The next test in our series on return to sport testing is the Star Excursion Balance Test. While many of you are familiar with the research regarding the test’s utility in predicting injury in the pre-participation setting, it seems to be less commonly implemented in return to sport testing. Remember, we are currently discharging our patients with modifiable risk factors for future injury.

Flux Capacitor from Time Traveling DeLorean from Back to the Future  Is it coincidence that it is in the shape of a Y?

Flux Capacitor from Time Traveling DeLorean from Back to the Future
Is it coincidence that it is in the shape of a Y?

So, how can the Star Excursion/Y Balance Test help us? You may have read the systematic review. But what amazes me  is that in the original paper we reviewed 36 articles extracted from 1998 to 2010, and since then over 30 additional research articles were published in 2011-13 (for a total of over 60 published articles on the Star Excursion/Y Balance Test). Here is a summary of what we know:

  • Reliable (Plisky et al 2009, Shaffer et al 2010, Gribble 2013)
  • Predictive of injury (Plisky 2006, Lehr 2013, de Naronha 2012)
  • Discriminant Validity
    • Identifies chronic ankle and ACL insufficiency (Hubbard 2007, Hertel 2006, Hale 2007, Akbari 2006, Nakagawa 2004 Gribble 2004, Olmstead 2002, Herrington 2009, Delahunt 2013)
    • Differentiates between athletes based on age, sport, gender (Plisky 2009, Thorpe & Ebersole 2008, Bressel et al 2007)
  • Improves after training (Filipa 2010, Fitzgerald 2010, Leavy 2010, Eisen 2010, McKeon 2008, Hale 2007, English 2007, Bouillon 2009, Kahle & Gribble 2009, Rasool & George 2007) even in the elderly! (Khale  et al 2013, Hosseini 2012, Sarvestani  et al 2012)
  • Improving Star Excursion Balance Test scores reduces injury risk (Steffen 2013)

There is no doubt in my mind that the Star Excursion Balance Test/Y Balance Test has the most research behind it compared to any other return to sport test. Most importantly though, it is the ONLY lower quarter test I know of that is reliable, predictive, modifiable AND improving  performance on it reduces injury risk.  Please let me know if I am missing a test that has ALL of those characteristics.

Ok, I agree I should be using Star Excursion Balance Test for return to sport, but what is considered a “passing” test?

Given that the Star Excursion/Y Balance Test is predictive of injury and that one of main goals with return to sport decision making is determining if the athlete is going to get hurt again, we should look at the studies that use the test to predict injury:

High School Basketball players (Plisky 2006)

– Players with anterior asymmetry of greater that 4 cm are at increased risk of injury

– Girls with a composite score (94%) in the bottom third of their peers are 6 times more likely to get injured

Collegiate Football Players (Lehr 2013)

– All injuries occurred in players with a composite score of less than 89% (Note that the composite risk cut point needs to be based on gender, sport, and age.)

Active College Students (de Naronha 2012)

– Posterolateral reach of less than 80% of limb length increase risk of ankle sprain. Interestingly, posterolateral reach of greater than 90% was protective of ankle sprain.

Collegiate Athletes (Lehr 2013)

– Those who had a previous injury and scored below the composite score risk cut point for their age, gender and sport OR had a greater than 4cm anterior reach asymmetry were in the high risk category

Bottom Line: Prior to return to sport (or at LEAST prior to discharge), your patients should demonstrate a symmetrical Star Excursion/Y Balance Test that is above the risk cut point for their peer group.

As we work our way through improving our return to sport testing, our first stop is at hop testing. Most rehabilitation professionals use some form of hop testing, but which hop tests should we use and what should our passing criteria be?

Which hop tests should I choose?boy hopping

While it is important to use double limb hopping as part of the progression in rehabilitation, it is unnecessary for return to sport and discharge testing. In a study by, Myer et al double limb activities did not identify the unilateral deficits found after ACL reconstruction. Here are the unilateral tests supported by research:

Single hop for distance
6m timed hop — I don’t use this one. This is not solely based on published research (although the reliability is the lowest of the hop tests), but what I have observed clinically and through studies we have done. Basically, unless you use timing gates, your stopwatch trigger finger error is pretty close to any right/left asymmetries you would find (except in the cases of severe asymmetry — which the other hop tests would pick up)
Triple hop
Triple crossover hop
Hop & Stop — I really like the concept of this one and I am starting to use it more clinically. There are normative values and you know what a big fan I am of using population specific values to determine risk. Jeremy Boone has written about the hop and stop here

The above tests are reliable and modifiable  (Munro & Herrington 2011Reid et al 2007). I have not seen any studies demonstrating the injury prediction value of these hop tests (if you do know of such studies, please let me know) but they do have decent discriminant validity.

Criteria for Discharge  and/or Return to Sport:

To me, the MOST important question is “What should the return to sport and/or discharge criteria be for hop testing?”

The most common return to sport criteria that I have come across in the literature is 85% and 90% Limb Symmetry Index (LSI). I believe neither of those is stringent enough. Remember, previous injury is the most consistently reported risk factor for future injury and we are currently discharging individuals with modifiable risk factors. So, on that basis alone, our standards should be higher.

But, let’s look at the research.  Reid et al 2007 repeated hop testing on 4 separate time points after ACL reconstruction (16 weeks, a couple times more that week, and at 24 weeks post op)  and  found good longitudinal and concurrent validity for the four hop tests.  However, consider this interesting fact from their research:

At 24 weeks post-op ACL reconstruction, the average overall Limb Symmetry Index was 88.5% and the average Lower Extremity Functional Scale score was 69.3. An athlete with a 69.3 LEFS would have moderate difficulty with the following activities

•“Your usual hobbies, recreational or sporting  activities”
•“Running on even ground”
•“Running on uneven ground”
•“Making sharp turns while running fast”

If someone reported this much difficulty with these activities (I realize this is an “average” report but their LSI report is also an “average”), should she return to sport? Bottom line: In this study, 89% hop testing LSI equates with moderate difficulty with simple sport activities. Thus, 90% is not enough. Also, just because someone has returned to sport (which is what is typically considered “success”) does not mean that she is not at substantially increased risk of injury.

Finally, Munro & Herrington 2011 found that the average LSI for the four hop tests was 100% (98.38 to 101.61%.) and that 100% of healthy subjects have at least an LSI of 90%. Based on these results, the researchers advocate that the return to sport LSI criteria be increased to 90%.

Given our current re-injury rate, I suggest hop testing LSI should at least be above 95% and recommend it to be above 97%-100%. Do you think we can achieve this in rehabilitation? Do you think we should use 90% for return to sport and 97-100% for discharge?

We’ve been discussing return to sport and discharge testing. In our last post, we met Jane, a 36 year old with knee and hip pain due to lack of systematic discharge testing after her ACL reconstruction 20 years earlier. This  left her with modifiable risk factors and now pain. Worse yet, she is trying to get into shape but is struggling due to this recent “injury.” Remember, we can prevent these injuries, but the key is systematic testing at return to sport and discharge. But before we get into the specific tests and criteria, let’s discuss how we should go about selecting those tests.

The Missing Link

Obviously, the test should be reliable and measure the domain that you are trying to test. But which domains should we test? Using a Delphi study method, Haines et al created a checklist of domains that an expert panel felt were important to include in return to sport testing. The domains that the experts suggested testing included:

      • pain
      • coordination
      • movement
      • balance
      • neuromuscular control
      • power
      • sport specific movements
      • strength and range of motion ** this is my addition (we will discuss the research related to these and risk of injury)

I think we all would agree with the above list, but how do we go about selecting the specific test and criteria for return to sport or discharge? I believe most of us already test those domains, but our current standard of care is leaving people with a substantial risk of future injury.

What are we missing?  I believe we are missing 3 key concepts in return to sport and discharge testing:

1) When possible, the tests we use should be predictive of injury

– Could you imagine if your primary care physician could do a few simple tests that could quickly give you a snapshot of your risk of a disease? Wouldn’t you expect her to perform them? As a matter of fact, they currently do (think heart rate and blood pressure). We owe this to our patients in rehabilitation as well. But when it comes to return to sport, I believe we put too much and too early emphasis on tests requiring high level physical function and other sport specific tests. While those are important, I  think we need to consider tests predictive of injury or that identify traits that lead to susceptibility to injury.

2) The tests need to be arranged in a hierarchical fashion ( This case study in BJSM is a start).

– Currently, I think we assume (often unconsciously) that if an athlete can hop/cut/run well, then they have the foundational requirements of ROM, strength,  basic movement and balance. Or, that those foundational traits are not as important. But frequently, this is not the case. There is little need to perform testing at higher levels of function if there is a fatal flaw in movement or balance at lower levels of function. If the athlete passes the higher level testing, they too ASSUME that they are good to go.

3) We need to set the minimum criteria for discharge to be near what a person at “Normal” risk would score on the test (and I would argue it should be even higher than that).

– Since we know that athletes who have been previously injured are more likely to be injured again and that motor control changes frequently remain after injury, we should demand that their test results are close to normal prior to discharge. What if you had a disease and your blood levels indicated that it was advanced and you underwent treatment and they retested your blood and found that you were better, but not normal. What would your response be? Mine would be “Is it possible to get it back to normal or is this as good as it gets?” We need to have the same attitude toward one of our largest, most expensive systems — the neuromuscular system

 So, with those concepts in mind, here is what I am now giving patients at the start of their care. This list includes most of my discharge criteria. Over the next several posts, I will go through the research regarding these tests as well as any others that are suggested. Add any tests that you think are missing below.

Not because we want to autograph our great work, but to signify that we have completed the safety checks to ensure we have removed all modifiable risk factors for injury. Why did surgeons implement signing the operative knee before surgery? As ridiculous as it sounds, the wrong knee had mistakenly been operated on. It doesn’t happen very often, but what it does, it can be catastrophic. Why should rehabilitation providers sign that they have removed all modifiable risk factors after rehabilitation?

Because we are unknowingly discharging  numerous patients with modifiable risk factors for future injury. In fact, almost certainly many more patients are being discharged with modifiable risk factors than wrong knees are being operated on — and the long-term consequences can be just as catastrophic.

Let’s hear what happened to Jane:

Jane walking with her child

Jane is a 36-years-old mother of two, whose youngest is 18 months. Since the birth of her children Jane’s priorities have shifted and she no longer gets to the gym as much as she’d like. She enjoys exercises, but with two kids and full-time job it’s hard to squeeze in a regular routine. As a result, Jane has put on few pounds, a fact that pushed her to recommit to getting back into shape despite her busy schedule.

In the course of her new workout routine, she developed hip and knee pain. She went to her physician and he diagnosed her with early onset knee osteoarthritis. How can that be, she’s only 36?

Looking back over Jane’s medical history, we discover that 20 years ago she had an ACL reconstruction, with several months of rehabilitation. Considering this prior injury, was Jane’s early onset of osteoarthritis just a natural course of the ACL tear, or was there something that could have been done differently to prevent her current condition? Let’s look at her post-operatively:

The rehabilitation provider that worked with Jane had her start with basic range of motion and strengthening and then progressed her through a myriad of exercises from low to high level. Finally, Jane was doing plyometrics (programs proven to reduce injury), running, and cutting and was ready to return to sport. Her strength and ROM looked good and so did her running and cutting. Jane said she was feeling great! So she went back to sport.

Here’s the problem: Previous injury is the most consistently reported risk factor for future injury in athletics. Here is one of my favorite injury epidemiologists summarizing his research findings:

“Looking at 70 teams, in 18 countries, over 8 seasons (9,000 injuries), we have found that previous injury is by far the greatest predictor of future injury in football.”

Jan Eckstrand
Soccer Industry Medical Symposium 2009

But what is more important is that, numerous researchers have found that modifiable risk factors remain after rehabilitation (eg. jump landing asymmetry remains 2 years after ACL reconstruction and predicts second ACL tear). If you would like to dive into that concept in more depth, check out this short video

What this means is that without standardized, systematic, and stringent return to sport and discharge testing, we are likely to discharge patients with modifiable risk factors. We MUST stop this. Since I have implemented systematic discharge and return to sport testing, I am SHOCKED to find out how frequently I am wrong — the patient appears to be normal (even by my “trained” eye) but testing reveals something completely different.

So, are you willing to sign your patient’s leg, arm or back? I am…..but in the mean time, I have to go apologize to some of my previous patients.  Fortunately, Jane is fictional but represents a large percentage of our patients.

Over the next several posts, I hope we can all discuss what the evidenced based discharge tests should be and what is considered passing. What tests do you think should be included? Post them below so we can discuss them in this forum.

Functional Movement Screen Injury Prediction Studies

O’Connor FG, Deuster PA, Davis J, Pappas CG, Knapik JJ. Functional movement screening: predicting injuries in officer candidates. Med Sci Sports Exerc. 2011 Dec;43(12):2224-30.

“Both Long Cycle and Short Cycle cohorts demonstrated higher injury risk among candidates who had scores ≤14 compared with those with scores >14 (LC: risk ratio (RR) = 1.65, 95% confidence interval = 1.05-2.59, P = 0.03; SC: RR = 1.91, 95% confidence interval = 1.21-3.01, P < 0.01). Overall, 79.8% of persons with scores ≤14 were in the group with fitness scores <280 (/300), whereas only 6.6% of candidates in the group with fitness scores ≥280 had scores ≤14.”

Take Home: Functional Movement Screen score is associated with injury risk in Marine officer candidates regardless of the length of the basic training session.


Kiesel K, Plisky PJ, Voight ML. Can Serious Injury in Professional Football be Predicted by a Preseason Functional Movement Screen? N Am J Sports Phys Ther. 2007 Aug;2(3):147-58.

“The results of this study suggest fundamental movement (as measured by the FMS™) is an identifiable risk factor for injury in professional football players. The findings of this study suggest professional football players with dysfunctional fundamental movement patterns as measured by the FMS(™) are more likely to suffer an injury than those scoring higher on the FMS™.”

Take Home: Performance on a basic test of fundamental movement patterns is helpful in predicting injuries in professional football players.


Chorba RS, Chorba DJ, Bouillon LE, Overmyer CA, Landis  JA. Use of functional movement screening tool to determine injury risk in female collegiate athletes. N Am J Sports  Phys Ther. 2010;5:47-54.

“A score of 14 or less on the FMS™ tool resulted in a 4-fold increase in risk of lower extremity injury in female collegiate athletes participating in fall and winter sports. The screening tool was able to predict injury in female athletes without a history of major musculoskeletal injury such as ACLR.”

Take Home: It is interesting to note that athletes with history ACL reconstruction were included in the study. This may indicate that the Functional Movement Screen may be able to pick up some of the motor control changes that occur after injury that place athletes at increased risk.

Asymmetries are common in the human body and can lead to a wild goose chase in musculoskeletal assessment.  But how do we know which asymmetries are important and will lead to injury? Well, let’s look at some common misconceptions as well as the research.

Wild Goose Chase

Common Misconceptions About Asymmetries

1.  If someone performs well at their sport with an asymmetry, the asymmetry doesn’t matter.

Who ever said that asymmetry IS related to performance? Asymmetry is related to injury risk, not necessarily performance. While I am concerned about performance, I am more concerned about keeping them in the sport and participating without being encumbered by injury.

 2. Asymmetries are only important if they cause pain.

I am mostly concerned with asymmetries that cause movement inefficiency or are related to injury risk. To me,  asymmetrical fundamental movement patterns will lead to injury or inefficiency (i.e. energy expenditure that is unnecessary for performance of the activity).

3. There is no research that indicates asymmetry increases risk of injury

Those who have an anterior reach distance asymmetry on the Y Balance Test (Star Excursion Balance Test) are at increased risk of injury in high school basketball and multiple collegiate sports (Plisky 2006, Lehr 2013)

Those who have an asymmetry on the Functional Movement Screen (Kiesel 2013 in press) are at increased risk of injury in professional football

Strength and flexibility asymmetries:

        • Athletes experienced more lower extremity injuries if they had knee flexor and hip extensor strength asymmetries (Knapick 1991Nadler 2001)
        • Eccentric hamstring strength asymmetries were at greater risk of sustaining a hamstring muscle strain. (Fousekis 2011)
        • Hamstring/quad ratio asymmetry (Soderman 2001)
        • Ankle strength asymmetry (Baumhauer 1995)

Asymmetrical landing patterns predict second ACL tear in previously reconstructed athletes (Paterno 2010)

Bottom Line: I really don’t put much stock into isolated bony asymmetries (e.g. torsions, misalignments, etc.), but I do feel that modifiable movement asymmetries that are related to risk of future injury are extremely important. Further, the literature is replete with studies that indicate asymmetries exist after pathology (Gribble 2013, Hewett 2013).  Since previous injury is the most robust risk factor for future injury, we owe it to our athletes to normalize these modifiable risk factors.

What do you think?


Balance Test - Post-Lat

In athletes with chronic ankle instability, 2 studies report that fatigue decreases the reach distance on both sides(Gribble 2004, Gribble 2007). However, the unstable side is affected to a greater degree. So, performing a fatigue protocol prior to testing for return to sport might be a good idea. It will amplify those remaining neuromuscular control deficits. But remember, it will also decrease the composite score as well, so the results might not be as comparable to the age, gender, and sport specific injury risk cut points. But, I wouldn’t want anyone’s composite score so close to the risk cut point that fatigue tips them over the edge. Another

You should also consider fatigue with pre-participation physicals. Many places use the Y Balance Test not only for risk identification, but also as a baseline measure for return to sport after musculoskeletal injury or concussion. So if the athletes have a heavy workout prior to testing, their scores may be a little lower. I think that may be important to note, but would not cause me to postpone testing.

What do you think?

What research is there to support using the Upper Quarter Y Balance Test for return to sport testing?

Just like other return to sport tests, there is very little in the literature (really nothing). As far as the Upper Quarter Y Balance Test, there are 2 research studies (Gorman et al 2012, Westrick et al 2012). Both studies found the Y Balance Test – Upper Quarter to be reliable. In addition, both studies found there was no difference in YBT-UQ performance between dominant and non-dominant limbs. This indicates that YBT-UQ performance may serve as a good measure in return to sport testing when rehabilitating shoulder and arm injuries. Westrick et al state:

“Similarity on the UQYBT between dominant and non-dominant limbs indicates that performance on this test using a noninjured UE may serve as a reasonable measure for “normal” when testing an injured UE.”

Y-Balance Test - Medial

Y-Balance Test - Infero Lat

Y-Balance Test - Sup Lat

We are also finding right/left symmetry on the YBT-UQ in professional and collegiate baseball players (including pitchers). So, I think if overhead athletes and healthy adults demonstrate symmetry on the YBT-UQ, that patients should demonstrate symmetry before return to sport/activity (or at least before discharge).

Other tests to consider are the Closed Kinetic Chain Upper Extremity Stability Test and the One Armed Hop test. But remember, these measure power (versus dynamic control near limit of stability) in a very limited dynamic range compared to the Y Balance Test. The YBT-UQ uniquely requires stability at the person’s limit of stability in a one-arm push up position unlike planks, side bridges, trunk flexor/extensor endurance tests and the CKCUEST. Westrick et al report:

“There was a significant fair to moderate association between performance on the UQYBT and the CKCUEST, LTET, and push-ups. These results suggest the tests are interrelated but do not necessarily assess equal components of UE CKC ability.”



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Phil Plisky

I want to change peoples lives through dialogue about injury prevention research and return to activity testing.

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