Final answer:
Muscular endurance refers to the ability of a muscle to continue to contract over a long time without becoming fatigued, which is different from muscular strength or power.
Step-by-step explanation:
The term that is best described as the number of repeated contractions a muscle or muscle group can perform against a resistance without fatiguing is endurance. Muscular endurance is a measure of how long a muscle can continue to exert a force or perform repeated actions without becoming exhausted. This is different from strength, which is the amount of force a muscle can produce in a single contraction, or power, which combines strength and speed. A repetition max refers to the maximum number of times an individual can lift a particular weight, which is a measure of strength, not endurance.
During exercise, motor units in a muscle are not all simultaneously active to prevent complete muscle fatigue, thus allowing for longer muscle contractions. This recruitment mechanism ensures more efficient utilization of skeletal muscles and contributes to muscle endurance. Additionally, the length-tension relationship within a sarcomere, which defines the optimal overlap for cross-bridges formation between actin and myosin, plays a role in the force generated and thus the endurance capacity of the muscle.