Physiological responses to running on a land and anti-gravity treadmill

Abstract

Exercise with partial body weight support can be used when pain or injury prevents exercise with full weight bearing. The purpose of this study was to determine differences in cardiorespiratory responses between running on a land treadmill and on an anti-gravity treadmill (AGT) during 30 min of exercise followed by a run to volitional fatigue. Participants (n = 12; age = 22.0 ± 4.3 years; height = 171.3 ± 6.4 cm; weight = 68.0 ± 13.0 kg) completed a familiarization session of submaximal treadmill running, two sessions on an AGT at two different body weight percentages (70 and 90%), and a run on a land treadmill. Participants returned for three additional exercise sessions: running on a land treadmill and on an AGT at 70 and 90% body weight. Each session included a 2-min self-paced warm-up, a 30-min run at 65-70% HRR, and a run to volitional fatigue at 95-100% HRR, all at 0% grade. Heart rate, oxygen consumption, energy expenditure, time to volitional fatigue, and other metabolic variables were measured. A one-way repeated measures ANOVA was used to determine differences in HR, VO2, EE, and TTE during each condition. Time to reach volitional fatigue was seven times greater for the 70% body weight and three times greater for the 90% body weight conditions on the AGT compared to the land treadmill condition. At 30 min of exercise, EE and VO2 during the 70 and 90% conditions on the AGT were less when compared to the land treadmill condition (p < .05), while HR during the 70% condition was less than 90% condition on the AGT (p = .013) and the land treadmill condition (p = .001). At volitional fatigue, HR was lower during the 70% condition compared to 90% condition on the AGT (p = .046), and VO2 was lower during the 70% condition on the AGT compared to the land treadmill condition (p = .005). Running with body weight support on the AGT may reduce metabolic demand. Increasing intensity or duration may allow for HR and VO2 responses to reach targeted levels during specific body weight support conditions.