Symptoms of a pulled hamstring consist of a sudden sharp pain at the back of the thigh, usually while sprinting or over stretching.
Hamsting strains are categorised into grade 1, grade 2 or grade 3 depending on how bad the injury is with grade 3 being the most severe.
How bad is my hamstring strain?
Grade 1 - With a grade 1 hamstring strain the athlete may have tightness in back of the thigh but will be able to walk normally. They will be aware of some discomfort and unable to operate at full speed. There will be little swelling and trying to bend the knee against resistance is unlikely to reproduce much pain.
Grade 2 - With a grade 2 hamstring strain the athletes gait will be affected and they will most likely be limping. Sudden twinges of pain during activity will be present. They may notice some swelling and pain will be reproduced when pressing in on the hamstring muscle as well as trying to bend the knee against resistance.
Grade 3 - A grade 3 hamstring strain is a severe injury involving a tear to half or all of the muscle. The athlete may need crutches to walk and will feel severe pain and weakness in the muscle. Swelling will be noticeable immediately and bruising will usually appear within 24 hours.
Diagnosing hamstring strains
A thorough assessment is important to properly diagnose a hamstring strain. We look at some simple techniques a therapist may use to determine the type and grade of injury.
Assessment of any injury usually begins with questions concerning the patients general health, previous injuries and how the current injury occurred. Hamstring strains which occur during sprinting often feel worse than those which happen as a result of over stretching but the recovery time is often shorted.
Specific tests for hamstring strains
The therapist will perform a series of specific tests to identify exactly where the injury and whether or whether referred pain is involved.
Straight leg raise - the therapist raises the leg off the couch as far as is comfortable for the patient, keeping the knee straight. This stretches the hamstring muscles and may reproduce the patients pain. The therapist should also observe how far the leg can be lifted. A normal range of motion is 80-90 degrees. Movement less than this and especially less than on the other side indicates that the hamstring muscles are tight.
Resisted knee flexion - the therapist provides resistance as the patient attempts to bend their knee. This causes the hamstring muscles to contract which will be painful in most hamstring strains. The strength of the muscle should also be compared to the other side as weakness may also suggest a hamstring strain.
Slump test - the slump test can be used to determine if there is neural or nerve involvement. The patient bends the head down, straightens one leg and points the toes up to the ceiling. The therapist will then push the patient forwards to increase the stretch. Pain shooting down the leg or reproduction of any other symptoms are a positive result. This may mean the sciatic nerve originating from the spine is contributing to symptoms.
Palpation - the therapist will feel or palpate the muscles, observing areas of pain, tension or gaps within the muscle. Pain in the hamstring area can indicate a strain to one or more of these three muscles. It can however, also be a symptom of many other conditions, including contusions, adductor or groin strains, sciatic pain, referred pain from the sacroiliac joint or lower back, gluteal trigger points and bursitis. A thorough assessment will help to determine the cause of the pain.