Which is NOT an adaptive change in the nervous system in response to resistance training?

The correct choice highlights an aspect of the nervous system's response to resistance training that is not typically classified as an adaptive change. While resistance training does lead to certain adaptations in neural function, increased motor unit firing synchronicity is less commonly emphasized compared to other adaptations.

When individuals engage in resistance training, the nervous system undergoes various adaptations to enhance performance and strength. Increased recruitment of motor units refers to the body’s ability to activate more muscle fibers simultaneously during exercise, which improves strength and power output. Similarly, the increased firing rate of the motor units involves the ability of the motor neurons to stimulate muscle fibers more frequently, contributing to greater force production.

In contrast, while motor unit firing synchronicity—where multiple motor units fire at the same time—can sometimes improve movement efficiency and coordination, it is not universally recognized as a primary adaptation from resistance training. The most notable changes typically revolve around motor unit recruitment and firing rates due to their direct impact on muscles during resistance exercises.

Additionally, increased protein synthesis, although related to muscular changes, pertains more to the muscle tissue itself rather than a direct adaptive change within the nervous system. This emphasizes the distinction between muscle adaptations and neural adaptations following resistance training.