ACL Injury Prevention Programs – Why They Aren’t Working for Young Athletes

In action-filled sports – most often in those that include cutting, jumping, pivoting, and contact or blows to the side of the body – the knee is at risk of being forced into a position where the ACL is vulnerable to tearing.

Young athletes are particularly vulnerable to such injuries, and in recent years “ACL injury prevention programs” have been touted as a potential solution to the problem. These programs prescribe specific exercises intended to strengthen and align the core, hip, knee and ankle. These are generally performed prior to play, with the thought being that the body will learn and remember the correct alignment during play.

However, despite the widespread adoption of these programs by coaches, teams, and parents, they have NOT resulted in a significant reduction of ACL tears in young athletes. Why not? A recent paper presented to the American Orthopaedic Society for Sports Medicine suggests that FATIGUE is one key reason.

Fatigue can overwhelm an athlete’s ability to maintain their best alignment of the knee, no matter how dutifully he or she has followed a regimen of injury-prevention exercises. And unless this key factor is addressed, we are unlikely to see a reduction in ACL tears among young athletes.

So what can coaches, parents, and athletes do to avoid what I call the “fatigue danger zone”?

1. Train for endurance and fatigue resistance. Be certain that endurance for the sport is up to par. Depending on position played, field and court athletes can run between up to seven miles per game. If the “fatigue danger zone” is to be avoided, athletes must train for cardiovascular endurance that meets or exceeds that required in their games.

At least 8 weeks before rigorous practice and competitive play begin, consider a program of running 3 to 7 miles, 3 to 4 times a week in order to build a solid cardiovascular base.. The goal is to build enough cardiovascular stamina to be able to maintain good hip, knee, and ankle alignment for the entire length of play, through both steady-state effort and intense bursts of activity. In addition, four weeks before competitive play, begin introducing of short  bursts of speed during these longer run. These sprint intervals can improve tolerance of changes in intensity required during play.

This base of endurance can help an athlete resist fatigue and be more likely to maintain good hip, knee, and ankle alignment for the entire length of play.

2. Attend to the basics. Outside of training, the most significant building blocks for preventing athletic fatigue are consistent sleep habits, proper nutrition and hydration – take them seriously.

3. Don’t let fatigue set in during play. The best protection from ACL injury is ensuring that an athlete rests BEFORE form suffers. Visible alignment and technique changes mean an athlete is fatigued and has already played into the danger zone! All the off-the-field injury-prevention exercises in the world can’t help once fatigue sets in and an athlete can no longer maintain correct alignment and proper form.

Even with a solid base of endurance training, athletes will sometimes exceed their limits, and when they do it is important to recognize it and take action. If an athlete is too fatigued to maintain correct hip, knee and ankle alignment, then that athlete needs to come off the field of play to rest until he or she has recovered. Most often this decision needs to be made by a coach or parent because athletes themselves are typically self-driven to continue to play. And this means that coaches and parents should be able to identify correct alignment and to know when an individual athlete is too fatigued to maintain it.

4. An ACL exercise protocol should be a workout in itself, so that the muscles that drive correct alignment and stabilize that alignment have to adapt to the demand. It’s not enough to simply go through the motions with fifteen repetitions of each exercise. Instead, real effort and multiple sets are required to fatigue the muscles to a point where those muscles and their neurological control system have to change.

5. An ACL exercise protocol should be performed after play as well as before. It’s easy to go through the motions and perform the exercises with proper alignment for a few repetitions when you’re fresh, but your body doesn’t learn anything during this process and isn’t forced to adapt. Doing the protocol when fatigued will force the muscles that control alignment to work at maintaining the correct position, and through this process have a better opportunity to direct alignment during intense play.

6. Be aware that exercises cannot insure correct alignment of the hip, knee and ankle during play. It is true that the correct movement pattern with the hip, knee and ankle alignment is best learned with focused exercise, but real injury prevention comes by incorporating that awareness into play and all the movements – pivoting, cutting, jumping, landing – that are a part of any given sport.

Try incorporating practice drills that combine active awareness of alignment with typical movements involved in a sport. That is, design sequences of moves like cutting, jumping, kicking, or passing, and repeat them while actively reinforcing alignment awareness. A coach, trainer, or parent is invaluable for making these drills effective, both because they can encourage correct alignment, as well as learn to identify when it goes wrong, so that (as in point 3) an athlete can be rested and recover before fatigue becomes a risk factor. Consider using video to record and analyze these technique drills, both to able to demonstrate correct alignment and to identify the point of fatigue, loss of form, and therefore the risk of an ACL tear.

7. Different athletes need different programs. The idea that a universal “team” participation with an ACL prevention exercise drill will effectively address everyone’s needs is grossly deficient. Some athletes are much more challenged to maintain correct alignment than others, and therefore some need much more work on endurance, strength and alignment for ACL injury prevention. This should be a priority for everyone involved – coach, parent, and athlete.


Don’t be lulled into a false sense of security by an ACL injury prevention protocol. They are helpful, but the statistics indicate that they are not reducing ACL injuries among young athletes. Recent research suggests that fatigue is a big reason for that. Vigorous practices and competitive games often fatigue athletes to a degree that negates any benefits of pre-play prevention exercises.  By incorporating the points above into your young athletes’ programs, you will be better prepared to them keep out of their “fatigue danger zone”, and thereby keep them healthy and on the field of play.

Further Reading:

Increasing Incidence of Anterior Cruciate Ligament Reconstruction JAMA 2017

Youth ACL Research – AOSSM 2018 Annual Meeting

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1 Comment

  1. bruce edwin roth

    Very good!

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