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Fitness-Fatigue Model For Real

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Fitness-Fatigue Model for Real

This is still a rough draft but I wanted to get it up. Now that I can edit again I'll probably be refining it or adding to it I've tried to keep it simple and limit the scope to the theory itself with just the briefest discussion of it's implications.

Fitness-Fatigue Model for Real

At any time preparedness is the difference between the positive effects of fitness and the negative affects of fatigue but since fatigue although very great doesn’t stick around very long we can take advantage of the fitness gained without overtraining. Intuitively it has to be this way or you’d never have any apparent progress. What it really means is that it allows us to take advantage of the fact that while the fatigue impulse may be twice as high as the fitness impulse the fatigue decays three times as fast. The fitness gained is still a result of the training impulse.

How is supercompensation so much different than fitness-fatigue? At its heart it’s not. You work out (the stressor) and performance decreases. How long performance decreases depends on training status and the degree to which homeostasis was disrupted. But after some period of time you recover and performance theoretically increases past the point at which you started. This doesn’t go away because we have a fancier theory to look at. You workout. You recover. You get more fit.

Earlier theories tend to look at the responces to training as a cause and effect relationship. Such as the SFRA concept (stimulus-fatigue-recovery-adaptation) which bares similarities to Seyles GAS theory. These theries are supported by observations and it is important to note that these observations are not inherently wrong.

Fitness-fatigue theory or dual factor simply enhances our understanding of this. It doesn’t just consider response to training but the factors involved and the interplay among them. It views fatigue and recovery as opposing forces rather than having a cause and effect relationship. What we had before with Seyle’s GAS theory is simply an initial period of fatigue followed by adaptation. However the initial fatigue of dual factor is very comparable to Seyle’s Alarm Stage.

But I use the term theory losely. What it really is is a statistical model used by scientist to help predict exercise response. It is not in itself a physiological theory that relates to sports improvement. It is a model that gives rise to a qualitative measurement of exercise response in individual athletes. Banister er al. proposed this mathematical model in 1975 as a way to understand the fluctuation of athletic performance throughout periods of heavy traingin separated by taper periods. It is a way to mathematically model and study the effects of training on an individual by generating fatigue and fitness profiles. The model followed as a way to look at the training not the other way around.

But let me be very clear about something. As I mentioned above the fitness gained is STILL a result of the training stressor. It is not a result of the degree of fatigue. Greater fatigue does not LEAD to greater fitness as has been suggested. This kind of thinking could actually lead to regressions in performance rather than improvements. Especially once you consider that increasing the frequency between similar training bouts gives rise to an exponential accumulation of fatigue and a progressively greater and longer duration of fatigue while the fitness response to a single bout goes down. In other words if a certain amount of work would give rise to a fitness response adding to that and accumulating fatigue would only lesson the impact of each successive bout past that point.

Disrupting homeostasis to the point that we initiate an adaptive response results in more fitness. But there is more to it that allows us to manipulate our training at various stages of our career.

The model was contrived as a way to study training response and thus maximize training effectiveness for an INDIVIDUAL. It takes into account the fatigue and fitness response of individual bouts as well as long term response over loading periods and taper periods. It is thought necessary to schedule successive training bouts when fatigue is disapating in order to maximize the fitness response and to prevent the exponential accumulation of fatigue. Then a taper period is undergone to dissipate any accumulated fatigue. Accumulation of fatigue is not a goal in itself. It is simply that once it does accumulate a tapering period is necessary to realize the full fitness potential of a training period. Training is scheduled according to the needs of the individual athlete and the competitive season.

That is because the fitness-fatigue model does not treat all fatigue after training the same. Different things cause different levels and durations of fatigue and fitness. So the two-factor model suggests ways in which we can periodize our training. It is NOT in and of itself a method of periodization.

For example, the training load, and total work performed, and training economy changes the magnitude and duration of the after-effects. Different types of work also. High volume inititates a much larger and immediate fatigue response than maximal intensity. High volume could be compared to the repetitive-effort days of Westside and maximal to the ME days. ME days must always precede RE days because of this. For DE days they fall differently depending of the status of the trainee. But from a simple perspective we can see that the weekly scheduling of a Westside routine will take into account facets of the two-factor model. It is scheduled to minimize accumulated fatigue for the individual. But a taper or deload period may be necessary when fatigue does accumulate, again, according to the needs of the athlete and the competitive season. This is the dual-factor model at work.

At whatever level of training you are, your preparedness is still the difference between fitness and fatigue and the effects of fitness can not be displayed unless fatigue has dissipated. This is really the central point.

This is true whether you are a beginner or advanced athlete. There is no “single factor training” as such. There is simply effective and less effective ways of training, just as there always have been. The effects of fatigue and recovery, their interplay, become more apparent the more advanced you get.

What is the real primary difference between looking at training in terms of “single factor” or “dual factor”? If you look at it in terms of single factor thinking you do not view fatigue as an independent factor but only consider recovery. Therefore if you fail to make progress your assumption is you did not fully recover. Obvious conclusion? More time to recover.

How many people actually work this way? Not many.

The definition of dual factor or "fitness-fatigue' itself, I.E. the one developed by some of the writers in the sticky is pretty much on it's surface an advanced periodization method and NOT a definition of the adaptation model itself.

This is the idea that the dual factor theory basically necessitates a long period of peaking fatigue (say 4 to 6 weeks) and then a peek. If you don’t do that you are “using single factor theory”. So the idea is that dual factor has replaced supercompensation and has therefore spelled out a surperior way of training for EVERY ATHLETE. This is complete nonsense.

This is the reality in a nutshell, you do not need to load for extended periods until you can no longer make progress during a shorter period. So an advanced athlete certainly cannot make progress on a workout to workout basis in a realistic manner. Why this is true is beyond my scope since there are so many parameters that would make different ways of training workout to workout fail for the advanced. And let’s forget all the comparisons to HIT, shall we, that’s a whole nother can of worms. Let’s just sufficeth to say that he can’t make any real good progress on the squat every workout.

So what would be the next step? Logically he would switch to making progress on the shortest time period possible for as long as possible. Instead of making progress every 36 to 72 hours he switches to a week (or 4 or 5 days or whatever). What has this got to do with single factor vs dual factor? Not a damn thing. A lot of confusion has been caused that is causing beginners to jump into advanced programs.

Advanced programs are for the advanced. Quite frankly that excludes most trainees. But those programs take advantage of one of the facets of the dual-factor model of adaptation. Programming and the theory that allows it to work are TWO DIFFERENT THINGS. Regardless, if they work it is because they are founded on experience and knowledge of advanced periodization. If they work it is because they coincide with how the body adapts (the theory) but ALSO because they coincide with the particular athlete’s needs at that time.

The athlete has been referred to as a dynamic machine and never a static model. You know a lot of people don't realize that you can react to a program one way in one stage of training and later on derive completely differnet results from that same program because of the state of the "adaptive system" at THAT PARTICULAR phase of development.

Hope that doesn't sound all "sciency" becaue it's not. It's just the opposite. Science the way is has traditionally been done would have you believe that the athlete IS a static model and that mathematical means can be used to measure adaptation accross a population. The fact is that a reliable model can only be developed for a test pool of one.

To say that an adaptation theory tells us there is a superior way of programming for everyone, even among a population of advanced athletes, is to say the same thing: we are static models instead of dynamic machines. But we are not. EVERYTHING changes. The ability to recover changes. The amount of work or stimulus that it takes to create an adaptive response is different for a beginner and an advanced athlete. And pretty much everyone falls in between that. Everyone is not the same.

But the theory does not say this so there is really no conflict. There is no single-factor versus dual-factor. Supercompensation still plays. The GAS model is not incorrect and opposed by the fitness fatigue model. The program a person should be on still depends on their training status just like it always has. And at each stage of the game recovery must be planned.

A load that is too stressful at any time can overwhelm the recovery process resulting in the need to re-plan recovery. This process doesn't change for a beginner through and advanced athlete. Only the time periods involved and the degree of the stressor needed does. The physiological process of adaptation is basically the same. Training gives rise to simultaneous fatigue and fitness manifestations and at any time preparedness is the difference between those two forces.  
EricT on 03-08-2007, 10:58 AM

Strength and Conditioning Journal: Vol. 25, No. 6, pp. 42–51.

The Fitness-Fatigue Model Revisited: Implications for Planning Short- and Long-Term Training

Loren Z.F. Chiu, MS, CSCS

Musculoskeletal Biomechanics Research Laboratory, University of Southern California
Jacque L. Barnes

Human Performance Laboratories, University of Memphis

ELITE ATHLETIC PERFORMANCE is dependent on a systemized training program. The general adaptation syndrome (GAS) was the original model from which periodization was designed (67). The GAS describes the physiological response of an organism to stress. A more comprehensive model of the physiological responses to training stimuli is the fitness-fatigue theory (1). In light of recent research examining resistance exercise overreaching and overtraining, it is prudent to review the fitness-fatigue theory and determine how it can be applied to strength and conditioning.

General Adaptation Syndrome

Initially described by Selye in 1956 (60), the GAS proposes that all stressors result in similar responses. The initial response, the alarm stage, is negative, with the physiological state of the organism decreasing following the imposition of stress. Secondary to the alarm stage is the resistance stage, where positive adaptations occur, returning the organism to homeostasis and possibly into a higher state, known as supercompensation. The exhaustion stage occurs when the imposed stress is greater than the adaptive reserves of the organism. This can happen when the magnitude of stress is too large or additional stressors occur. As the response is supposedly similar for all stressors, the magnitude and duration of training determine the magnitude and duration of adaptation.

In traditional periodization models, there are multiple bouts of training, resulting in multiple flights of alarm and resistance stages (63, 67). Periodically reducing volume load may prevent the exhaustion stage (63, 67). If the individual reaches the exhaustion stage, overtraining occurs.

Fitness-Fatigue Model

Proposed in 1982 by Bannister (1), the fitness-fatigue model argues that different training stresses result in different physiological responses. The state of the organism without training is the baseline level, which represents the individual's general fitness. Training results in 2 after-effects, which can positively or negatively influence performance: fitness and fatigue (Figure 1 ). For strength and power athletes, factors that affect general fitness include muscle cross-sectional area, muscle contractile protein composition, and muscle metabolic enzyme concentrations (23, 24, 44, 62). For endurance athletes, both cardio-respiratory factors and muscular factors affect general fitness (53). Examples of these are maximal oxygen consumption, mitochondrial density, and muscle capillarization. General fitness increases with training age; thus elite athletes have higher general fitness than novices do.

The fitness after-effect is a positive physiological response, whereas the fatigue after-effect is a negative physiological response. The interaction between these 2 after-effects results in the change in performance following the stimulus (1, 67). It is important to note here that the fitness-fatigue model is not necessarily an alternative to the GAS, but rather a better representation of stimulus and response. Indeed, the resultant change in performance as described in this model is identical to the GAS. The distinction of fitness and fatigue after-effects, however, is important for the development of training paradigms.

Fitness after-effects, whether acute or chronic, appear to be primarily neural in nature. Facilitation of the peripheral nervous system occurs via optimal magnitude and rate of activation of the neuromuscular complex, coactivation of intrafusal fibers, and decreased autogenic inhibition (20–22, 27–34, 38–41, 51, 52). Central nervous system activity increases through up-regulation of the alpha- and beta-receptors and greater catecholamine release (12).

Fatigue after-effects are both neural and metabolic in nature. Down-regulation of the alpha- and beta-receptors or decreasing the release of catecholamines can decrease nervous system function (12, 25, 28, 35). Metabolic fatigue is primarily due to decreased storage and availability of energy substrates (10, 25, 45, 64, 67).

The magnitude and duration of the after-effects is dependent on the stimulus, where Bannister (1) initially proposed that training impulse, an indicator of physiological work, was the sole variable. In general, the fatigue after-effect is large in magnitude with a brief duration. This results in the initial decrease in performance (similar to Selye's alarm stage). The fitness after-effect has a dull magnitude, but a long duration. This manifests as a long-term improvement in performance (similar to Selye's resistance stage).

Evidence of After-Effects

Evidence of the existence of 2 after-effects, as opposed to a single unified response, exists in the physiological literature. Similarly, there is an absence of evidence supporting the single unified response proposed by Selye (60). The initial bases for the GAS are the endocrine responses to stress (60, 67). These endocrine responses, however, are not the same for all exercise regimes. Higher-volume training results in an acute decrease in circulating testosteron, whereas higher-intensity training results in an acute increase in circulating testosteron (46, 47, 49). High-volume, moderate-intensity exercise increases growth hormone, but low-volume, very high-intensity training has no growth hormone response (47, 49). Correspondingly, a brief decrease in performance can occur regardless of the increase or decrease in circulating hormones (35–38, 40, 41). The original propositions of the GAS are thus far too simplistic to accurately describe the physiological response to stimuli.

Perhaps the best evidence of fitness and fatigue after-effects is the physiological phenomenon posttetanic potentiation. Posttetanic potentiation is the increase in muscle twitch force following voluntary or involuntary maximal contractions (9). Brown and von Euler (3) reported that successive contractions in isolated muscle preparations resulted in greater force production. Further research in animals and humans corroborated these findings, indicating that maximal voluntary contractions resulted in an increase in performance (9, 11, 19, 42, 57). Interestingly, individuals competing in sports respond favorably, whereas recreationally trained individuals fatigued after the maximal voluntary contractions (9). Chiu et al. (9) speculated that the athletic individuals had a greater potentiation response (fitness after-effect) and less fatigue compared with the recreationally trained individuals.

Physiologically, maximal contractions cause a depletion of creatine phosphate, an accumulation of extracellular potassium, and an increase in intramuscular calcium and hydrogen (53). These changes contribute to decreased muscle force production. Alternatively, maximal contractions result in phosphorylation of the regulatory myosin light chain and the H-reflex (9, 19, 42, 57). The regulatory myosin light chain is a protein that regulates the rate of muscle contraction. Phosphorylation of this protein increases the rate of binding of actin and myosin, resulting in faster muscle contraction (57). The H-reflex is a reflexive neural signal, which when superimposed on voluntary muscle activation, increases the strength of the electrical impulse, thus activating more motor units (19).

In addition to these acute responses, short-term training adaptations support the fitness-fatigue model. Fry et al. (16) found that following 3 weeks of high relative intensity resistance exercise, strength did not change, whereas speed decreased. Subjects performed near maximal lifts 3 days per week using the free-weight barbell squat. Sprint performance decreased following training, with a 10% increase in 9.1-m run time. This differential response between strength and speed occurs repeatedly in resistance exercise overtraining studies and is supportive of different responses to stress (12, 13, 15, 16, 45, 58).

Stimulus and Response

Bannister (1) suggested that training impulse—the product of heart rate (or exercise intensity) and exercise duration—was the appropriate measure for the training stimulus. Training impulse is a measure of total work performed, and a similar measure exists for resistance exercise, called volume load (64). Volume load refers to the total kilograms of weight lifted. Whether training impulse (for endurance activities) or volume load (for resistance exercise), this notion that total work is the stimulus responsible for short- and long-term adaptation is intellectually appealing. However, the research by Fry et al. (12, 13, 15, 16) shows that exercise with high load or high intensity in absence of high volume loads results in both positive and negative adaptations (45, 58). Thus for a single bout of exercise, absolute load, training intensity, and total work are responsible for the magnitude and duration of the fitness and fatigue after-effects (4–7, 20–22, 29–32, 34, 40, 51, 52, 56).

This important revelation illustrates the differing impacts of the GAS and fitness-fatigue theory. The GAS theory states that total work alone, regardless of the magnitude of stress, is responsible for the responses. In the fitness-fatigue model, both the amount and magnitude of the stimulus contributes to the post-exercise response. Indeed, this distinction may demonstrate the complexity of the fitness-fatigue model. Absolute load, training intensity, and total work appear to have their own fitness and fatigue after-effects. Therefore, the original model—having 1 fitness after-effect and 1 fatigue after-effect—may be misleading. There may actually be multiple fitness after-effects and multiple fatigue after-effects (Figure 2 ).

Although each specific fitness and fatigue after-effect is independent of each other, they have a cumulative effect. Of primary concern is the summation of fatigue after-effects. Individual fatigue after-effects are specific responses to stimuli; however, these responses can have a systemic effect, in particular affecting the immune system. When fatigue after-effects are small and brief, the systemic effect is small. However, stressful periods of training without sufficient recovery result in an accumulation of fatigue and an increase in the systemic or main fatigue after-effect.

The existence of multiple fitness and fatigue after-effects may explain why individual physical qualities respond differently to variations in training. For example, empirical evidence in weightlifters finds that in periods of maximal strength training, explosive strength and muscular endurance suffer. Similarly, strength is impaired when the emphasis is on explosive strength (2). If different fitness after-effects exist for absolute strength, explosive strength, and muscular endurance, they should be specific to the mode of training best suited for that physical quality. Thus when the emphasis of training is on one and not the other physical qualities, the other specific fitness after-effects diminish and that specific aspect of performance increases.

Implications for Training

For novice athletes, the emphasis of training is on improving the general fitness level. The general fitness aspect of the fitness-fatigue theory explains why beginners tend to respond to any type of training program. When beginners train, general fitness adaptations occur without substantial fitness and fatigue after-effects. Novices cannot train with sufficient absolute load, intensity, or volume to elicit large fitness and fatigue after-effects. Thus beginners adapt so that they can tolerate greater absolute loads, exercise intensities, and training volumes.

Regardless of the training parameters, adaptations in beginners performing resistance exercise include muscle hypertrophy and shift of myosin heavy chain IIb to IIa (8, 53, 55, 62). Maximal oxygen consumption, increased mitochondrial density, and increased capillarization result from most types of endurance training (53). An explanation for the divergence in performance adaptations between different programs is the rate and magnitude of adaptations, rather than the type of adaptations (55). These adaptations are stable and do not tend to regress unless a prolonged period of detraining occurs (43, 44, 48).

Elite athletes have developed a high general fitness level; thus the training emphasis shifts to specific fitness adaptations. The highest level of performance occurs when fatigue after-effects are minimal and fitness after-effects are maximal. Mathematical functions can represent the fitness and fatigue after-effects (1, 4–7). As the after-effects decay, they follow an asymptotic function where the after-effect approaches but does not reach zero. Thus it is impossible for fitness or fatigue to exist independently. Bannister (1) proposes that it is better to have high fitness with moderate fatigue, rather than moderate fitness and low fatigue. Manipulating training parameters can alter the magnitude and durations of these after-effects, producing the optimal level of performance. From the temporal pattern of the fatigue after-effect, it is important to note that maximal performance does not occur immediately after the training phase.

Delayed Training Effect

The delayed training effect is a direct consequence of the fitness-fatigue model. Following a period of stressful training, the magnitude of specific fitness and fatigue after-effects is high. A period of training involving reduced total work and relative intensity is required to remove the fatigue after-effects (1, 67). When applied before a major competition, this phase is a taper (14, 18, 27, 54, 61, 65). Although widely applied in coaching circles, the acknowledgment of the delayed training effect has been missing in scientific research. Without a taper period, it is difficult to interpret the true impact of a training program. Preliminary evidence suggests 96 hours of rest may be necessary in recreationally trained individuals for optimal strength performance (65).

The period of rest required for maximal strength and velocity adaptations to manifest may depend on the nature of the training (59). Training involving concentric-only or eccentric-only movements requires 10–14 days of rest for optimal strength and velocity adaptations. For typical eccentric-concentric exercise, strength and velocity were greatest 21 days following termination of training. Whether the concentric-only, eccentric-only, or eccentric-concentric exercise modes were directly responsible for the different taper times is disputable, as eccentric-concentric training would involve roughly twice the volume load as the other modalities. Regardless, the major finding is in support of a delayed training effect.

It is rare, however, for elite athletes to completely abstain from training the last weeks before competition. Although a drastic reduction in volume load occurs during these few weeks, empirically, intensity remains high. This is especially true in elite weightlifters. The brief, infrequent imposition of high-intensity training may maintain or increase the specific fitness after-effects without substantially affecting fatigue after-effects (16, 43, 64). Therefore, this period is more than simply removing the fatigue after-effect; this period also maximizes the magnitude of the fitness after-effect. Thus, rather than taper, a more appropriate term for this phase of training may be ramping.

Short-Term Overreaching

The fitness-fatigue theory and delayed training effect are important to consider in planning the training of elite athletes. Elite athletes can tolerate greater volume load and training intensity than novices and require more stress to stimulate adaptations. The frequent imposition of these stresses, however, makes the athlete more susceptible to overtraining. The need for variation in volume load and intensity are the rationale behind short-term overreaching (12, 64, 67).

Short-term overreaching is the deliberate imposition of stressful training for brief periods interspersed with periods of recovery (12, 64). These stressful periods result in large fitness and fatigue after-effects. As the duration of the fitness after-effect is longer than the fatigue after-effect, a period of rest allows fatigue to diminish while fitness remains high. Stone and Fry (64) and Fry (12) have proposed that this frequent cycling of training and recovery phases is necessary to improve performance in elite athletes.


It is important to consider that the fitness and fatigue after-effects are dynamic and not static entities. If training occurs while fatigue after-effects persist, additional after-effects will superimpose on existing ones, exacerbating the maladaptations (1). However, performance decrements may not occur due to the positive effect of the fitness after-effects. Over time, the persistent addition of fatigue after-effects results in a depletion in the athlete's adaptive abilities, resulting in overtraining. It is here that the GAS falls short in explaining why performance drops sharply when overtraining occurs. Following the GAS model, performance should decrease progressively with additional stressors, which empirically is not the case. With the fitness-fatigue model, fatigue accumulates, and at the point when fatigue after-effects greatly exceed fitness after-effects, overtraining occurs.

We must be careful in labeling overtraining, as it typically requires a prolonged period of stressful training to reach (12, 64). Coaches and sport scientists should not underestimate the adaptive abilities of the human body (14). Most individuals will never reach a true overtraining state. Prior research in elite athletes has found an ability to tolerate twofold or threefold increases in training volume for periods of 1–3 weeks (14, 64).

With resistance exercise, recreationally trained individuals are able to maintain or increase strength with 3–5 d/wk of training with near maximal loads (>90% 1 repetition maximum [1RM]; 13, 16). Velocity-related performances, such as sprinting, decrease at this frequency and intensity of training. A training frequency of 7 d/wk for 2 consecutive weeks results in large strength decrements (15, 58). Thus training with excessive loads results in overtraining faster than training with excessive volume.

Similarly, overtraining resulting from load and intensity manipulations appears to resolve faster than overtraining resulting from excess training volume. Lehmann et al. (50) found performance impairments in overtrained endurance athletes as much as 1 year following reduction in training stress. Overtraining from increased loads or training intensity should resolve within a few weeks of rest (16, 45, 64).

Long-Term Planning

Although it has fallen out of favor among many strength and conditioning professionals, the traditional periodization model holds concepts that are still important for planning training programs. Perhaps the most important is the inverse relationship between volume and intensity (63). If we remember that longer durations are required to overtrain and recover from overtraining, with training volume it would be prudent to only use higher training volumes early in the training plan.

Higher frequency of training, and therefore higher training volume, increases the duration of the fatigue effect associated with a single training session (4). This may be tolerable early in the training year when fatigue has not accumulated; however, if training frequency remains high throughout the training year, the ability to recover is impaired (4). Reducing training volume toward the midpoint of the training year will allow sufficient time for fatigue to diminish. The use of higher training volume early in the training plan also results in increased adaptive abilities, which would be useful later in the training year (14).

Intensity manipulations result in more predictable responses than volume manipulation, whether positive or negative (9, 20, 21, 25, 29, 32, 35–38, 40, 51, 52, 56). Thus as the competition period nears, it is wise to reduce training volume to avoid prolonged fatigue after-effects while addressing training intensity to maximize the fitness after-effects.

Typically, sequencing of long-term training is in a multidirectional fashion. With multidirectional training, athletes train multiple physical qualities in the same period. For elite athletes, it may be necessary to train in a unidirectional fashion, where emphasis is on only 1 physical quality during a given training period. For example, an athlete may perform a 4-week block of training focusing on strength only (67). The unidirectional method usually results in short-term overreaching of the trained quality.

Some coaches and scientists suggest that consecutive overreaching phases are possible, so long as each phase is unidirectional and emphasizes a different physical quality (67). This concurs with the proposed revised fitness-fatigue model involving multiple fitness and fatigue after-effects. The fatigue after-effect specific to 1 physical quality should not hamper the performance of another physical quality. This applies so long as systemic maladaptations, such as impaired immune system function, do not occur. Thus even with unidirectional sequencing, the training plan should include brief periods for recovery.

Dynamics of the Training Day

A single training session can influence subsequent training sessions, both positively and negatively (2, 26, 40, 66). The effect depends on the type of training performed. From the research literature, there are 3 distinctive types of strength training, which have differing physiological effects on the organism: maximal strength, maximal intensity, and maximal work (67). Maximal strength training involves near-maximal loads lifted for multiple sets of few repetitions. Maximal intensity training uses submaximal loads lifted with maximal acceleration for multiple sets of low to moderate repetitions. Maximal work training involves a high volume of lifts with submaximal loads.

Maximal intensity training has the largest fitness after-effect, which is of short duration (9, 19, 34, 51, 52). Maximal work training has the smallest fitness after-effect, yet the duration is longest (25). Maximal strength training has a smaller fitness after-effect than maximal intensity training (9, 19, 34, 51, 52). The fatigue after-effects are similar, with maximal intensity resulting in large fatigue for a brief period and maximal work resulting in low-levels of fatigue for a prolonged period (5–7, 9, 17, 19, 25, 34, 51, 52, 56, 66).

In planning a single training session, maximal intensity and maximal strength training always precede maximal work. The onset of fatigue with maximal work training is nearly immediate, as opposed to maximal intensity and strength, where the fitness after-effect offsets fatigue (17, 25). Elite athletes can perform maximal strength training before maximal intensity. This sequencing takes advantage of the posttetanic potentiation phenomenon (9). Lesser-trained athletes, however, should always perform maximal intensity training before maximal strength training. Elite athletes may also use this sequencing. In lesser-trained individuals, fatigue follows maximal strength training, impairing maximal intensity performance (9, 11).

Rather than training multiple strength qualities in a single training session, dividing training into multiple sessions per day may be appropriate. Even when total training volume was equal, athletes who trained twice per day improved strength more than individuals who trained only once per day (26). Only athletes who have a high level of general fitness should perform multiple daily training sessions. From preliminary research, maximal strength training sessions precede maximal intensity sessions. The large fatigue after-effect from maximal intensity training appears to manifest during the session or in the intersession interval (2, 66). This fatigue after-effect negatively affects maximal strength, but not explosive strength (2). A single maximal intensity training session results in decreased force production during a second training session 4–6 hours later. The earlier training session does not affect explosive strength or training velocity. Again, when training multiple times per day, maximal work training occurs last.

Short-Term Training

When concurrently training multiple strength qualities, early in the week the emphasis should be on maximal intensity. As the fatigue after-effect is shortest for maximal intensity training, this arrangement has the smallest negative effect on subsequent days of training. Additionally, the large fitness after-effect may positively influence subsequent training days. A day emphasizing maximal strength occurs after days of maximal intensity training, so it does not negatively affect the maximal intensity training sessions. Similarly, maximal work occurs toward the end of the week, closer to days of rest, which will allow fatigue to recover.

In general, training sessions resulting in a large fitness after-effect and a brief fatigue after-effect should occur early in the training week. The positive change in performance from the fitness after-effect allows the athlete to train harder in subsequent days. Training sessions resulting in a longer fatigue after-effect occur later in the training week, immediately before rest days. The rest days allow fatigue to subside. Even 1 day per week of rest can be sufficient for recovery (12, 13).


High-level human performance requires years of diligent training. Coaches and athletes should not leave performance adaptations to chance. Proper planning and organization of training results in the desired performance outcomes, and empirical and scientific evidence is in support of modeling training after the fitness-fatigue theory. From the design of the yearly training structure to each individual training session, an athlete's training plan should account for fitness and fatigue after-effects in an effort to maximize the effects of training. σ


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