Final answer:
When equal torque and resistance occur in an MTU, the muscle experience isometric contraction, producing tension without changing its length. Maximum recruitment of this muscle state cannot be sustained long due to high energy demands. Proper training can enhance muscle strength and connective tissue resilience.
Step-by-step explanation:
When an MTU (muscle tendon unit) produces equal torque and resistance, there is no net movement within the muscle, meaning that the muscle is in isometric contraction. This condition occurs when muscle fibers generate tension through the formation of cross-bridges between actin and myosin filaments, but the overall length of the muscle does not change because the contraction force is balanced by an equal external resistance. In situations of maximum muscle recruitment, the tension produced is great, but this state cannot be maintained for extended periods due to the high energy demands and potential for muscle fatigue. Effective muscle training can incorporate knowledge of the force-torque relationship, gradually increasing muscle strength and connective tissue development to support higher contraction forces without causing damage.