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In a nutshell, this study took advantage of some prior studies that have been mentioning how effective eccentric work may be for preventing hamstring injuries. Hamstring pulls are a nightmare for any sport coach, and especially track coaches. I am always looking for ways to keep my athlete’s hamstrings healthy. Two things I have picked up in the last year have been mandatory soft tissue work prior to practice via softballs/lacrosse balls, and then a higher priority on glute strengthening. After seeing the results of this study, you can bet that next year, eccentrically based hamstring work in full ranges of motion will also be in there. Here are some details of the study and why I will be including this in my athlete's training.
When athletes pull a hamstring, it takes a long time, on average, to get that hamstring back to full strength. Research is cited in this study that showed that levels are only around 90% at 6 weeks post-injury and it took 16 weeks to return to full strength. Because of the length of this time frame, Thorborg proposed that the focus of rehab needs to be on replicating the function of the hamstrings, rather than the amount of time it takes to restore full strength.
In regards to hamstring function, there have been some excellent recent findings. One idea has been that eccentric based hamstring work will cause the highest amount of torques the hamstring can produce to be at it's longer ranges of motion, rather than shorter ranges. Many hamstring pulls and tears occur directly before ground contact in the sprinting motion, when the hamstring is in an elongated state. Because of this, it makes sense that working hamstrings hard eccentrically through a full range of motion can help build strength and maximal torque in the range where the pulls may occur.
For Thorborg’s study, data was collected from 942 soccer players. It was found that putting players on a 10-week rehabilitation program of Nordic Hamstring Curls caused a reduction in hamstring re-injuries by 70%! (The Nordic Hamstring Curl is a eccentric natural glute-ham raise, [You must be registered and logged in to see this link.]
Based on this study, I would strongly recommend the inclusion of some full-length eccentric based work for hamstrings into your own training program, whether that be through the Nordic Curl, Glute-Ham, Romanian Deadlift, or standard leg curl. Another nice trick to maximize the eccentric output of each exercise can be to use two legs for the concentric portion, and then only one leg for the way down. For example, if you were using a lying hamstring curl on a machine, you would lift the weight concentrically (up) with two legs, and then take a leg away to lower the weight with only the other leg. Hopefully, we will see a vast reduction in hamstring pulls in athletes in the near future with this method.