Anterior Cruciate Ligament Reconstruction (ACLr) is one of the most common surgeries performed due to a sports injury. ACLr rehab and ACL prevention training is one of the hottest topics in the sports medicine world. The reality is while 80% of ACL reconstruction (ACLr) patients return to some form of sport, only 65% return to the same sporting level and 55% return to sport at a competitive level within 1-2 years post ACLR (1). In this article, we will cover ACL return to sport testing as well as some of the alarming statistics regarding this topic.


The Return To Sport Journey

Unfortunately for those who are not professional athletes, the return to sport (RTS) path after ACLR is very unpredictable. There are so many ebbs and flows, and twists and turns, that it is almost impossible to predict. The main reasons for this are that the rehab program is bloody hard work and life gets in the way sometimes.

For the professional athlete, the RTS path is a little bit more predictable, and you’ll find that a high percentage of them will be back training and playing sport within 8-12 months. There are many reasons for this, with the main reasons being they get paid to do their rehab, they have a large team of medical services at their disposal, there are external pressures from a number of different stakeholders to RTS as soon as possible, and they are more likely to be much fitter and stronger than most of the age-matched general population.


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knee prehab program the prehab guys return to sport ACL

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ACL Return To Sport Testing Performance Testing Research

What is becoming clear, however, in regards to predicting a safe and successful RTS, is that recent research is indicating that the decision to RTS should be based on meeting key performance criteria, rather than allowing the player to RTS based on time-frames alone, or getting cleared to play from the orthopedic surgeon based on a series of static clinical tests. The results of two recent studies looking at ACL re-injury rates have been summarized below…


Grindem et al (2016)

  • They looked at 106 competitive athletes who recently had ACLR surgery and they had 5 key ACL return to sport testing performance criteria they wanted the player to achieve before clearing the player to RTS. They were;


  • Quads strength within 10% of the uninjured side


  • 4 single leg hop tests; with no more than 10% difference between sides



  • 38% of athletes who RTS despite not passing RTS criteria re-injured their ACL


  • Only 5% of athletes who did meet all 5 RTS criteria re-injured their ACL


  • Of the players who re-injured their ACL, 39% of them did so when they RTS earlier than 9 months, whereas 19% reinjured their ACL when they waited to RTS after 9 months


  • This lead the authors to conclude that for every 1-month delay in RTS, the re-injury rate was reduced by 51%


  • Lastly, and is in fact no surprise, 4 of the subjects in this trial who RTS within 5 months of their ACLR (against medical advice), all subsequently re-injured their ACL within 2 months of playing sport.


Krytsis et al (2016)

  • These authors looked at 158 athletes and used the same key RTS performance criteria as mentioned above, with the addition of an agility drill (T-Test)



  • All of the 158 athletes in this group returned to their previous competitive level of sport at an average of 229 days (approximately 8 months) post-op.


  • 26 players (16.5%) re-injured their graft at some point with 17 (65%) of them re-injuring their ACL within 6 months after RTS.


  • Furthermore, 11 (7%) injured their other ACL.


  • In regards to meeting performance criteria prior to RTS, 33% chose to RTS despite not meeting all 6 key criteria and subsequently reinjured their ACL,


  • Only 10% of the players who did met all 6 criteria, and were passed fit to RTS, subsequently reinjured their ACL.


How To Do You Know If You Are Ready To Return To Sport?


How To Perform ACL Return To Sport Testing

Single Leg Hop Test

The goal of this test is to jump as far as possible on each leg, aiming to “stick” the landing. The performance goal is to have the recently injured limb within 10% of the uninjured limb. Poor performance on this hop test (>10% difference between limbs) can identify those at risk of re-injury.

Video Highlights

Using technology from force plates, we can appreciate the ground reaction force (GRF) vector during the landing phase of the task. In the top left box of the first video, the vector is medial to the knee. If the vector were to move laterally outside the knee due to compensatory trunk lean or the knee collapsing in, there would be an increased valgus moment on the knee. The position of knee valgus places an increased load on the ACL. Uncontrolled, excessive dynamic knee valgus with a high acceleration rate is what ultimately can tear the ACL.


acl rehab wesley wang prehab guys


Triple Hop Test

The goal of this test is to consecutively hop three times as far as possible on the same leg, aiming to “stick” the final landing. The performance goal is to have the recently injured limb within 10% of the uninjured limb. Poor performance on this hop test (>10% difference between limbs) can identify those at risk of re-injury. This test is especially important to assess prior to RTS as it puts a very high demand and impacts on one leg. It is a great movement test to look at strength, stability, and motor control.

Video Highlights

Not only should you assess the final landing, but also the initiation and landing of each hop! You can appreciate more dynamic knee valgus during the second hop landing compared to the final hop landing.


Learn Plyometric Progressions For ACL Rehab!

Proper plyometric training is an important part of rehabilitation after an ACL reconstruction. Watch this video to learn more about the principles of plyometric progressions for rehab!


Crossover Triple Hop Test

The goal of this test is to consecutively hop three times as far as possible on the same leg while alternatively crossing over a line, aiming to “stick” the final landing. The performance goal is to have the recently injured limb within 10% of the uninjured limb. Poor performance on this hop test (>10% difference between limbs) can identify those at risk of re-injury.

Video Highlights

 This test is unique from the others as it adds a lateral component to the movement. With this addition, there is an increase in frontal and transverse plane forces directed at the knee. In this video, jumping from right to left in the medial direction is more challenging as it increases the valgus moment placed on the knee as compared to jumping in the other direction. This requires the athlete to work harder to decelerate the knee from moving through excessive dynamic knee valgus. You can appreciate the differences between the second and final landing!


knee extension machine ACL return to sport testing prehab guys


Six Meter Timed Hop Test

The goal of this test is to consecutively hop as fast as possible on the same leg for six meters, aiming to “stick” the final landing. The performance goal is to have the recently injured limb within 10% of the uninjured limb. Poor performance on this hop test (>10% difference between limbs) can identify those at risk of re-injury.


Video Highlights

 This test is unique from the others as it adds a time component goal to the movement, which helps to evaluate the individual’s LE power compacity. Being able to evaluate an individual’s LE power after ACLR is very important! Keep in mind with this speed addition, the athlete’s focus could shift from the quality of the movement to the quantity (time) spent performing the test. It is important to remind the athlete not to sacrifice the quality of their movement for a better time.


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Quadriceps  Strength

If there was only one test you were allowed to perform for ACL return to sport testing, The Prehab Guys would agree quad strength is the most important test. Although we do not have a video for this, the goal is to have a perfect Limb Symmetry Index (LSI) with quad strength, meaning side-to-side your quad strength is even. However, the most ideal situation would have similar LSI to pre-injury levels, if not even MORE strength (meaning >100% LSI)

One thing to take away from these trials is that you can still re-injure your ACL graft despite meeting the key ACL return to sport testing performance criteria, but your risk is much much lower if you do. Moreover, from the second trial I summarized, the average time for the players to RTS was only 8 months, whereas the first trial recommended that RTS be delayed to at least 9 months. It would very interesting to see if the re-injury rates of the second trial would be lower if the players were given an extra month, at least, to continue with further strength and conditioning and neuromuscular retraining. If you believe hip weakness is a potential factor limiting the player from returning to the sport, be sure to check out this article for hip stability ideas.


Closing Thoughts

In summary, we should be educating our patients and athletes that they can return to training and RTS with a reduced risk of ACL re-injury, anytime after the 9-month mark. However, before they even contemplate stepping onto the field for a competitive game, they should also be cleared clinically by their orthopedic surgeon and they absolutely must meet ALL the following key RTS criteria before doing so:

  • Quads strength: no more than 10% difference between sides


  • ACL return to sport testing: 4 single-leg hop tests: no more than 10% difference between limbs


  • T-Test agility drill performed in under 11 seconds.


  • Note: The last study also mentioned that an abnormal hamstring to quad ratio was found during testing that was a contributing factor to future ACL injury. This testing was performed on a laboratory machine (isokinetic) which is difficult to translate clinically. For those who have access to hand-held dynamometry; As a general rule the player should also have a Quad: Hamstring ratio of <1.5:1 before RTS


One very important thing to remember is that these ACL return to sport testing performance criteria should also be tested in a fatigued state at the end of a training session, as it is well established that fatigue has been shown to be a contributing factor to ACL injury. Remember, we need to be training and testing our players for the worst-case scenario of their sport, not just the average demands! If your athlete’s sport is soccer, be sure to incorporate these soccer prehab exercises in their training program!

As always please feel free to share this post with colleagues, patients, family, and friends, and please comment if you have other RTS tests that you like to do with your patients/athletes. As I have said many times before, I have a passion for injury prevention, so the more this research can be spread far and wide, the more health professionals will be on board with this information, then the better outcomes we’ll see in all of our patients long into the future! So there you have it, a pretty solid evidence-based approach to determining an athlete’s or patient’s readiness to RTS after ACLR.


Optimize The Health of Your Knee

knee prehab program the prehab guys return to sport ACL

Knee discomfort is one of the reasons why people end up sitting out but that’s about to change through the tag team champs of the world: education and movement. The knee must be strong enough to create its own muscular forces and be the traffic director for force passing through. Therefore, to have a successful outcome your program must include not just the knee but the core, hip, and ankle. Teamwork makes the dream work, ready to be part of the team?



  1. Grindem H, Snyder-Mackler L, Moksnes H, et al. Simple decision rules can reduce reinjury risk by 84 % after ACL reconstruction: the Delaware-Oslo ACL cohort study. Br J Sports Med. 2016;50(13):804–8.
  2. Kyritsis P, Bahr R, Landreau P, Miladi R, Witvrouw E (2016) Likelihood of ACL graft rupture: not meeting six clinical discharge criteria before return to sport is associated with a four times greater risk of rupture. Br J Sports Med 50(15):946–951


About The Author

Mick Hughes is the Head Physiotherapist and High-Performance Manager for the Collingwood Magpies Netball Team in the Suncorp Super Netball League. He also consults part-time at The Melbourne Sports Medicine Centre.  Clinically his area of interest is the lower limb, specifically the knee and ankle.


Instagram: @mickhughesphysio





Disclaimer – The content here is designed for information & education purposes only and is not intended for medical advice.

About the author : [P]rehab


  1. Simon bakkioui May 30, 2018 at 9:26 am

    My question is if a plater goes thru all the test earlier than sex month with only 10% from the health leg , what to do ??
    I realeased two players to play games of soccer five months after ACL op. One years ago ……

    • Michael Lau June 8, 2018 at 4:30 pm

      Hi Simon not sure I fully understand your questions…However 5 months post ACLr is wayyyy to soon and the risk of reinjury is too high. I would suggest rehabing the player a bit more…

  2. Theo Nimely May 26, 2022 at 9:52 am

    Why if I’m 11 months post operation and I can’t complete all the RTS criteria’s, what is my chance here when I RTS??

    • Team [P]rehab May 26, 2022 at 10:19 am

      Hi Theo!

      Excellent question, thank you for it! Unfortunately, we can’t provide direct medical advice on this platform due to legality. In regards to return to sport following ACL reconstruction, there are so many variables that differ from person to person; therefore, it is essentially impossible to say that every single person who has surgery on their ACL will return to sport at the exact same time. Some examples of variables are age, how extensive the surgery was, were there other injuries in addition to the ACL, what are the demands of the sport someone is returning to, is this the first time they have injured or is it recurrent? You can see how situations differ from person to person.

      Keep up the hard work. You are going to get there. And when you do, DOMINATE!!


      Team [P]rehab

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