Effect of pedalling rates on physiological response during endurance cycling

This study was undertaken to examine the effect of different pedalling cade nces upon various physiological responses during endurance cycling exercise . Eight well-trained triathletes cycled three times for 30 min each at an i ntensity corresponding to 80% of their maximal aerobic power output. The fi rst test was performed at a freely chosen cadence (FCC); two others at FCC- 20% and FCC+20%, which corresponded approximately to the range of cadences habitually used by road racing cyclists. The mean (SD) FCC, FCC-20% and FCC +20% were equal to 86 (4), 69 (3) and 103 (5) rpm respectively. Heart rate (HR), oxygen uptake ((V) over dot O-2), minute ventilation ((V) over dot(E) ) and respiratory exchange ratio (R) were analysed during three periods: be tween the 4th and 5th, 14th and 15th, and 29th and 30th min. A significant effect of time (P<0.01) was found at the three cadences for HR, (V) over do t O-2. The (V) over dot(E) and R were significantly (P<0.05) greater at FCC +20% compared to FCC-20% at the 5th and 15th min but not at the 30th min. N evertheless, no significant effect of cadence was observed in HR and (V) ov er dot O-2. These results suggest that, during high intensity exercise such as that encountered during a time-trial race, well-trained triathletes can easily adapt to the changes in cadence allowed by the classical gear ratio s used in practice.