Human muscle power generating capability during cycling at different pedalling rates

Abstract

Human locomotory performance is dependent upon the ability of skeletal muscle to generate mechanical power, and sustain that power -that is, resist fatigue. Not surprisingly the factors influencing this capability have attracted the attention of many investigators dating back to and beyond the beginning of this century (see e.g. Benedict & Cathcart, 1913;Krogh & Lindhard, 1920;Hill, 1922;Lupton, 1923;Dickenson, 1928;Wilkie, 1960Wilkie, , 1981Carnevale & Gaesser, 1991;McNaughton & Thomas, 1996). However, although there are a number of studies which have examined the maximum power of human locomotory muscles, and many more which have examined the constraints and limitations to sustained exercise -especially with respect to aerobic and anaerobic energy supply -rather few data are available from studies which have examined, in the same subjects, the relationship between maximum power and the power delivered in sustained exercise, and there are almost no data on the effect that movement frequency has on that relationship. In part, this paucity of data is due to the technical difficulty of measuring maximal power output at a constant known movement frequency in human locomotion. In seeking to address this difficulty, one of us developed an isokinetic cycle ergometer which enabled the maximum power generated by the main locomotory muscles to be measured over a range of movement frequencies (Sargeant et al. 1981). Subsequently, the ergometer system was modified so that the power could be measured continuously at the foot-pedal interface either during submaximal exercise, or during a maximum effort with the system switched to its isokinetic The effect of different pedalling rates (40, 60, 80, 100 and 120 rev min¢) on power generating capability, oxygen uptake (ýOµ) and blood lactate concentration [La]b during incremental tests was studied in seven subjects. No significant differences in ýOµ,max were found (mean ± s.d., 5.31 ± 0.13 l min¢). The final external power output delivered to the ergometer during incremental tests (PI,max) was not significantly different when cycling at 60, 80 or 100 rev min¢ (366 ± 5 W). A significant decrease in PI,max of •60 W was observed at 40 and 120 rev min¢ compared with 60 and 100 rev min¢, respectively (P < 0.01). At 120 rev min¢ there was also a pronounced upward shift of the ýOµ-power output (ýOµ-P) relationship. At 50 W ÄýOµ between 80 and 100 rev min¢ amounted to +0.43 l min¢ but to +0.87 l min¢ between 100 and 120 rev min¢. The power output corresponding to 2 and 4 mmol l¢ blood lactate concentration (P[La]2 and P[La]4 ) was also significantly lower (> 50 W) at 120 rev min¢ (P < 0.01) while pedalling at 40, 60, 80 and 100 rev min¢ showed no significant difference. The maximal peak power output (PM,max) during 10 s sprints increased with pedalling rate up to 100 rev min¢. Our study indicates that with increasing pedalling rate the reserves in power generating capability increase, as illustrated by the PI,maxÏPM,max ratio (54.8, 44.8, 38.1, 34.6, 29.2%), the P[La]4ÏPM,max ratio (50.4...

Effect of pedalling rates on physiological response during endurance cycling

“…These data suggest a higher contribution of anaerobic metabolism to power production in the first 15 min at FCC + 20%. Moreover, they corroborate those of Zoladz et al (2000) who showed that beyond 100 rpm there is a decrease in external power that can be delivered at a given V0 2 with an associated earlier onset of metabolic acidosis. Importantly, this could be disadvantageous for maintained high intensity exercise.…”

“…The maximal power during a 10 s sprint (Zoladz et al 2000) 2. The power generating capabilities following high intensity cycling exercise close to 90% VO2max (Beelen and Sargeant 1993) the reasons behind the choice of a particular cadence during endurance cycling and the corresponding GR by cyclists remain unclear.…”

Influence of duty cycle on the time course of muscle fatigue and the onset of neuromuscular compensation during exhaustive dynamic isolated limb exercise

“…3) that permitted subjects to provide positive physical work (J) by applying force against the ergometer throughout the limb's extension. We anticipated that the mechanical power outputs sustained at a subject's peak rate of oxygen uptake would be similar between the experimental conditions, because mechanical power does not appear to vary substantially with limb cadence at this intensity (5,49,54). The physical consequence (Eq.…”

Isokinetic muscle strength and short term cycling power of road cyclists

“…The maximal peak power output during 10 s sprints show higher values in pedalling rates at 100 rpm and 120 rpm and are lower in cadences of 60, 80 and 140 rpm (Zoladz et al, 2000). Van Soest and Casius (2000) found in musculoskeletal modelling that best cadence to achieve short time maximum power is near 120 rpm.…”