A hamstring injury is a strain or tear to one or more of the three large muscles at the back of the thigh (or their tendons at the back of the knee). It is a common and painful sports injury, particularly in exercises involving running and jumping, or with sudden stopping and starting.
The length of time it takes to recover from a hamstring strain or tear will depend on how severe the injury is.
What are the hamstrings?
The three hamstring muscles form the bulk of the muscle at the back of your thigh. They end in strong, thick tendons at the back of the knee. The term 'hamstrings' is used to refer both to the muscles and to their tendons. During a hamstring strain, one or more of these muscles or tendons gets overstretched, often suddenly, and may even tear.
What do the hamstrings do?
The hamstrings bend the knee. They also straighten out the hip when you move your thigh backwards. These big muscles are not very active in normal walking, but are crucial in power activities such as running and jumping. This was well-known in mediaeval times, when a sword-wielding knight would disable an opponent by a slice across the back of the thigh. Slave masters were also known to cut the hamstrings of slaves to make escape less likely. The origin of the term 'hamstrung', meaning to have been crippled or held back, is derived from these practices. People with sedentary lifestyles may use their very hamstrings little and so may have weak hamstrings. Athletes, on the other hand, athletes need healthy, well-conditioned hamstrings.
How common are hamstring injuries?
Hamstring strains are common, particularly in athletes, and slightly more common in women. They are painful, and usually sudden, and you would be unlikely to injure your hamstrings without noticing at once.The three grades of hamstring injury are:
- Grade 1: a mild muscle strain - likely to recover in a few days.
- Grade 2: a partial muscle tear.
- Grade 3: a complete muscle tear - may take weeks or months to heal; most commonly seen in active athletes.
What causes hamstring injuries?
Hamstring injuries are often caused by rapid acceleration activities and sudden explosive movements when running or initiating running. They are common in sports such as soccer, football, and track.
How bad is are hamstring injuries?
Hamstring tears and strains most often occur at the middle of the back of the thigh where the muscle joins its tendon or at the base of the buttocks. The injuries vary in severity.
A minor strain is classified as a grade I tear, whereas a complete tear (rupture) is classified as a grade III tear. Grade II tears are partial ruptures. Getting a hamstring strain or tear is more likely if:
- You don't warm up and stretch before exercising.
- The muscles in the front of your thigh (the quadriceps) are a lot stronger than your hamstrings (see below).
- You're a teenager going through a growth spurt.
Hamstrings versus quadriceps
Hamstring strength isn't the only important factor in injury. What probably matters more is the comparative strength of the hamstrings compared to the quadriceps muscles at the front of the thigh. Many people have strong quadriceps that overpower their hamstrings - and this is particularly true in women. This imbalance is often the root cause of injury. Even if an athlete has stronger hamstrings than another athlete, if he or she has much stronger quadriceps there will still be a high risk for injuries. This is because it's the quadriceps which straighten the knee and make the opposite movement to the hamstrings. It is, effectively, partly the power of the quadriceps that can suddenly stretch the hamstrings. Highly trained runners tend to spend time working on their hamstrings to correct this problem. Recreational runners may not realise that they need to do so.
Grade I injuries tend to be mild in that they tend to heal fully with only minor aggravation to the injured person, particularly in those who don't do the kinds of exercise that really need the hamstrings.
Grade 2 and 3 injuries take longer. Severely torn muscle can be debilitating for a long time and can be career-threatening to the professional athlete.
What does a hamstring injury feel like?
You may feel or hear a pop, followed immediately by severe pain in the affected leg after sudden lunging, jumping or sprinting. The muscle will often feel tight and tender, and go into cramp or spasm. In severe cases, there can be swelling and bruising. Walking may be painful. You may be unable to stand.
The back of the leg will feel tight, tender and possibly bruised. With more severe injury, swelling and a black and blue or bruised appearance will follow. In some cases there may be a gap in the muscle that you can actually feel by touching it.
Mild hamstring strains may not hurt too much. But severe ones can be very painful, making it impossible to walk or even stand.
What is the treatment for a hamstring strain?
Grade 1-2, minor to moderate hamstring strains, usually heal on their own. During the first few days after the injury, you should rest the affected leg. Follow the 'RICE' steps below:
- Rest - keep your leg as still as you possibly can and avoid physical activity.
- Ice - apply ice to your hamstring for about 20 minutes, two to three times a day. (Don't apply it directly to your skin; you can use a bag of frozen peas wrapped in a tea towel.)
- Compression - a compression bandage can help reduce pain and swelling.
- Elevation - keep your leg slightly raised while sitting to help reduce swelling.
- Take painkillers. Non-steroidal anti-inflammatory painkillers like ibuprofen will help with pain and swelling. These medicines may have side-effects, such as an increased risk of bleeding and ulcers. They should be used only short-term, unless your doctor specifically says otherwise.
- Strengthening your hamstrings is the best protection against hamstring strain.
- In severe cases where the muscle is torn, you may need surgery. The surgeon will repair the muscles and re-attach them.
Recovering from a hamstring injury may take from days, to months, depending on how severe the strain or tear is. A grade 3 injury can take several months to heal: you'll be unable to resume training or play sport during this time.
Most hamstring injuries, even grade 3 injuries, heal without surgery. In severe cases, crutches or splinting may be necessary. In rare cases, where there is a complete rupture where the hamstrings join the pelvic bones at the top, surgery is necessary.
How can I return to fitness?
Lack of use, particularly if splinting, results in muscle shrinkage and the formation of scar tissue where the tear is healing. Excessive scar tissue prevents healthy muscle function, as it doesn't stretch and move as normal muscle does..
To avoid these complications rehabilitation exercises need to begin early. After a few days, once the pain has subsided, you should start to do regular gentle hamstring stretches followed by a programme of gentle exercise, such as walking and cycling, and hamstring strengthening exercises. Always warm up before exercising and cool down and stretch afterwards. Stop if pain returns.
To avoid injuring yourself again, you should only return to a full level of activity when your hamstring muscles are strong enough. Re-introduce running only gradually. Your physiotherapist will be able to advise you about this and advise on a suitable graded exercise programme.
Re-injury is extremely common and is often due to avoidable premature return to sport by athletes desperate to get back to fitness. Sportsmen are highly motivated and are likely to have set personal goals for training, timing and performance. However, re-injury not only prolongs recovery, it also increases the risk of permanent damage.
What can I expect from rehabilitation?
- Control of pain and swelling and acceptable range of motion and flexibility.
- A gradual strengthening programme should follow.
- When strength has returned, a gradual return to the desired sport can be attempted. Full return is usually possible only after maximal flexibility and strength have been obtained.
- Depending on the severity of injury, full rehabilitation may take several months.
Can hamstring injuries be prevented?
As with all sports-related muscle injuries, the risks can be reduced by close attention to muscle strength and flexibility.
- A regular stretching programme as well as a period of warm-up and stretching before the intended athletic activity will reduce the risk.
- A well-balanced diet is essential to avoid electrolyte imbalance and lack of fluid in the body (dehydration).
- Avoid dehydration, which can lead to muscle cramping, thereby increasing the chance of muscle injury.
- Excessive body weight increases the risk of muscle injuries in the lower legs.
- Some experts have also advocated the use of nutritional supplements, such as anti-oxidants.
- Improve the imbalance between hamstrings and (much stronger) quadriceps. You can either increase hamstring strength or reduce quadriceps strength. Examples of methods to improve your hamstring-to-quadriceps strength ratio would be:
- Horizontal power manoeuvres, such as repeated single leg broad jumps; combined with
- Resistance training that targets the hamstrings.
What is the outlook (prognosis) for hamstring injuries?
The outlook is generally good, but can require a period of rest by avoiding running and athletic competition. The length required for recovery varies depending on the severity of the muscle injury.
Dr Mary Lowth
Dr Mary Lowth
Dr Hayley Willacy