Shepard, R. J. (1978). Aerobic versus anaerobic training for success in various athletic events. Canadian Journal of Applied Sport Sciences, 3, 9-15.


Single Maximum Contraction Events

Examples: throwing a baseball, jumping for a basketball rebound, lifting a weight in a power-lifting competition.

Important Features

  1. Explosive force is the principal capacity that is used. It is determined by the following characteristics: (a) the total number of muscle fibers that can be recruited (predominantly slow-twitch fibers with as many fast-twitch fibers as can be enlisted for the effort level); (b) the magnitude of the force beyond the 50 percent effort level (this will be mainly influenced by the number of fast-twitch fibers that are used); and (c) the activity of the enzyme ATPase and the resultant rate of energy transfer from phosphate stores to the bonding of the muscle proteins actin and myosin.

  2. The mechanical resistive forces that exist in the body are: (a) muscle viscosity (which is greatly affected by core temperature and to a lesser extent the degree of hydration in the body); (b) the degree of relaxation in the antagonist muscles; and (c) the inertia of the body parts that are to be employed in the action (this has direct bearing on when body segments are initiated in any movement, for example, the quicker a segment needs to be employed the greater is the energy cost to mobilize that segment).

  3. The performance capacities which surround biomechanics and skill learning are timing, skill, and agility. These combine to form a coordinated smooth movement that produces an efficient explosive force.

Training for single maximum contraction events is determined more by learning and practice characteristics than physical changes which occur within the muscle or body. Such training is best achieved through maximally specific practice trials with adequate between-trials recovery. The provision of performance feedback that can be used to improve the quality of the skill efficiency is equally important.

The volume of correct performances at competition intensity, that is, specific skill learning, is the major training determinant for performance improvement in this class of activity. A relatively well-trained non-specific endurance capacity could assist the development of stress tolerance, application to training, and recovery rates.

Since most improvement in these events comes from skill-learning sources, one should expect to continually improve throughout a sporting career provided the skill training is correct and stimulates continual efficiency development. As long as the physiological capacities associated with the sport are sanely developed and maintained, an extensive career in high-level performance is possible.

Very Brief Events (less than 10 seconds)

Examples: Running a 50 meter dash, performing a long jump, sprinting in cover defense in football, running between bases in baseball.

Important Features

  1. The anaerobic power that is available. This is affected by: (a) the energy transfer ability of ATPase and CPase to the bonding of actin and myosin in muscle contraction; (b) the total number of muscle fibers used; (c) the proportion of fast-twitch fibers used in each single action in the total event; and (d) towards the upper limit of this type of activity there may be some demand placed on the lactacid energy system so that some lactic acid is formed although it will not reach very high levels.

  2. The mechanical resistive forces in the body are: (a) muscle viscosity, (b) the degree of relaxation in the antagonist muscles, and (c) the inertia in the various body parts that are moved. The mechanical resistive forces outside of the body are (a) energy loss due to friction with the ground and/or performance medium (water and/or air), (b) air resistance, and (c) the raising and lowering of the center of gravity (the less the better).

  3. The performance capacities which surround biomechanics and skill learning are timing, skill, and agility. These combine to form a coordinated smooth movement that produces an efficient explosive force. Each individual action needs to be cyclically performed so that the most efficient and productive movement is repeated. This requires much training of a specific nature so that evenness of force application at a maximum intensity is learned. Since performance determinants are primarily based in skill learning, auxiliary training using simple activities (e.g., weight training, rebounding) and unrelated activities are not likely to influence any performance improvements. The major learning task is to develop and control forced movements that exceed the normal ballistic velocity of the limbs that are used. Since that is unnatural, the amount of exact and specific training that occurs will determine the ability to execute efficiently. From a physiological viewpoint, there should be sufficient training performed to overload the alactacid energy system so that it improves (the amount of improvement may be as much as 20 percent but that will translate into extending maximum performance by only a few seconds).

The best forms of training for these activities are specific repetition and ultra-short training. An emphasis on all types of general physiological training will have no benefit and could even be detrimental because of the development of excessive general fatigue and inappropriate movement patterns.

Training at specific maximum intensities with sufficient recovery between trials is the major conditioning principle for these events. The most significant performance improvements are likely to result from skill enhancement. This means that performance improvements should be expected throughout an athlete's career. A relatively well-trained endurance capability could assist the development of stress tolerance, application to training, and recovery rates.

Brief Events (10 to 60 seconds)

Examples: Running a 400 meter race; cycling in a 1000 meter sprint; swimming a 100 meter butterfly race; participating in a goal-line to goal-line move in rugby.

Important Features

  1. The alactacid energy system is exhausted early in the event performance (usually within 10 seconds).

  2. The lactacid energy system breaks down glycogen in the absence of oxygen to form lactic acid and hydrogen protons. Maximum lactic acid values can be reached within 40 seconds and after that performance deteriorates very rapidly. Thus, with activities that last longer than 40 seconds it is not possible to perform maximally for the duration of the event, consequently, some compromise in effort intensity will have to be made to endure to the completion of the task.

  3. The trained capacity of the alactacid and lactacid energy systems will influence performance. The alactacid system can only be improved with marginal consequences (usually no more than an extra two seconds). The lactacid system can be trained to improve by as much as 20 percent depending upon the initial level of training. This means that maximum performances can be extended by no more than about 10 seconds as a result of physiological conditioning.

    The physiological components altered by training are: (a) the ATP and CP stores in the muscles, (b) the amount of glycogen (stored in the muscles and liver) and blood glucose that can be used, (c) the activity of the glycolytic enzymes in the muscles, and (d) the ability of the body to buffer (tolerate) higher levels of lactic acid.

  4. The resistive forces within and external to the body are similar to those incurred in very brief events (described above).

  5. Performance capacities which surround biomechanics and skill learning are timing, skill, and agility. These combine to form a coordinated smooth movement that produces the highest level of skill efficiency and an optimal level of effort while appropriating the limited capacities of the alactacid and lactacid energy systems in the most efficient manner. Each individual action needs to be cyclically performed so that the most efficient and productive movement is repeated. This requires much training of a specific nature so that the evenness of force application is learned at the highest intensity that can be maintained for the event. Since these activities are largely influenced by skill learning, auxiliary training using simple activities (e.g., weight training, rebounding) and unrelated activities are not likely to contribute to any performance improvement value in intermediate or higher level athletes. The amount of exact and specific training that occurs will determine the ability to execute with the greatest mechanical efficiency. From a physiological viewpoint, there should be sufficient training performed to overload the alactacid energy system so that it improves. Training the lactacid energy system is also necessary. Its improvement is best achieved by experiencing 100 percent effort levels at training. However, such training is particularly exhausting and its repetition will be governed by the rate of recovery between training stimuli. In order to experience a sufficient number of skill repetitions so that efficiency of movement can be learned, ultra-short training would seem to be the most appropriate form of conditioning. The ceiling level of training for these two energy systems can be achieved in a relatively short time (from five to seven weeks) so coaches should be very wary of overtraining. Since skill learning is still important as a training emphasis, it would seem to be advisable to condition the energy systems at a rate that is slower than maximal. Such a conservative approach would reduce the possibility of accrued fatigue interfering with skill learning and development.

It is still unlikely that auxiliary simple or unrelated training activities will have any effect on performance improvement in these events. Unrelated activities, if done at a low intensity, could serve as active recovery pursuits and in that role could be beneficial. The development of a general endurance capacity would also increase the ability of an athlete to recover more quickly between repetitions of training stimuli and to perform greater training volumes. However, if that endurance capacity is developed using the same activity as the event itself it could be counter productive (e.g., endurance running reduces the capacity to sprint). Thus, endurance needs to be developed in a multilateral activity (e.g., runners should row, cyclists should run).

The best form of training is specific repetition training and ultra-short training. All types of general physiological training will not be beneficial and could even be detrimental because of excessive general fatigue and the development of inappropriate movement patterns.

The importance of physiological training is greater for brief events than for the two previous performance classifications. Significant functional changes can be achieved by using correct applications of training stimuli. However, the skill of executing the most efficient action for the longest duration is still a learning-determined phenomenon. Thus, the factors that surround skill learning, and the repetition of correct trials should dominate the focus of training for these activities and will be the greatest contributors to performance improvements.

Sustained Events (60 seconds to 60 minutes)

Examples: Playing a game of rugby football; swimming 1500 meters; running 10,000 meters; playing a game of basketball.

Important Features

  1. The greatest proportion of energy in these events is contributed by the aerobic energy system. At various stages during and often at the end of an event high lactic acid levels can be incurred. If they occur during the event there usually needs to be some recovery period to return lactic acid to tolerable levels (normally 4 mM or less). In sustained cyclic events such as running, swimming, cycling, and cross-country skiing, there is an exaggerated use of the lactacid energy system at the start and end of the event. There is also some exploitation of the alactacid energy system but its overall contribution to such an extended performance is virtually negligible. Thus, performance improvements through physical training should come from the aerobic and, to a lesser extent, the anaerobic energy systems.

    (a) Aerobic power can be improved by 5 to 20 percent depending upon the initial fitness level of the athlete. Even an improvement of five percent is of greater influence when compared to what can be contributed by the lactacid energy system. Thus, the principal emphasis of training should be on aerobic adaptation which will produce marked changes in the physiological structure and capacity of an individual.

    (b) The lactacid system is influenced by the original strength of the individual. Theory suggests that the greater the strength of a person, the fewer the number of fibers that need to be contracted to perform a certain level of work (this means the less anaerobic work that needs to be performed per standard unit of performance). Alternatively, a higher working capacity can be maintained if a stronger individual is required to perform at a standard effort level. This contention may be true when general training is initiated but it probably is not relevant once specific training commences. It is best to plan to achieve strength improvements before starting specific training for these events.

    (c) The choice of fuel for the exercise will determine the magnitude of the performance. Although the major fuel will be fat, the amount of stored glycogen and blood glucose will affect the amount of work that can be done (particularly in anaerobic conditions). Thus, carbohydrate loading is important for events at the upper extreme of this classification.

  2. The resistance forces involved are the same as those discussed for the previous two performance classifications.

  3. Skill factors are still important. The factor which differentiates champions from lesser performers of like capacities, is the ability to perform work with greater efficiency, that is, at a reduced oxygen cost. The training of smooth actions which limit unnecessary movements and produce the greatest direct forces for the least energy cost are features of the skill of performing that need to be taught and learned. Training the skill characteristics should emphasize periodic assessments of the metabolic cost of performing at various intensities. Once physiological capacities have been shown to have reached their ceiling levels, the training emphasis should be altered to produce higher performance standards for the same metabolic cost. If there is no change in physiological adaptation once it has been maximized and there is no attempt to change the skill and efficiency of movement then one should not expect performance to improve to any marked degree. Once physiological capacities have been maximized, further performance improvements can only be achieved through skill and psychological factors.

An "experience" factor that needs to be developed is the ability of the athlete to allocate resources so that maximum exhaustion occurs as the finish line is crossed or the final whistle is blown. This capacity can be learned and should be an outcome of the type of training that is programmed.

The best forms of training for these activities are (a) those which establish an aerobic base through various forms of continuous training in the principal activity of the sport; (b) training stimuli which allow aerobic adaptation to occur at the intensity of the intended performance (e.g., various forms of specific interval training); and (c) repetition training of varying durations that also require competition-specific intensities (some of these may go to exhaustion as a means of promoting anaerobic adaptation).

The use of auxiliary training in conjunction with specific training will be of no value. Specific training is essential for developing performance efficiency which should be the main focus of the total training program. Although conditioning is important, skill and psychology will be the avenues for taking athletes beyond the level of performance that can be supported purely through maximized physiological adaptation.

Training at less than competition intensity is beneficial as long as it is balanced by at least an equivalent amount of time spent on specific-performance intensity training. A coaching emphasis on the development of the most efficient form of movement and energy resource allocation will be the major determinant of performance improvements in superior athletes.

Prolonged Events (60 minutes and longer)

Examples: playing a game of soccer; running a marathon; competing in a triathlon; cycling in a road race; a 2-hour training session in swimming.

Important Features

  1. The factors concerned with this class of activity are similar to those of the previous classification. What does become increasingly important is the ability to spare and conserve energy resources so that glycogen depletion does not occur during the performance. A large amount of energy will be supplied through fat metabolism but glycogen will still be used to a lesser degree. However, since the body only has sufficient stored carbohydrates to fuel about 90 minutes of work (120 minutes under carbohydrate-loaded conditions) there still is the possibility that glycogen supplies can be exhausted. Diet and the type of training that is followed will be critical for fine-tuning the relative use of fat and glycogen for aerobic work.

  2. Temperature regulation, heat acclimatization, clothing, diet, fluid replacement, altitude, pollution, and fatigue are features which moderate the level of training quality and volume as well as competitive performances. Appropriate adjustments and acclimatization procedures need to be taken to minimize the impact of these factors.

  3. Of all the activity classifications prolonged events require the greatest amount of training. This means that psychological factors, particularly motivation, goal-setting, feedback, and knowledge of progress will be very influential for maintaining a sustained application to training. Psychological problems and overuse injuries are usually indicators of an overtrained state. The monitoring of the adaptive responses of athletes to the training volumes and frequencies is particularly important to avoid overtraining.

The skill of performing the task-relevant activities still remains an ominous factor for determining ultimate success in prolonged events. As athletes mature and their physiological capacities no longer develop, performances can still improve further because of changes in skill and efficiency of movement. These features should become the major focus of training once a training work-ethic and extensive history of training have been established in mature athletes.



  1. Skill development is neurologically based and therefore, in advanced athletes, is specific to each and every minor variation of activity. If a high-level athlete attempts to deliberately transfer some elements of one skill to another then the target activity will be adversely affected, that is, made worse rather than better. On the other hand, in beginning athletes general concepts and gross skill-pattern elements from one activity can be transferred to another to form a starting point for new learning. For example, if someone has never played squash but has considerable background and competency in tennis then some tennis elements can be used in the initial squash lessons. An observer watching the player's first attempts at squash will be left with the impression that the "new" player has a good "innate ability" or "natural flair" for the sport. Usually, such an initial positive transfer from a "similar" activity gives a new participant an advantage in the early stages of learning but that advantage is lost over other "disadvantaged" players as they experience learning in the new activity (i.e., they catch up). In some circumstances, the initial positive transfer elements can be detrimental if they are retained rather than adjusted to exactly what is required in the new activity. That phenomenon leads to the situation where an athlete appears to be good in the early stages of sport involvement but later on does not improve as much as might be expected.

  2. The training of skills must be specific. Repetition of the exact intensity required for competition performance is the only option that should be contemplated by the coach once the quality and technical features of a skill have been maximized. Where skill is a major determinant of sporting success when compared to the importance of physical conditioning, competition-specific skill practices should take precedence over any other form of non-specific physical conditioning. Consequently, the physical conditioning of skill-dependent sports should use forms of training that allow the exact skill to be practiced while undergoing physiological stimulation. The forms of conditioning that are most appropriate in such cases are interval and ultra-short training. Interval training should be designed to maintain the exact skill performance quality by adjusting recovery and task durations.

  3. There are some sports where the gains in performance will be markedly more than in others. When a participant engages in an "unnatural" activity (e.g., swimming, kayaking) there is a large potential for improvement because of the low baseline from which training commences. On the other hand, for sports which are already part of an individual's life-style activities (e.g., running, throwing) the scope for improvement is more restricted since participants are already partially adapted and their level of baseline performance competency is much higher than those for "unnatural" sports.

  4. When the mechanical efficiency of a sport is naturally low (e.g., swimming) minor gains in efficiency translate into large gains in performance. This leads to the perception of a beginning athlete having some "natural" flair for an activity because of rapid and obvious improvements. Noticeable performance changes that occur during conditioning and the repetition of skills will seem to be a direct result of programming. However, such impressions are based on the false premise that training is directly responsible for the observed improvements. Usually, the real reason is that the potential for improvement is so great that virtually doing anything will produce an improved performance, particularly in the early stages of skill development. For example, the sheer repetition of a skill pattern that is erroneous will produce an improvement through the reduction in skill pattern variance (which is a factor involved with inefficiency). Thus, training with poor technique will produce improvements but only to a reduced ceiling level. Many coaches are lulled into a false sense of security because of athletes' quick performance changes that result from an initial emphasis on physical conditioning that involves many repetitions of a single skill. Since that emphasis appears to be very productive and reinforcing to the coach's behavior and program, it continues to be emphasized long after improvements have ceased. The result of that unproductive persistence is that many athletes are subjected to monotonous training that does not result in performance improvements. This occurs despite the fact that complex and unnatural sporting activities provide the greatest opportunities for improvement. Athletes in such sports should expect to continually improve in performance as skill efficiency is elevated. Coaches in sports such as swimming, pole-vaulting, rowing, triathlon, and most team and court games, who do not stimulate performance improvements in athletes can usually be charged with incorrect and improper coaching methods and content (even at the highest levels of performance).

Body Build

There are some general features of body-structure that are worthy of consideration when planning training programs.

  1. Excess fat is usually a hindrance to performance except in very long distance swimming. Some target event athletes have been fat and successful but that has usually been achieved despite obesity, not because of it.

  2. In contact and combative sports, increased or superior levels of muscle mass are an advantage. As well as being directly related to the potential for strength and power movements, the increased mass also serves to create greater momentum and obstacles for opponents. This feature justifies the cliche "a good big athlete will always beat a good small athlete."

  3. In sports where explosiveness and power are important, weight gains that are achieved through increases in muscle mass are best when restricted to the muscles used to produce the power for the activity. This means that "bulking-up" in muscles that do not contribute to performance productivity is counter-productive to improvement. Thus, the nature of the capacities that are required in a sport will dictate what developmental emphases should be stressed.

  4. Somewhat allied to the above point is the principle that excessive muscle development (particularly bulk) can be a hindrance to performance. This is very important for activities where the extra bulk has to be transported for a considerable period of time (e.g., in a football game, in a long race).

  5. It is possible that strength gains which produce increased capillarization in prime-mover muscle groups used in sustained activities (e.g., the quadriceps in cycling) could be an advantage because increased blood flow during intensive effort would be facilitated. Research evidence suggests that endurance performance is not enhanced by strength gains (e.g., Hurley, Seals, Ehsani, Carter, Dalskey, Hagberg, & Holloszy, 1983) so this possibility should not be used as a justification for strength programs.

  6. Heavy endurance training may produce small (30-40%) increases in the cross-section of active muscle fibers but can also lead to protein loss from inactive muscle areas. This means that overall body weight may not change but body shape will. For example, long-distance runners tend to lose or have diminished muscle mass in the torso and arms while their legs appear to be quite well-developed. A similar appearance is also often attributed to road-race cyclists.

  7. The loss of muscle mass is particularly noticeable in muscles that are not exercised after they have been specifically adapted through training. This often occurs during a period of inactivity caused by injury or ritualized detraining (e.g., a winter of inactivity). Performances cannot return to previous levels until those losses and in particular, muscular development, are corrected. This has direct relevance to performance expectations placed on athletes returning from periods of inactivity. Those expectations are often excessive and unrealistic.

Cardiorespiratory Power

A fitness base of endurance training is a modern requirement for almost all sports. Aerobic fitness affects temperament, mental capacities, and work capabilities. An athlete can perform longer and better both mentally and physically when the aerobic system is trained. Aerobic training only needs to be specific when it is an important capacity for performance (e.g., running, swimming, rowing, triathlon, and intermittent team and court games). It does not need to be specific for activities such as yachting, shooting, and baseball, where mental persistence and acuity are large determinants of sporting success.

  1. Aerobic capacity (usually measured through maximum oxygen uptake--VO2max) can be increased by as much as 20 percent depending upon the initial level of fitness and the use of graded-stepped overloads as training stimuli. On the other hand, the better the initial level of aerobic fitness, the less it will contribute to performance improvements.

  2. Some of the major adaptations that occur through aerobic training are: (a) increased tone of peripheral veins; (b) greater contractility in the heart (it can pump more forcefully); (c) increased stroke volume (more blood is pumped per beat); (d) more effective blood flow distribution between active and inactive muscles, (e) increased mass in the heart muscle (it has better endurance capabilities by having more muscle to pump longer); and (f) the number and size of mitochondria are increased within each working muscle which facilitates a greater use of oxygen to produce ATP.

  3. Endurance adaptations do not only occur in the muscles that are involved with generating force in a specific activity. In the early stages of training, adaptation primarily occurs in the muscles that support breathing and cardiovascular system function. Consequently, early gains in endurance occur mainly because of training effects in central oxygen transport system features. That adaptation makes it possible to then adapt peripheral structures.

Tissue Adaptations

When describing training changes it is assumed that diet is adequate. Sufficient carbohydrates have to be presented to replenish depleted stores and sufficient protein has to be ingested to allow strength development. In normal diets, fat intake is usually sufficient, and in many cases, may be excessive.

  1. Muscle hypertrophy results from intense stimuli which increase the synthesis of new protein. It only happens after sufficient training and skill development have used existing physical resources maximally (a result of the neurological reorganization that occurs with the introduction of strength training programs). Hypertrophy cannot occur if protein intake is too low. Light work loads may induce some hypertrophy in untrained individuals but it is usually of such a minute nature that it is not readily noticeable.

  2. Some of the most important and influential factors that result from physical conditioning occur at the cellular level in the muscles, that is, the majority of training effects are peripheral. The number and size of mitochondria, the amount of myoglobin, the amounts of ATP and CP that are stored, and the concentrations of key enzymes associated with particular energy systems are increased.

  3. Training is specific and selective of the types of muscle fibers used. That selectivity will determine the nature of training effects and the type of performance that is improved.

  4. The type of activity that is pursued will use different forms of fuel. Aerobic training will use fat and glycogen as its principal fuel sources. Lactacid training will use glycogen and to a lesser extent ATP and CP. Alactacid training will use ATP and CP. This means that the carry-over from one form of training to another is small and that specific training needs to be repeated to maximize the improvements that are possible from each energy system.

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