by Essentials of Strength Training and Conditioning-4th Edition With Web Resource
Kinetic Select May 2017
The following is an exclusive excerpt from the book Essentials of Strength Training and Conditioning-4th Edition, published by Human Kinetics. All text and images provided by Human Kinetics.
A successful training program allows for management of the adaptive and recovery responses to specific interventions that are delivered in a structured way (28). The ultimate success of any training program centers on its ability to induce specific physiological adaptations and translate those adaptations into increases in performance. At the center of this process is the ability to manage the adaptive response, handle accumulated fatigue, and capitalize on the aftereffects established from the various training factors encountered.
The strength of a periodized training plan lies in its ability to sequence and structure the training interventions in order to manage all of these factors and peak performance at appropriate time points (4-6,51,59,63). Ultimately, peak performance can be optimized only for short periods of time (7-14 days), and the average time it can be maintained is inversely related to the average intensity of the training plan (17,33,59). In order to elucidate how periodized training models can manage these factors, three basic mechanistic theories have been established: the General Adaptation Syndrome (GAS), stimulus-fatigue-recovery-adaptation theory, and the fitness–fatigue paradigm (22,28,59,65).
• Periodization is the logical and systematic process of sequencing and integrating training interventions in order to achieve peak performance at appropriate time points.
In 1956, Hans Selye, a pioneering researcher on the biological effects of exposure to stressful stimuli, presented the basic concepts of the GAS in which a three-stage response to stress (alarm, resistance, and exhaustion) was defined (54,55). While not originally conceptualized in the context of physical training, over time the GAS has become one of the foundational concepts from which periodization theories have been developed (21,59). Any time the body experiences a novel, new, or more intense stress than previously applied (e.g., lifting a heavier training load or a greater volume-load; see chapter 17), the initial response, or alarm phase, is an accumulation of fatigue, soreness, stiffness, or reduction in energetic stores that results in a reduction in performance capacity (59).
Depending on the magnitude of the stress encountered by the athlete, this response may last several hours, days, or weeks. After this initial response, the body moves into the resistance phase, in which it adapts to the stimulus and returns to a normal functional capacity. If the training stress is appropriately structured and not excessive, these adaptive responses can result in specific biochemical, structural, and mechanical adjustments that further elevate the athlete’s performance capacity, resulting in what is termed supercompensation (58).
If, however, the stress persists for an extended period of time, the athlete can move into the exhaustion phase. If this occurs, the athlete is demonstrating an inability to adapt to the imposed stressors and will present some of the same symptoms noted in the alarm phase. Ultimately, when athletes reach the exhaustion phase they are most likely experiencing overreaching or overtraining responses (20). From a training perspective, excessive loading, monotonous training, and overly varied training can all result in the occurrence of the exhaustion phase.
Additionally, the responses to training can be affected by other non–training-related stress (e.g., occupational issues, insufficient sleep, relationship, poor diet) that can contribute to the overall stress level experienced by the athlete. Ultimately, the strength and conditioning professional should strive to avoid the occurrence of this phase of the GAS through the proper planning and management (periodization) of training stressors. Although the actual dimensions (i.e., slope, magnitude, and timing) of the curve shown in Figure 21.1 are highly individualized, the figure represents the basic application of the GAS to training responses.
The stimulus-fatigue-recovery-adaptation theory is an extension of the GAS and suggests that training stimuli produce a general response (Figure 21.2) that is influenced by the overall magnitude of the training stressor (59). Specifically, the greater the overall magnitude of the workload encountered, the more fatigue accumulates and the longer the delay before complete recovery and adaption can occur. As the athlete recovers from and adapts to the training stimuli, fatigue will dissipate, and preparedness and performance increase.
If no new training stimulus is introduced, a state of involution or detraining (i.e., a reduced overall capacity, to below the current baseline) is observed. In contrast, if a new training stimulus is introduced, the process is repeated. This basic pattern is present whenever an athlete is exposed to a training exercise, session, day, or cycle within a periodized training plan. It should be noted that while recovery is an important part of the training process, it is not always necessary to reach a state of complete recovery before engaging in a new bout or session of training (49). The manipulation of workloads and training intensities through use of light and heavy sessions or days of training can be used to modulate fatigue and recovery responses (9,19) while allowing for fitness to be either increased or maintained.
Conceptually, this theory serves as the foundation for sequential periodization models in that these models allow for the manipulation of various training factors to modulate the athlete’s overall fatigue levels, rate of recovery, and adaptive response to the training stimuli.
Generally, there is a summation of the two primary training aftereffects (i.e., fitness and fatigue) in response to training interventions that influence the athlete’s level of preparedness (3,14,66). Zatsiorsky (65) presents the classic explanation of these relationships as the fitness– fatigue paradigm (Figure 21.3). Ultimately, every training bout, session, or cycle creates both fatigue and fitness aftereffects, which summate to create a state of preparedness (14,65). When training loads are the highest, fitness becomes elevated; but because of the high training loads, a concomitant increase in fatigue occurs. When fitness and fatigue are summed in this case, the level of fatigue results in a reduction in preparedness.
On the other hand, when training workloads are low, little fatigue occurs and minimal fitness is developed, resulting in a low level of preparedness. Thus the sequencing of training loads becomes important in that it allows for training workloads to be varied in a systematic manner. An important thing to remember is that fatigue dissipates at a faster rate than fitness, thus allowing preparedness to become elevated if appropriate training strategies are used to retain fitness while reducing fatigue (25,28). While the fitness–fatigue paradigm is classically represented as one fatigue, fitness, and preparedness curve, it is likely that each training factor stimulates its own individual fitness, fatigue, and preparedness aftereffect response (14,59).
These aftereffects are often considered to be residual training effects and serve as a fundamental concept underlying the use of sequential periodization models (25,28). Ultimately, the residual training effects of one training period have the potential to affect the level of preparedness in subsequent training periods, depending on the overall structure of the periodized training plan (28).
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