Muscular Adaptation

The principle of Darwinism may be a broad description of how natural selection has influenced the evolution of species, but a specific set of definitions on muscular adaptation can shed further light on why this “survival of the fittest” theory has a strong foundation.

General Adaptation Syndrome

General Adaptation Syndrome is the umbrella of adaptation. It is how the body adapts to circumstances in which it is placed. These circumstances can involve stress in the form of weight or load, and can even be environmental such as atmosphere or climate. At first, the body will experience a shock to the change presented. Physiologically this will take shape in the form of cardiovascular and neurological responses to increase blood flow and neuromuscular signals to react to the event. This is followed by a resistance development where the body becomes more efficient at responding to the stressors placed on it. Lastly, the body reaches exhaustion which results in pain, fatigue, and potentially injury.

Principle of Specificity

The Principle of Specificity, or the “SAID (specific adaptation to imposed demands)” (Clark, 2018, p. 307), dictates that the body will adapt to very specific demands in very specific ways. A rudimentary example of this is the formation of a callous when playing guitar as the fingers repeatedly experience the same stressor and adapt. In terms of muscular fitness, this is directly related to the format of training in which a client participates. Exercising with higher weight and lower reps will elicit a much different response than lower weight with higher reps. The body responds by focusing on the growth of Type II or Type I muscle fibers respectively.

Progressive Adaptation

Progressive Adaptation allows the individual to improve targeted mechanisms of growth through selective resistance training. Stabilization, muscular endurance, muscular hypertrophy, strength, and power are such mechanisms of growth. Stabilization training will engage the appropriate muscles during chosen exercises so that the primary mover is providing the main force production while the stabilizing muscles are focused on their role instead of overcoming the primary. Muscular endurance goes hand in hand with stability as it refers to the muscular ability to maintain stabilization throughout longer periods of time. Muscular hypertrophy is directly indicated by the growth in the physical size of the muscles, in particular, the fibers themselves, as they respond to increased load. Strength could then be seen as the capacity for each fiber to create tension in comparison to the physical growth of hypertrophy. Lastly, power is a combination of several aforementioned components with a time dimension added. More force over a smaller amount of time is the adaptation of power.

The general adaptation syndrome is beneficial when a change in occupation may illicit the need for physiological changes. This could be someone transitioning from a desk job to a warehouse position that may involve lifting that was not done before. The body will adapt as required by the circumstance. Specificity is crucial for those looking to improve in specific areas such as an Olympic sprinter who needs to focus on training for speed rather than endurance. Lastly, progressive adaptation is valuable for someone who has the goal of obtaining a similar physical appearance to the Grecian ideal as they prioritize muscular hypertrophy for those muscle groups that need to adjust to match size and appearance.


Clark, M. A., Lucett, S. C., McGill, E., Montel, I., & Sutton, B. (2018). NASM essentials of personal fitness training. Burlington, MA: Jones & Bartlett Learning.

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