The hamstrings are a group of muscles that cover the posterior (back of the) thigh. The hamstrings are made up of three separate muscles;
- Biceps Femoris (short and long head)
The job of the hamstrings is to flex the knee, adduct the thigh and extend the hip. They aren’t used heavily in standing and walking; however become integral in activities such as running, jumping and changing direction. For this reason, hamstring strains are one of the most common injuries sustained in sport.
The muscles originate on the ischial tuberosity, the ‘seat bone’ of the pelvis, insert onto the medial portion of the tibia (semimembranosus and semitendinosus) or the lateral part of the fibula (biceps femoris) and are innervated by the sciatic nerve. When put under pressure, these muscles get overloaded and may start to strain and tear.
Hamstring Injury Grading
Hamstring strains are graded depending on their severity:
Grade 1 – Mild
- May feel more like an ache or a tightness and sometimes doesn’t present until activity has finished
- Overstretching of the muscle without any tears to fibres
- No loss of muscle strength or flexibility however there may be some tightness in the muscle at end of range movement
- Some pain on weight bearing activities especially when walking up hill or climbing stairs
Grade 2 – Moderate
- Partial tear in the muscle
- Reduction in strength and flexibility of the muscle
- Immediate pain and more severe
- Pain on muscle stretch, may not be able to fully extend the knee
- Pain on contraction especially against resistance
- Muscle is tender to touch
- May walk with a limp
Grade 3 – Severe
- Severe tear or complete rupture of the muscle
- Sudden sharp pain in back of thigh
- Pain on walking
- Bruising after the tear occurs may be visible as a result of bleeding in the tissue
- May require surgical repair
Who Suffers from Hamstring Strains?
While it is possible for anybody to strain their hamstrings, it is more prevalent in athletes, especially those who have to take off with quick pace such as sprinters, and in kicking sports such as football and rugby. They are also common in sports that involve sudden stopping, starting and change of directions e.g. netball and tennis.
One of the biggest causes of strains is an imbalance between the quadriceps and the hamstrings. Tight quadriceps on the front of the thigh can rotate the pelvis forward resulting in tightened hamstrings, and an increased risk of strain. Weak gluteal muscles can also cause overloaded hamstrings as they work together during a majority of movements and the hamstrings are left to pick up the slack. An imbalance between strength and flexibility can also increase the risk of strain as by strengthening muscles, they risk shortening due to tension.
Other factors such as fatigue, inadequate warm up time, poor lumbo-pelvic stability, previous injury history, decreased flexibility and posture as well as environmental factors such as playing surface can all play a part.
How are Hamstring Strains Treated?
Usually mild to moderate strains heal on their own with time, in the initial phase it is best to rest and avoid any aggravating activities. Crutches may be useful to decrease the amount of weight placed through the leg if walking is painful. Over the counter analgesia and anti-inflammatories can be used for pain relief, if these are not adequate or are being required long term then it is best to seek advice from a medical professional.
At home treatments can include ice, compression and elevation to limit swelling. Although it is difficult to keep a leg above the level of the heart (the optimal position for swelling reduction,) it’s a good idea to keep the leg elevated on the couch or on the bed potentially using extra pillows if needed.
Once the initial inflammation has resolved, focus can turn to strengthening and stretching
Strengthening the hamstring muscles helps to make them more resistant to strain, however it can also cause shortening and tightening and therefore care needs to be taken not to cause overuse injuries or decreased flexibility. Muscle fascicles of shorter length are at greater risk of tearing due to overstretching. One method of preventing muscle shortening is by incorporating eccentric strengthening, where the muscles strengthen during the lengthening movement, the eccentric contraction.
Eccentric strengthening is the most researched and accepted method of preventing hamstring injuries, reducing the risk of primary and secondary injuries. It can result in a change in muscle physiology, even lengthening the biceps femoris long head muscle fibres.
Any strengthening program should be accompanied with an appropriate stretching routine. By improving the flexibility of the hamstring muscles, they will be less likely to overstretch and tear. Stretching can be broken down into static stretching and dynamic stretching.
Motor Control & Stability
Hamstrings can become overloaded by poor stability around the pelvis and the lower back. By strengthening this intricate region, specifically improving glute strength and muscle control, there will be less pressure on the hamstring muscles and a reduced risk of injury. Core strengthening will also benefit lumbo-pelvic stability.
It’s important not to rush back into activity, as returning to sport or intense exercise too soon can cause an increased risk of re-injury. There are always alternative exercises that can be done in order to maintain cardiovascular fitness and strength during recovery e.g. swimming or water running. Patients should be pain free and have regained full range of movement before thinking about returning to sport.