Objective: To compare the rates of energy expenditure at given rating of perceived exertion (RPE) levels among 6 different indoor exercise machines.
Design: Repeated measures design.
Participants: Healthy young-adult volunteers, including 8 men and 5 women.
Interventions: 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.
Main outcome measure: 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.