General Principles of Periodization
When exploring the classic literature, it is clear that periodization is a method for employing sequential or phasic alterations in the workload, training focus, and training tasks contained within the microcycle, mesocycle, and annual training plan. The approach depends on the goals established for the specified training period (38, 52, 58). A periodized training plan that is properly designed provides a framework for appropriately sequencing training so that training tasks, content, and workloads are varied at a multitude of levels in a logical, phasic pattern in order to ensure the development of specific physiological and performance outcomes at predetermined time points.
In order for specific physiological responses and performance outcomes to develop, an appropriately sequenced and structured periodized training plan allows for the management of the recovery and adaptation processes (12, 18, 52, 64, 80). Since peak performance can only be maintained for brief periods of time (8-14 days) (9, 45, 55), the actual sequential structure of the periodized training plan is an essential consideration (64, 80, 85). Generally, the average intensity of the factors addressed by the training plan is inversely related to the average time that peak performance can be maintained and the overall magnitude of the performance peak (17, 38, 80).
For example, if the average intensity of all the training factors is high, the performance will elevate rapidly, but it will only be maintained for very brief periods. If, however, a more logical sequential modulation of training intensity is used, the period of peak performance can be extended. The magnitude of performance gain can also be significantly greater. Three basic mechanistic theories provide a foundational understanding for how periodization manages the recovery and adaptive responses: the general adaptive syndrome (GAS) (80, 88), stimulus-fatigue-recovery-adaptation theory (68, 80), and the fitness-fatigue theory (80, 88).
General Adaptive Syndrome
The general adaptive syndrome (GAS) is one of the foundational theories from which the concept of periodization of training was developed (78, 85). First conceptualized in 1956 by Hans Selye, the GAS describes the body’s specific response to stress, either physical or emotional (68). These physiological responses appear to be similar regardless of what stimulates the stress. While the GAS does not explain all the responses to stress, it does offer a potential model that explains the adaptive responses to a training stimulus (figure 11.1) (27, 78).
When a training stress is introduced, the initial response, or alarm phase, reduces performance capacity as a result of accumulated fatigue, soreness, stiffness, and a reduction in energy stores (78). The alarm phase initiates the adaptive responses that are central to the resistance phase of the GAS. If the training stressors are not excessive and are planned appropriately, the adaptive responses will occur during the resistance phase. Performance will be either returned to baseline or elevated to new higher levels (supercompensation). Conversely, if the training stress is excessive, performance will be further reduced in response to the athlete’s inability to adapt to the training stress, resulting in what is considered to be an overtraining response (20). From the standpoint of training response, it is important to realize that all stressors are additive and that factors external to the training program (e.g., interpersonal relationships, nutrition, and career stress) can affect the athlete’s ability to adapt to the stressors introduced by the training program.
Whenever a training stimulus is applied, there is a general response that has been termed the stimulus-fatigue-recovery-adaptation theory (figure 11.2) (80). The initial response to a training stressor is an accumulation of fatigue, which results in a reduction in both preparedness and performance. The amount of accumulated fatigue and the corresponding reduction in preparedness and performance is proportional to the magnitude and duration of the workload encountered. As fatigue is dissipated and the recovery process is initiated, both preparedness and performance increase. If no new training stimulus is encountered after recovery and adaptation are completed, then preparedness and performance capacity will eventually decline. This is generally considered to be a state of involution.
When closely examining the general response to a training stimulus, it appears that the magnitude of the stimulus plays an integral role in determining the time course of the recovery-adaptation portion of the process. For example, if the magnitude of the training load is substantial, a larger amount of fatigue will be generated, lengthening the time frame necessary for recovery and adaptation (66, 80). Conversely, if the training load is reduced, less fatigue will accumulate and the recovery-adaptation process will occur at a more rapid rate. This phenomenon is often referred to as the delayed training effect, in which the magnitude and duration of loading dictate the length of time necessary for recovery and adaptation. The modulation of the time course of the recovery-adaptation process through the appropriate variation and sequencing of workloads is a central theme of periodization.
In order to effectively develop periodized training plans, it is important to realize that the general pattern of response to a training stimulus can occur as a result of a single exercise, training session, training day, microcycle, mesocycle, or macrocycle. It is important to note that it is not necessary to have complete recovery prior to initiating a subsequent training stimulus (58). In fact, it may be more prudent to modulate training intensities or workloads with the use of heavy or light days of training in order to facilitate recovery (19) while attempting to continue to develop fitness. Ultimately, the ability to appropriately sequence training stimuli is based on the manipulation of training factors in order to take advantage of the recovery-adaptation process. In fact, this process serves as a foundation for several sequential models of training presented in the periodization literature (64, 83, 84).
One sequential model that is largely based on the stimulus-fatigue-recovery-adaptation theory is the concentrated loading or conjugated sequencing model presented by several authors in the literature (figure 11.3) (64, 80, 83, 84). In this scenario, a concentrated training load (64, 80), or accumulation
load (43, 44, 88), is applied for a specific period of time (80). After this application of intentionally high training loads, there is a significant reduction in the training load, and training is returned to normal levels. This is often referred to as the transmutation phase, where preparedness and performance are elevated (69, 83-85). The final phase of this loading paradigm involves a further reduction in training load. This is sometimes referred to as a peak, taper, or realization phase (43, 44, 55, 84, 85, 88). During this phase, preparedness and performance generally supercompensate in response to the further reduction in fatigue that is stimulated by the reduction in training load (55). If, however, this phase is extended for too long (>14 days), involution, or a reduction in preparedness or performance, will occur.
Through the manipulation of training variables, an appropriately sequenced and integrated periodized training plan allows for the management of the accumulated fatigue and the process of recovery and adaptation. It also directs the training responses toward the targeted outcomes. If training loads are haphazardly applied and inappropriately sequenced, achieving performance goals becomes less likely as a result of the mismanagement of fatigue and or recovery.
The fitness-fatigue paradigm partially explains the relationships among fitness, fatigue, and preparedness (80, 88). It also gives a more complete picture of the physiological responses to a training stimulus (11). In this paradigm, the two aftereffects of training, fatigue and fitness, summate and exert an influence on the preparedness of the athlete (11, 88). The classic depiction of the fitness-fatigue theory presents the cumulative effects of training as one fatigue and one fitness curve (figure 11.4) (11, 80). In reality, multiple fitness and fatigue aftereffects likely exist in response to training that are interdependent and exert a cumulative effect (figure 11.5) (11).
The possibility of multiple fitness and fatigue aftereffects offers a partial explanation as to why there are individual response differences to variations in training (11, 80). Conceptually, the aftereffects of training are considered as residual training effects. They serve as the basis for sequential training (43, 44, 82, 85). Sequential training suggests that the rate of decay for a residual training effect can be modulated with either minimal training stimulus or through the periodic dosing of the specified training factor. Additionally, the residual effects of one training period can phase, potentiate, or elevate the level of preparedness of the subsequent periods, depending on the loading paradigms employed.
When the GAS, stimulus-fatigue-recovery-adaptation theory, and the fitness-fatigue theory are examined collectively, it is very clear that the ability to balance the development of various levels of fitness while facilitating the decay of fatigue is essential in modulating the adaptive responses to a training plan. An essential concept that allows for the appropriate modulation of training factors relates to sequencing training interventions to facilitate the management of fatigue and fitness while controlling the athlete’s preparedness (64). Therefore, it is crucial when designing training interventions that the actual sequential pattern be considered in the context of how the training intervention is structured. This allows for the management of fatigue while maximizing the recovery adaptation process.
Ultimately, it results in the optimization of specific fitness parameters at key points so that preparedness and performance are elevated at the appropriate times.