Pulled Hamstring / Hamstring Strain

What is a pulled hamstring or hamstring strain?

A hamstring strain or a pulled hamstring as it is sometimes called is a tear in one or more of the hamstrings muscles. Strictly speaking there are three hamstring muscles (Semitendinosus, Semimembranosus and Biceps femoris) which are known as the hamstring muscle group. These muscles all originate from the ischial tuberosity of the pelvis (see figure 1). Biceps femoris, in addition, has a second portion, known as the small head, that originates from the lower outer portion of the femur bone itself.

The rear portion of adductor magnus is sometimes also considered as a hamstring muscle due to its alignment. All of these muscles travel across the knee joint - semitendinosus and semimembranosus insert into the medial (inner) aspect of the tibia while the biceps femoris inserts at the head of the fibula bone on the outside of the lower leg.

The hamstrings function predominantly in extending the hip and flexing the knee joints. Understanding how the hamstrings work give vital clues as to their modes of injury. Acute, mild to severe hamstring strains are extremely common in sprinters and hurdle jumpers and in all sports that involve sprinting activities, such as football and rugby.

How is the hamstring strained?

During sprinting the hamstring muscles work extremely hard to decelerate the tibia as it swings out. In addition, once the foot is on the ground the hamstrings function in extending the hip back which in turn allows the other leg to move forwards. It is in this phase just before the foot strikes the ground that the hamstrings, most commonly the biceps femoris muscle, become injured as the muscles are maximally activated and are approaching their maximum length. There are a number of factors that increase the risk of an individual to a pulled hamstring:

Age: The older the individual the greater at risk to a pulled hamstring.
Previous Injury: Prior injuries to the hamstrings or adductor muscles can greatly increase the risk of the hamstrings to future damage.
Flexibility: Research suggests that the greater the flexibility of the hamstrings the less prone they are to injury.
Hamstring strength: Similarly studies have shown that lack of hamstring strength is strongly linked to a susceptibility to a pulled hamstring.
Lumbosacral nerve impingement: Nerve impingement in L5-S1 can lead to associated hamstring muscle weakness.
Tiredness and fitness: When a player is fatigued he/she loses coordination between within certain muscle groups. The biceps femoris muscle is known to become damaged due its two portions being innervated by two separate nerves. In states of tiredness, lack of synchronization between these two nerves can lead to a mismatch in firing resulting in a pulled hamstring.

A pulled hamstring rarely manifests as a result of contact-If you have taken an impact to the back of the leg it should be treated as a contusion until found to be otherwise.

Symptoms of a Pulled Hamstring:

A sudden sharp pain at the back of the leg during exercise-most probably during sprinting or high velocity movements
Hamstring muscles going into spasm-will be associated with pain on stretch and contraction.
Swelling and bruising.
If the rupture is severe a gap in the muscle may be felt.

Severity of Pulled Hamstring:

Strains are graded 1, 2 or 3 depending on severity. Grade 1 consists of minor tears within the muscle. A grade 2 is a partial tear in the muscle and grade 3 is a severe or complete rupture of the muscle.

Grade 1: What does it feel like?

May have tightness in the posterior thigh.
Probably able to walk normally however will be aware of some discomfort
Minimal swelling.
Lying on front and trying to bend the knee against resistance probably won't produce much pain.

Grade 2: What does it feel like?

Gait will be affected-limp may be present .
May be associated with occasional sudden twinges of pain during activity.
May notice swelling.
Pressure increases pain.
Flexing the knee against resistance causes pain.
Might be unable to fully straighten the knee.

Grade 3: What does it feel like?

Walking severely affected- may need walking aids such as crutches
Severe pain- particularly during activity such as knee flexion.
Noticeable swelling visible immediately.

Treatment of a Pulled Hamstring:

What can the athlete do?

It is vitally important that treatment for a pulled hamstring starts immediately following injury. The most important phase for treatment is the first 48 hours post-injury. In this time the following can be carried out by the athlete themself:

Use R.I.C.E. (Rest, Ice, Compress, Elevate) technique
Use a compression bandage to minimize intra muscular bleeding.
Early mobilization of the injured lower limb is vital for the correct rehabilitation of the muscle. This includes stretching and strengthening exercises throughout the pain free range. These can aid with decreasing the swelling in the area. In addition, exercise will ensure that any new material will be laid down in correct orientation thus reducing the risk of subsequent injuries.
See a sports injury specialist.

What can a Sports Injury Specialist do?

Use sports massage techniques to speed up recovery- these are extremely important in the rehabilitation of the injury as massage breaks down the new collagen network allowing for correct fibre realignment and minimizing scar tissue. In addition massage can increase the blood flow to the injured area. Visit out sports massage page to learn specialized massage techniques for a pulled hamstring.
Use ultrasound and electrical stimulation.
Prescribe a rehabilitation program
Advise on specific stretches
Provide mobility aids such as crutches
Provide an MRI scan to ascertain the amount of damage sustained
In severe ruptures surgery may be needed to repair the damage

Prevention of Pulled Hamstrings:

One of the most important methods of preventing a pulled hamstring is to warm up correctly- this has been scientifically proven to reduce the risk of hamstring strain. This should consist of some light aerobic exercise.
A specific strengthening program for the hamstring muscle group is vital in those athletes regularly undertaking sprinting and high velocity sports.
It is extremely important to continue to strengthen all other muscles in the region of the thighs, pelvis and lower back to ensure correct muscle balance
Stretching both before and after exercise
Regular deep tissue sports massage can help prevent muscle strains by identifying tight knots and weak points in the muscle.
Thermal pants are thought to decrease the risk of injury.

Further information on Hamstring strains:

Injury Forum