Hamstring Strain

You push off the ground to sprint, or you change directions too quickly and you feel a snap in the back of your leg. The pain is extreme and you cannot continue. This brief moment where you took your body passed its limits may have resulted in a hamstring strain.

What is a Hamstring Strain?

A hamstring strain can range anywhere from the detachment of a few muscle fibers to the complete rupture of the muscle.1 The hamstring is divided into three muscles on the back of the thigh: the semimembranosus, the semitendinosus, and the biceps femoris. The hamstrings begin in the glutes and descend down the back of the leg and cross the knee. The hamstrings assist in hip extension and knee flexion. A hamstring strain is one of the most common injuries in the thigh, and the head of the biceps femoris is the usually the site of injury.

There are three levels of a hamstring strain. A grade 1 hamstring strain is characterized by a tear of less than 20% of the fibers in the hamstring.[1] A grade 2 hamstring strain occurs when approximately 70% of the hamstring fibers are torn.1 Finally, a grade 3 hamstring strain is the result of a tear of greater than 70% of the hamstring fibers.[1]

Sports Commonly Associated with Hamstring Strain:

Hamstring strains can occur due to quick movements, changes of direction, or over-stretching. The sport most commonly associated with hamstring strains is sprinting in track and field. Soccer, gymnastics, football, basketball, running, hurdling, and plyometrics are all sports associated with hamstring strains.

Causes:

Quick movements that accentuate the muscular imbalance between the quadriceps muscles and the hamstring muscles have been known to cause hamstring strains. The hamstrings should be 60-70% of the strength of the quadriceps muscles.1 Additional causes of hamstring strains include tired muscles, poor posture, leg-length discrepancy, or tight hamstrings.

The hamstring muscles function to help decelerate the leg during high kicks or the beginning of a sprint. Sudden changes of directions or beginning exercises too quickly are often causes of hamstring strains. Additionally, a lack of flexibility or a lack of warm up can predispose and individual to this condition.

Symptoms:

The symptoms of hamstring strains are dependent on what level of injury has occurred. Grade 1 hamstring strains present with muscle soreness during movement. They also demonstrate point tenderness. Often times these strains cannot be identified until after activity and are characterized by muscle spasm and pain.[1]

A grade 2 hamstring strain is a moderate hamstring tear and is characterized by a snap, tear, or pop. Severe pain and a loss of function along with an inability to flex the knee will be evident in this type of injury. This strain will be very painful and can be identified nearly immediately after occurring.[1]

A grade 3 hamstring tear results in temporary disability and bruising. There is extreme swelling, tenderness, loss of function, and there will be a large balling up of the muscle or a palpable gap in between the muscle fibers.[1]

Prevention:

The best way to prevent hamstring injury is to warm up completely prior to activity and to participate in a regular stretching routine. Warm up prior to activity should be in the form of a 5-10 minute cardiovascular exercise at a mild intensity along with dynamic stretching (or stretching while moving). After activity, the athlete should participate in static stretching.

The other way to prevent hamstring injury is to complete strengthening exercises in order to maintain a balance between the strength of the hamstrings and the quadriceps. This balance allows the body to move in a more efficient manner and limits the stress between the eccentric and concentric contractions.

Treatment:

Modalities:

The initial treatment of a hamstring strain is to prevent swelling and bruising. The use of ice can help to decrease cell metabolism and therefore limit swelling. An Ace-Bandage can be used and wrapped from the knee up toward the hip, over-lapping each portion of the bandage by half.

Stretching:

Gentle stretching is important for the healing of the hamstring strain. Initial stretching can be done with the athlete lying on his or her back with a strap of a towel wrapped around the foot of the injured leg. The athlete can then use the ends of the towel to gently pull the leg into the air until a stretch is felt. The stretch should not be painful. After the initial phase of healing, stretching can become less conservative.[2]

Strengthening:

Hamstring strengthening should not begin until the injury is outside of the initial healing phase and strengthening should not cause additional pain. In order to limit the reoccurrence of hamstring injury, strengthening can occur as a preventative measure. A single leg RDL (Russian Deadlift) can be completed by standing on one leg and, while keeping the back straight leaning forward and lifting the other leg behind. This exercise can be done with and without weights. Other exercises such as glute bridges and deadlifts can be used to strengthen the hamstrings.

References:

1. Prentice, William E. Principles of Athletic Training: a Competency-Based Approach. McGraw-Hill, 2014.

2. Higgins, Michael. Therapeutic Exercise: from Theory to Practice. F.A. Davis Company, 2011.