How Necessary is Hamstring Strengthening for Preventing ACL Injury?

FOR ATHLETES:  

Bottom line info you need to #GETBETTER

The hamstring muscles work with the ACL (anterior cruciate ligament) to maintain knee stability during sports.  Research over the past few years has shown that females who injured their ACL’s had weaker hamstrings than uninjured females or males.  Because of this, the sports medicine community thought that strengthening the hamstrings would decrease risk for ACL injury.  Furthermore, we thought that training the hamstring muscles on the back of the knee to work with the quadriceps muscles on the front of the knee (aka “co-contraction”) would make the knee even more stable and less vulnerable to injury.  The muscles would basically act as shock absorbers to the knee during sports-  think of all the impact a knee goes through during a run, a soccer match, or a basketball game.

However, a recent study showed that just coaching athletes to “land softly” and bend their knees more during single leg plyometrics lowered the impact forces through the knee.   No strengthening program needed- just modification of athletes’ landing form!   And even more shocking was the fact that when the impact forces decreased, the amount of hamstring/quadriceps co-contraction decreased too.   Yes-  you are reading that right- the hamstrings didn’t really have much to do with the possible decrease in injury risk.

So is hamstring strengthening really the key to reducing ACL injury risk like we thought?  Well…I always recommend that strengthening the posterior chain is VERY important.  And this study doesn’t change my opinion much.  However, in terms of ACL injury risk reduction we may have to increase our focus on re-training athletes’ form with plyometrics and agility.  Proper form with these drills is really important-  while landing from plyometrics and when planting/cutting for agility drills-  bend the knees and hips like you are about to sit in a chair.   Get in the habit of doing this every time  you train to build “muscle memory”


 

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