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.

The back consists of large, complex muscles that support your trunk and spine. There are many types of back muscles, and they are all essential, helping you walk, bend, twist, and hold your body ...

Muscles and nerve fibers allow a person to move their body and enable the internal organs to function. There are more than 600 muscles in the human body. People also have different types of muscle. A ...