Comparison Of Cardiorespiratory Responses During Body Weight-supported Treadmill And Standard Treadmill Exercise

Abstract

Treadmills that partially support body weight are used in some rehabilitation settings. Cardiorespiratory responses to this type of exercise have been reported in very few published studies. PURPOSE: To determine the cardiorespiratory response to graded exercise on a standard treadmill (ST) and body weight-supported treadmill (BWST). METHODS: In random order, 20-36 yr old adults (n = 6 males, 4 females) performed BWST and ST trials. Identical exercise sessions were performed on each treadmill except 25% of body weight was supported by the BWST. On each treadmill a two-minute warm up was performed at 2 mph and 0% grade, followed by 6 minutes of exercise at 3% grade at each of the following treadmill velocities: 3, 4.5, and 6 mph. Expired respiratory gases were analyzed each minute. Steady state heart rate, VO2, VCO2 and RER were calculated as the average value during the final three minutes of each 6 min exercise stage. Blood pressure and RPE were recorded during the final minute of each stage. A 2x3 repeated measures ANOVA was used to determine significant differences at the p<.05 level, and the LSD method for post hoc analyses. RESULTS: There was a significant difference (p<.05) in absolute VO2 between ST and BWST at 4.5 mph (2.14±.39 v 1.42±.27 l[BULLET OPERATOR]min-1) and 6 mph (2.75±.58 v 1.79±.40 l[BULLET OPERATOR]min-1). Relative VO2 was significantly different (p<.05) at each exercise intensity between treadmills (ST v BWST: 16.0±1.1 v 13.6±1.2; 31.2±2.0 v 20.6±2.4; 39.8±1.9 v 25.8±2.9 ml[BULLET OPERATOR]kg-1[BULLET OPERATOR]min-1). There was a significant difference (p<.05) in VCO2 between the ST and BWST at 4.5 mph (2.10±.43 v 1.32±.26 l[BULLET OPERATOR]min-1) and 6 mph (2.88±.63 v 1.68±.39 l[BULLET OPERATOR]min-1). There was a significant difference (p<.05) in RER between the ST (1.05±.08) and BWST (.94±.06) at 6 mph. The HR was significantly different (p<.05) between ST and BWST at 4.5 mph (162±17 v 128±17 bpm) and 6 mph (182±13 v 146±17 bpm). There was a significant increase (p<.05) in SBP on the ST (144±20 v 163±25 v 175±22 mmHg) and BWST (128±11 v 143±13 v 155±16 mmHg) at each exercise intensity. There were no significant differences in DBP at any point during exercise. There was a significant difference (p<.05) in RPE on the ST at 6 mph (15±1), 4.5 mph (12±1), and 3 mph (9±1). CONCLUSION: There appears to be a lower cardiorespiratory response during body weight-supported exercise and traditional treadmill exercise.