To the Editor.
—The article by Dr Zeni and colleagues1 concerning energy expenditure and rating of perceived exertion (RPE) using different exercise machines was somewhat misleading and potentially counterproductive to promoting fitness in the general population. In the "Comment" section, the authors stated, "If exercise intensity is established by perceived effort, treadmill walking/running will result in the greatest energy expenditure and cardiorespiratory stimulus." Although this statement was certainly consistent with the study results, the study design was biased toward favoring one form of exercise over the others.The participants in this study, while fairly fit, were nevertheless untrained exercisers. The authors never revealed how these participants became fit before the study, but the implication of the "habituation" process is that they were not proficient in the technical sports represented by most of the exercise machines used. This was a crucial flaw in study design. The impression conveyed by the
Yannios T. Energy Expenditure With Indoor Exercise Equipment. JAMA. 1996;276(8):604-605. doi:10.1001/jama.1996.03540080026016