A sprain is an injury to a ligament, whereas a strain involves damage to a muscle or tendon when these tissues are stretched or torn. A muscle spasm, or cramp, is a sudden, involuntary contraction of ...

Medically reviewed by Oluseun Olufade, MD A repetitive strain injury (RSI) is an injury caused by performing repeated motions over extended periods. It's often caused by common activities like typing, ...