Sports Medicine Research: In the Lab & In the Field: Minding the Gap: Connecting Pre-season Screenings with Prospective Injury Data (Sports Med Res)
Monday, January 26, 2015

Minding the Gap: Connecting Pre-season Screenings with Prospective Injury Data

Association of Y Balance Test Reach Asymmetry and Injury in Division I Athletes

Smith CA, Chimera NJ, Warren M. Med Sci Sport Exerc. 2015; 47(1): 136-141.

Take Home Message: Anterior reach asymmetry larger than 4 cm on the Y Balance test was associated with increased risk of non-contact injury in a sample of collegiate athletes.

Clinicians need an efficient and accurate screening strategy that can be used across multiple sports and genders to identify athletes at risk for musculoskeletal injury. This could help identify individuals who need interventions to potentially prevent injuries. The Y balance test, a measure of dynamic balance during single leg stance, may be an ideal screening test. This study investigated the link between Y Balance Test results, collected during pre-participation physicals, and non-contact injuries over the course of a season. The researchers hypothesized that anterior asymmetrical reach would be related with increased risk of noncontact lower extremity injury. Additionally, they thought that a lower composite score would increase an athlete’s chance of a noncontact injury. Athletes completed the Y Balance Test scores prior to the start of the season. Throughout the season, the authors prospectively monitored athletes for noncontact injuries. An injury was defined as an event where the athlete sought treatment in the athletic training room and required athletic trainer attention. To assess the association between Y Balance Test scores and injury risk, the researchers calculated the asymmetry between left and right sides in the anterior, posterior medial, and posterior lateral directions by calculating the absolute difference in reach distance between limbs. Additionally, they calculated a composite score by averaging right and left reach distances, which were normalized to weight-bearing leg length. Overall, 81 out of 184 participants sustained a noncontact injury. The mean composite score was not different between the injured and non-injured groups and no differences were found for asymmetries in any direction. The researchers determined that an asymmetry greater than 4 cm was the best cut-point to identify athletes who sustained an injury but the sensitivity and specificity were moderate at 59% and 72%, respectively. Based on this cut point, an athlete with greater than 4 cm anterior asymmetry is more than twice as likely to sustain an injury as an athlete with no asymmetry. No other asymmetries were related to a new injury.

This study is the first to prospectively investigate a collegiate population to assess if Y Balance Test scores predicted injury incidence. While anterior asymmetry was associated with sustaining an injury its clinical use as a screening tool, without any other tests, may be limited. The authors acknowledged a few limiting factors to consider with this study. Specifically, the definition of injury is not consistent with other definitions in the literature. While it may be clinically meaningful to define an injury as needing an athletic trainer’s attention the athlete may not present with traditional signs of trauma. Additionally, the inclusion of overuse injuries as a non-contact injury complicates the study because the onset of symptoms may not coincide with when an athlete reports to an athletic trainer. It is possible that the Y Balance Test may be an effective screening tool for acute noncontact injuries but it is difficult to test at this point. While more evidence is needed, it may be beneficial to collect the Y Balance test results during preparticipation examinations if time and resources permit. If an athlete has an anterior asymmetry greater than 4 cm we should perhaps review his/her chart to see if there are other warning signs that the athlete may be at an increased risk of injury (e.g., history of previous injury) and if so develop an injury prevention strategy. Sports medicine staff should also complete regular surveillance of injury events to fully understand patterns of injuries in their setting to help identify characteristics related to injuries like athlete characteristics (e.g., balance), training characteristics, teams, or playing surfaces.  

Questions for Discussion: How do you define injury in your setting? Do you use tools like the Y Balance Test in pre-participation physicals to aid your understanding of injury risk?

Written By:  Laura McDonald
Reviewed by: Jeffrey Driban

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SMITH, C., CHIMERA, N., & WARREN, M. (2015). Association of Y Balance Test Reach Asymmetry and Injury in Division I Athletes Medicine & Science in Sports & Exercise, 47 (1), 136-141 DOI: 10.1249/MSS.0000000000000380


Stacy Schurr, ATC said...

I have been doing a little research on different screening methods for my graduate thesis, and I agree with your comments on this article. This is a great starting strategy for using a specific method and prospectively studying its relationship to injuries. There are limitations, like those mentioned in the article. Like you stated as well, it is important to look back the patients' charts for history of previous injury, potential complicating factors, etc. Another factor I've come across while studying the literature is the area of injury. Most studies utilizing the Y Balance test focus on the ankle, so I always wonder about its effectiveness on other areas of the lower extremity. I also think it would be interesting to use this strategy on high school, Division II or III, and recreational athletes to see if there are similarities in effectiveness of the test.

Laura M. McDonald, PhD, ATC said...

Thanks for your comment, Stacy! There is absolutely a need to continue to develop and prospectively assess the ability of these screening tools to understand risk. Your point about generalization of these tests to the lower extremity, versus a specific joint, is interesting. It would be ideal to find a common test predictive both for the upper and lower extremities. Besides Y-Balance, are there are other tools you are finding in your graduate research?

Sandra Koen,ATC said...

I think looking at asymmetries as a screening tool is an interesting thought, especially in collegiate athletes who are sometimes one sided dominant because of the sport they play. Someone who plays volleyball, basketball or lacrosse that perform the same motion with their dominant side may be stronger and more developed compared bilaterally, therefore causing obvious differences between their right and left sides It would be interesting to look at high school athletes and see if there were any patterns as well, because their bodies are still developing and growing. I agree with previous injuries being a confounding factor, since rehabilitation could have enhanced the balance/flexibility of that side. In general, I think it would be very tough to come up with one screening tool that is predictive of injuries for all sports, but I think starting out with something like the Y Balance test is good as long as the other factors are taken into consideration.

Laura M. McDonald, PhD, ATC said...

Thanks for your input, Sandra. I think consensus among clinicians would point to a multifactorial approach to prediction, as you mentioned. Scoring of the Y Balance is typically normalized to limb length, however, your point about dominant vs. non-dominant differences raises a great question about other normalization factors to consider.

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