The Influence of the Aquatic Environment on Gait Initiation: A Pilot Study

Abstract

Aquatic therapies are used to restore step initiation in people with locomotor disabilities. However, there is lack of evidence of underlining mechanisms of gait initiation in water. We investigated center of pressure (CoP), vertical and anterior-posterior impulse forces, and kinematics of the first step performed in water in comparison with overground walking. The peaks of anticipatory postural adjustment (APA) and the sections of CoP trajectories were longer in water than on land. Impulse forces were increased in water compared with land. Range of motion (ROM) of ankle joint increased in water while knee joint ROM did not change. We suggest that the aquatic environment may facilitate gait initiation training by allowing a longer step execution with greater stimuli and imposed resistance for the phases of gait initiation.

Muscle Activation and Distribution during Four Test/Functional Tasks: A Comparison between Dry-Land and Aquatic Environments for Healthy Older and Young Adults

“…However, it is unknown how is the neuromuscular activity during gait initiation at a slower and comfortable speed. A potential reduction in the gait initiation step due to the greater influence of drag resistance has been discussed [58]. Their results reported same step length in the water could be at the expense of increasing neuromuscular activity, as we highlighted in our findings in tonic muscles during gait initiation, which peak correlates with the length and speed of the first step in the anteroposterior direction [57].…”

“…No studies have been found that analysed the same task as the present study. However, previous studies have analysed the level of muscle activation during walking in both environments (land and water), observing that there is a higher level of muscle activation on the land than in water, as seen in the present study [20,38,41,56,58,63].…”

“…The higher trunk muscle activity is related to the anteroposterior ground reaction force. In healthy subjects forward impulse forces were increased during gait initiation [57,58]. Drag force and turbulence refer to the resistive effects of the internal friction of fluid during motion [1].…”

“…The significant differences observed could be explained by different factors. First of all, there is a need to maintain the active trunk musculature to balance the drag force of water [54,58]. In water, body weight is reduced, and the need for muscle activation to work against the force of gravity is lower; however, when the subject moves, it is necessary to overcome the drag force produced by water.…”