Muscular endurance refers to the ability to resist muscular fatigue or to persist in physical activity. Along with muscular strength, cardiovascular endurance, flexibility, and body composition — muscular endurance is one of the five primary components of physical health. Like muscular strength, endurance is developed by placing a greater than normal physical demand on the muscles, thereby forcing adaptation. Adaptation takes place on the neurological, cellular, and tissue level to better equip the muscles to cope with the demands placed on them.
Not to be confused with muscular strength, endurance is a measure of the ability to sustain muscular activity over time. While there is no clear distinction between cardiovascular endurance and muscular endurance — both require muscular activity over extended periods — there are identifiable differences. The limiting factor of cardiovascular endurance is primarily the capacities of the heart and lungs, rather than the physiology of the muscles themselves. Endurance typically involves a greater resistance, and generally cannot be sustained for as long as cardiovascular activities.
Muscular endurance training can increase bone mineral density, improve tolerance to lactic acid concentrations, and strengthen the integrity of muscular connective tissue. Additionally, there is considerable crossover between endurance training and other aspects of muscle and cardiovascular conditioning. Training to increase muscular endurance, then, can benefit muscular strength and cardiovascular endurance as well.
In addition to personal levels of physical conditioning, endurance can be affected by factors such as hydration, level of fatigue, and nutritional status. To work efficiently, muscle cells require adequate stores of carbohydrates in the form of glycogen, as well as readily available water, calcium, and creatine phosphate within the cell. Observing a sensible, balanced diet, along with sufficient rest and fluid intake, helps to promote maximum endurance.
Typical endurance training programs focus on resistance training with high numbers of repetitions and low to moderate weight loads. A range of 30-50 percent of the athlete's one repetition maximum test will normally allow sufficient resistance to develop endurance without being too heavy. Whereas strictly power-oriented training programs generally recommend performing eight repetitions or fewer per set, endurance exercises should be carried out for a minimum of 12 repetitions over several sets.
Martial arts, gymnastics, and military training typically involve workouts that tend to build endurance. Calisthenic exercises — such as push-ups, sit-ups, and lunges — are excellent choices for endurance-building workouts. For very little cost, one can devise a highly effective training program that utilizes only body-weight resistance and limited equipment, that will also benefit other aspects of physical fitness.