The condition in which the muscles in the leg are injured is called a leg strain. This occurs when the muscle is stretched beyond its normal length causing small rips called microtears in the fibers of the muscle. A strain to the leg may also occur if there is a forceful tightening or contraction of a muscle or group of muscles. A strain may also cause problems in the tendon, the cable-like cord which connects the muscles to the bones.
Each muscle is comprised of a network of thin strands called fibers held together by a thin membrane. When the muscle is overly stretched and the integrity of the muscle network is compromised, pain and swelling can occur. Pain from leg strain is increased when the movement which caused the injury is repeated.
The amount of injury sustained from a leg strain is classified by a grading system. A Grade 1 strain is where there is a small amount of stretching resulting in a limited number of fibers that are damaged. There may be some tenderness present but overall movement is intact. A Grade 2 leg strain presents with an increase in pain and swelling.
When the muscle tear is extensive or actually causes the muscle to rip away from the tendon, it is considered to be a Grade 3 leg strain. Grade 3 leg strains cause significant swelling and pain issues. Mobility may be severely limited or there may be an inability to move the affected area at all. There also may be a visible deformity in the look of the muscle.
A leg strain can occur in any muscle of the leg. An injury to the calf muscle, referred to as a "gastrocnemius strain" after the muscle that is injured, can be caused by a sudden forceful movement of the toes upwards. This causes a stress on the calf and can tear the fibers of the muscle. Leg strains can also occur in the hamstrings or back of the knee, and the quadriceps, or thigh muscles. Straining of the posterior knee or thigh muscles is a common injury seen with jogging, running or sprinting.
To prevent a leg strain, a comprehensive stretching routine and proper physical training can be beneficial. Treatment of a leg strain includes the application of ice to reduce swelling issues. A stoppage of activity is also required to rest the area and allow healing of the muscle fibers. In extreme cases, where mobility is severely limited and healing is hampered, surgical repair of the muscle fibers may be necessary.