Repetitive Head Impacts Influence On The Postural Control System During An Athletic Season

Abstract

Evidence suggests that a concussive blow negatively impacts the postural control system post-injury. However, little is known regarding the role of repetitive head impacts on posture over the course of one athletic season. PURPOSE: The purpose of this study was to investigate changes in the postural control system after a season of repetitive head impacts (RHI) in Division 1 football athletes using traditional and nontraditional measures of posture. METHODS: Fourteen Division I football players (CON) (age = 20.4 ± 1.12 years) and fourteen non-contact athletes (NON) (2 male, 11 female; age=19.85 ± 1.21 years) completed a single trial of two minutes of eyes open quiet upright stance on a force platform (1000Hz) prior to athletic participation (PRE) and at the end of the athletic season (POST). All CON athletes wore helmets outfitted with Head Impact Telemetry (HIT) sensors and total number of RHI and linear accelerations forces of each RHI were recorded. Center of Pressure (CoP) Peak Excursion Velocity (PV), Sample Entropy (SampEn), in the anteroposterior (AP) and mediolateral (ML) directions, and 95% Confidence Ellipse (CE) were calculated at both PRE and POST. RESULTS: CON group experienced 649.5±496.8 mean number of impacts, 27.1±3.0 mean linear accelerations, with ≈1% of total player impacts exceeded 98g over the course of the season. Mixed model ANOVAs (2 groups x 2 assessment periods) revealed no significant interactions (p=0.499) at PRE (CON=0.54 ± 0.14: NON=0.68 ± 0.12; p=0.499) or POST (CON=0.56 ± 0.12: NON=0.68 ± 0.13; p=0.499) in the SampEn AP direction and no significant interactions (p=0.984) at PRE (CON=0.49 ± 0.08: NON=0.47 ± 0.07) or POST (CON=0.46 ± 0.11: NON=0.50 ± 0.11) in the SampEn ML direction. No significant interactions were observed for PV AP (p=0.262) or ML (p=0.977) directions, and 95% CE (p=0.327). CONCLUSIONS: A single season of repetitive head impacts in college football did not negatively affect the postural control system when measured by traditional (PV and 95% CE) and nontraditional (SampEn) calculations of CoP. These measures are highly sensitive in determining postural instability during quiet upright stance immediately and longitudinally post-concussion. Future research needs to address the impact of RHI on dual-task performance and functional measures of postural control.