A new jump-landing protocol identifies differences in healthy, coper, and unstable ankles in collegiate athletes
Liu K, Dierkes C, Blair L. Sports Biomechanics. 2016, 15(3):245-254. dx.doi.org/10.1080/14763141.2016.1158859
Take Home Message: The jump-landing protocol was able to distinguish between healthy, ‘coper’, and unstable ankles. This protocol may be useful for identifying athletes at increased risk for injury, and as a return to play indicator following rehabilitation.
Ankle sprains are one of the most common athletic injuries, and suffering a single sprain increases the risk for future sprains, which may lead to chronic ankle issues. A functional deficit identified in individuals with chronic ankle problems is reduced postural stability. Time to stabilize (the time it takes to regain stability after a dynamic movement) is one way to identify ankle instability; however, many time to stabilize protocols are not challenging enough for an athletic population. Therefore the authors wanted to develop a sport-specific jump-landing protocol that involves a large vertical displacement and multi-directional components that could identify differences in healthy, ‘coper’, and unstable groups. The authors placed 61 Division I college athletes (29 males, 32 females) into 1 of 3 groups (healthy, coper, unstable) based on their ankle injury history and score on the Cumberland Ankle Instability Tool. A forward and lateral jump landing protocol was completed for the jump-landing test. In the forward test, participants were instructed to take two preparatory steps, take off from a single leg, jump to an indicator, and land single-legged onto a force plate with the opposite limb. For the lateral test, participants took two side shuffle steps, took off from a single leg, jumped to an indicator, and landed single-legged onto a force plate on the opposite limb. The indicator was positioned at 50% of the athlete’s maximum vertical jump for both jumping tasks. All participants were instructed to land in the middle of the force plate, stabilize as quickly as possible on the single test leg, and remain motionless for 5 seconds. The results showed that the unstable group required more time to stabilize compared to other healthy and coper groups for both forward and lateral hops.
The jump-landing protocol was able to identify differences in time to stabilize among college athletes. It involved three different components: (1) preparatory steps into the jump, (2) both forward and lateral propulsions of the body and (3) a vertical displacement of the body. Other jump-landing protocols incorporate at most two of these components and previous studies were unable to identify differences between groups. Therefore, the researchers suggest that all 3 components are necessary in a time to stabilize protocol to identify athletes at risk for chronic ankle instability. However, the limitations of the study should be noted such as the small, homogenous sample size, which may not be generalizable to other populations, such as high school or recreational athletes. Identifying athletes at high risk for chronic ankle instability is important for medical professional to ascertain since it can help reduce the number of games/practices the athletes lose, and lessen the long-term burden of injury. If the jump-landing protocol is effective at identifying athletes at increased risk for injury then coaches and clinicians can use this information when developing strength training and/or rehabilitation procedures.
Questions for Discussion: What are the best exercises to improve dynamic stability in athletes with chronic ankle instability? Would it be possible to replace the force plate with some form of wearable motion tracking device that could make the test more available to athletes that do not have access to force plates?
Written by: Matt Prebble, MPH, CSCS
Reviewed by: Jane McDevitt