A muscle strain is an injury to a muscle or a tendon — the fibrous tissue that connects muscles to bones. Minor injuries may only overstretch a muscle or tendon, while more severe injuries may involve partial or complete tears in these tissues.
Sometimes called pulled muscles, strains commonly occur in the lower back and in the muscles at the back of the thigh (hamstrings).
The difference between a strain and a sprain is that a strain involves an injury to a muscle or to the band of tissue that attaches a muscle to a bone, while a sprain injures the bands of tissue that connect two bones together.
Initial treatment includes rest, ice, compression, and elevation. Mild strains can be successfully treated at home. Severe strains sometimes require surgical repair.