Adaptation in Gait to Body-Weight Unloading

Abstract

Modifications in load-related sensory input during unloaded walking can lead to recalibration of the body schema and result in aftereffects. The main objective of this study was to identify the adaptive changes in gait and body-weight perception produced by unloaded walking. Gait performance during treadmill walking was assessed in 12 young participants before and after 30 min of unloaded walking (38% body weight) by measuring lower limb kinematics, temporal gait measures, and electromyography (EMG). A customized weight-perception scale was used to assess perception of body weight. Participants perceived their body weight to be significantly heavier than normal after unloading while walking. Angular displacement about ankle and knee was significantly reduced immediately after unloaded walking, while temporal gait parameters remained unchanged. The EMG activity in some muscles was significantly reduced after unloading. These findings indicate that walking at reduced body weight results in alterations in segmental kinematics, neuromuscular activity, and perception of body weight, which are the aftereffects of motor adaptation to altered load-related afferent information produced by unloading. Understanding the adaptive responses of gait to unloading and the time course of the aftereffects will be useful for practitioners who use body-weight unloading for rehabilitation. Appl. Sci. 2019, 9, 4494 2 of 18 walking [6][7][8]). Adaptive changes in step length and double support time are observed during split-belt walk. Similarly, in another paradigm, the effect of increased trunk rotation during walking was studied by having the subjects walk along the circumference of a rotating disc for 2 h [9]. Subsequently, after the adaptation session, the subjects were found to produce curved walking trajectories. Likewise, adaptive changes in heading direction in response to modifications of the direction of optical flow was also observed after exposing subjects to a visual scene that gave the perception of walking along the perimeter of a room [10].Body-weight unloading (BWU) using various types of body-weight support systems is used to study locomotor adaptation in response to reduced load input [11][12][13][14]. Load-related sensory information is essential for regulating the timing, phasing, and magnitude of neural activities that generate locomotor patterns during stepping [15][16][17]. They also help in maintaining balance control during locomotion and gait termination [18][19][20]. Lower-body positive pressure (LBPP) is an emerging technology that is used to provide body-weight support [21]. It consists of an air chamber that covers the lower part of the body. When inflated with positive pressure, the lower part of the body is lifted upwards from the hips and the body weight is reduced. LBPP is regarded as one of the superior methods of unweighting when compared to upper-body harness [21]. Upper-body harness partially supports the body weight and results in the formation of pressure points. LBPP on the other hand results...

Special Issue: Movement Biomechanics and Motor Control

“…This special issue provides a demonstration of this. The papers collected deal with anticipatory postural adjustments [2] and anticipatory locomotor adjustments [3], strategies to tackle obstacles [2][3][4], the effects of weight unloading on gait [5], posture control in special populations: ataxic children [6] and obese subjects [7], surface perturbation during posture [8], effects of sensory information and feedback on postural control [9,10], elderly behavior during a motor-motor double task [11], upper limb control [12,13], different aspects related to running: ankle joint dynamic stiffness [14] and fatigue [15]. There is also a flash on an ecologic condition where a pedestrian has to program its strategy to cross a road in between two moving vehicles [16], and a study on visual-manual control in monkeys [17].…”