart rate (to maintain your level of fitness) or risk entering the zone of OT which may take a month or two to recover.
How long do you need to rest? If you have made a significant increase in your training schedule, and have been at it for 3 weeks or more, the chances are that you are entering that gray zone of overreaching. If so, recovery (and again this means keeping your general level of aerobic activity at 70% max. heart rate, not complete inactivity) takes at least 3 days and often up to several weeks as opposed to the normal recovery cycle of less than 3 days. The implication in that situation is that you may need more than 1 or 2 days of rest before a big event to perform at your personal best.
As in all aspects of personal training programs there is individual variability, so it is up to you to decide where to draw your own line. But remember that rest is a key part of any training program and may be the toughest training choice you'll have to make.
And finally, don't forget to pay particular attention to post exercise carbohydrate replacement. Part of the fatigue of overtraining may be related to chronically inadequate muscle glycogen stores from poor post training ride dietary habits.
PERCEIVED EFFORT
How hard am I working? Am I pushing myself and getting the maximum from my training efforts? These are common questions for those of us focused on a high quality workout. Although Heart Rate Monitors are touted as THE only way to know the exact intensity level of your cardiovascular workout, there is a cheaper, easier alternative - the Rating of Perceived Exertion (RPE) scale {below} proposed by G. A. Borg in 1982 (Med Sci in Sports Exer. 14(5):377-81, 1982).
The RPE scale ranges from 6 to 20, and includes a literal description for each level of exercise intensity. It was designed so adding a 0 to the level of exertion would give a rough estimate of your heart rate i.e. if you were resting (a 6 on the scale) your heart rate would be in the neighborhood of 60. Although RPE isn’t accurate enough for detailed physiologic studies, research has demonstrated an amazingly high correlation for any individual from day to day. In other words if you felt you were exercising at a 13 (somewhat hard) on two different days, and checked your heart rate, it would be quite similar.
How can you use the RPE scale? First familiarize yourself with the levels. Then, using a treadmill or wind trainer, rate your own level of exertion BEFORE you check your pulse rate. With a little practice you will find that you will be amazingly accurate in predicting your heart rate. At that point you can use your own RPE instead of a heart rate monitor to monitor the intensity of the day’s workout.
RPE can change as fitness improves (a higher heart rate for any level of perceived exertion) and with factors such as hydration, carbohydrate status, and ambient temperature. So recalibrate your own RPE scale regularly during the season if you are using this tool in your training.
RPE scale
• 6 - resting
• 7 - very, very light
• 9 - very light
• 11 - fairly light
• 13 - somewhat hard
• 15 - hard
• 17 - very hard
• 19 - very, very hard

Post Ride Recovery and the Training Program
Ask a cyclist about their training program and you will hear about mileage, intervals, and nutritional secrets. Only recently has post ride recovery made it onto the list of priorities. Yet successful cyclists know that preparation for the next ride begins even as the current one is being completed.
POST EXERCISE FATIGUE
A cyclist may experience 4 distinct types of fatigue.
• The bonk (fatigue resulting from muscle glycogen depletion) usually develops 1 to 2 hours into a ride. It is a particular problem if "on the bike" glucose supplements are not used to extend internal muscle glycogen stores.
• Post ride fatigue is a normal response to several hours of vigorous exercise and indicates we are pushing our training limits. It leads to improved performance the next time out.
• Overreaching is the next step up - the fatigue we feel at the end of a particularly hard week of riding. It is really just an extension of #2, and will, with recovery, make us faster and stronger.
• Over training is the debilitating and often long term (lasting weeks to months) fatigue which limits rather than stimulates improvement in performance.
A regular rider needs to constantly assess his or her level of post ride fatigue, maintaining a sensitivity to the fine line that separates post exercise fatigue (a stimulus to improvement) and overtraining (which can only hinder future performance). Most training programs include at least one and sometimes two rest days per week as well as a day or two of easy spinning as insurance against overtraining - generally based on practical experience which has demonstrated the risks of pushing too hard for too long.
Over reaching is a normal part of the training cycle, but if you find that your performance is not improving with a few recovery days, it's time to take a break and switch to alternative aerobic activities (at 70% maximum heart rate) to maintain your cardiovascular fitness. The alternative is to risk entering the zone of overtraining which may then require a month or two to recover.
Although it may seem paradoxical, rest is a key component of all training programs and may be actually be one of the toughest training choices you'll have to make.
NUTRITION
Carbohydrates are the primary energy source for cyclists involved in elite performance events. Fats are more important in slower, endurance events, while protein maintains and repairs cells and tissue.
Muscle fatigue (the "bonk") occurs when the body's liver and muscle carbohydrate (glycogen) is depleted and the exercising muscle must by necessity shift to fat metabolism as a source of energy. One component of overtraining may be a failure to adequately replace the muscle glycogen depleted as a result of daily training.
To minimize the risk of the bonk and overtraining, it is important to maximize body glycogen stores by:
• eating a high carbohydrate diet in the days and hours before your ride
• using carbohydrate supplements while riding
• using the immediate post ride recovery interval to begin rebuilding carbohydrate stores.
As far as the pre ride period, the traditional carbohydrate loading program (which includes a carbohydrate depletion phase by avoiding all carbohydrates for several days followed by forcing carbohydrates for the 3 days immediately prior to the event)to maximize glycogen stores is not essential. A high carbohydrate diet alone (without the preceding carbohydrate depletion phase) will provide 90% of the benefits of the full program while avoiding the digestive turmoil that changes in diet required by the carbohydrate depletion phase can produce. {NOTE: Although any increase in glycogen stores WILL increase the DURATION of exercise to fatigue, they WILL NOT increase MAXIMUM PERFORMANCE (VO2max)}
Maximizing carbohydrate replacement while riding is important for events of more than 2 hours. At least 1 to 2 grams of carbohydrate per minute can be absorbed and utilized to supplement pre ride glycogen stores and help sustain prolonged exercise. In extreme events such as the Tour de France, as much as 50% of the daily energy expenditures can be provided by supplements taken while on the bike.
Finally, one needs to take advantage of the glycogen repletion window that is open in the 4 hours immediately following vigorous exercise. During this time, orally ingested carbohydrates will be converted into muscle glycogen at 3 times the normal rate - and the earlier the better as some data suggests a 50% fall in the repeltion rate by 2 hours and a return to a normal repletion rate by 4 hours. (Ivy JL et al,J Appl Physiol 1988 Apr;64(4):1480-5). The slowing rate of glycogen storage occurs even when plasma glucose and insulin levels remain elevated with oral supplements. Overall, muscle glycogen stores are replenished at a rate of approximately 5% per hour. And while it may require up to 48 hours for maximal muscle glycogen replacement following a 2 hour ride, for all practical purposes these glycogen stores are almost completely rebuilt in the first 24 hours post event.
How much glucose is enough during this 4 hour interval? Ivy JL et al (J Appl Physiol 1988 Nov;65(5):2018-23) studied eight subjects who had cycled for 2 h on three separate occasions to deplete their muscle glycogen stores. Immediately and 2 h after exercise they consumed either 0 (P), 1.5 (L), or 3.0 g glucose/kg body wt (H) of a 50% glucose polymer solution. By the end of the 4 h-recovery period, blood glucose and insulin were still significantly above the preexercise concentrations in both treatment groups. Muscle glycogen storage was significantly increased above the basal rate after ingestion of either glucose polymer supplement. However, the rates of muscle glycogen storage were not different between the L and H treatments during the first 2 h (L, 5.2 vs. H, 5.8 mumol.g wet wt-1.h-1) or the second 2 h of recovery (L, 4.0 vs. H, 4.5 mumol.g wet wt-1. h-1).
So now we know that there is an upper limit beyond which muscle glycogen replacement rates will not increase. Is the type of carbohydrate important? Blom PC et al (Med Sci Sports Exerc 1987 Oct;19(5):491-6) studied the effect of fructose, sucrose, and glucose on muscle glycogen synthesis during the first 6 h after exhaustive bicycle exercise. When 0.70 g/kg body weight of glucose, sucrose or fructose were given orally at 0, 2, and 4 h after exercise, the rates of glycogen synthesis were 5.8, 6.2, and 3.2 mmol/kg/h respectively. Thus the answer appears to be NO (although there was the suggestion that fructose was the least beneficial).
Does it make a difference how one eats in the 24 hour post exercise period? Burke LM et al (Am J Clin Nutr 1996 Jul;64(1):115-9) compared the intake of large carbohydrate meals ("gorging") with a pattern of frequent, small, carbohydrate snacks ("nibbling") on eight well-trained triathletes after an exercise trial (2 h at 75% VO2max followed by four 30-s sprints) to deplete muscle glycogen. The subjects consumed the same diet composed exclusively of high-GI carbohydrate foods, providing 10 g carbohydrate/kg body mass. The "gorging" trial provided the food as four large meals of equal carbohydrate content eaten at 0, 4, 8, and 20 h of recovery, whereas in the "nibbling" trial each of the meals was divided into four snacks and fed at hourly intervals (0-11, 20-23 h). There was no significant difference in muscle glycogen storage between the two groups over the 24 h (gorging: 74.1 mmol/kg wet wt; nibbling: 94.5 mmol/kg wet wt). The results of this study suggest that there is no difference in postexercise glycogen storage over 24 h when a high-carbohydrate diet is fed as small frequent snacks or as large meals.
For the athlete involved in a rigorous daily training program, or in a multiday event, this glycogen window can be used to get a jump on the normal repletion process, thus minimizing the risk of chronic glycogen depletion (and the fatigue that goes along with it). There is also suggestive evidence that the muscle stiffness occuring after vigorous exercise is related to muscle glycogen depletion. If so, rapid repletion may have the added benefit of minimizing this day after effect as well. One caution - many simple carbohydrate snacks such as chocolate chip cookies are more than 30% fat and if eaten in large quantities might exceed the recommended daily fat intake of 20-30% of Calories. Complex carbohydrates such as pasta, bread, and rice offer an alternative with significantly more carbohydrate per gram or ounce. And over the last few years, there has also been a push to market special recovery drinks. However any high carbohydrate food or drink will work as well and save you a few dollars to boot.
Will a carbohydrate/protein drink enhance glycogen repletion during this glycogen window as compared to a pure glucose drink alone? Although it had been originally been suggested in 1992 that the addition of protein to a carbohydrate supplement would enhance the rate of muscle glycogen resynthesis after endurance exercise (Zawadzki et al., J. Appl.Physiol. 72: 1854-1859, 1992), Roy et al (J Appl Physiol 1998 Mar;84(3):890-6) proved that the difference was not protein per se, but the fact that the two drinks were not Calorically equal.
They compared the effect of isoenergetic CHO (1 g/kg) and CHO/Pro/fat (66% CHO, 23% Pro, 11% fat) defined formula drinks and placebo (Pl) given immediately (t = 0 h) and 1 h (t = +1 h) after resistance exercise in 10 healthy young men. The rate of glycogen resynthesis was significantly greater for both CHO/Pro/fat and CHO (23.0 and 19.3 mmol/kg dry muscle/h, respectively) vs. Pl (Ex = 2.8 and Control = 1.4 mmol/kg dry muscle/h). These results demonstrated that after a bout of resistance exercise, consumption of an isoenergetic CHO or CHO/Pro/fat formula drink resulted in SIMILAR rates of muscle glycogen resynthesis during this 2 to 4 hour glycogen window.
Perhaps the protein makes a difference over a longer period of time? Burke LM et al (J Appl Physiol 1995 Jun;78(6):2187-92) decided to investigate whether the addition of fat and protein to carbohydrate feedings in the 24 hour post exercise period affects muscle glycogen storage. Eight well-trained triathletes undertook an exercise trial (2 h at 75% peak O2 consumption, followed by four 30-s sprints) on three occasions, each 1 wk apart. For 24 h after each trial, the subjects rested and were assigned to the following diets in randomized order: control(C) diet (CHO = 7g/kg1/day), added fat and protein (FP) diet (C diet + 1.6 g/kg/day fat + 1.2 g/kg/day protein), and matched-energy diet [C diet + 4.8g/kg/day additional CHO (Polycose) to match the additional energy in the FP diet]. Meals were eaten at t = 0, 4, 8, and 21 h of recovery. There were no differences between trials in muscle glycogen storage over 24 h in equal Caloric diets of carbohydrate alone vs. CHO/Pro/fat. (C 85.8, FP 80.5, matched-energy, 87.9 mmol/kg wet wt).
SPECIFIC POST RIDE (RECOVERY) DIETARY RECOMMENDATIONS:
• take in 3 to 4 gm carbohydrate/kg BW in the 4 hours post ride - start immediately
• consider using a high Caloric density glucose polymer sports drink
• eat at least 600 gm carb/day for the next 2 days to maximize repletion of muscle and liver glycogen.
HOW MUCH SHOULD YOU EAT?
Estimating your Caloric replacement needs is always a challenge. And as
CHANGE IN WEIGHT (IN LBS) = (CALORIES BURNED - CALORIES CONSUMED)/3500
you will see the results reflected in the bathroom scales.
Regular physical exercise will help to protect your muscles (at the expense of fat) during periods of negative Caloric balance so you will not lose significant muscle mass even if you underestimate your Calorie needs. However, if you overshoot on the Calorie replacement, and especially if you have been exercising at a slow pace (which will preferentially burn fat Calories while maintaining muscle glycogen stores),any post ride carbohydrate loading may find muscle glycogen stores already "filled" and any additional carbohydrate Calories will be converted directly into fat.
THE BOTTOM LINE
Eat a high carbohydrate diet(60 to 70% carbohydrate, low in fat), the diet that is best for endurance performance . Do weight training to maintain upper body muscle mass. And keep an eye on the bathroom scale to determine if you have estimated replacement needs correctly. With a regular exercise program, a modest weight gain should be in muscle mass and any weight loss from fat.
FLUIDS
Although water does not provide Caloric energy, adequate hydration is at least as important to good athletic performance as the food you eat. One of the biggest mistakes of many competitive athletes is failing to replace fluid losses associated with exercise. This is especially the case in cycling as rapid skin evaporation decreases the sense of perspiring and imparts a false sense of only minimal fluid loss when sweat production and loss through the lungs can easily exceed 2 quarts per hour. For a successful ride, it is essential that you start off adequately hydrated, begin fluid replacement early, and drink regularly during the ride. In fact, a South African report on two groups of cyclists, one consciously rehydrating, the other no, exercising at 90% of their maximum demonstrated a measurable difference in physical performance as early as 15 minutes into the study.
Total body fluid losses during exercise lead to a diminished plasma volume (the fluid actually circulating within the blood vessels) as well as a lowered muscle water content. As fluid loss progresses, there is a direct effect on physiologic function and athletic performance. An unreplaced water loss equla to 2% of base line body weight will impact heat regulation, at 3% there is a measurable effect on muscle cell contraction times, and when fluid loss reaches 4% of body weight there is a measurable 5% to 10% drop in performance. In addition, one study demonstrated that this performance effect can persist for 4 hours after rehydration takes place - emphasizing the need to anticipate and regularly replace fluid losses. Maintaining plasma volume is one of the hidden keys to optimal physical performance. So make it a point to weigh yourself both before and after the ride - most of your weight loss will be fluid, and 2 pounds is equal to 1 quart. A drop of a pound or two won't impair performance, but a greater drop indicates the need to reassess your on the bike program. And use the post ride period to begin replacement of any excess losses. If you do so, you will be well rewarded the next time out.
But as a word of warning to those who practice the philosophy of "if a little is good, a lot is better", there are also risks with overcorrecting the water losses of exercise. There have been reports of hyponatremia (low blood sodium concentration) with seizures in marathon runners who have over replaced sweat losses (salt and water) with pure water. And this risk increases for longer events (more than 5 hours). Weighing yourself regularly on long rides will help you tailor YOUR OWN PERSONAL replacement program. A weight gain of more that 1 or 2 pounds will indicate that you are overcorrecting your water losses and may be placing yourself at risk for this unusual metabolic condition.

Respiratory Muscle Function in Highly Trained Athletes
Air from your surroundings is brought into the lungs during pulmonary ventilation. After being adequately warmed and moistened in the upper ariways (nasal passages, trachea, and bronchii) it ultimately moves through the bronchioles and alveolar ducts to the alveoli where gas exchange occurs - oxygen diffusing across the alveolar lining nto the blood and carbon dioxide out into the alveoli.
The diaphragm muscle makes an airtight separation between the abdominal and thoracic cavities. During inspiration it flattens, increasing the space (and negative pressure relative to the atmosphere) in the thoracic cavity while decreasing the volume of the abdominal cavity (unless the abdominal muscle relax to offset this effect). During exercise, the intercostal muscles and other thoracic wall muscles (the accessory muscles of respiration) contract to aid the expansion (and increase the negative pressure) in the thoracic cavity. During expiration the opposite occurs in the diaphragm and accessory respiratory muscles, the thoracic cavity decreases in size, and air flows out of the lungs.
RESPIRATORY MUSCLE TRAINING
Would specific respiratory muscle training help the performance of trained, elite athletes?? Let’s see what facts are available. The first question is whether repiratory specific training can improve respiratory muscle mechanics.
As shown by the following study, the answer is a definite YES. Leith DE & Bradley M (J Appl Physiol 1976 Oct;41(4):508-16 Ventilatory muscle strength and endurance training.) studied respiratory mechanics in young volunteers before and after 5-wk training programs limited to the ventilatory muscles. Four strength trainers (S) performed repeated static maximum inspiratory and expiratory maneuvers against obstructed airways. Four endurance trainers (E) performed voluntary normocarbic hyperpnea to exhaustion. Subjects spent 30-45 min each day in these exercises, 5 days a week. Four control subjects (C) did no training. We attempted to minimize the effect of learning. S increased pressure maximums by about 55%, but vital capacity and total lung capacity by only about 4%. Initially all subjects could sustain hyperpnea at about 81% of their control 15-s maximum voluntary ventilation (MVV) for 15 min; E increased this to about 96% and increased their MVV by 14% as well. No other statistically significant changes were recognized in any group. We conclude that ventilatory muscle strength or endurance can be specifically increased by appropriate ventilatory muscle training programs.
The next question is "Does it make a difference in performance?"
Boutellier U et al (Eur J Appl Physiol Occup Physiol 1992;65(4):347-53 The respiratory system as an exercise limiting factor in normal trained subjects.) had previously looked at the effect of specific respiratory muscle training for submaximal exercise (64% peak oxygen consumption) in normal sedentary subjects. These subjects were able to increase breathing endurance by almost 300% and cycle endurance by 50% after isolated respiratory training. They then studied normal, endurance trained subjects to see if they would also benefit from respiratory training. Breathing and cycle endurance as well as maximal oxygen consumption (VO2max) and anaerobic threshold were measured in eight subjects. Subsequently, the subjects trained their respiratory muscles for 4 weeks by breathing 85-160 l.min-1 for 30 min daily. Otherwise they continued their habitual endurance training. After respiratory training, the performance tests made at the beginning of the study were repeated. Respiratory training increased breathing endurance from 6.1 (SD 1.8) min to about 40 min. Cycle endurance at the anaerobic threshold [77 (SD 6) %VO2max] was improved from 22.8 (SD 8.3) min to 31.5 (SD 12.6) min while VO2max and the anaerobic threshold remained essentially the same. Therefore, the endurance of respiratory muscles can be improved remarkably even in trained subjects. Respiratory muscle fatigue induced hyperventilation which limited cycle performance at the anaerobic threshold. After respiratory training, minute ventilation for a given exercise intensity was reduced and cycle performance at the anaerobic threshold was prolonged. They concluded that the respiratory system was a potentially exercise limiting factor in normal, endurance trained subjects.
Boutellier U (Med Sci Sports Exerc 1998 Jul;30(7):1169-72 Respiratory muscle fitness and exercise endurance in healthy humans.) looked at the effects of four weeks of isolated respiratory training (30 min normocapnic hyperpnea, 5 d.wk-1) and demonstrated this significantly increased the endurance time of respiratory muscles and the endurance time of constant-load bicycle tests in sedentary as well as physically active subjects once respiratory muscles had recovered from the training. Minute ventilation and blood lactate concentration were reduced during post-training exercise. Furthermore, respiratory trained subjects had lost the sensation of breathlessness. Maximal oxygen consumption was not affected by respiratory training. The mechanism by which respiratory training improves overall physical performance is as yet unknown.
This supported the supposition that respiratory training is of benefit for sedentary individuals, decreasing their sensation of breathlessness with exercise, and probably was of some additional benefit to more active individuals who exercise on a regular basis. However the definition of "endurance trained" in the first article is not clear from this abstract and the fact that their anaerobic threshhold was at 77%VO2 max suggests that these were less than the "elite" trained athletes studied in the following two articles.
Inbar O et al (Specific inspiratory muscle training in well-trained endurance athletes. Med Sci Sports Exerc 2000 Jul;32(7):1233-7) looked at the hypothesis that specific inspiratory muscle training (SIMT) would result in improvement in respiratory muscle function and thereupon in aerobic capacity in well-trained endurance athletes. METHODS: Twenty well-trained endurance athletes volunteered to the study and were randomized into two groups: 10 athletes comprised the training group and received SIMT, and 10 athletes were assigned to a control group and received sham training. Inspiratory training was performed using a threshold inspiratory muscle trainer, for 0.5 h x d(-1) six times a week for 10 wk. Subjects in the control group received sham training with the same device, but with no resistance. RESULTS: Inspiratory muscle strength (PImax) increased significantly from 142.2 +/- 24.8 to 177.2 +/- 32.9 cm H2O (P < 0.005) in the training group but remained unchanged in the control group. Inspiratory muscle endurance (PmPeak) also increased significantly, from 121.6 +/- 13.7 to 154.4 +/- 22.1 cm H2O (P < 0.005), in the training group, but not in the control group. The improvement in the inspiratory muscle performance in the training group was not associated with improvement in peak VEmax, VO2max breathing reserve (BR). or arterial O2 saturation (%SaO2), measured during or at the peak of the exercise test. CONCLUSIONS: It may be concluded that 10 wk of SIMT can increase the inspiratory muscle performance in well-trained athletes. However, this increase was NOT associated with improvement in aerobic capacity, as determined by VO2max, or in arterial O2 desaturation during maximal graded exercise challenge.
These conclusions were confirmed by another study by Fairbarn MS et al (Int J Sports Med 1991 Feb;12(1):66-70 Improved respiratory muscle endurance (RME) of highly trained cyclists and the effects on maximal exercise performance.) who set out to determine whether the RME of highly trained cyclists could be enhanced and if so, to determine the effects of improved RME on their maximal exercise performance. Ten male cyclists (maximal oxygen consumption (VO2max) greater than 60 ml/kg-1) began the study by performing 3 tests. These were VO2max, RME measured as maximal sustainable ventilatory capacity (MSVC) and maximal exercise endurance (tlim) measured by an endurance cycling test to exhaustion at 90% of their maximal power output. Five subjects then completed 4 weeks of isocapnic hyperpnea training (16 session) and 5 subjects were controls. Following this training interval, each subject repeated the initial tests. After the RME training, the MSVC increased from 155 +/- 11 to 174 +/- 12 l/min (p = 0.004) for the training subjects while there was no change in the controls (155 +/- 26 and 150 +/- 34 l/min). There were no statistically significant changes for any of the 10 subjects in either the maximal exercise performance (VO2max = 66.1 +/- 4.7 to 66.5 +/- 4.8 ml.kg-1) or the maximal exercise endurance (tlim = 335 +/- 79 to 385 +/- 158 sec). They concluded that 4 weeks of respiratory muscle endurance training increased respiratory muscle endurance but had NO effect on the maximal cycling performance of highly trained cyclists.
But the final results may not yet be in. Dr Alison McConnell (Sport & Exercise Physiology, Brunel University, UK) per personal communication on 03 Oct, 2000, writes: "As a research scientist that has been working on inspiratory muscle training (IMT) and fatigue for many years, I was pleased to see your exposition on the subject. However, I was disappointed that you were not able to provide a comprehensive review of the subject area and may therefore have gained (and communicated) a false impression of the efficacy of IMT."
"The paper that you cite by Inbar is an interesting one, because the authors actually looked at all the wrong things with respect to factors that would be likely to change following this type of training. A paper from my research group will shortly be published in Med. Sci. Sports Exerc. indicting that inspiratory muscle training improves rowing performance in hightly trained rowers by some 2% more than a placebo group. The performance model used in this study was a 'real world' test of performance consisting of a 6 minute all out rowing effort, as well as a 5000m time trial. The coach to the GB Men's eight (Olympic Gold medalists in Sydney) was so impressed by this, and other data from my group, that I was invited to prepare an IMT programme for the squad which they adhered to in the 3 months building up to the Games."
The problem with many of the early studies in this field (e.g. Fairbarn) is that there experiemntal design and execution was weak and the data are therefore difficult to interpret. I am convinced that ALL athletes can benefit from IMT (and I have the data to support my view). The mechanism is not linked to VO2max, but is related to lactate turn-over and possibly blood flow redistribution away from the trained diaphragm in favour of locomotor muscles (look at papers by Dempsey, Harms and Whitter on blood flow distribution in response to changes in respiratory work). If you want more information about my research please feel free to email me: alison.mcconnell@brunel.ac.uk. You might also take a look at other research published by Christina Spengler who works with Boutellier."
So what can we conclude from these studies? Bottom line:
• Inspiratory muscle fatigue does occur with prolonged high intensity exercise and can be delayed by specific inspiratory muscle training (IMT).
• There is controversy as to whether a normal training regimen adequately trains respiratory muscles to meet the needs of the activity for which the athlete is training. This includes meeting the oxygen and carbon dioxide exchange requirements of the endranece athlete’s cardiovascular system, by providing adequate ambient air to the alveoli, as well as by decreasing lactic acid production from the repiratory muscles themselves for the appropriate level of respiratory activity.
• The muscular capacity for pulmonary ventilation MAY limit physical performance in the highly trained athletes.
• Further studies should help to clarify whether specific respiratory training (IMT) may improve the performance of the elite endurance athlete.
PURSED LIP BREATHING
Does pursed lip breathing provide an advantage by creating a back pressure to keep the collapsing airways open? According to Frand Day MD (fday@powercranks.com) "Back pressure to keep the airways open on exhalation is really only necessary in seriously diseased lungs (such as seen in intensive care units). This is not normally necessary in athletes whose lungs are functioning normally (asthma attacks aside, where purse lips breathing is of littlebenefit). Moving air in and out of the lungs is a simple matter of physics. The volume of air moved depends upon the anatomy of the airways and the delta P (pressure) between the alveoli and the outside. On inhalation the expanding chest tends to open the airways, somewhat reducing the delta p necessary to move the required amount of air but exhalation tends to close the airways, requiring a higher delta p, but pursing the lips does nothing to change the required delta p if the lungs have normal amounts of elastic supportive tissue that normally keeps the airways open. As stated before, this increased back pressure is most useful is seriously diseased lungs and I am not aware of any data to show it useful in normal athletes."
DECREASED LUNG CAPACITY WITH ENDURANCE EVENTS
A recent report indicated that lung function tests of endurance athletes during "ultra" marathon sports events has indicated a progressive decrease in lung volume and expiration rates of between 5% and 20% ,commonly indicative of asthma related disease. These results were noted in various sports events including canoeing, running, skiing and cycling. It was postulated that these athletes exhibited symptoms of exercise induced asthma. Does exercise cause spasm in the lung airways in all athletes, not just asthmatics??
There is some evidence that endurance athletes may become sensitised to allergens (proteins that cam bring on an asthma attack) and other environmental toxins the longer they are involved in their sport. This may be why such a high percentage of elite athletes are on medications for "exercise induced asthma".
But with exercise induced asthma (which is the same as any other asthma), vital capacity diminishes with even a few minutes of beginning easy exercise. In ultra endurance athletes, there is most likely another factor (something that would occur in everyone such as fatique or dehydration) causing lower lung volumes and muscular efficiency that slowly evolves as exercise continues. This still to be identified factor,not asthma, reduces vital capacity if the event was long enough and becomes the most logical reason why such a high percentage would show reduced lung capacity.

THREE TRAINING OPTIONS
A focused training program can increase VO2max by 15 to 30% over a 3 month period and up to 50% over 2 years. And conversely, there is a rapid drop off in metabolic adaptations with in a few weeks of stopping training although changes in numbers of muscle capillaries and skeletal and cardiac muscle fiber size probably occur more slowly.
Metabolic adaptations include changes in lactic acid removal which contribute to the ability to perform exercise at a higher level of %VO2max for longer periods of time, and changes in lipid metabolism which provide extra Calories from fat (to supplement those from pure glycogen and glucose metabolism) at a specified level of activity (%VO2max) which supports a longer duration of exercise to fatigue.
Training also results in physical changes in the muscles that improve your tolerance for the stresses of prolonged exertion. These include a change in the ratio of slow to fast twitch muscle fibers as well as a strengthening of the connective tissue between muscle fibers which translates into less microtrauma (i.e. less post exercise discomfort) with exercise.
And not every training session (in your program) needs to stress the cardiovascular system. In fact a successful program needs to be balanced with at least two days per week at less than maximal cardiovascular intensity to allow for mental and physical recovery.
TRAINING INTENSITY
Is more better? Not necessarily. Although the exact optimum for training intensity is unknown (and probably varies by a few percent between individuals) it is generally accepted that maximum aerobic improvement occurs at 85% VO2max (approximately 90% of your max. heart rate). And REGULAR training above this level will increase the potential for injury without a corresponding increase in cardiovascular or musculoskeletal training benefits. Lower levels of exercise - 60% maximum heart rate for 45 minutes or 70% maximum heart rate for 20 minutes - will modestly improve (or at least maintain) general cardiovascular conditioning but the "long slow distance" approach to endurance training where your maximum heart rate is always limited to 60 to 80% VO2max will not optimize your personal performance for high level aerobic events. For example, a West Virginia U. study assigned 15 women to either a low intensity (132 beats per minute) or high intensity (163 bpm) group exercising for 45 minutes, 4 times a week. There was an increase in VO2max for members of the high intensity group, but not the low intensity one.
TRAINING DURATION
There is no easy answer as to the optimum duration for a high intensity training session as training is an interaction of both intensity as well as time. 10 minutes of 70% maximum heart rate will be of some benefit, but 30 to 40 minutes are even better. Does going 60 minutes give you a proportionally greater benefit? Maybe not as there is clearly a point at which the negative effects of exercise on breaking down and injuring muscle tissue outweight the cardiovascular benefits. Or does 30 minutes of 80% MHR equate to 40 minutes at 70% i.e. increase the intensity to compensate for decreasing the duration? For endurance perhaps, but certainly not for improving your VO2max.
As proof that there is an upper limit for the benefits of aerobic training, a group of swimmers training 1.5 hours per day was compared to a group training with two equivalent 1.5 hour sessions. There was no difference in the final performance, power, or endurance between the two groups. For aerobic training (continuous, not intervals) at less than 90% maximum heart rate it makes the most sense to look at the duration of the planned event, and trained at the same level of anticipated performance (%VO2max) for a duration equal to that of the event pkus an additional 10 to 20%.
TRAINING FREQUENCY
It appears that maximum aerobic conditioning (increasing VO2max) occurs with 3 workout days per week. So unless one is trying to burn Calories to lose weight, or is working on increasing mileage to get the musculoskeletal system (back, shoulders) in shape for a long endurance event on the bike, it is better to take off 2 to 3 days per week to allow for muscle and ligament repair and decrease the risk of cumulative stress resulting in an increase in training injuries. And interestingly, it appears that these 3 days per week will maximize aerobic conditioning equally in any combination - i.e. 3 days in a row with 4 off, alternating days, etc.
Studies on maintaining the benefits of aerobic training revealed that a 2/3 reduction in training frequency i.e. going from 6 days a week to 2 days a week (keeping the same intensity for each individual workout) maintained the gains. You can cut a 60 minute, 6 per week program to 60 minutes, 2 times a week (and perhaps even to a 30 minute session 6 times a week) and maintain your aerobic fitness level, BUT you CANNOT maintain a similar fitness level by cutting the intensity of the 60 minute session and keeping it at 6 times per week. If intensity is held constant, the frequency and duration of exeercise required to maintain fitness are much less than the effort needed to attain that fitness level in the first place.
METHODS OF TRAINING
Training needs to be structured for the intensity and duration of the planned sporting event. Anaerobic (oxygen independent) exercise is generally brief (less than 60 seconds in duration) and is fueled by the anaerobic energy pathways in the cell (ATP, creatine phosphate). The classic anaerobic sport is weightlifting. Sprint activities also use anaerobic pathways. If the sprint lasts more than 5 or 10 seconds, lactic acid production (and clearance) also becomes an issue because of the negative effects of lactic acid on muscle performance. Training focused on anaerobic activities will enhance the ATP and CP energy transfer pathways in the cell as well as improving the tolerance for and clearance of lactic acid.
Aerobic training (more important for cycling and other sporting events lasting more than 60 seconds) on the other hand provides its benefits by improving the cardiovascular and oxygen delivery systems to the muscle cell. These include improvements in both cardiac output (amount of blood pumped by the heart per minute) and at the muscle fiber level where there is an increase in the removal or extraction of oxygen from the blood cells in the capillaries. In addition, there is an improvement in the efficiency of the cellular metabolic pathways which convert glucose into ATP.
As the level of exertion (measured by %VO2max) increases, there is a slow transition towards anaerobic metabolism in the muscle. There are always areas of relatively lesser perfusion within the muscle that are functioning anaerobically. So even at 50 to 60% VO2max some anaerobic conditioning is occuring. But at 85% VO2max (the "anaerobic threshhold" for most individuals) there is an abrupt increase in anaerobic metabolism throughout the entire muscle. So even though some cross training of the anaerobic systems takes place during exercise at 60 to 80% VO2max, a training program for sprint performance needs to include several exercise sessions per week above 85%VO2max. Long slow distance may be good training for aerobic, endurance events, but it will not improve your sprint performance. Both aerobic and anaerobic exercise sessions need to be included in a training program, but it is the balance of the amount of each type of exercise (aerobic vs anaerobic; interval training, continuous training, and fartlek training) in the overall program that determines its suitability for the competitive event for which you are training.
INTERVAL TRAINING
Doing intervals refers to sandwiching periods of intense physical activity between periods of recovery to allow longer periods of training time at your peak performance levels. One study in runners demonstrated that continuous, maximal performance levels could be sustained for only 0.8 miles before exhaustion occurred, while a similar level of peak exertion could be maintained for a cumulative distance (duration) of over 4 miles when intervals were used.
If one is training for sprints of up to 20 seconds in duration (which do not involve significant lactic acid buildup and basically are training the ATP and CP systems), it is recommended that the duration of the training interval should be increased by 1 to 5 seconds over the usual best time for that sprint distance with exercise intensity or maximum effort being unchanged,. For example, if one is training for a 100 yard dash, and has a personal best of 12 seconds, the training interval should be a 13 or 14 seconds sprint at the same pace (ignoring the total distance being covered in the 13 or 14 seconds). And a relief period 3 times longer than the training interval is recommended for recovery - 42 seconds in this example.
Training for longer intervals (up to several minutes) produces significant lactic acid along with stressing the anaerobic metabolic pathways. To train for these longer distances (several minutes of maximum output), it is suggested that the distance being trained for be subdivided, and the training interval effort focused on that shorter distance. For example, if one is training for a personal best mile ride on the bike, and the best time for the entire mile is 3 minutes on the bike with the best 1/4 mile segment being 30 seconds and the best 1/2 mile segment being 80 seconds, the training interval could be set at either 1/4 or 1/2 mile and the time for this training interval set at your personal best minus 3 to 5 seconds. In this example the training interval might be chosen as 1/4 mile with a goal of a 25 second time. And the rest interval should be 2 times the training interval (as lactic acid clearance does not require the same recovery time as recharging the intracellular metabolic machinery).
But training program drop out rates can double when intervals are used, so they should be used judiciously. Don't use them all year round, consider a twice a week program during your peak season, and separate each session by at least 48 hours to allow adequate recovery. If your long ride is on the weekend, Tuesday and Thursday make the most sense. The goal should be 10 to 20 minutes of hard pedaling per training interval session, not counting warm up, recovery, or cool down. A good place to start is with 5 minutes of peak effort.
One approach is to use one day a week for short intervals (i.e. five 60 second and five 90 second intervals) and a second for longer intervals (two 3 minute and two 5 minute intervals). Allow 3 to 5 minutes for recovery between intervals and don't forget a 20 to 30 minute warm up and a 15 minute cool down. It has been shown that as few as a half dozen 5 minute intervals (separated by one minute recoveries) during a 300 km training week will improve both time trial and peak performance.
If you have a heart rate monitor, an alternative is to key intervals to your maximum heart rate. Ride your intervals at 80 to 90% of your maximum heart rate and spin easily until your heart rate drops to 60 to 65% of maximum.
CONTINUOUS TRAINING (LSD)
Continuous training refers to aerobic activity performed at 60 to 90% VO2max for an hour or more. When done at the lower end of this range, it is often referred to as long, slow distance (LSD) training. This level of training is ideal for those starting off an exercise program, those wishing to maximize Caloric expenditure for weight loss purposes, and as an option for an active "rest" day in a weekly aerobic training program.
This level of exertion can be maintained for hours at slightly less intensity than used in personal competitive events in the past, and is particularly suited for endurance event training. It is thought to have a preferential beneficial effect on the slow twitch muscle fibers (as opposed to the fast twitch fibers used in sprint interval training). It is suggested that a distance of 2 to 5 times the actual competitive event be chosen for this daily segment of the weekly training program.
FARTLEK TRAINING
This form of training is a combination of interval and LSD training. It is not as structured as an interval program being based on the personal perception of exertion rather than specific time or distance intervals. It mimics the "sprint to the line" that is part of many road races. While there is little scientific proof of its benefits it makes sense physiologically, and psychologically it adds a feeling of freedom to those long slow days. How many sprints, and for how long?? The choice is up to you, but the intervals are probably in the neighborhood of those used for interval training.
KEY POINTS FOR AN AEROBIC TRAINING PROGRAM
• Training needs to be structured for the intensity and duration of the planned sporting event.
• Long slow distance training is important at the beginning of the training season and for very long endurance events.
• Maximum aerobic improvement occurs at 85% VO2max (90% max. heart rate).
• Maximum aerobic conditioning (increasing VO2max) occurs with 3 workout days per week at or above 85% VO2max. Additional training days should be at a slower pace to allow recovery and build musculoskeletal strength.
• Intervals can be ridden for one or two of these days.
• Exercising at less than 85% VO2max will improve general cardiovascular conditioning and overall musculoskeletal tolerance. It is suggested that one day a week be alloted to a long slow training ride equal to a distance of 2 to 5 times the actual competitive event.
• In training for endurance events (less than 90% maximum heart rate), train at the level of anticipated performance (%VO2max, %MHR)) and with a long training ride equal to that of the event + 10 to 20%.
(see also USING A HEART RATE MONITOR)
PUTTING THIS ALL TOGETHER, a good weekly training program:
• is built on a good training base at the beginning of the season.
• 3 days of high level cardiovascular activity (2 of which may be intervals)
• 1 day training ride equal to the duration of the event and at a similar intensity
• 1 day LONG slow recovery ride
• the other 2 days should be spent off the bike or used for a short slow ride to "loosen up"

Training vs Genetics
It’s interesting to speculate whether genetics or training/attitude determine a world class cyclist. I put the following question (from one of this websire’s readers) to an online coaching forum and will summarize the answers below.
"I am a 20 year old competitive middle distance track runner, but I am considering the possibility of becoming a cyclist. I have biomechanical problems of the feet that I feel will make it impossible for me to compete at the very highest level as a runner. My question is what sort of physiological/anatomical characteristics does it take to be a world class cylcist, and how do I tell if I have those features? I have a good aerobic system with a H.R that does not rise easily in training, plus I have good short distance sprinting speed. Could these be transferred effectively into cycling? Also is it necessary to have naturally large quad musculature to be an elite cyclists?"
There was a general consensus that almost anyone, of normal stature and physiology, could become a world class cyclist if they were willing to make the physical and mental commitment necessary AND they choose their event (sprint versus endurance) wisely based upon their physiological characteristics. In that regard, cycling is a sport in which people of all sizes and builds can participate and be very competitive.
And although genetic factors may come into play and have a significant affect at the very highest level of competition, most people are so far from those limits it's more an excuse than anything else to quote "genetics" as an excuse for poor performance. The biggest single thing that affects performance and potential is ATTITUDE with TRAINING close behind. Any benefits of gentics would pertain mostly to true sprinters and much less to those requiring endurance. Basicall y genetics brings predisposition, but an athlete's environment (training, diet/nutrition, attitude, etc.) dictate outcome.
The one measure often quoted as a measure of a world class ability endurance cyclist (ie the Tour De France) is a VO2 max of at least 80ml/O2/kg/min. Sprinters tend to be just under the 80 mark.
But there was general agreement that VO2 max testing is like IQ testing, there is not much correlation between it and anything else besides taking the test. If VO2 max testing has any utility it is in identifying athletes that may have more potential than has been recognized through other means. Low VO2 max testing, however, does not make it impossible to develop a high level of performance.
How much can VO2max be improved with training? A few thought that a 10% increment might be the most that could be trained. While others, based on personal experience, felt that over the years maximal oxygen uptake could increase significantly more than 10%.
Finally, there was consesus that training not only increases the VO2max, but improves technique. And the effective translation of the VO2 into useful work is the result of that training. Which is why someone with slightly lower VO2 can beat those who "test" higher 
 

EXERCISE PHYSIOLOGY - CONDITIONING
Regularly aerobic exercise (walking, running, cycling, etc.) stimulates cardiovascular system and muscle cells leading to structural and metabolic changes which improve work capacity - both for endurance and sprint activities. Additional health benefits include a decrease in resting heart rate and a lowering of maximal blood pressure with sub maximal exercise. These changes can be noted with an exercise program sustaining 60% of your maximum heart rate for 30 minutes, 4 times a week. Understanding the physiology behind this training effect will also help you to understand the rationale for developing an effective training program.
OXYGEN CONSUMPTION
Oxygen consumption by the muscle, expressed in terms of VO2, reflects the amount of oxygen utilized for cell metabolism and energy production during a specified period of time. Maximum oxygen consumption, VO2max., is an individual’s upper limit of aerobic (or oxygen dependent) metabolism. It depends on several factors including lung capacity (getting oxygen from the air we breath into the blood passing through the lungs), cardiac output (above), and the ability of the muscle cells to extract oxygen from the blood passing through the muscle. The sum of these factors, resulting in an increased oxygen uptake per minute by the working muscle, is expressed in the increased VO2 max. Seen with aerobic training.
At levels of exertion greater than the VO2 max, the energy requirements of the cells outstrip the ability of the cardiovascular system to deliver the oxygen required for aerobic metabolism to the individual muscle cells, and oxygen independent or anaerobic energy production begins. Anaerobic metabolism is not only less efficient, with a more rapid depletion of muscle glycogen stores, but also results in a build up of lactic acid and other metabolites that ultimately limit performance even when adequate glycogen stores remain. This lactic acid is metabolised AFTER exercise levels decrease and excess oxygen is again available to the muscle cell. Its degradation is responsible for the oxygen debt or recovery phase that follows anaerobic exercise.
MEASURES OF CARDIOVASCULAR FITNESS
VO2 max. VO2max., or maximum oxygen uptake, is considered the gold standard measurement of cardiovascular, pulmonary, and muscle cell fitness. It indicates (in millilitres per kilogram of body weight) the maximum amount of oxygen your muscles can process in a defined period of time. The VO2 max for an elite cyclist can range from 70 to more than 80 ml/kg/minute, and performance at this level can be sustained for a few minutes at most. It is usually measured on a treadmill or bicycle ergo meter at a sports medicine clinic with the appropriate equipment. With training, you will increase both your absolute VO2max as well as your ability to ride for longer periods at a higher percentage of it.


The following criteria indicate attainment of your VO2 max.
• VO2 plateau - no further increase in VO2 even with an increase in work rate
• Heart rate within 10 beats of the age predicted heart rate (this leads to the concept of using your maximum heart rate as a surrogate for your VO2 max. in training programs)
• Plasma lactate levels in excess of 7 mm/litre
For those of you interested in the mathematical expression of VO2 max., it is the product of the arterial venous oxygen difference (the oxygen content of blood leaving the heart versus that returning to the heart i.e. extracted by the working skeletal muscles) and the maximal cardiac output. This is also called the Fick equation.
Anaerobic Threshold is also known as lactate threshold. The AT is the level of effort (usually expressed as a percentage of VO2 max.) at which the body begins to produce more lactate than can be removed. Above this point there is a rapid increase in blood lactate levels. Some physiologists also call it the pulse rate deflection point (see the Concini test below). It is also the maximum effort you can maintain for a long periods. Obviously the more you exceed your LT or AT the more quickly lactic acid will accumulate and impair your performance.
As most cyclists don’t have access to lab facilities, you can estimate your AT with a 30-minute (about 10 mile) time trial. The average heart rate you can maintain is a good approximation of your AT.
The AT will improve with training, and cyclists with a higher AT can work t a higher level of energy expenditure for longer periods, defeating opponents of equal (or even greater) physical strength but with lower AT’s. Anaerobic intervals will improve the AT and are designed to be done at heart rates above your personal AT. They can be sustained for only 15 sec to 2 minutes, but will improve your AT fitness.
Concini Test Another method of measuring your AT (and LT) is the Concini test. As a cyclist’s efforts increase, their heart rate generally increases in a direct relationship to the energy expended (a linear relationship). But at some point the heart rate begins to level off even as the speed (and energy expenditure) continues to increase. This is the anaerobic threshold, that point at which oxygen cannot reach the muscles fast enough, lactate accumulates, and performance suffers. After an appropriate warm up, using a single gear and a relatively high speed, the rider gradually increases his or her speed by 1 km per hour every 300 meters or so. Heart rate is graphed versus speed, and the break point on the graph is the AT.
Lactate Threshold Recent work has focused on the blood lactate threshold (LT) as a reflection of an individual's level of training. The lactate threshold is that % of VO2 max. at which the cardiovascular system can no longer provide adequate oxygen for all the exercising muscle cells and lactic acid starts to accumulate in those muscle cells (and subsequently in the blood as well). At high levels of activity (below 100% VO @ max), it is likely that there are always a few muscle cells (not muscles, but a small number of cells within those muscles) that are relatively deficient in oxygen and thus producing lactic acid. But this lactic acid is quickly metabolised by other cells that are still operating on an aerobic level. At some point, however, the balance between production of lactic acid and its removal by body systems shifts towards accumulation. This point is the LT and it is usually slightly below 100% VO2 max., and it will improve with training (move closer to 100% VO2max). As those with an increased LT not only experience less physical deterioration in muscle cell performance but also use less glycogen for ATP production at any level of performance, an improvement in LT allows the individual to perform at maximal levels for a longer period of time before muscle performance deteriorates because of a lack of adequate energy (glycogen) stores.
Resting heart rate, your heart rate on awakening in the morning, is a simple but effective indicator of your level of training. It will fall as you train, but then begin to rise again with over training.
THE CARDIOVASCULAR SYSTEM
The major reason for an increase in exercise capacity with an aerobic training program is the rise in the maximal cardiac output (amount of blood pumped by the heart per minute). It plays a bigger role in increasing maximal exercise performance than does the increase in oxygen uptake and utilization by the skeletal muscle cells. Since our maximal heart rate does not change, and may even be lower, following exercise training, this increase in cardiac output is the result of a higher stroke volume (amount of blood pumped per heart beat). Cardiac output = stroke volume x heart rate.
The increase in stroke volume is a result of both a hypertrophy (enlargement) of the left ventricle muscle (athlete’s heart) as well as an enhancement of the heart’s contractile state, probably mediated by the autonomic nervous system.
THE SKELETAL MUSCLES
There are two types of fibres: type I, or slow twitch, and type II or fast twitch. The slow twitch fibres are more energy efficient and use both fats and carbohydrates as an energy source. They are the major muscle fibres in use at 70-80% VO2 max. Fast twitch fibres on the other hand are less efficient, use mainly glycogen as fuel, and are called into action for sprints as the athlete approaches 100% of maximum performance. Although the ratios of slow to fast twitch fibres are generally controlled by genetic (inherited) factors, this ratio does change (often over years) with an ongoing training program.
Along with these visible changes in the muscle cells, there are microscopic and metabolic changes at the muscle cell level with exercise. These include an increase in the size and number of the muscle cell mitochondria, an increase in the activity of various metabolic enzymes in the muscle cells, and an increase in the number of capillaries in the muscle that supply blood to the individual muscle cells. The net result is an increase in the amount of oxygen extracted from the blood in a single pass through the muscle (the arterial - venous oxygen difference).

EXERCISE PHYSIOLOGY - ENERGY REQUIREMENTS
CONTENTS
• Terminology
• Friction
• Equipment and rider weight
• Air resistance and drafting
• The bottom line - how many Calories do you need when cycling
o Baseline metabolic rate (BMR)
o Caloric expenditure of exercise
o Thermal effect
• Relative energy needs of other activities
• Energy requirements in a cold environment
The energy needed to move a cyclist and his bicycle over any distance increases with the distance to be covered as well as the speed of the ride. The Calories to provide that energy are supplied directly from the digestive tract to the muscles from food we have recently eaten or are taken from the body's internal energy stores (fat, glycogen).
TERMINOLOGY First let's review our terminology. In physical science (physics, chemistry), a calorie (small "c") is defined as the amount of energy required to raise the temperature of 1 gram of water 1 degree centigrade. As this unit is too small to easily express the energy use in biologic systems the Calorie (large "C"), which is equivalent to 1000 calories (small c again) or 1 kcal is used in articles on human energy metabolism and nutrition. Most nutritionists forget the capital "C" when they are writing about "calories" (S/B Calories), so don't get confused.
Approximately 60% of all the Caloric energy in the food we eat is lost as heat during formation of ATP (adenosine triphosphate), the intermediate high-energy molecule used by the muscle cell for muscle contraction. Additional energy, again as heat production, is lost as ATP is metabolised to fuel the actual mechanical work of muscle fibre contraction. The net result is that only 25% of the Caloric energy in the food we eat is actually used directly for the mechanical work of the muscle cells.
The bicycle itself much more efficient with over 95% of the muscle energy supplied to the pedals being translated into forward motion, and less than 5% lost (again as heat) from the rolling resistance of the tires, bearing friction, etc.
FRICTION in cycling can be minimized by:
• Keeping bearings and chain well lubricated
• Using light oil in bearings and bottom bracket for time trials
• Using light greases - paraffin gives more resistance than grease
• Using tires with a small "footprint"
• Keeping tires inflated to maximum to decrease rolling resistance
• Using thinner, more flexible tires (less energy taken up in sidewall deformation)
EQUIPMENT AND RIDER WEIGHT IN CYCLING A heavier rider (frontal surface area remaining the same - remember wind resistance!) will descend a hill faster than a lighter one. This seems to fly in the face of that fact you learned in physics about all objects falling at the same speed independent of their weight. But when going down a hill, there is the slope to be taken into account. Steady state speed down a long hill is the result of the balance of the propulsive forces (total rider/bike weight x the sine of the angle of the hill) and the resistive forces, with the heavier rider coming out ahead unless (s)he has a significantly larger surface area (and thus wind resistance factor). To give some perspective, if twin brothers weighing 175 pounds decided to descend a medium slope hill and agreed to ride similar bikes, in similar positions for aerodynamic style, etc., and one carried 25 pounds of lead shot, the heavier one would go 26.73 mph while the younger one would be slightly slower at 25 mph.
However, climbing is another issue, and here gravity is a major concern with the lighter ride having the definite advantage. And in rolling terrain with ups and downs, the lighter rider also has the net overall advantage.
Weight is also a factor in sprinting (acceleration) events. It takes more energy to accelerate a heavier rider/bike combination in a sprint, and extra weight in some bike components (rims for example) may require twice as much energy to accelerate than an equal weight in the frame. This means you should upgrade (read lighten) your tires, rims, crankset, and shoes before you spend any extra $$ to decrease your frames weight an equal amount.
And we seem to forget too often that the weight we carry - the extra water bottle, the larger heavier tool set, and even that extra pancake we ate in the morning - all require additional energy on the ride. We might be able to drop a few ounces here with as much impact on our performance as that expensive titanium item we've been saving to buy.
AIR RESISTANCE AND DRAFTING Air resistance (the resistance of the air to the movement of the cyclist/bicycle) consumes a significant proportion of the energy required for a ride. Air resistance increases with the rate of travel relative to the mass of air ie the "air" speed. That is why a head wind will increase the energy expenditure per mile for a set ground speed (air speed is greater than ground speed) while a tailwind will decrease them (air speed less than the ground speed). This relationship is an "exponential" one, which means that doubling the air speed MORE THAN doubles energy expenditure per mile travelled.
As an aside, a recent study demonstrated that a headwind on an out and back course always results in a slower total ride time than for the same course ridden in calm conditions. The time gained on the return trip with a tail wind doesn't make up for the loss from grinding into the wind on the way out. For a 12 mph wind, total time will rise by about 7%.
Remember that the "speed" that determines energy needs is the AIR speed (i.e. the resistance of the air mass to your body and bike as you ride) and is not the GROUND speed from your computer. A head wind should be added to your ground speed to determine air resistance, while a tail wind should be subtracted from your ground speed. If you think about it, this makes sense - it is always easier to ride with a tail wind.
At cycling speeds greater than 15 mph, the energy needed to overcome AIR RESISTANCE exceeds that of the rolling and mechanical resistance in the bike. For example, going from 7.5 mph to 20 mph, mechanical resistance increases by 225%, rolling resistance by 363%, and air resistance by 1800%. This is why drafting (which cuts down relative air speed and air resistance) provides such an advantage in high speed events. A recent study demonstrated that at 20 mph, drafting a single rider reduced energy requirements (measured by VO2) by 18% and at 25 mph by 27%.
Wind tunnel results reveal that eliminating 10 grams of drag (the drag created by projecting 4.5 inches of a pencil into the air stream) will provide a 158-foot finish line advantage to a cyclist in a 25-mile time trial. That baggy jersey or upright position may be costing you minutes.
One also should consider the effect of air resistance on other moving parts of the bicycle. For example, using aerodynamic rims with 16 to 18 spokes (vs. the normal 32 to 36) provided a 7% decrease in air resistance at 25 mph, compared to a 4% advantage of a single rear or set of disc wheels.
SHOCKS/SUSPENSION Shocks, both front and rear, will affect your riding over uneven terrain on a mountain bike. Front shocks decrease vibration transmitted to the shoulders and allow more concentration on the course (no energy issues here). The older rear suspended bikes without a rigid rear triangle could absorb some pedal/rear wheel energy, but this is less of an issue with the newer rear suspensions. One study did compare rigid frame (RIG), front shock (FS), and fully suspended (FSR) mountain bikes using the same riders and course. The front suspended bikes finished 80 seconds ahead of the RIG and FSR bikes over a 31-minute course!
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THE BOTTOM LINE - HOW MANY CALORIES DO YOU "BURN" WHILE CYCLING?
To calculate the Caloric requirements of cycling, you need to include the Calories used to maintain your basic life processes if you were not exercising (the BMR) and the Calories used for physical activity itself. A third component called the "thermic effect of food" refers to the energy expended in digesting, absorbing, and transporting food energy to the cells in the body. Thus the total Calories need can be calculated as:
CALORIC NEED = CAL(bmr) + CAL(physical efforts) + CAL(thermic effect)
I'll address each of these below, but as a rule, the average American, pursuing the average recreational activities and chores of daily living (mowing the lawn, etc.), uses:
1. 23% of their Calories for physical activity
2. 10% of their daily Calories for the thermic effect
3. 67% of their Calories for the BMR
Now let's be more specific so you can calculate your own Caloric needs.
BASELINE METABOLIC RATE The basal metabolic rate (BMR) or resting metabolic rate (RMR) is defined as the energy requirements of the human body at rest and reflects our Caloric needs to maintain basic life processes. These Calories need to be replaced whether or not one exercises.
You can estimate your BMR with the following formulae:
• BMR (men) in Cal/day = 10.2 times weight in kilograms + 879
• BMR (women) in Cal/day = 7.18 times body weight in kg + 795
(One pound = 454 grams or .454 kg)
These are replacement Calories and already take into account the inefficiency of digestion, transformation to ATP, etc. mentioned above.
The BMR is about 5 to 10% lower in women than in men. This does not reflect a sex difference in the metabolic rate of similar tissues, but exists because women generally have more body fat than men of similar weight, and muscle tissue is more metabolically active than fat.
Let's digress for a moment and address three common misconceptions about the BMR.
• First BMR drops in the winter. The BMR is determined by total body weight and the amount of muscle mass (fat and muscle tissue burn Calories at different rates), not the ambient temperature. Requirements to maintain your body temperature in a cold environment are IN ADDITION to this basal rate which remains unchanged.
• Second, experienced or trained athletes can "tune" their metabolism and become more efficient. Untrue. A trained athlete will become smoother in style, and adopt other energy saving techniques, but their basic energy needs for any level of energy expenditure (or Caloric output) while exercising are the same as you and I.
• Finally, metabolism slows with age. BMR does drop with age, but this is related to a loss of total muscle mass, rather than the aging process itself. Generally people lose about 25% of their lean body mass per decade after the age of 30 and will, in concert, drop their BMR by 2 to 3 % per decade. And the drop in BMR is entirely explained by that drop in muscle mass from inactivity. In comparisons between young and middle aged trained men having the same fat free body mass, measures of the BMR were similar. So keep on exercising!






CALORIC EXPENDITURE OF EXERCISE All sports require additional energy expenditure above the BMR. Most of the time you will see these given in ranges based on the intensity of the exercise (we often become less efficient at higher levels of exertion as our form deteriorates; where wind resistance is an issue, it factors into the equation as well) and are calculated for the person of average build (if you are heavier, they need to be adjusted upwards as it takes more energy to move your body in whatever sport is being discussed.)
Since this homepage is related to cycling, I'll confine my detailed comments to that sport (see below for a general comparison with other athletic activities).
Energy needs are a combination of those used for cycling on the flats plus the requirements to gain elevation (to lift you and the bike against gravity) if you are climbing or riding over uneven terrain. The total Caloric expenditure for any ride can be calculated specifically, but assuming:
• An average rider (75 kg, 10 kg bike)
• Level terrain
• That you need to eat 4 times as many Calories as are being expended (see inefficiency of the human machine above)
The following is a good estimate for replacement Caloric needs for the exercise component alone:
• 5 mph - 7.4 Cal/mile - 37 Cal/hr
• 10 mph - 13.4 Cal/mile - 134 Cal/hr
• 15 mph - 23.4 Cal/mile - 351 Cal/hr
• 20 mph - 37.3 Cal/mile - 746 Cal/hr
• 25 mph - 55.3 Cal/mile - 1383 Cal/hr
• 30 mph - 77.2 Cal/mile - 2316 Cal/hr
(Note the more than doubling of Cal expended as speed doubles because of that exponential effect of wind resistance. And your speed is "air speed", so add any headwind to your ground speed and subtract a tailwind.)
THERMIC EFFECT This is a straight 10% of all the Calories you actually eat, so you can easily calculate it. (You add up CAL(bmr) and CAL(physical effort) that need to be replaced and add another 10% to cover the energy needs of digestion and absorption.)
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RELATIVE ENERGY NEEDS OF OTHER ATHLETIC ACTIVITIES For the average person (150 lbs), on level ground, at recreational levels of exertion, the following give a general idea of energy expenditures.
• Walking 130 Cal/Mile
• Jogging/Running 130 Cal/Mile
• Cycling 30 Cal/Mile
ENERGY REQUIREMENTS IN A COLD ENVIRONMENT It was mentioned that a cold environment does NOT increase the BMR but requires the expenditure of additional Calories to maintain a constant body temperature. Many cyclists will train during the winter months, and of course the wind chill effect from riding will accentuate any heat loss. How many additional Calories are needed? Roughly 16 Calories per day for every degree F below 98.6. Although one can argue about exact BMRs and find different formulae to calculate basal Caloric requirements, the only formula I am aware of that corrects for the ambient temperature is:
Cal requirements/day = 4660-(15.9 x temperature in degrees F)
Again, this was for an individual exposed for long periods to the ambient temperature, not just a several hour ride. Unfortunately the level of activity was not defined and for cycling wind chill may decrease the effective temperature even further. Does exercising in the cold markedly increase Caloric needs? Probably not by a big factor for most of us, but it again demonstrates the multitude of variables we need to consider as we try to estimate the Caloric needs of exercise and cycling.

EXERCISE PHYSIOLOGY - SKELETAL MUSCLE
Skeletal muscles makes up over 1/2 of the body weight in a lean individual. All muscles (quadriceps, biceps, etc.) are composed of thousands of muscle cells. And these individual muscle cells contain two proteins - actin and myosin - that chemically interact and shorten the cell (and along with it the muscle itself) when the muscle cells are stimulated by a nerve impulse. The interaction of the actin-myosin complex, which results in the shortening or contraction of the muscle cell, requires the energy in the form of ATP.
TWO TYPES OF MUSCLE FIBERS
The muscle cells contain two distinct types of muscle cells or fibres.
Type I (slow twitch, SO fibres) - These muscle cells shorten at a relatively slow speed and generate energy from both fats and carbohydrates via aerobic metabolism. They are the major muscle fibre in use at 70-80% VO2max. Type I cell characteristics include:
• High concentration of mitochondria for aerobic metabolism
• Increased intracellular myoglobin (which gives the muscle its characteristic red colour) to store and transport O2
• Low concentration of glycolytic enzymes used for anaerobic metabolism
• Relatively fatigue resistant
Type II (fast twitch, FG fibres) - These muscle cells are less efficient than the slow twitch cells and are almost entirely dependent on glycogen as fuel. They are called into action for sprints when the athlete approaches 100% of their maximum performance (and are working in the anaerobic range above 100% VO2max). Type II cell characteristics include:
• low concentration of mitochondria
• high concentration of ATP and glycolytic (ATPase) enzymes
• a rate of shortening 3 to 5 times that of a type I muscle cell
The relative proportion of type I and type II fibres within a muscle varies from person to person and is determined by genetics (i.e. inheritance from your parents). However, with limits, this ratio can be modified with exercise and training. Successful endurance athletes have a preponderance of slow twitch muscle fibres (up to 90% of the fibres in the calf in cross country skiers) while sprinters have more fast twitch fibres. Short term studies in bicyclists (5 months) failed to show a change in the ratio of cell types (percentage of slow vs. fast twitch fibres) in leg muscles, but a longer multi-year study has suggested that this ratio can change with time, continuing to change for at least 5 years with regular training.
But even without a change in the ratio of cell types, there is no question that both slow and fast twitch fibres can markedly improve their metabolic capacity with training. (See also Principles of Training)
MEASUREMENT OF ENERGY OUTPUT (POWER)
Energy output (or work) is expressed in terms of power (the amount of work done during a specified unit of time). Sprints and other all-out physical activities require maximal activation of the ATP-CP energy system and the magnitude of this energy release reflects the maximal muscle power of the athlete. These test are generally limited by the amount of ATP and CP available in the cell - about 6 seconds.
For those of you interested in how your energy output might relate to others, here's some information from Malcolm Firth from an online coaching forum. (From the facts on the amount of ATP-CP available to the muscle cell, it should be noted that Malcolm's maximum power output over several minutes is not the same, and would be lower than, a brief sprint for several seconds):
"In February 1998 I did a small research project in which a group of 24 cyclists were asked to do two tests on a CompuTrainer (an electomegnetically braked turbo trainer). The first of these was a step increased load test to voluntary exhaustion in which the load began at 100 watts and was increased at approx 20 watts per minute. After a break of at least three hours the cyclists then rode a simulated ten miles time trial on the CompuTrainer with the instruction to complete the distance as quickly as possible. Some of the data is summarised below:
• Average Age: 33.17yr (standard deviation 12.97, range 16yr-61yr)
• Average Max Power for 1 min: 367.46 watts (st dev 62.74w, range 263w-487w)
• Average Max Heart Rate: 187.29bpm (st dev 12.16bpm, range 163bpm-211bpm)
• Average 10 mile Time: 25min 52sec (st dev 1min 50sec, range 29min 09sec - 23min 02sec)
• Average 10 mile Power Output: 286.46 watts (st dev 49.88w, range 215w - 375w)
• Average 10 mile Heart Rate: 177.08bpm (st dev 11.78bpm, range 145bpm-199bpm)
The average 10-mile heart rate worked out at 94.5% of the mean max heart rate. (st dev 2.81%, range 88.41%-97.41%). If you go to my web site at http://www.msfirth.freeserve.co.uk you will find an article giving details on how to use the average ten miles heart rate to estimate heart rates for other training and racing intensities."

EXERCISE PHYSIOLOGY - CELL ENERGY METABOLISM
All foods are composed of carbohydrates, fats, and protein. Carbohydrates are the primary energy source for the average cyclist and for all athletes involved in short, maximum performance events. Fats, which can also serve as an energy source for cell functions assume more importance in endurance events done at less than 50% VO2 max. Proteins are used to maintain and repair body tissues.
OXIDATION & ATP
Food energy is released through a chemical reaction with oxygen in a process called oxidation. When this occurs outside the body - for example the burning of oil (a fat) in a lamp or the use of a flaming sugar cube (a carbohydrate) as a decoration in a dessert - this energy is released as heat and light. In the body however, food energy needs to be released more slowly and in a form that can be harnessed for basic cell functions and transformed into mechanical movement by the muscle cells.
This is accomplished by "refining" the three basic food materials (carbohydrate, fat, and protein), converting them into a single common chemical compound adenosine triphosphate (ATP). It is this ATP, synthesized as the cell metabolises (or breaks down) these three basic foods that transfers the energy content of all foods into muscle action.
ATP is composed of a base (adenosine), a sugar (ribose) and three phosphate groups. The chemical bonds between the phosphate groups contain the energy, which is stored in this molecule. And it is the breaking of these bonds (as ATP is converted into ADP or adenosine diphosphate) that provides the energy to power muscle contractions and other cellular functions.
PRODUCTION OF ATP - THREE PATHWAYS
There is a limited capacity to store ATP in the cell, and at maximum work levels this ATP stored in the muscle cells is depleted in several seconds. In order to sustain physical activity, the cells need to continually replenish or resynthesize their ATP. There are three pathways to accomplish this, and which one the cell uses depends on the level and duration of the physical activity.
The first breaks down phosphocreatine - another high energy, phosphate-bearing molecule found in all muscle cells - to directly resynthesize ATP. But it is also in limited supply and provides at most another 5 to 10 seconds of energy, limiting its usefulness to sprint type activities. At this point, the body must switch to either of two other biologic processes to regenerate ATP - one requiring oxygen (aerobic) and another that does not (anaerobic).
Glycolysis, also known as anaerobic metabolism, breaks down carbohydrates (glucose, glycogen) in the muscle cell to release energy to resynthesize ATP. Anaerobic metabolism is limited by the build-up of lactic acid, which begins within minutes and degrades athletic performance by impairing muscle cell contraction and producing actual physical discomfort or pain. As a result, anaerobic glycolysis can be used only for short bursts of high-level activity lasting several minutes at most. It cannot supply the ATP needed for longer, endurance activities. Those will require the third pathway, aerobic metabolism.
Aerobic metabolism, which requires oxygen and is a collection of multiple chemical processes in the cell, can produce ATP from the energy in all three-food elements - carbohydrates, fats, and protein.
THE BALANCE OF AEROBIC AND ANAEROBIC METABOLISM
As one begins to exercise, the anaerobic pathway assures adequate ATP energy while the body increases breathing and heart rate to ensure adequate oxygen delivery to the cell. As more oxygen becomes available, the aerobic pathways pick up the slack and the anaerobic metabolism falls off. However, anaerobic pathways continue to provide a small amount of ATP energy, and lactic acid is still being produced. However the small amount of lactic acid is readily metabolised by the liver and muscle cells and does not accumulate to the degree that occurs at high levels of anaerobic ATP activity (as in a sprint, for example).
The muscle cells use aerobic pathways preferentially until our VO2 max is reached, at which time inadequate oxygen is available to the muscle cell to continue ATP production and the phosphocreatine system, or anaerobic metabolism cover the extra energy needs. Then, when the level of activity returns to an aerobic levels (less than VO2max), adequate oxygen is available to allow the regeneration of phosphocreatine and the metabolism (clearance) of the excess lactic acid produced during the sprint type activity. With training, multiple changes occur in the cardiovascular and muscular systems that support higher levels and longer durations of physical activity before anaerobic pathways become involved, and also clear lactic acid more quickly which translates into a faster recovery from anaerobic sprints.
ENERGY CONTENT OF CARBOHYDRATES, FATS, AND PROTEIN
The energy contained in equal weights of carbohydrate, fat, and protein varies. It is measured in Calories (note the capital C). Carbohydrates and protein both contain 4.1 Calories per gram (120 Calories per ounce) while the energy "density" of fat is more than double at 9 Calories per gram. The disadvantage of fat as a fuel for exercise is the fact that fat is metabolised through pathways that differ from carbohydrates and can support an exercise level equivalent to 50% VO2 max at most. This makes it the ideal fuel for endurance events, but unacceptable for high-level aerobic (or sprint) type activities.
Carbohydrate metabolism is much more efficient than fat metabolism when adequate oxygen is available (ie during aerobic metabolism). But once VO2max has been reached, and anaerobic metabolism takes over, the efficiency of carbohydrates as an energy source drop off dramatically. Carbohydrate metabolism will produce 19 times as many units of ATP per gram when metabolised in the presence of adequate cell oxygen supplies (aerobic) as opposed to its metabolism in an oxygen deficient (anaerobic) environment.

ENERGY REQUIREMENTS OF CYCLING
(Expressed in terms of number of Calories ingested)
I. Level road (Eh=energy replacement required-horizontal component)
This is the formula to calculate the number of Calories needed (to be eaten) to replace those expended riding on level terrain.

• Pw = v x [3.509 + {0.2581 x (v)(v)}]
• Pc = Pw/4186.8
• Ce = Pc x T
• Ci = Ce/Eef = Eh
Where:
• Pw = power (watts)
• v = velocity or speed (m/sec)*
• Pc = power (Cal/sec)
• T = time (sec)
• Ce = Calories expended at the pedals
• Ci = Calories ingested = Eh
• Eef = efficiency of the human machine in converting food Calories (~25%)
• Eh = energy replacement requirements (Calories to be eaten) - horizontal component
Assumptions:
• 75 kg rider**
• 10 kg bike
• Level surface
• No head wind*
*Speed is your AIR speed (ie the resistance you are pedalling against is the resistance of the air to your body and bike as you ride) and is not your GROUND speed off your computer. So if there is a head wind, add that speed to your ground speed to determine the velocity for this formula. And if it is a tail wind, subtract it from your ground speed. If you think about it, this makes sense - it is always easier to ride with a tail wind. This formula quantitates how much easier.
**(Unfortunately, this formula is for an "ideal" rider of 75 kg. I could not find the original derivation and so cannot give you the exact changes if your weight is more or less than 75 kg. But biking is NOT an exact science, and this formula will at least get you into the right ballpark)
Definitions and conversion factors:
• 1 watt = 1 joule/second
• 1 Cal = 1000 calories = 4186.8 joules = 4186.8 watts

II. Vertical Distance (Ev = energy replacement required-vertical component)
When the terrain is not level, and there is vertical gain, this formula calculates the number of Calories that would need to be eaten to replace those expended for the vertical component only.
• W = F x D
• Ce = W/CF
• Ci = Ce/Eef = Ev
Where:
• W = work (ft-lbs or kg-m)
• F = Force from gravity (lbs or kg)
• D = distance vertically (ft or m)
• Ce = Calories expended at the pedals
• CF = conversion factor of 3907 or 418 (for American and International Units respectively)
• Ci = Calories ingested = Ev
• Eef = efficiency of the human machine in converting food Calories (~25%)
• Ev = energy replacement requirements (Calories to be eaten) - vertical
Definitions and conversion factors:
• 1 Cal = 1000 calories = 4184.8 joules
• 1 joule = 74 ft-lb = 0.10 kg-m
• 1 Cal = 3097 ft-lb = 418 kg-m
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III. TOTAL ENERGY REQUIREMENTS - UNEVEN TERRAIN
By combining the calculations for the horizontal component of energy expenditure and the component from vertical gain, the TOTAL Caloric replacement needs for your ride can be determined.
Etotal = Eh + Ev
And finally, don't forget the approximately 50 Cal/hour for basal metabolism.

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AN EXAMPLE
A 165-pound cyclist (75 kg) rides a 10-mile hilly route at an average speed of 15 mph (6.7 meter/sec). During the ride, he climbs 1500 feet (457 meters). His bicycle weighs 22 pounds (10 kg). How many Calories will he need to eat to replace the energy expended??
• Pw = 6.7 m/sec [3.509 + {0.2581 (6.7)(6.7)}]
• = 6.7 [3.509 + 11.586]
• = 101 watts
• Pc = 101/4186.8 = 0.024 Cal/sec
• T = 10/15 = 0.66 hr
• = 0.66 x 3600 sec/hr
• = 2376 sec
• Ce = 0.024 x 2376 sec = 57 Cal
• Ci = 57 Cal/.25 = 228 Cal = Eh
• W = 85 kg x 457 meters
• = 38845 kg-m
• Ce = 38845/418 = 92 Cal
• Ci = 92/0.25 = 371 Cal = Ev
• Et = Eh + Ev
• = 228 Cal + 371 Cal
• = 599 Cal to replace those expended
• (plus approx 50 Cal/hr x 2/3 hrs to replace BMR Calories)
• = 599 + (2/3 x 50) = 632 total Cal to be eaten