Final answer:
Holding a light load until exhaustion requires graduated recruitment of motor units from smaller to larger, eventually leading to all motor units being activated for a brief period to maintain force output, which is 'True'.
Step-by-step explanation:
True or False: If holding a light load past exhaustion, it is likely that all Motor Units (MUs) have been recruited. This statement is True. When performing a task that requires muscle endurance, such as holding a light load until exhaustion, the nervous system recruits motor units in a graduated fashion from smaller to larger until it is necessary to use all available motor units to maintain the load as muscles become fatigued. Eventually, all motor units may be activated to attempt to sustain the required force output. However, maximal recruitment occurs for very brief periods because of the high energy demands and risk of complete muscle fatigue.