Toward stimulating the central generator of stepping

Normal subjects were asked to walk at five different speeds while adopting four defined postures. Normal walking was used as a control. The lower limbs were either medially or laterally rotated about 30°, while the trunk was either inclined about 15° forward or backward. These postures were not fixed with splints but were voluntarily maintained during walking. Regressions were calculated which helped to determine changes in gait from control at equal velocities and stride durations. Maximum velocity decreased significantly in all cases except when the trunk was inclined forward. This decrease of velocity was due to decrease of stride length; stride frequency increased significantly. For lateral and medial rotations of the lower limbs, stance and double support phases increased while swing time decreased; no changes occurred in these phases of stride for the trunk postures. The test postures were selected as they were expected to stimulate receptors in the hip to transmit sensory feedback that could drive the stepping pattern generators. Since at a constant velocity stride frequency increased and swing decreased, it is suggested that medial and lateral rotations of the lower limbs about the hip joint are effective in exciting the appropriate hip joint receptors to transmit sensory feedback that can drive the generator circuit.