No single muscle group gets as much attention (and funding) in the research world as hamstrings.  It’s a money muscle.  Pardon the pun.  

 

Hamstring injuries are the most common muscle injury in sports that involve high-speed running.  And one of the most common muscle injuries we see in clinic.

 

And even if you don’t have a hamstring issue, staying up to date on hamstring injury rehab is critical for us as clinicians and important for all of us because we can use the principles from this research to guide other muscle injuries.  One pivotal finding from hamstring research over the last couple decades is that hamstring lengthening exercises are critical for injury prevention and for injury rehabilitation to return to athletic competition.    Just for clarification hamstring lengthening exercises and eccentric exercises are synonymous and are used interchangeably in this article.  

    

Check back to one of our very first therapy thursday videos where Pete outlined the Nordic Eccentric Hamstring Protocol circa 2011.  This was the early days of our clinic (Pete and I may have still been manning the phones ourselves at that point!!).  It was also the relatively early days of understanding the importance of fully restoring strength and function of the hamstring in the lengthening phase for safe (minimal risk of re-injury) and efficient (number of days) return to sport.  

 

Fast forward a decade and we are still digging deep to optimize the use of eccentric hamstring exercises for hamstring rehab and prevention.

 

Some researchers and clinicians have suggested that using hamstring lengthening exercises earlier in a rehab plan will get an athlete back to return to play faster.  It’s a question we often wrestle with as well, how early should we push to build in some level of eccentric exercises.  

 

A recent randomized trial done by the experienced Aspetar group out of Qatar tested this theory with a well designed randomized controlled trial (the often sought gold pinnacle of research).  90 male athletes (between 18-36 years old) were randomly assigned a treatment group after MRI confirmation of a hamstring tear from training or competing in a sport.  

 

The phased criteria based rehabilitation approach followed in this research was originally published in 2014 and can be found in Table 1 or seen in this video  

 

Both groups received a similar rehab program with the only difference being when the lengthening exercises were incorporated.  In the early lengthening group, lengthening exercises were introduced on day one of rehabilitation.  In the delayed lengthening group, lengthening exercises were introduced after being able to run more than 70% of self-rated maximal speed (rehabilitation program stage three).  The “delayed” timeline has been the more conventional approach used by the Aspetar group in previous studies.

 

The results are interesting, although not entirely conclusive (see meme of clinician banging head on a desk).  The official author’s conclusion, based on statistical significance, found there is no difference in how long it took to be cleared for return to play or in re-injury rates.  

 

However when we dig into the results a little bit the median number of days for return to play was 23 day for the early lengthening group and 33 for the delayed lengthening group.  Total re-injuries over the following year were the same in both groups (6 each).  This difference looks POTENTIALLY clinically significant although it was not found to be statistically significant.  We won’t bore you with the difference here, but for stats junkies this study may have ultimately been underpowered due to greater loss of participant follow up and completion than anticipated. 

 

Ultimately from a clinical perspective there is reason to be optimistic and intrigued by this research.  The signal of the findings do seem to favour early use of lengthening exercises, especially if time to return to sport is the primary concern.

 

For an easy way to implement lengthening exercises early in a hamstring injury check out this therapy thursday video from 2018.

 

It’s worth pointing out how far this research has come on hamstring injuries and why we should celebrate these efforts.  About 20 years ago the key elements of a hamstring rehabilitation plan were thought to be stretching and range of motion.  Range of motion gives the obvious signs of clinical improvement, so that has always been low hanging fruit to “see change”.  But when we compare the time to return to play from an often referenced study in 2004 the average return to play was 5.5 weeks (and had higher rates of re-injury).

 

This means 2 weeks less weeks of rehab and 2 more weeks playing the sport you love!