Muscle knots are highly irritated muscle fibers that have tightened into a ball in one area of your muscle. These painful, tender spots can feel sore and often occur in your upper back, shoulders, or ...

Touching your toes depends on the flexibility of your hamstrings, calves, ankles, glutes, hips, and lower back. Tightness in any one area can limit your reach. You may be able to improve flexibility ...

A muscle spasm — also known as a charley horse, muscle cramp or twitch — is a sudden, involuntary movement in one or more muscles. Common causes include stress, exercise, or dehydration, but nerve ...

The muscular system works to control the movement of our body and internal organs. Muscle tissue contains something called muscle fibers. Muscle fibers consist of a single muscle cell. They help to ...