A muscle strain is the stretching or tearing of muscle fibers. A muscle strain can be caused by sports, exercise, a sudden movement, or trying to lift something that is too heavy. Symptoms of a muscle strain include pain, tightness, swelling, tenderness, and the inability to move the muscle very well.
Reviewed By: Linda J. Vorvick, MD, Clinical Associate Professor, Department of Family Medicine, UW Medicine, School of Medicine, University of Washington, Seattle, WA. Also reviewed by David Zieve, MD, MHA, Medical Director, Brenda Conaway, Editorial Director, and the A.D.A.M. Editorial team.