Concussion induces gait inter-joint coordination variability under conditions of divided attention and obstacle crossing.

This study investigated the effect of concussion on the pattern and variability of inter-joint coordination during level walking (Level), obstacle crossing (OB), and walking with a concurrent cognitive test (ATT). Gait analyses of 23 concussed and 23 matched healthy adults were performed. Continuous relative phase (CRP), derived from phase angles of two adjacent joints, was used to assess inter-joint coordination. Cross-correlation measures and root-mean-square (RMS) differences were used to compare CRP patterns of the Level condition to those of OB and ATT conditions, respectively. Deviation phase (DP) was used to evaluate variability of inter-joint coordination for each task. For hip-knee and knee-ankle CRP patterns, RMS differences between OB and Level and between ATT and Level in concussed subjects were significantly greater than those of healthy adults. No significant group differences were detected for the cross-correlation measures of hip-knee and knee-ankle CRP patterns. In stance phase, a significant task effect on DP values was detected in hip-knee inter-joint coordination. For knee-ankle inter-joint coordination, concussed subjects showed significantly greater DP values than healthy controls during OB and ATT. In swing phase, concussed individuals showed greater DP values in hip-knee and knee-ankle inter-joint coordination compared to healthy controls. The findings suggest that the ability to modulate inter-joint coordination patterns when accommodating to gait perturbations is affected by concussion.