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.
Linda J. Vorvick, MD, Medical Director, MEDEX Northwest Division of Physician Assistant Studies, University of Washington, School of Medicine. Also reviewed by David Zieve, MD, MHA, Medical Director, A.D.A.M., Inc.