title: Energy expenditure with indoor exercise machines.
abstract: OBJECTIVE
  To compare the rates of energy expenditure at given rating of perceived exertion (RPE) levels among 6 different indoor exercise machines.
  
  
  METHODS
  Repeated measures design.
  
  
  METHODS
  Healthy young-adult volunteers, including 8 men and 5 women.
  
  
  METHODS
  Subjects underwent a 4-week habituation period to become familiar with the RPE scale and exercise on an Airdyne, a cross-country skiing simulator, a cycle ergometer, a rowing ergometer, a stair stepper, and a treadmill. Following habituation, each subject completed an exercise test with each exercise machine. The exercise test comprised 3 stages of 5 minutes at self-selected work rates corresponding to RPE values of 11 (fairly light), 13 (somewhat hard), and 15 (hard). Oxygen consumption, from which the rate of energy expenditure was calculated, was measured during the last minute of each 5-minute exercise stage. Heart rate was measured during the last minute of each stage of the exercise test, and blood lactate levels were obtained immediately after each exercise stage.
  
  
  METHODS
  Rate of energy expenditure at specified RPE values.
  
  
  RESULTS
  Rates of energy expenditure at a given RPE varied by 1093 kJ/h (261 kcal/h) for the exercise machines. The treadmill induced higher (P < .05) rates of energy expenditure for fixed RPE values than all other exercise machines. The cross-country skiing simulator, rowing ergometer, and stair stepper induced higher (P < .05) rates of energy expenditure than the Airdyne and cycle ergometer. Heart rate varied significantly (P < .01) among exercise machines, with the highest values associated with the treadmill and the stair stepper. Lactate concentration varied significantly (P = .004), with highest values associated with use of the stair stepper and the rowing ergometer.
  
  
  CONCLUSIONS
  Under the conditions of the study, the treadmill is the optimal indoor exercise machine for enhancing energy expenditure when perceived exertion is used to establish exercise intensity.
authors.affiliation: Sports Performance and Technology Laboratory, Medical Colloege of Wisconsin, Milwaukee, USA.
authors.forename: A I
authors.initials: AI
authors.lastname: Zeni
authors.forename: M D
authors.initials: MD
authors.lastname: Hoffman
authors.forename: P S
authors.initials: PS
authors.lastname: Clifford
mesh_terms: D000328:Adult; D004734:Energy Metabolism; D004864:Equipment and Supplies; D015444:Exercise / Q000502:physiology; D005080:Exercise Test / Q000295:instrumentation; D005260:Female; D006339:Heart Rate; D006801:Humans; D007773:Lactates / Q000097:blood; D019344:Lactic Acid; D008297:Male; D010101:Oxygen Consumption
chemical_list: D007773:Lactates; D019344:Lactic Acid