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.

Skeletal muscle cells facilitate voluntary movements such as walking, running, and other forms of exercise. They are comprised of thin, tubular cells called muscle or myofibres due to their threadlike ...

A physical therapist explains why downhill walking causes more injuries and how to build strength safely.