Differential Effects of Acute and Multiple Concussions on Gait Initiation Performance.

Abstract Objective To identify the effect of acute and multiple concussions on gait initiation performance. Design Cohort Study Setting University Research Center Participants A population based sample of 45 participants divided into three groups: No Prior Concussion, > 3 Prior Concussions, and Acute Concussion. The Acute Concussion participants were assessed within 24 hours of their concussion. Participants were matched based on 1) sport, 2) position, and 3) anthropometric measures. Interventions Participants were tested on a single occasion and performed five trials of gait initiation on four force plates. The No Prior Concussion and > 3 Prior Concussion groups were tested out of their primary athletic season. Main Outcome Measures The dependent variables were the posterior and lateral displacement and velocity of the center of pressure (COP) during the anticipatory postural adjustment phase and initial step kinematics (step length and step velocity). Comparisons between groups used a One-Way ANOVA with Tukey Post-Hoc when significant effects were identified and effect sizes were calculated. Results There were significant effects for group for all six outcome measures with large effect sizes. Post-hoc tests identified differences between Acute Concussion and No Prior Concussion for all measures. The > 3 Concussion group and No Prior History group were different for COP posterior displacement (4.91 + 1.09 cm and 4.91 + 1.09 cm respectively, p=0.032, d=0.91) and velocity (0.18 + 0.06 m/s and 0.27 + 0.08 m/s respectively, p=0.002, d=1.27). Conclusion There was continuum of performance identified whereby the Acute Concussion participants performed worse and the No Prior Concussion participants performed the best. The > 3 Prior Concussion generally fell between these two groups, but only statistical significance on COP posterior displacement and velocity. These results suggest there may be subtle neurophysiological deficits present in collegiate student-athletes with > 3 Prior Concussions and further investigation over the lifespan is warranted.