With training, it is possible to consciously contract more muscle fibers, increasing the force of contraction.

• A. True
• B. False
• C. Not determinable
• D. Only in cardiac muscle

Answer: (A)

With training, the nervous system becomes better at voluntarily activating more motor units and firing them more rapidly, and the muscles can grow larger, all of which together increase the force a contraction can produce. Through strength training, your brain learns to recruit a greater number of motor units at a given effort and to synchronize their firing more effectively, so more fibers contribute to the contraction. Hypertrophy adds to this by increasing the muscle’s cross-sectional area, allowing each fiber to generate more tension. Cardiac muscle isn’t under conscious control, so the idea that this only applies there isn’t correct. Not determinable isn’t appropriate because there’s clear evidence of these adaptations with training. Thus, the statement is true.