The temporal-spatial and ground reaction impulses of turning gait: is turning symmetrical?

Abstract

This study had two aims. Firstly, to characterise the temporal-spatial and ground reaction impulse adjustments, compared to straight gait, required to complete step turns to the left and to the right and secondly, to assess if the turns were asymmetrical. Seven participants were instructed to perform 90 degrees step turns to the left and right. The actual angle turned was less for both turns (right 80.2+/-5.5 degrees , left 82.8+/-5.3 degrees ). Data were collected using a 7 camera VICON infra-red motion analysis system (120 Hz) and a Kistler force plate (600 Hz). Adjustments were made in the approach, turn and depart strides compared to straight gait. The mean velocity was significantly lower and the stride was significantly shorter in the approach stride before the turn (p<0.0125) compared to straight gait, indicating a possible feed-forward mechanism prior to turning. Velocity was significantly lower and the stride length significantly shorter during the depart stride (p<0.0125) compared to straight gait. Participants did not return to a normal pattern within one stride. For the turn step, the velocity, step length and step width were all significantly different (p<0.0125) compared to straight gait. The turning ground reaction impulses were significantly greater (p<0.0125) compared to straight gait, indicating a need for increased support, medial shift, braking and propulsion. The turns to the left and right were statistically asymmetrical (p<0.0125) in 11 of the 18 variables. However, impulses were generally symmetrical, which does not generally support the functional asymmetry theory, though the contributions to propulsion were significantly greater when turning from the dominant limb.