Generalized Theories of Training

Generalized training theories are very simple models that are used broadly to solve practical problems. They include only the most essential features of training, omitting numerous others. These theories (models) serve as the most general concepts for coaching and are used especially for conditioning and planning training programs.

One-Factor Theory (Theory of Supercompensation)
In one-factor theory, the immediate training effect of a workout is considered as a depletion of certain biochemical substances. The level of preparedness (potential sport performance) is assumed to vary due to the amount of these biochemical substances. The best example would be muscle glycogen depletion after a hard workout. After the restoration (recovery/rest) period, it is believed that the biochemical substances are increased above the initial level. This is called supercompensation and the time with this higher level of the substance is called the supercompensation phase. If the rest intervals between training sessions are too short, the level of an athlete's preparedness decreases. If the rest intervals are the right length and coincides with the supercompensation phase, perparedness increases. If the rest intervals are too long, preparedness is thought not to change. Coaches and athletes should seek both optimal rest intervals between training sessions and optimal training loads in each workout, so that training sessions land within the supercompensation phase.

For several decades this was the prevailing model, however, it is not without it's downsides. For instance, the existence of the supercompensation phase has not been experimentally proven for the majority of metabolic substances. Glycogen supercompensation HAS been proven and can be achieved by proper programming and carbohydrate loading, however, this effect cannot be reproduced regularly and is used for competition, not training. Due to these and several other reasons, this theory has been losing popularity.

Two-Factor Theory (Fitness-Fatigue)
Two-factor theory is based on the idea that preparedness is NOT stable, but rather varies with time. The immediate effect after a workout is considered a combination of fitness gain (prompted by workout) and fatigue. After a workout, preparedness increases due to fitness gain, but also diminishes due to fatigue. The final outcome is determined by the summation of the positive and negative changes. The fitness gain (physical fitness) is relatively small in magnitude but long lasting, whereas fatigue is relatively large in magnitude, but short lasting. In a most crude estimation, it is assumed that after one workout with an average training load, fitness gain and fatigue differ by a factor of three: the fatigue is three times shorter than the fitness gain. Basically, this means that if fatigue from a workout lasted 24 hours, the fitness gain would last for 72 hours.

According to this theory, the time between successive training sessions should be selected so that the fatigue effects are nonexistent and the fitness gains prevail. This model has been becoming more popular among coaches and is used mainly to plan training, especially during the final training days before competition.

References
Zatsiorsky, V., and Kraemer, J. (2006). Science and Practice of Strength Training. Champaign, Illinois: Human Kinetics