Hamstring Muscle Strain

Written by Carolina Vaccari 

A muscle strain is a mechanical stress that occurs when a muscle is suddenly and intensely stretched and the fibers within it are not able to cope with the load applied. As a result the muscle fibres can tear. The result can vary from a milder strain that affects few muscular fibers to a more severe lesion that includes the complete rupture of the muscle. The most common causative mechanisms are an overstretch or an eccentric contraction of the muscle.

A muscle strain can be classified into different grades depending on the fibers affected:

• GRADE I – mild strain. The lesion involves few fibers and full active and passive range of motion is preserved. The pain and the tenderness usually arise the following day.
• GRADE II – moderate strain. The lesion affects half of the muscle and it is accompanied by swelling and a reduced muscular strenght. The onset of the pain is acute and significant.
• GRADE III – severe strain. The complete rupture of the muscle occurs and severe swelling and loss of muscle functionality is observed. Pain is acute and intense.

The hamstrings are a group of 3 muscles (biceps femoris, semitendinosus and semimembranosus) located at the back of the thigh. Strains of these muscles are usually caused by an intense and sudden mechanical stress which leads to a violent extensive contraction. As any muscle strains, several degrees of injury are classified based on the intensity of the trauma and the fibers involved:

• GRADE I: Patients might complain about stiffness and pain to the back of the leg and a mild swelling can be detected. Walking and knee bending are usually preserved.
• GRADE II: Half of the muscle fibres are usually involved. Patients present acute local pain associated with swelling and occasional loss of function. Walking can be affected as well as active knee bending against resistance can be painful.
• GRADE III: Consists of a severe (more than half of the fibers of the muscles) or complete rupture of the muscle. Swelling, pain, loss of function and muscle weakness are acute and significant.

The symptoms of a muscle strain vary according to the severity of the injury. However, they commonly include:

• Swelling, bruising or redness
• Pain at rest and during passive/active movements
• Difficulty/ inability to use the muscle
• Muscle weakness

Symptoms of a Hamstring Muscle Strain are usually described as a sudden “popping”/tearing feeling that occurs in the back of the thigh. Based on the grade of severity, swelling and bruising can be present, even though they might occur a few days after the injury. Pain, local tenderness, loss of motion and decreased strength and decreased length of the hamstrings are common signs and symptoms. Other neurological symptoms such as tingling, numbness or lower extremities weakness are usually absent.

Overall, a muscle strain is more likely to occur when there is a sudden increase in intensity, duration or frequency of activity. Three type of muscles are more inclined to get injured:

• Two-joint muscles. The movement in one joint passively stretches the muscles predisposing to overstretching strain.
• Muscles that contract eccentrically. This type of contraction may change the muscle tension with a risk of overloading it and injuring it.
• Muscles which present lots of muscle fiber type II. These muscles, such as hamstring, quadriceps, rotator cuffs, can develop a high-speed contraction leading to a major risk of injury.

Dynamic sports such as football or rugby, involving sprinting, jumping and regular eccentric contractions of the hamstrings, are usually considered risk factors for hamstring strains and injuries.

• Other factors that might contribute to increasing the risk of hamstring strain include:
• Older age
• Lack of hamstring flexibility
• Previous injury to the knee, lumbar spine, calves or hamstring themselves
• Postural imbalance such as poor core stability or tight hip flexors, lumbar/pelvis abnormalities (e.g. excessive lumbar lordosis or anterior pelvic tilt). For instance, thigh psoas muscles, which are hip flexors, can increase the lordosis of the lumbar spine predisposing to higher risk of hamstring strain.

A good case history, a full understanding of how the injury occurred and an accurate examination are usually sufficient to suspect and diagnose a muscle strain. In more suspicious cases, some investigations can be suggested to exclude other possibilities. They include X-ray, ultrasound, MRI.

When a hamstring strain is suspected, during the examination the therapist will evaluate:

• Gait assessment: Usually patients with hamstring strain present a shorter walking gait, even though other physical signs, such as oedema, might be absent.
• Observation: Any bruising or obvious swelling will be observed.
• Palpation: A palpable defect in the musculotendon area is usually found and its palpation usually exacerbates the pain.
• Range of motion testing: testing of the active (patient doing the movement) and passive ( practitioner doing the movement) will be carried out at both the hip and knee joints. The most common range of motion test used to test the length and flexibility of the hamstrings is the passive straight leg raise test. When assessing the length of a muscle post injury the report of the onset of pain and stiffness during testing will decipher the extent of available joint motion. Knee extension tests are also examined due to the hamstrings role in flexing the knee.

Minor to moderate hamstring muscle strains can heal on their own with proper rest and following self care guidelines. In cases where the hamstring strain is a grade 3 and the muscle is fully torn, surgery will be required.

Following the initial onset of injury it is always recommended to follow the RICE protocol following injury for the following 2-3 days. RICE stands for Rest, Ice, Compression and Elevation.

• Rest – refrain from doing too much activity on your leg. In severe cases the use of crutches may be recommended.
• Ice – apply cold packs for around 20 minutes at a time for around 2-3 hours a day. Make sure not to apply ice directly to the skin. Using a bag of frozen peas wrapped in a tea towel works just as well as using a cold gel pack.
• Compression – use a compression bandage to prevent any additional swelling. Edema kinesiology taping can also be used to help with reducing swelling. Speak to one of our osteopaths to find out more.
• Elevation – another way to help reduce the swelling is to elevate your leg higher than your heart. This can be done when resting and lying down place a few cushions underneath the leg to bring the leg higher than your heart.

Conservative treatment includes:

Medication – Pain Relief medication such as paracetamol can be used to help with reducing the pain. Non-steroidal anti-inflammatory medication such as ibuprofen may also be suggested as this can help with reducing inflammation. Before taking any new medication it is always recommended to speak to your GP as not all medication is suitable for everyone.

Physical Therapy – Physical therapists such as physiotherapy and osteopaths are qualified in treating sports injuries such as muscle hamstring strains. Treatment will aim to: reduce swelling and pain and improve the flexibility and strength of the hamstring muscles. Your rehabilitation program will first focus on flexibility with gentle stretching exercises. As the hamstring starts to heal the practitioner will progress on to gentle strengthening exercises, increasing the load as progression is made.

Surgical Intervention

Surgical intervention Is rare and only used in cases where there is complete rupture of the hamstrings muscle. Your orthopedic surgeon will discuss the best type of surgery appropriate for you, as well as the risks and benefits of the surgery.

After your surgery non-weight bearing may be recommended by your surgeon for a period of time. The amount of non-weight bearing time needed will depend on the type of injury obtained and surgery needed. Your rehabilitation programme will then take place.

It is important to follow a guided and individualized rehabilitation programme for hamstring muscle strain. This is so as to not create further injury. Below are a few examples of exercises that may be incorporated into your exercise programme in the initial stages of rehabilitation.

Isometric Hamstring Contraction. Sit on the floor with your injured leg slightly bent and your opposite leg stretched out long. Start with your leg bent at 30°. Begin by pushing the heel of the injured leg into the floor, this will tighten the hamstring muscle. Make sure to not move the leg. Hold for 10 seconds and repeat 6 times. As you progress this exercise you can increase the knee bend to 60° and then 90°.

Sciatic nerve floss – This exercise can be used to gently stretch the hamstring muscles. Sit on a surface that allows your legs to be lifted off the ground ever so slightly. Sit tall with good posture. Begin by slowly straightening the leg of the affected side until a slight stretching feeling is felt in the leg. Then bring the leg back down to the initial starting position. Repeat 10 times.