Gait symmetry quantification during treadmill walking

Normal gait has often been assumed to be symmetric, though several papers have reported the differences in gait parameters between the limbs. A few papers have discussed the temporo-spatial and kinematic symmetry in healthy adults using different statistical and mathematical calculations and no consensus exists on the methodology. The aim of this study was to define symmetry in long term treadmill walking and to compare mathematical symmetry indices. Fifteen minutes of walking of three healthy young adults was recorded bilaterally using two 50 Hz video cameras and temporal gait parameters (stance, swing and stride times) were defined using footswitches. Symmetry between the limbs was analysed using three different indices. The results indicated that despite the symmetry on the stride times, asymmetries were seen in the parameters reflecting within limb phase ratios. The three indices provided very little differences in outcome. When defining symmetry one should carefully select the analysed gait parameters.