Exercise Responses During Partial Body-Weight Supported Treadmill Walking and Running in Healthy Individuals

Abstract

Use of lower body positive pressure represents a unique approach to provision of partial body-weight support during treadmill exercise. Previous research has shown that application of this type of body-weight support during running results in lower peak ground reaction forces for a given energy expenditure. PURPOSE: Determine if the relationships of rating of perceived effort (RPE) and heart rate (HR) with oxygen uptake (VO2) during treadmill exercise are altered by partial body-weight support via lower body positive pressure. METHODS: Each subject (3 men, 3 women; mean ± SD age = 42.7±11.4 years) completed graded submaximal exercise tests at 0%, 25% and 50% body-weight support. HR and blood pressure (BP) were measured after 3 min of standing. Then VO2, HR and RPE were measured at the end of each 4-min exercise stage. The protocol consisted of 4 walking stages, and running stages that continued until the subject reached an RPE of 13 ("somewhat hard"). RESULTS: Standing HR was lower (p<0.05) and systolic BP was higher (p<0.05) while standing at 50% body-weight support compared with 0% body-weight support. Mean (±SD) HRs were 64±10, 62±11 and 54±4 beats/min and systolic BPs were 112±6, 114±6 and 119±9 mmHg at 0%, 25% and 50% body-weight support, respectively. The relationship of HR with VO2 was not affected by body-weight support across walking or running speeds. The VO2 at an RPE of 7 (walking) was not different among conditions (11.3±2.8, 9.5±2.1 and 10.4±1.7 ml/kg/min for 0%, 25% and 50% body-weight support, respectively). In contrast, the VO2 at an RPE of 12 (running) was significantly higher (p<0.05) at 0% (32.2±4.8 ml/kg/min) compared with 50% (26.3±3.6 ml/kg/min) body-weight support, whereas the 25% body-weight support condition (28.9±5.0 ml/kg/min) was not statistically different from the other conditions. CONCLUSION: There was no difference in energy expenditure for a specified RPE during walking with partial body-weight support compared with unsupported walking. Since there are associated reductions in ground reaction forces during partial body-weight supported walking, further research should examine whether the body-weight support favorably alters the relationships of RPE and pain rating with energy expenditure in those with lower body joint pain. Supported by AlterG, Inc.