Dealing with running hamstring injuries, part one

Introducing the hamstrings
The hamstrings are a group of three muscles that run down the back of the leg from the bone that you sit on (ischial tuberosity) to the lower leg just below the knee. They are attached to the two bones of the lower leg, the tibia (on the inside) and fibula (on the outside).

What do hamstrings do in running terms?
If you asked a medical student this question they would probably answer by saying that the hamstrings produce flexion (bending) at the knee. However, their function is very much more complicated than this and therein lies the problem.

Because the hamstrings pass across two joints (hip and knee), when they contract (shorten) they have the potential to cause movement at both joints. To make things even more complicated, what effect their contraction has on the leg will depend on whether the leg is supporting weight.

With the foot and leg off the ground the hamstrings action will draw the whole of the leg back. This is referred to as extension at the hip joint. If the whole leg is prevented from moving back either by contraction of the hip flexors which lie in front of the hip joint or by physically blocking the leg’s movement, then the knee will bend, bringing the heel up.

When the leg is supporting the body weight with the foot fixed on the ground, contraction of the hamstrings will act in the opposite direction with the leg moving the body forward rather than the body moving the leg back during running.

To make it even more complicated (just a little), all of the above describes the muscle working concentrically. In other words the muscle contracts and shortens and brings the two ends (and their attachments) closer together. Sometimes the hamstrings have to work eccentrically to oppose strong muscle activity moving the leg in the opposite way during running.

If the leg is swinging forwards this can only happen under full control if something is applying the brakes, and that something is the hamstrings. Muscles have to work hardest when they are working in this way and this is when the hamstring will be more prone to injury.

Cross-country running and hamstrings
So what has any of this got to do with cross-country running? As the hamstrings are inserted into the two lower leg bones (two towards the inside and one on the outside) they have one more trick they can perform and that is rotation of the lower leg in either direction when the knee is bent.

The amount of rotation is small and it is probably easier to think of the hamstrings as stabilising the knee and preventing rotation in the opposite direction. When running on a slippery or uneven surface the hamstring muscles have to continually work eccentrically to stop the foot slipping forward or the knee twisting. Particularly over longer distances, the running muscles will become fatigued and complain in the only way they know how – by causing pain. This is more likely to appear gradually and sometimes only after the activity has stopped.

Footballers and sprint runners
Footballers may also suffer from this type of injury due to sudden changes of direction and changing their balance during a match. This happens more often towards the end of each half of the game when the muscles are most fatigued.

Sprint runners often suffer more from the more dramatic type of injury that makes them leap in the air clutching the back of their leg. This tends to occur when the stride is lengthening during acceleration.

At this stage the muscle is being asked to contract whilst lengthening (working eccentrically) as the knee straightens whilst at the same time contracting and shortening (working concentrically) to pull the leg back at the hip. If the co-ordination of this is not precise, or the sprint runner overstrides, then the muscle will be placed under excessive tension. This is when a tear might occur.

Which runners are most at risk?
When any muscle is subjected to stress, weakness or insufficient flexibility it will make a tear more likely. Imbalance between the strength of opposing muscle groups (for example: hamstrings versus quadriceps) is also thought to play a role.

This situation can arise when the quadriceps become overly developed as a result of poorly planned weight training. As the hamstrings arise from the pelvis then a forward tilted pelvis (which makes your rear end stick out) will increase the tension placed on the hamstrings, as will a stiff lower back.

Hamstrings that are fatigued or glycogen depleted are also at increased risk and overuse by too much hill or speed work or running on slippery ground also increases the risk of injury.

A word of warning to runners
Pain down the back of the leg does not always mean the hamstrings are to blame. The main nerve to the leg muscles (sciatic nerve) runs down the back of the leg deep to the muscles. Pressure on this nerve due to back problems can produce pain very similar to hamstring pain.

Moreover, irritation of this nerve can produce a situation of 'adverse neural tension' which can then cause abnormal function in the hamstring muscles. For those reasons, obtaining an accurate diagnosis from a chartered physiotherapist or a sports doctor is a sensible precaution prior to embarking on a running recovery programme.

Hope for runners...
For those of you who have trouble-free hamstrings the good news is that by taking certain precautions and carrying out a few straightforward exercises you should be able to keep them healthy.

For those who have previously struggled with hamstring problems, the road ahead may be somewhat longer but by careful attention to flexibility and muscle balance it is almost always possible to be running freely again without having to resort to the surgeon’s knife.