Final answer:
The principle of specificity or specific adaptation to imposed demands (SAID) states that specific exercises elicit targeted adaptations to improve fitness goals. This principle is essential for increasing muscular strength and size through strength training, or enhancing endurance through aerobic exercises based on individual muscle fiber composition.
Step-by-step explanation:
The principle that states specific exercise elicits specific adaptations, creating specific training effects, is known as the principle of specificity or specific adaptation to imposed demands (SAID). This principle is crucial in designing effective workout programs that meet specific fitness goals. For instance, to improve muscular strength, you should engage in strength training exercises with increasing intensity, such as progressively lifting heavier weights. This increase in intensity leads to muscle hypertrophy, where structural proteins are added to muscle fibers, increasing cell diameter.
Conversely, for improving endurance, exercises that recruit slow-twitch muscle fibers like long-distance running or cycling should be practiced. These activities enhance aerobic efficiency through the production of more mitochondria, allowing muscles to sustain contractions for longer periods. Lack of exercise or incorrect training can lead to muscle atrophy or sarcopenia, which is the loss of muscle mass and structural proteins due to decreased muscle use or aging.
It's essential to recognize that individuals may respond differently to exercise due to genetic variations in muscle fiber composition. Nevertheless, adhering to the principle of specificity ensures that the chosen exercises correspond directly to the desired outcomes, whether it's increased muscle mass, strength, or endurance.