Influence Of Body Weight Support On Physiological Responses During Lateral And Forward Locomotion

Lower body positive pressure treadmills are designed to provide an upward directed force to the user. This body weight support (BWS) mechanism effectively reduces body weight. Using different directions of locomotion are common in training and rehabilitation setting, but there is limited research on the physiological responses of lateral locomotion and no research on the influence of BWS on physiological responses during lateral locomotion. PURPOSE: To investigate the physiological responses during lateral and forward locomotion with different levels of BWS at self-selected paces (Lateral 0%BWS 1.4 ± 0.2 m/s, 20%BWS 1.5 ± 0.2 m/s, 50%BWS 2.0 ± 0.3 m/s; Forward 0%BWS 2.7 ± 0.3 m/s, 20%BWS 3.0 ± 0.5 m/s, 50%BWS 3.2 ± 0.7 m/s). METHODS: Participants (n = 8; 25.6 ± 5.4 years) completed lateral and forward treadmill locomotion conditions with 0%BWS, 20%BWS, and 50%BWS. Prior to testing, the self-selected speed was determined for each direction-BWS combination. Physiological responses were collected during 3-minute conditions. The rate of oxygen consumption (VO2) and carbon dioxide exhaled (VCO2) were each averaged over the last 1-min. VO2 and VCO2 were each analyzed using a 2 (direction) x 3 (BWS) repeated measures analysis of variance. RESULTS: Both VO2 and VCO2 were each influenced by the interaction between BWS and direction (p < 0.05). Using planned comparisons, it was determined that at 0%BWS, VO2 during forward (32.7 ± 4.2 ml·kg-1·min-1) locomotion was greater than that during lateral (25.44 ± 4.9 ml·kg-1·min-1) locomotion (p < 0.05). Also, at 20%BWS, VO2 was greater during forward (30.1 ± 3.1 ml·kg-1·min-1) vs. lateral (23.62 ± 5.4 ml·kg-1·min-1, p < 0.05) conditions but not for 50%BWS (p > 0.05). VCO2 was greater during forward (27 ± 4.5 ml·kg-1·min-1) vs. lateral (21.3 ± 4.4 ml·kg-1·min-1) for 0%BWS (p < 0.05) and 20%BWS conditions (forward 24.2 ± 2.6 ml·kg-1·min-1; lateral 29.6 ± 4.9 ml·kg-1·min-1: p < 0.05) but not for 50%BWS (p > 0.05). CONCLUSIONS: When speed is self-selected, the increase in BWS resulted in similar physiological responses during lateral and forward locomotion. However, when less BWS was provided, forward locomotion required a greater physiological response vs. lateral when speed was self-selected. Supported by JSPS Grant Number 20 K11336