Which of the following best describes muscular endurance?

Muscular endurance is defined as the ability of a muscle or group of muscles to perform repeated contractions over time without significant fatigue. This characteristic is essential for activities that require sustained effort, such as running, cycling, or performing multiple repetitions of a given exercise.

In contrast, the other options pertain to different aspects of physical fitness. Lifting heavy weights relates more to muscular strength, which focuses on the maximum amount of force that a muscle can generate in a single effort. The capacity for high-intensity activities is connected to anaerobic power and strength rather than endurance, which specifically assesses how long muscles can sustain activity over time. Lastly, the ability to stretch your muscles pertains to flexibility, which is a separate component of fitness and does not directly relate to the endurance of muscle contractions.

Therefore, the emphasis on repeated contractions is what accurately captures the essence of muscular endurance.