Six adult male volunteers of similar body size (x̄ ± SD:ht = 184.6 ± 6.4 cm; wt = 80.86 ± 2.7 kg) and aerobic exercise capacity (VO₂ = 38 ± 3.1 ml·kg⁻¹. min⁻¹) were tested to determine what physiological and perceptual differences existed during endurance cycling using a Powercam (Houdaille, Inc.) crank system (CAM) as compared to a standard crank system (STD). Following preliminary tests to determine the subject's working capacity, each was assigned to ride either in the CAM or STD mode for 1 hour using a gear ratio that would require an effort equal to 70% of the VO₂ max. After a minimum of 72 hours between trials, subjects were retested in the converse mode. Measurements that included HR, BP, VO₂, surface EMG, and RPE were monitored at 15 minute intervals during both tests. Responses were very similar across modes and between subjects. Although subjects demonstrated responses that may indicate an improved efficiency for a particular mode, the group did not display patterns that would indicate efficiency for the Powercam crank system. / M.S.