Acute and Longitudinal Effects of Sport-related Concussion on Reactive Balance.

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.

Instrumented Static and Reactive Balance in Collegiate Athletes: Normative Values and Minimal Detectable Change.

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.

Reactive balance assessments complement clinical baseline concussion assessments in collegiate athletes.

CONTEXT: Current clinical concussion evaluations assess balance deficits using static or dynamic balance tasks while largely ignoring reactive balance. Including a reactive balance assessment in current evaluations might provide a more comprehensive concussion evaluation. OBJECTIVE: The purpose of this study was to determine if redundancy exists within current clinical baseline assessments of concussion and whether reactive balance adds unique information to these evaluations. DESIGN: Cross Sectional Study. SETTING: Clinical Assessment. PATIENTS OR OTHER PARTICIPANTS: Two cohorts of data were collected at the beginning of the athletic season from healthy NCAA Division I athletes. Within the first cohort (n = 191), correlation analyses with clinical scores and inertial measurements were run between the ImPACT (Immediate Post-Concussion Assessment and Cognitive Tool), the BESS (Balance Error Scoring System), the modified Push and Release (mP&R), and instrumented mP&R (I-mP&R) to determine the strength of a relationship between these concussion tests. Within the second cohort (n = 88), correlation analyses were run between the BESS, the mP&R, Timed Tandem Gait, Walking with eyes closed, and clinical reaction time to determine the strength of the relationship between these concussion evaluation tests. MAIN OUTCOME MEASURES: ImPACT cognitive indices, BESS and mP&R clinical score and instrumented measures (BESS sway; I-mP&R time to stability, latency, and step length), TTG and Walking time to completion, and clinical reaction time. RESULTS: The strongest inter-instrument correlation value was r= 0.347, which was considered a weak correlation, between clinical reaction time and single task time to stability from the I-mP&R. The I-mP&R and mP&R clinical scores were weakly associated with the other assessments. CONCLUSION: The weak correlations between inter-assessment variables indicates that there is little redundancy within the current clinical evaluations. Furthermore, reactive balance represents a unique domain of function that may improve the comprehensiveness of clinical assessments.