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.

What Are Eccentric and Concentric Contractions? Eccentric contractions occur when a muscle lengthens under load, such as lowering a dumbbell during a biceps curl. Concentric contractions happen when ...

The origin is the end of a muscle which is attached to a fixed bone. The insertion is the other end of the muscle that is attached to the bone which moves. Muscular contractions are defined as the ...