A hamstring strain is a tear on one or more of the hamstring muscles. It is a common sports injury. Generally the hamstring muscle is overstretched beyond its limits and due to this the muscle tissues is torn. The hamstring consists of three hamstring muscles. These muscles are the Semitendinosus, Semimembranosus and the Biceps femora’s.

The prime role of the hamstring muscles is to flex the lap and to move the thigh backwards so as to meet the hip. A person who understands perfectly well how the hamstring works will know the mode of injuries to expect. Sporting events that involves sprinting such as football, rugby and athletics causes mild to severe strains. Hamstring strains are graded in three groups depending on the severity. Grade I consists of negligible tears within the muscle. In this grade you will be able to walk in a normal way but you will experience some discomfort. There will be minimal swelling and tightness in the posterior thigh.

Grade II is characterized by partial tear in the muscle. Walking will be affected as you will be limping and there will be a bit of swelling. Your activities will be affected as sudden twinges of pain will be felt as pressure builds. The inability to straighten the knee fully and therefore flexing it against resistance causes a great deal of pain. Grade III is the most severe as it can be a complete rapture of the muscle. Unlike in the other grades, walking will be completely affected as you may require walking aid like crutches. There is severe pain in the event that the knee is flexed and swelling is so much visible. When a strain is so severe and the muscles are under so much pressure, they rapture and sometimes leave gaps. Resting on your stomach on the ground and then bending the knee without putting pressure on it will reduce the pain.