Muscle contraction is the tightening, shortening, or lengthening of muscles when you do some activity. It can happen when you hold or pick up something, or when you stretch or exercise with weights.

Medically reviewed by Jennifer Steinhoff, MD Key Takeaways Muscle strength grading helps evaluate muscle strength on a scale ...

For people with paralysis or amputation, neuroprosthetic systems that artificially stimulate muscle contraction with electrical current can help them regain limb function. However, despite many years ...

The flow of water within a muscle fiber may dictate how quickly muscle can contract, according to a new study. The flow of water within a muscle fiber may dictate how quickly muscle can contract, ...