Mixed

Failure to expand motor unit size via reinnervation distinguishes sarcopenic older men from healthy older men, indicating that successful motor unit remodeling is a critical mechanism for preserving muscle mass during aging.

For older men, maintaining muscle mass requires more than just resistance training; it requires preserving the neural connection to the muscle. The research suggests that healthy aging involves the nervous system compensating for neuron loss by expanding the size of remaining motor units. Sarcopenia may be characterized by a failure of this neural compensation mechanism. Therefore, interventions should focus on neuromuscular health and potentially high-threshold motor unit recruitment, not just muscle hypertrophy.