Metabolic and Cardiovascular Effects of Body Weight Support Treadmill Walking in Healthy Adults

Abstract

Purpose: Limited and conflicting evidence exists regarding the metabolic and cardiovascular responses of body weight support (BWS) treadmill training (BWSTT). The purpose of this study was to describe the metabolic (as assessed by oxygen uptake) and cardiovascular responses to varying levels of BWSTT in healthy adult subjects. Methods: Twenty-one subjects (10 females; 34.5 [6.7] yr.; 74.6 [14.3] kg; 170.8 [6.9] cm; 26.1 [5.3] kg/m2) provided their informed consent to participate in 3 5-minute walking trials at a self-selected treadmill speed, with BWS of 0%, 15%, and 30%. Test order was randomized. Subjects rested at least 5 minutes between trials and did not begin another trial until the heart rate (HR) was <5 bpm of HR rest. Mean HR, blood pressure (BP), oxygen uptake, and rating of perceived exertion (RPE) were determined from the last 3 minutes of each trial. Mean values for all variables were assessed for difference between trials using repeated-measures analysis of variance. Results: At rest, HR was 78.2 (11.5) bpm and BP was 121.2 (7.9)/76.9 (8.0) mm Hg. Mean walking speed of subjects was 65.4 m/min. Heart rate and systolic BP significantly (P < .05) increased from rest with exercise at each level of BWS, with no significant difference in diastolic BP seen from rest to exercise at all BWS levels. There was no statistical difference among levels of BWS for HR, BP, RPE, oxygen uptake, respiratory exchange ratio, respiratory rate, tidal volume, and metabolic equivalent of tasks. Conclusions: Healthy adult subjects walking at self-selected speeds at BWS levels up to 30% fail to demonstrate significant changes in metabolic and cardiovascular responses.

Impact of Varying Exercise Intensity on Oxygen Uptake and Cardiovascular Response during Body Weight Supported Treadmill Walking in Healthy Adults

“…In contrast to the above investigations, several studies [13,14,19] have found no change in VO 2 with BWSTT. Hoffman and Donaghe [13] showed through linear regression analysis similar response to VO 2 and HR in 12 healthy subjects walking at 25% and 50% BWS.…”

“…From this predicted value, VO 2 levels of 35% and 50% VO 2 max were calculated, and treadmill speed (maximum of 91.1 m/min) and grade values were calculated for subsequent laboratory testing [25]. These exercise intensities were selected to approximate self-selected speeds of subjects from previous investigations at this laboratory [19,20].…”

“…Table 1 summarizes the subject characteristics. The original test protocol called for testing 20 subjects to match similar work done by this laboratory [19,20], however the impact of the COVID-19 pandemic limited data collection to the defined 11 subjects. A power test [23] using previous study VO 2 data indicated that 10 subjects would be necessary to identify a true difference Body weight supported treadmill training commonly involves a mechanical lift or harness system over a treadmill that works to unload a calculated percentage of body weight while also providing upright stabilization and support for the individual.…”

“…Results indicated no significant difference in VO 2 among the subject trials. Van Zant, et al [19] studied healthy adults aged 18-50 walking at a self-selected speed (approximating 36-40% age normative VO 2 max) with BWS at 0, 15%, 30%, and found no significant changes in VO 2 or cardiovascular (HR and BP) responses.…”