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.
More than 30 types of muscular dystrophy have been identified. They all cause problems with movement due to muscle protein defects caused by genetic mutations. Muscular dystrophy is a group of ...
Institute of Human Anatomy - IOHA on MSN

The different types of muscle in your body

Discover the three main types of muscle in the human body and their distinct functions.