Final answer:
The statement is true; the CNS recruits the smallest motor units first when new force is required, progressing to larger ones as more force is needed. This is part of the muscle contraction process allowing precise control over muscle tension and movement.
Step-by-step explanation:
The statement, 'In order to produce greater force for any performance, the CNS will recruit the smallest motor unit first', is true. This concept is known as the size principle. Initially, the central nervous system (CNS) recruits the smallest motor units, which have more excitable, lower-threshold motor neurons and control smaller muscle fibers. This results in a minimal force output suitable for precise, low-force tasks. As the requirement for force increases, larger motor units with higher-threshold motor neurons and larger muscle fibers are recruited. This hierarchical recruitment is a key strategy in muscle contraction and force production, allowing for everything from gentle to very powerful movements.
Additionally, the nervous system can vary muscle contraction force by changing the frequency of action potentials and by the number of myofibers activated. Muscle fibers respond fully when stimulated by their innervating neuron, with full recruitment leading to maximal force production. However, this maximal force is unsustainable due to energy demands, so the CNS recruits motor units alternately, maintaining contractions over longer periods and preventing muscle fatigue.