Muscle strain, muscle pull, or even a muscle tear refers to damage to a muscle or its attaching tendons.You can put undue pressure on muscles during the course of normal daily activities, with sudden heavy lifting, during sports, or while performing work tasks.uscle damage can be in the form of tearing (part or all) of the muscle fibers and the tendons attached to the muscle. The tearing of the muscle can also damage small blood vessels, causing local bleeding, or bruising, and pain caused by irritation of the nerve endings in the area.