What is the order of motor unit recruitment in a high rep set?

In a high-rep set, motor unit recruitment typically follows the size principle, where smaller motor units are recruited first before larger ones. Initially, low-threshold, fatigue-resistant type I muscle fibers are activated to sustain endurance. As the set progresses and fatigue increases, larger motor units, which include fast-twitch type II fibers, are recruited to generate greater force. This sequential recruitment helps optimize performance and efficiency during prolonged activities.