Association of Dynamic Balance With Sports-Related Concussion: A Prospective Cohort Study

Abstract

Background: Concussion is one of the most common sports-related injuries, with little understood about the modifiable and non-modifiable risk factors. Researchers have yet to evaluate the association between modifiable sensorimotor function variables and concussive injury. Purpose: Investigate the association between dynamic balance performance, a discrete measure of sensorimotor function, and concussive injuries. Study Design: Prospective Cohort Study Methods: One-hundred and nine elite male Rugby Union players were baseline tested in dynamic balance performance while wearing an inertial sensor, and prospectively followed during the 2016/2017 Rugby Union season. The sample entropy of the inertial sensor gyroscope magnitude signal was derived to provide a discrete measure of dynamic balance performance. Logistic regression modelling was then used to investigate the association between the novel digital biomarker of balance performance, known risk factors of concussion (concussion history, age and playing position) and subsequent concussive injury. Results: Participant demographic data (mean ± SD) was as follows: age: 22.6±3.6 years; height: 185±6.5 cm; weight: 98.9±12.5 Kg; BMI: 28.9±2.9 kg/m 2 ; leg length: 98.8±5.5 cm. Of the 109 players, 44 (40.3%) had a previous history of concussion, while 21 (19.3%) sustained a concussion during the follow-up period. The receiver operatic curve analysis for the anterior sample entropy demonstrated a statistically significant area under the curve (0.64; 95%CI = 0.52 to 0.76; p < 0.05), with the cutoff score of anterior sample entropy ≥ 1.2, that maximized the sensitivity (76.2%) and specificity (53.4%) for identifying individuals who subsequently sustained a concussion. Players with sub-optimal balance performance at baseline were at a 2.81 greater odds (95% CI = 1.02-7.74) of sustaining a concussion during the Rugby Union season than those with optimal balance performance, even when controlling for concussion history. Conclusion: Rugby Union players who possess poorer dynamic balance performance as measured by a wearable inertial sensor during the Y Balance Test have a three-times higher relative risk of sustaining 3 a sports-related concussion, even when controlling for previous history of concussion. These findings have important implications for future research and clinical practice, as it identifies a potential modifiable risk-factor. Further research is required to investigate this association in a large cohort, consisting of males and females, across a range of sports. Clinical Relevance: This study has identified a modifiable risk-factor for concussion in Rugby Union players, suggesting movement control and balance training interventions may help reduce the incidence of concussion in this population.

Athletes with a concussion history in the last two years have impairments in dynamic balance performance

“…The intra-session reliability and inter-session reliability of the data acquisition parameters and sensor mounting location have been previously published. 14,15 Furthermore, recent research has demonstrated the discriminant validity of the inertial sensorbased approach, 13,20 as well as highlighted the capacity of the assessment to capture balance deficits with are associated with an increased risk of concussion in rugby union players. 15 It has previously been reported that investigating the discriminant capabilities of inertial sensor-based variables may be the most appropriate method for validation of these tools.…”

“…14,15 Furthermore, recent research has demonstrated the discriminant validity of the inertial sensorbased approach, 13,20 as well as highlighted the capacity of the assessment to capture balance deficits with are associated with an increased risk of concussion in rugby union players. 15 It has previously been reported that investigating the discriminant capabilities of inertial sensor-based variables may be the most appropriate method for validation of these tools. 21 In line with the YBT guidelines, individuals completed four practice trials followed by three recorded trials in the three defined directions: anterior (ANT), posteromedial (PM), and posterolateral (PL) to eliminate the training effect associated with YBT completion.…”

“…Entropy measures are unitless non-linear measures of the regularity or complexity of a time-series, commonly used in the analysis of movement data. [15][16][17]24 Jerk, the rate of change of acceleration, was computed by finding the time-derivative of the three axes of acceleration. The jerk magnitude was then calculated using the vector magnitude of the jerk x, y, and z signals.…”

“…4 Furthermore, the use of inertial sensor technology may help address some of the limitations of the traditional clinical assessments which have shown no utility in identifying those at an increased risk of musculoskeletal injury post-concussion. 34 For example, recent prospective research by Johnston et al 15 reported that Rugby Union players with poorer dynamic balance performance measured using inertial sensor technology during the YBT were at a three times greater relative-risk of concussion than individuals with optimal performance. Additionally, individuals with impaired dynamic balance performance have been shown to possess an increased risk of sustaining lower limb injuries such as lateral ankle sprains 35 and anterior cruciate ligament ruptures.…”

“…5 For example, recent research has shown that a single lumbar-worn inertial sensor can provide a valid and reliable measure of dynamic movement control during the YBT. 13,14 Early investigations of this approach within the clinical context have shown that it may have value in identifying athletes at a three-times higher relative risk of sustaining a concussion, 15 as well as identifying post-concussion deficits. 6 Therefore, the inertial sensor instrumentation of the YBT may allow for the accessible and objective quantification of sensorimotor performance outside of the laboratory environment, helping to identify individuals who may be at an increased risk of future injury.…”