Angular movements of the pelvis and lumbar spine during self-selected and slow walking speeds

We studied the effect of walking at a self-selected and at a slower speed o n the angular movements of the pelvis and lumbar spine. We also studied how interpretation of speed effects on lumbar spine. movements was influenced by frame of reference, either relative to the pelvis or relative to a globa l reference frame. Twenty-seven subjects without pathology walked on a trea dmill at either self-selected or 60% of self-selected speed. The movements of the pelvis and lumbar spine, as represented by surface markers, were rec orded by videocameras and the three-dimensional angles computed by the PEAK motion measurement system. Results indicated that the amplitudes of pelvic list (P < 0.05) and pelvic axial rotation (P < 0.05) were decreased at slo w walking speed. Relative to the pelvis, the amplitude df lumbar lateral fl exion was decreased with slower walking (P < 0.01). In contrast when lumbar spine movements were measured relative to a global reference frame, no dif ferences were detected due to decreased walking speed. This suggests, first ly, that the effect. of walking speed when evaluating the significance of d ecreased movements of the pelvis and of the lumbar spine (relative to the:p elvis) of subjects walking at slower than self-selected speeds should bk co nsidered and secondly, that movement:of the lumbar spine should be interpre ted with respect to a frame of reference. (C) 1999 Elsevier Science B.V. Al l rights reserved.