Effects of acute concussion on centre of pressure variables during quiet stance

Objective To examine how acute sport-related concussion influences centre of pressure (COP) sway during quiet stance Design Prospective cohort Setting Laboratory Participants Eighty-seven male contact-sport (football and hockey) athletes entered the study. Seven subjects (age range 17–22) were concussed and completed follow-up testing 72-hours, two-weeks, and one-month following the injury. Intervention One-minute eyes-open and eyes-closed quiet stance trials were performed on a force plate (NDI True Impluse) with feet hip-width apart. Force plate data and SCAT3 were collected at each time point. Outcome measures Root-mean-square COP displacement (RMSd) and mean COP velocity were quantified in the anterior/posterior (AP) and medial/lateral (ML) directions. Independent variables included condition (2) and time (4) Main results RM-ANOVA indicated a main effect of time for all outcomes: AP-RMSd (p=0.006), AP mean velocity (p=0.012), ML-RMSd (p=0.001), ML mean velocity (p=0.001). Pairwise comparisons indicated reductions at 2-weeks in AP-RMSd (0.05, 95% CI: −0.672, 0.000), and AP mean velocity (p=0.039, 95% CI: −1.275, −0.036). ML-RMSd was reduced 1 month post-concussion (p=0.021, 95% CI: −0.365, −0.034). Change scores from baseline to 72-hours were correclated between: AP-RMSd and Balance Error Scoring System (r=0.878, p=0.009), AP mean velocity and Standardised Assessment of Concussion (SAC) (r=−0.822, p=0.023), and ML mean velocity and SAC (r=−0.836, p=0.019). Conclusions Measures of COP sway during quiet stance revealed alterations in displacement and velocity that persisted up to one-month following a sports-related concussion. These COP alterations exceeded the duration of clinical recovery (median return-to-play: 14 days) indicating that clinical recovery does not equal physiological recovery. Competing interests None.