Human muscle power generating capability during cycling at different pedalling rates

The effect of different pedalling rates (40, 60, 80, 100 and 120 rev min(-1)) on power generating capability, oxygen uptake (V(over dot)(O2)) and blood lactate concentration [La](b) during incremental tests was studied in seven subjects. No significant differences in V(over dot)(O2max) were found (mean +/- S.D., 5.31 +/- 0.13 l min(-1)). The final external power output delivered to the ergometer during incremental tests (P-I,P-max) was not significantly different when cycling at 60, 80 or 100 rev min(-1) (366 +/- 5 W). A significant decrease in P-I,P-max of similar to 60 W was observed at 40 and 120 rev min(-1) compared with 60 and 100 rev min(-1), respectively (P < 0.01). At 120 rev min(-1) there was also a pronounced upward shift of the V(over dot)(O2)-power output (V(over dot)(O2)-P) relationship. At 50 W Delta V(over dot)(O2) between 80 and 100 rev min(-1) amounted to +0.43 l min(-1) but to +0.87 l min(-1) between 100 and 120 rev min(-1). The power output corresponding to 2 and 4 mmol l(-1) blood lactate concentration (P-[La]2, and P-[La]4 ) was also significantly lower (> 50 W) at 120 rev min(-1) (P < 0.01) while pedalling at 40, 60, 80 and 100 rev min(-1) showed no significant difference. The maximal peak power output (P-M,P-max) during 10 s sprints increased with pedalling rate up to 100 rev min(-1). Our study indicates that viith increasing pedalling rate the reserves in power generating capability increase, as illustrated by the P-I,P-max/P-M,P-max ratio (54.8, 44.8, 38.1, 34.6, 29.2%), the P-[La]4/P-M,P-max ratio (50.4, 38.9, 31.0, 27.7, 22.9%) and the P-[La]2/P-M,P-max ratio (42.8, 33.5, 25.6, 23.1, 15.6%) increases. Taking into consideration the V(over dot)(O2,max) the P-I,P-max and the reserve in power generating capability we concluded that choosing a high pedalling rate when performing high intensity cycling exercise may be beneficial since it provides greater reserve in power generating capability and this may be advantageous to the muscle in terms of resisting fatigue. However, beyond 100 rev min(-1) there is a decrease in external power that can be delivered for an given V(over dot)(O2) with an associated earlier onset of metabolic acidosis and clearly this will be disadvantageous for sustained high intensity exercise.