Cardiovascular Responses of Trained Cyclists to Different Pedaling Rates at a Constant Power Output on a Cycle Ergometer

Previous research has not resolved the issue as to which pedaling rate is the most efficient in terms of oxygen uptake (VO2) for competitive cyclists. The purpose of this study was to determine the most efficient pedaling rate (30, 60, or 90 rpm) at steady state submaximal cycling (720 kpm/min) for trained cyclists. Eight healthy subjects (all male) were examined during steady state exercise for each of the three trials for which work rate was kept constant with varying pedal rate and resistance. Variables included oxygen uptake, cardiac output, heart rate, stroke volume, arterio-venous O2 difference, respiratory exchange ratio, and respiratory rate. Basic descriptive statistics (mean, standard deviation, etc.) and one-factor analysis of variance with repeated measures were used to analyze the data. Significance was set at 95% (p\u3c0.05) for the data. Results showed that VO2 (L/min and ml/kg/min), heart rate, and VCO2 were significantly lower (p\u3c0.05) for 60 rpm compared to 30 rpm and 90 rpm. Minute ventilator volume was significantly lower (p\u3c0.05) for 60 rpm compared to 90 rpm. Respiratory exchange ratio was significantly lower (p\u3c0.05) for 30 rpm and 60 rpm compared to 90 rpm. It is hypothesized that at low pedal rates the muscle fibers are in a longer period of contraction and at high pedal rates more muscle fibers are recruited to stabilize the trunk. Each of these will result in a decrease in efficiency for the competitive cyclist. The results indicate that 60 rpm is more efficient for the competitive cyclist when compared to the low pedal rate of 30 rpm and the high pedal rate of 90 rpm at an absolute steady state work rate of 720 kpm/min