Final answer:
A muscle develops its maximal force at an intermediate length due to the optimal overlap between actin and myosin filaments in the sarcomeres.
Step-by-step explanation:
The question pertains to the optimal length at which a muscle develops its maximal force. This is related to the length-tension relationship in the muscle's sarcomeres, which are the basic contractile units of muscle fibers. A muscle develops its maximal force at an intermediate length, where the overlap between the actin and myosin filaments in the sarcomeres is optimal for cross-bridge formation. When the muscle is at either a very shortened or overly stretched length, the force production is less efficient.
When it comes to recruiting motor units within a muscle for contraction, the nervous system is strategic in maximizing efficiency and preventing fatigue. Motor units are generally not all active at the same time; some rest while others are active, allowing for prolonged contraction without complete muscle fatigue. This mechanism allows muscles to generate stronger forces when more motor units are active.