Heavy resistance training leads to changes in motor unit size such that all motor units increase in size due to recruitment of high-threshold units. What is this effect best described as?

Heavy resistance training leads to changes in motor unit size such that all motor units increase in size due to recruitment of high-threshold units. What is this effect best described as?

• A. Decreases Firing Thresholds
• B. Increases Recruitment Of High-Threshold Motor Units
• C. Selective Atrophy Of Low-Threshold Units
• D. Decreases Maximum Force

Answer: (B)

Neural adaptations from heavy resistance training increase the recruitment of high-threshold motor units. When you lift heavy loads, the nervous system becomes better at activating larger motor neurons that innervate fast-twitch fibers, so these high-threshold units contribute more to force production. Over time, this leads to greater overall muscle strength as these units are recruited more readily and with greater drive. The other ideas don’t fit as well: while recruitment thresholds can shift with training, the defining description here is the increased recruitment of high-threshold motor units; selective atrophy of low-threshold units isn’t supported by typical strength training adaptations; and decreasing maximum force contradicts the gains seen with heavy training.

Neural adaptations from heavy resistance training increase the recruitment of high-threshold motor units. When you lift heavy loads, the nervous system becomes better at activating larger motor neurons that innervate fast-twitch fibers, so these high-threshold units contribute more to force production. Over time, this leads to greater overall muscle strength as these units are recruited more readily and with greater drive. The other ideas don’t fit as well: while recruitment thresholds can shift with training, the defining description here is the increased recruitment of high-threshold motor units; selective atrophy of low-threshold units isn’t supported by typical strength training adaptations; and decreasing maximum force contradicts the gains seen with heavy training.