Hamstring Injuries – Easily preventable!
As we are approaching the summer months people are becoming more active. The GAA championship season for many clubs is about to or has commenced. Like every other year I notice an increase in the number of hamstring related injuries coming through the clinic doors.
Prevalence of hamstring injuries
Hamstring injuries are common in sports which involve sprinting, kicking and sudden accelerations. Given the high incidence of such injuries and time missed from training/playing interventions that reduce hamstring injuries should be a priority for must clubs/athletes/players.
What causes hamstring injuries?
In order to be able to reduce the likelihood of hamstring injuries, it is first necessary to identify and understand the factors that contribute to hamstring injuries.
It has been reported that most hamstring strains occur during maximal sprinting, as this is when the forward movement of the leg is at its fastest. The eccentric overload (muscle contracting as it is lengthening) can put large strain on the hamstring muscle and lead to injury. If there is inadequate hamstring muscle strength then this overload will be more pronounced.
It has also been suggested that hamstrings are susceptible to injury during the rapid change from their eccentric to concentric action, this can occur when the force exerted whilst changing the direction of movement may exceed the limits tolerated by the muscle. This suggests that strength imbalance is also a factor in hamstring injuries.
A study amongst track and field athletes, a proportion of which had suffered from hamstring strains over a two year period were divided into two groups. The injured group (those who had suffered a hamstring injuries in the past two years) and uninjured groups( those who had not suffered a hamstring injury in the past two years) these two groups were then compared using various strength measures. In the injured group they found that they had relatively weak hamstrings compared to quadriceps on either side ( the injured leg or none injured leg)
According to at least half a dozen recent studies, almost two thirds of hamstring injuries may be preventable by strengthening weakened hamstrings. The exercise recommended is the Nordic Hamstring exercise.
What is a Nordic Hamstring Exercise
After warming up, kneel on the ground, with a someone behind you securing your ankles. Then as slowly as possible, lean forward letting your chest approach the ground. Use your hamstrings to slow down your forward momentum until you can no longer resist gravity. Put out your arms in front of you at this point to stop your fall. Allow your chest to touch the ground, then push yourself upright to repeat the exercise.
A study in 2011 which involved 942 Danish soccer players being randomly assigned to either an off-season program of the Nordic exercise or normal training. The next season, those following the Nordic exercise program experienced 70 percent fewer injuries than the control-group athletes. Players who had previously suffered hamstring injuries saw 85 percent fewer injuries.
How Does the Nordic Hamstring Exercise Work
The Nordic exercise works because it is an eccentric exercise. Eccentric muscle contractions occur when a muscle extends as it contracts. Lower a weight during a biceps curl,(straightening your forearm) for instance, and your forearm muscles lengthen at the same time as they clench. Lift that same weight upward (flex your forearm), and the contractions become concentric, shortening as they contract.
In general, eccentric contractions result in more force moving through the muscle than occurs during concentric ones. Eccentric exercises also seem to create changes in the nervous system that result in improved coordination between brain and muscles.