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.

Men and women who briefly contracted their arm muscles as hard as possible once daily increased their biceps strength by up to 12 percent in a month. By Gretchen Reynolds Could three seconds a day of ...

SCULPTING A SET of strong, muscular arms is high among the top priorities guys have at the gym. The big arms ideal is often thought to be a purely aesthetic pursuit—and for some trainees, that might ...

Ken Nosaka does not work for, consult, own shares in or receive funding from any company or organization that would benefit from this article, and has disclosed no relevant affiliations beyond their ...