I spend a lot of my day as a Podiatrist talking to parents about Hamstrings. These days most kids with lower limb injuries present to the clinic with tight hamstrings… and there is definitely a correlation. This blog is all about the wonderful world of hamstrings! How they function as we walk and run… and what happens when they are too tight or too weak.

Hamstrings

I love this Picture because it so clearly shows the origin of the 3 hamstrings at the base of the hip in an area known as the ischial tuberosity (which is deep into the base of the bottom) and how they extend right down the back of the leg before they separate around the knee joint and insertion into the leg bones. See how long they are? They are a super important muscle group that imposes a lot of domination on hip, knee and foot position. The 3 individual muscles that make up the hamstrings group are called Biceps femoris, Semi-membranosus, Semi-tendinosus.

WALKING

During walking, the hamstring group will engage to slow and reduce flexion at the hip of the striding front leg. The opposite Hamstring of the back leg will also engage the prevent the hip from flexing/shifting too far forward. The hamstrings act against each other. Their main job is to stabilise the hip position, flex the knee and help propel the body forward through swing phase of walking. When Hamstrings function as they should we will have a dynamic and stable walking pattern.

RUNNING

When running the action of the hamstrings is to stop the knee from hyper-extending/locking in contact phase when the foot meets ground. They also work to flex the knee during the swing phase movement of the leg (when its moving through the air). It is important the hamstring muscles remain strong so that the quadriceps muscles at the front of the leg don’t dominate running action. If the quadriceps overtake running action they can cause tightening of the hamstring position and place them at risk of reach tissue threshold causing injury.

WHEN HAMSTRINGS ARE TIGHT AND/OR WEAK?

When pulled tight the hamstrings have the ability to change the position of the hip and lower back. They also can create change down at the foot. Seems strange they would effect the foot position when they anchor below the knee. It is due to the sagittal joint nature of the knee we often see the tightness in the hamstrings link in with tightness in gastroc-soleous complex. This will effect the heel strike force of the gait pattern. Put simply, if the hamstrings are tight its common that the calf muscle is too… and therefore load at the heel strike is effected considerably.

So why do they get tight and weak? Sometimes it can be weakness is other core muscle groups that are supposed to work alongside the hamstrings to create movement. The Glutes (bottom muscles) are a big offenders here. Weakness in the Glutes often overload the hamstrings. The hamstrings will tighten to stabilise the hip at a greater force when the glutes lack strength. We may also see the hamstrings tighten in kids that have yet to be diagnosed and managed for joint hypermobility syndrome. The hamstrings will tighten to stabilise joint position of the hips and knees in order to protect the joints from hyper-extension.

Where a weak or tight hamstring pulls the pelvis in an anterior tilted direction a curvature may occur through the lumbo-sacral area of the spine. Take a look at this picture. In the first frame you can see how the bottom sits out, there is little curve in the lower back and the belly also pops out. Tight Hamstrings can cause a shift in the pelvis in an Anterior (forward) direction. If the hamstrings continue to act around this postural alignment the force of that walking and running will be taken up in other tissues of the lower limb mechanics. This position may cause the lower abdominals to weaken, the hip flexors to tighten, and at the knee we often see a flexed knee position arise.

The mechanics of the hamstrings really do effect full body positioning. It is so important we get onto these early.

HOW TO CHECK HAMSTRING FLEXIBILITY

The golden rule with hamstring flexibility is that we like to have at least 70 degrees range of motion on hamstring stretch. We check this by moving the leg back towards the body in a straight line. Any less than this we are going to see change at the hips, knees or at the feet. Below is a quick demonstration video you can use to check your child’s hamstrings.