Physiological Responses to Body Weight–Supported Treadmill Exercise in Healthy Adults

Hoffman MD, Donaghe HE. Physiological responses to body weight–supported treadmill exercise in healthy adults.ObjectiveTo determine whether the relationships of heart rate, rating of perceived exertion (RPE), and ground reaction forces (GRFs) with oxygen consumption rate (V̇o2) during treadmill exercise are altered by partial body weight support (BWS) via lower-body positive pressure.DesignRepeated-measures design.SettingExercise physiology laboratory.ParticipantsHealthy, active adults (N=12); mean age ± SD, 45.1±12.6 years.InterventionsNot applicable.Main Outcome MeasuresV̇o2, heart rate, RPE, and GRFs were measured during walking and running at 3 levels (0%, 25%, 50%) of BWS. Before exercise, standing heart rate and blood pressure were measured under each BWS condition.ResultsStanding heart rates were 7 beats/min lower (P<.05) and systolic blood pressures were 10mmHg higher (P<.001) at 50% BWS compared with 0% BWS, but mean blood pressure while standing and the relationship of heart rate with V̇o2 during walking and running were not altered by BWS. While walking, the RPE at a V̇o2 of 10 mL · kg–1 · min–1 was statistically lower (P<.05) at 0% BWS compared with 25% and 50% BWS (mean values, 7 vs 8 points), but RPE was not different among conditions while running at a V̇o2 of 25 mL · kg–1 · min–1. Peak normal GRFs at specified V̇o2 levels and RPE values were reduced (P<.05) with increasing BWS for walking and running.ConclusionsBecause partial BWS does not alter the relationship of heart rate with V̇o2 during exercise and has minimal effect on the relationship of RPE with V̇o2, training heart rate and RPE values do not appear to require adjustment with partial BWS. Reduced GRFs at specified V̇o2 levels from partial BWS suggest that there are important clinical applications of this technology.