Reliability and Validity of a Mobile Device Application for Use in Sports-Related Concussion Balance Assessment

Abstract

Background Balance assessment is necessary when evaluating athletes after a concussion. We investigated a mobile device application (app) for providing valid, reliable, and objective measures of static balance. Objectives The mobile device app would demonstrate similar test–retest reliability to force platform center of pressure (COP) sway variables and that SWAY scores and force platform COP sway variables would demonstrate good correlation coefficients. Methods Twenty-six healthy adults performed balance stances on a force platform while holding a mobile device equipped with SWAY (Sway Medical LLC) to measure postural sway based on acceleration changes detected by the mobile device's accelerometer. Participants completed four series of three 10-second stances (feet together, tandem, and single leg), twice with eyes open and twice with eyes closed. Test–retest reliability was assessed using intraclass correlation coefficients (ICC). Concurrent validity of SWAY scores and COP sway variables were determined with Pearson correlation coefficients. Results Reliability of SWAY scores was comparable to force platform results for the same test condition (ICC = 0.21–0.57). Validity showed moderate associations between SWAY scores and COP sway variables during tandem stance (r = –0.430 to –0.493). Lower SWAY scores, indicating instability, were associated with greater COP sway. Discussion The SWAY app is a valid and reliable tool when measuring balance of healthy individuals in tandem stance. Further study of clinical populations is needed prior to assessment use. Conclusion The SWAY app has potential for objective clinical and sideline evaluations of concussed athletes, although continued evaluation is needed.

Reliability, Validity and Utility of Inertial Sensor Systems for Postural Control Assessment in Sport Science and Medicine Applications: A Systematic Review

“…Of the 14 studies that investigated concurrent validity, ten utilised a force platform system as the gold standard [26][27][28][29][30][31][32][33][34][35], while five used 3D optoelectronic motion capture [12,[36][37][38][39]. One study used both motion capture and a force platform during the comparison [29].…”

“…Two studies investigated the SOT protocol, reporting a r 2 = 0.15 to 0.92 and average error of between 5.8% and 10.42% [26,33] across the different conditions. A further seven studies investigated the concurrent validity of various combinations of static stance positions [27,30,32,[36][37][38][39]. Of these seven studies, five provided adequate details pertaining to their results to allow comparison, with Abe et al [36] not directly comparing the gold standard and inertial sensor variables and Seimetz et al [32] not reporting any quantified statistical comparison.…”

“…A single prospective cohort study investigated the association of inertial sensor-based PC assessment scores with sports related injuries in a cohort of collegiate American football players, reporting that players with poorer PC were at a 5.19 times greater-odds of sustaining a sports related injury [61]. Table here 3.6 MEASUREMENT RELIABILITY Thirteen of the included studies were identified as assessing measurement reliability [16,27,28,33,40,41,45,47,58,[62][63][64][65]. Eleven of these studies investigated intra-session test retest reliability, demonstrating reliability ranging from poor to excellent (ICC = 0.03 to 0.97) [16,27,33,40,41,45,47,58,[63][64][65], while five studies reported poor to excellent (ICC = 0.02 to 0.95) inter-session reliability [16,28,[62][63][64].…”

“…The BESS/mBESS is a standardised static balance assessment protocol, commonly used following sports related concussion [71]. Importantly, three of these studies did not fully disclose the methods for calculating the variable of interest [27,34,35]. All four studies demonstrated significant correlations between the 'gold-standard' and the sensor derived variables, with higher correlations typically observed during more challenging stance positions such as SLS and TS [12,27,34,35].…”

“…Seven out of nine studies investigating static stance positions provided sufficient data to allow for comparisons of concurrent validity [27-31, 37, 38]. Four of these seven studies demonstrated a significant correlation between the lumbar/sternum and force platform variables [27][28][29][30]. Furthermore, a single study investigated the concurrent validity of inertial sensors in quantifying dynamic PC, demonstrating that the sensorbased DPSI accelerometer variables were highly correlated with the force platform measures [28].…”