RESUMEN
Postural instability is a common observation after concussions, with balance assessments playing a crucial role in clinical evaluations. Widely used post-concussion balance tests focus primarily on static and dynamic balance, excluding the critical aspect of reactive balance. This study investigated the acute and longitudinal effects of concussion on reactive balance in collegiate athletes. The assessments were conducted at pre-season baseline and 4 post-concussion timepoints: acute, pre-return-to-play, post-return-to-play, and six months post-concussion. The instrumented-modified Push and Release test measured reactive balance. Longitudinal effects of concussions on time to stability and step latency metrics were investigated applying Generalized Estimating Equations. Acutely after concussion, athletes demonstrated impaired reactive balance, indicated by longer times to stability, in dual-task conditions ( p = 0.004). These acute impairments were transient and recovered over time. Exploratory analyses revealed that athletes who sustained their first lifetime concussion exhibited both acute ( p = 0.037) and longitudinal ( p = 0.004 at post-return-to-play) impairments in single- and dual-task compared to controls with no lifetime concussion. This comprehensive evaluation provides insights into the multifaceted nature of post-concussion impairments and emphasizes the importance of considering cognitive demand and history of concussions in assessing athletes' balance.
RESUMEN
CONTEXT: Wearable sensors are increasingly popular in concussion research because of their objective quantification of subtle balance deficits. However, normative data and minimum detectable change values are necessary to serve as a references for diagnostic use and tracking longitudinal recovery. OBJECTIVE: Identify normative values and minimal detectable change values for instrumented static and reactive balance tests, an instrumented static Mediolateral Root Mean Square (ML RMS) sway standing balance assessment, and the instrumented, modified Push & Release (I-mP&R), respectively. DESIGN: Cross-Sectional Study. SETTING: Clinical Setting. PATIENTS OR OTHER PARTICIPANTS: Normative static ML RMS sway and I-mP&R data were collected on 377 (n=184 females) healthy National Collegiate Athletic Association Division I athletes at the beginning of their competitive seasons. Test-retest data were collected in 36 healthy control athletes based on standard recovery timelines after concussion. RESULTS: Descriptive statistics, intraclass correlation coefficients (ICC), and minimal detectable change (MDC) values were calculated for primary outcomes of mediolateral (ML) root-mean-square (RMS) sway in a static double limb-stance standing on firm ground and a foam block, and time to stability and latency from the I-mP&R in single- and dual-task conditions. RESULTS: Normative outcomes across static ML RMS sway and I-mP&R were sensitive to sex and type of footwear. ML RMS sway demonstrated moderate reliability in the firm condition (ICC=0.73; MDC=2.7cm/s2), but poor reliability in the foam condition (ICC=0.43; MDC=11.1cm/s2). Single- and dual-task time to stability from the I-mP&R exhibited good reliability (ICC=0.84 and 0.80, respectfully; MDC=0.25s, 0.59s, respectfully). Latency from the I-mP&R had poor to moderate reliability (ICC=0.38, 0.55; MDC=107ms, 105ms). CONCLUSIONS: Sex-matched references should be used for instrumented static and reactive balance assessments. Footwear may explain variability in static ML RMS sway and time to stability of the I-mP&R. Moderate-to-good reliability suggest time to stability from the I-mP&R and ML RMS static sway on firm ground can be used for longitudinal assessments.