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.

A concentric contraction is a type of muscle activation that causes tension on your muscle as it shortens. As your muscle shortens, it generates enough force to move an object. This is the most ...

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