What term describes a muscle's ability to repeatedly contract without fatiguing?

Muscular endurance refers to a muscle's ability to sustain repeated contractions over time without experiencing fatigue. In practical terms, this means that someone with good muscular endurance can perform activities such as running, cycling, or doing multiple repetitions of an exercise for an extended period. This capacity is essential for various physical activities that require prolonged effort.

The other choices do not accurately capture this specific characteristic. Muscular strength relates to the maximum amount of force that a muscle can produce in a single effort, while muscular fitness encompasses a broader range of strength, endurance, and flexibility. Muscular tone refers to the continuous and passive partial contraction of the muscles, which contributes to posture and readiness for action but does not specifically address the concept of fatigue during repeated contractions. Therefore, muscular endurance is the precise term that describes the ability to perform sustained muscle contractions without quickly becoming fatigued.