title: A comparison of ambulatory oxygen consumption during circuit training and aerobic exercise in patients with chronic heart failure.
abstract: OBJECTIVE
  This study compared the exercise intensity of a combined aerobic and resistance exercise circuit training session with the exercise intensity of continuous aerobic exercise in patients with chronic heart failure (CHF).
  
  
  METHODS
  Peak oxygen consumption (VO2peak) and muscular strength (1 repetition maximum) were assessed in six CHF patients (age 62 +/- 3 years). Heart rate, rate of perceived exertion (RPE), blood pressures, ambulatory oxygen consumption (VO2), and ventilatory data were measured during two types of exercise: continuous cycling on a bicycle ergometer (aerobic [AER] session) and combined AER and resistance exercise (circuit training [CIR] session).
  
  
  RESULTS
  There were no significant differences in VO2, RPE, heart rate, or hemodynamic responses (rate pressure product, diastolic blood pressure, or mean arterial pressure) during exercise, between the two sessions. Systolic blood pressure was significantly lower during CIR (P < 0.05). Minute ventilation and tidal volume were significantly higher (P < 0.0001 and P < 0.01, respectively) and respiratory frequency significantly lower (P < 0.005) during CIR. During CIR, RPE significantly correlated with VO2 (P < 0.01), whereas heart rate did not. Conversely, during the AER session HR correlated with VO2 (P < 0.01), but RPE did not.
  
  
  CONCLUSIONS
  Circuit training is a well-tolerated form of exercise training for CHF patients that is associated with similar oxygen and hemodynamic demand to aerobic exercise. Results suggest that RPE may be a better method of prescribing and monitoring exercise intensity during CIR, with heart rate the preferred measure of intensity during aerobic exercise.
authors.affiliation: Department of Human Movement and Exercise Science, University of Western Australia, Nedlands 6907, Western Australia. brevis@cyllene.uwa.edu.au
authors.forename: D J
authors.initials: DJ
authors.lastname: Green
authors.forename: K
authors.initials: K
authors.lastname: Watts
authors.forename: A J
authors.initials: AJ
authors.lastname: Maiorana
authors.forename: J G
authors.initials: JG
authors.lastname: O'Driscoll
mesh_terms: D000368:Aged; D001696:Biomechanical Phenomena; D002908:Chronic Disease; D015444:Exercise / Q000502:physiology*; D006333:Heart Failure / Q000503:physiopathology* / Q000628:therapy; D006439:Hemodynamics / Q000502:physiology; D006801:Humans; D008297:Male; D008875:Middle Aged; D018670:Monitoring, Ambulatory; D010101:Oxygen Consumption / Q000502:physiology*; D010806:Physical Education and Training / Q000379:methods*; D013990:Tidal Volume / Q000502:physiology