—In the article by Dr Zeni and colleagues,1 energy expenditure was compared across 6 different types of indoor exercise equipment with exercise RPE held constant. The authors concluded that "under the conditions of the study," the treadmill was "the optimal indoor exercise machine for enhancing energy expenditure when perceived exertion is used to establish exercise intensity." Although this conclusion may be fair enough, this study has been widely misinterpreted as showing that exercise on a treadmill is superior to exercise on the other 5 types of indoor exercise equipment.
In Figures 1 and 2 in the article, it was apparent that both rate of energy expenditure and heart rate were greater at any level of perceived exertion on the treadmill than on any other piece of equipment, and, indeed, the figures were virtually superimposable on each other. However, it is not surprising that individuals expended more energy at each
Rippe JM. Energy Expenditure With Indoor Exercise Equipment. JAMA. 1996;276(8):605. doi:10.1001/jama.1996.03540080027017