Why do muscles get bigger when weights are lifted?


Quick Answer

When muscles work, as they do when lifting a heavy load, they experience stress that tears the muscles' fibers, according to Weight Watchers. The body repairs those microscopic tears, creating bigger and stronger muscle fibers. Muscle soreness the day or two after exercising can indicate that one has fatigued muscles enough to build them.

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Why do muscles get bigger when weights are lifted?
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Full Answer

To build muscle, one can use a cycle of stress, rest and repeat, explains Weight Watchers. During the stress phase, one lifts weights or moves the body aerobically through activities such as walking, swimming, biking or running, until the muscles are overloaded but not exhausted. Next, one must allow the muscles to repair and recover by resting for up to 48 hours. Injury can result from inadequate rest followed by too strenuous an activity. Adequate sleep and good nutrition also contribute to muscle healing and injury prevention. To continue muscle building, muscles are next worked again by being stressed or overloaded.

During exercise, Weight Watchers counsels that one must not push beyond pain, because pain is a sign of injury. In general, bigger muscles, such as those in the legs, buttocks and arms, require a larger load and a longer recovery time to get stronger, while smaller muscles require a smaller load and a shorter recovery time.

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