title: Physiological responses to body weight--supported treadmill exercise in healthy adults.
abstract: OBJECTIVE
  To determine whether the relationships of heart rate, rating of perceived exertion (RPE), and ground reaction forces (GRFs) with oxygen consumption rate (Vo(2)) during treadmill exercise are altered by partial body weight support (BWS) via lower-body positive pressure.
  
  
  METHODS
  Repeated-measures design.
  
  
  METHODS
  Exercise physiology laboratory.
  
  
  METHODS
  Healthy, active adults (N=12); mean age ± SD, 45.1±12.6 years.
  
  
  METHODS
  Not applicable.
  
  
  METHODS
  Vo(2), 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.
  
  
  RESULTS
  Standing 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 Vo(2) during walking and running were not altered by BWS. While walking, the RPE at a Vo(2) 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 Vo(2) of 25 mL · kg(-1) · min(-1). Peak normal GRFs at specified Vo(2) levels and RPE values were reduced (P<.05) with increasing BWS for walking and running.
  
  
  CONCLUSIONS
  Because partial BWS does not alter the relationship of heart rate with Vo(2) during exercise and has minimal effect on the relationship of RPE with Vo(2), training heart rate and RPE values do not appear to require adjustment with partial BWS. Reduced GRFs at specified Vo(2) levels from partial BWS suggest that there are important clinical applications of this technology.
authors.affiliation: Department of Physical Medicine and Rehabilitation, Department of Veterans Affairs, Northern California Health Care System, and University of California Davis Medical Center, Sacramento, CA 95655-1200, USA. martin.hoffman@va.gov
authors.forename: Martin D
authors.initials: MD
authors.lastname: Hoffman
authors.forename: Haylee E
authors.initials: HE
authors.lastname: Donaghe
mesh_terms: D000328:Adult; D015444:Exercise / Q000502:physiology*; D005080:Exercise Test; D005260:Female; D006339:Heart Rate / Q000528:radiation effects*; D006801:Humans; D008297:Male; D008875:Middle Aged; D010101:Oxygen Consumption / Q000502:physiology*; D055815:Young Adult