Factors affecting the increased energy expenditure during passive cycling.

Short-duration passive cycling, during which a motor drives the pedals, elevates metabolic energy expenditure. Our purpose was to investigate the feasibility of passive cycling as a physical inactivity countermeasure by quantifying how the number of legs involved, cycling cadence, and habituation influence energy expenditure. Eleven non-cyclists participated. We compared one- and two-leg passive cycling at cadences of 60 and 90 RPM. To investigate if there are habituation effects, we conducted multiple 5-min trials and a prolonged 30-min passive cycling trial. The increase in energy expenditure above rest during passive cycling was significantly greater for two legs compared to one leg (39 vs. 16% at 60 RPM and 96 vs. 45% at 90 RPM). The increase in energy expenditure above rest was greater for 90 versus 60 RPM two-leg passive cycling (96 vs. 39%; p < 0.001). Repeated trials showed no evidence of habituation and the increase in energy expenditure was maintained for the duration of the 30-min trial. In conclusion, energy expenditure during passive cycling is directly related to the number of legs involved and cycling cadence. Two-leg passive cycling at 90 RPM resulted in energy expenditures similar to the walking workstation, suggesting its potential as a physical inactivity countermeasure.