Your Hamstrings are the large muscles located at the back of your thigh. They start at your sitting bones and end below the back of your knee. A strained Hamstring is one of the most common injuries in sports which involve sprinting such as football or rugby. It usually occurs when the knee is extended in front of you such as with kicking a ball or when the heel strikes the floor during running. The strain can be graded according to severity and there are several factors that can predispose you to the injury.
The main functions of the Hamstrings are bending the knee and extending the hip therefore the opposite muscle would be the Quads which are responsible for extending the knee and flexing the hip. When your Hamstrings are weak and your quads are much stronger, it can create an imbalance when forcefully straightening the knee, placing a lot of stress on the Hamstrings which could lead to strains or tears in the muscle tissue. Another mechanism of injury is when the Hamstrings are not able to absorb the shock of loading the muscle and then rebound i.e. the contact phase of the foot on the floor when running.
The symptoms may vary according to the severity of the strain. Typically, it involves a sudden sharp and severe pain at the back of the thigh, buttocks or occasionally the knee. Sometimes a “pop” can be heard accompanied by bruising. Bending over, straightening or bending the knee reproduces the pain and the hamstring will be painful to touch.
A gr I injury is where the muscle is just pulled with no tear in the muscle fibres. You may still be able to walk normally.
A gr II injury involves some tears in the muscle fibres leading to swelling and muscle tenderness. Walking will be difficult as well as bending the knee against resistance.
A Gr III injury is a complete tear of the muscle. It usually involves a sudden intense pain that prevents any further activity. Sometimes crutches are necessary and bruising usually occurs.
The severity of the injury will determine the length of recovery. Initial management should include RICE (rest, ice, compression, elevation). Minors strains can heal within a few days where a severe strain can take up to 6 months. Hamstring injuries have a high recurrence rate therefore appropriate healing and rehabilitation in vital.
Some factors may make you more susceptible to a Hamstring injury such as having previously strained your Hamstring, lack of warming up, poor technique, fatigue, and posture and poor lumbo-pelvic control. It is important to note that pain in the Hamstring may also be due to referred pain from other structures such as the lower back or sciatic nerve which passes through the area and will have completing different treatment approaches.
Treatment usually involves correcting the predisposing factors, soft tissue work to promote healing and prevent excessive scar tissue formation, followed by progressive stretching and strengthening of the hamstrings, especially the eccentric control of the muscle. An accurate diagnosis and appropriate rehabilitation program could reduce your chances of reinjuring the muscle and is highly recommended.