One of the biggest risk factors for hamstring strains and re-injury rates is a decrease in hamstring flexibility and reduced extensibility of the musculotendon unit due to residual scare tissue. As we described in the past two episodes, the eccentric control of the hamstrings is vital in preventing a hamstring strain. But what good is all the eccentric strength in the world, if the actual length of the hamstrings is too short?
After a hamstring strain, scar tissue will inevitably develop and can even be seen on an athlete’s MRI after returning to sport symptom free. Scar tissue is much stiffer than the normal contractile tissue it replaces, thus altering the biomechanics of the muscle itself. This biomechanical change also shortens the length at which the hamstrings can generate their highest peak force. This means that the hamstrings are now WEAKER at their maximum length, which is the exact opposite of what we want. You can obliterate the scar tissue adhesions and restore an optimal peak force musculotendon length by performing soft tissue mobilizations of the scar tissue or hamstring stretching, like the PNF stretch shown in this video.