More Rationale for ACL Injury Prevention Programs for Youth Female Athletes

There is fairly definitive evidence that females have lower hamstring strength and subsequently lower hamstring-to-quadriceps (H:Q) strength ratios in comparison to men. This has a significant impact on the ACL injury rates in female athletes, as the hamstring assists in protecting anterior tibial translation and strain on the ACL. Thus, ACL injury prevention programs have traditionally incorporated exercises to enhance this ratio.
Yet another study has been released in the latest issue of the American Journal of Sports Medicine by researchers out of Norway looking at the H:Q ratio, but this time in a group of prepubescent children from 7 – 12 years old. The study looked at isokinetic strength of 368 children. The results show that hamstring strength and H:Q ratio was significantly lower girls between the ages of 8-12. No significant differences were observed in 7 year old subjects, though the amount of females was lowest in this group. I am not sure if the results would have been the same if the group size was larger. In total, boys had a 10% increase in H:Q ratio.

Clinical Implications

It is well known that injury prevent programs have been shown to be effective in preventing ACL injuries, especially in female athletes. Based on the results of this study, it is apparent that some of the musculoskeletal gender differences that have been associated with a higher incidence of ACL injuries in females are present in children under the age of 12. Thus, it may be advantageous for young female athlete to begin injury prevention programs designed to enhance hamstring to quadriceps ratios.

One particular program that I have read about lately is the PEP program developed by Holly Silvers and the Santa Monica ACL Prevention Project. PEP stands for Prevent injury, Enhance Performance.” I have not used this program myself but I like the concept and it was backed up by a research report in the August 2008 issue of AJSM that demonstrated that subjects that did not perform the program had a 3.3x higher injury rate. The program consist of a 15-minute training session designed to be performed as a warm-up prior to athletics. The program includes running, agility, stretching, strengthening, and plyometric exercises in the format of a dynamic warm-up that can be performed in a group setting.
Another program that is popular is the Sportsmetrics program developed by Dr. Frank Noyes and the group at Cincinnati Sports Medicine. This program has been around for several years and has some research implemeneted within the program components. If you are interested, they also have a full certification program. Here is a video about the program:

Follow the above links for more details on the programs. Has anyone tried the PEP, Sportsmetric, or similar ACL injury prevention program? If so, tell us about your experience and share any recommendations.
7 replies
  1. Kristin
    Kristin says:

    There was recently a similar article published in the Journal of Bone and Joint Surgery (2010) that explained these differences between men and women during a soccer kick. The study was conducted using male and female college soccer players, and data showed females use different muscles when kicking which may contribute to why females tear their ACL more often.

    On Good Morning San Diego, there was also a news segment discussing why female athletes are more likely to have an ACL tear. You can check it out at:

  2. Mike Reinold
    Mike Reinold says:

    Wow, Thanks for the comment Tommy and contributing for the readers. That is great of you to offer your contact info. Keep up the great work, you are doing wonders for our profession and our athletes!


  3. Tommy Campbell
    Tommy Campbell says:

    Great questions. Please feel free to email or call me at [email protected] or 513-794-8472 and I would be happy to go into more detail with you. To quickly answer some of the questions: Sportsmetrics is set up to train individuals as well as teams. And there is likely a site near you as we have 600 across the nation. We do extensive testing to determine which athlete are more at risk, but definitely understand that all female athletes pose some risk for serious knee injury so everyone gets trained, but the testing allows us to focus even more attention on those that appear to be at a greater risk. We also do extensive post testing to determine progress and we have research data that back up all these answers. Overuse is typically not a problem as we are a preseason condition program as well so a mixture of Sportsmetrics ACL prevention and Sportsmetrics speed and agility allows most coaches to use our programs for conditioning and their own programs for teaching and improving skill. We are the largest non-profit and first scientifically proven ACL prevention program in the world. I would also like to thank you for your interest in ACL prevention be it Sportsmetrics or other. This is truly an epidemic and the more attention the topic gets, the more prevention the girls will have, and that give them the ability to enjoy their sports career from a young age and beyond, and not spend their seasons on the sidelines. I am more than happy to answer any questions that anyone may have. Please don't hesitate to call or email.
    Tommy Campbell
    Director of Sportsmetrics
    Cincinnati SportsMedicine Research & Education Foundation
    [email protected]

  4. Mike Reinold
    Mike Reinold says:

    Great question Amy. The PEP program itself is designed to be performed by the whole team at the same time. I like this idea and like the way they integrate it into a pre-activity event. This way it is more of a dynamic warm-up and should help with your volume question. If a team or even individual students are fortunate enough to have the resources to be screened for risk factors, that is where I would go with the Sportsmetric program.

  5. amy castillo
    amy castillo says:

    Since we are on the topic of ACL injury prevention, I would like to pose some clinical/program design considerations for everyone. With these type programs – Who gets the training (everyone on a team, those at risk)? What are good clinical tests to determine who is at risk and then if the risk has been eliminated? Ages to start, in light of this most recent article 8 years? Volume – with athletes already on the borderline of overuse will these programs help and can they hurt?

  6. Mike Reinold
    Mike Reinold says:

    Scott, you bring up some good points. My comments above were in direct response to an article published in this month’s AJSM relating to H:Q ratio. They are in now way intended to say that this is the best or only way to prevent ACL injuries. In fact, the programs mentioned above try to reduced injuries through a combination of training techniques. I want to use this blog to present new research with a slant on what I feel are the clinical implications.

    That being said, the Sportsmetrics program mentioned above actually originated from research on jump/land and cutting mechanics. They do have some research that is similar to what you mentioned. They look at mechanics in children and the effect of a training program on reducing injuries, but I am not aware of a study that documented faults and injury rates over time. Sounds like a great study idea, though! Follow the link above to visit their site and read some of their research.

  7. Scott M. Cameron, PT, MS
    Scott M. Cameron, PT, MS says:

    I would agree that there is some value to the H:Q ratio. But what about the importance neuromotor control with respect to jump training and correcting landing mechanics. Have there been any studies that have corrrected mechanical “faults” (i.e. excessive valgus/IR) with landing in children and followed them long-term to determine if this reduces their incidence of ACL tear as they age? Could it be possible that emphasis on motor control with landing versus strength training (trying to improve H:Q ratio) early in life is more effective at preventing ACL injuries?

    Scott M. Cameron, PT, MS

Comments are closed.