Muscular endurance is the ability of the muscles to perform a physical activity over a period of time without muscle fatigue. It involves the support of the circulatory and respiratory systems for the production of energy. Energy is needed by the contracting muscles to sustain the repetitions of the physical activity. The oxygen and nutrients for this energy are delivered by the respiratory and circulatory systems to the muscles. These systems also remove the toxic waste by-products from the muscle cells.

Using light weights and performing many repetitions of an exercise (low resistance, high repetitions) will increase muscular endurance. This form of exercise is often referred to as muscle toning or body sculpturing.