Measurement of maximal power output in isokinetic and non-isokinetic cycling. A comparison of two methods

The main goal of the study was to compare maximal power output and power ou tput at different pedalling frequencies obtained during isokinetic all-out tests with maximal power output obtained during a single all-out sprint (ag ainst the same braking force for every subject). Sixty healthy male subject s participated in the study. The ergometer system used in this study has th ree operating modes: the isokinetic mode (maintaining pedal crank velocity constant at a present level), a revolution dependent mode and a revolution independent mode. In all three operating nodes the effective forcer are mon itored by means of strain gauge, All subjects performed a single all-out sp rint against a braking force of 20 Newton and an all-out isokinetic cycling test consisting of ten 10 s bouts of maximal cycling at speeds ranging fro m 50 rpm to 140 rpm. In both tests, irrespective of which test mode was use d, the mean power for a complete crank revolution showed parabolic relation ships to crank velocity. For the isokinetic test, the subjects showed a pea k power (IsoW(peak)) of 15.3 +/- 1.7 W/kg corresponding to an optimal veloc ity of 115 +/- 8.6 rpm. For the force-velocity test NonisoW(peak) (the high est power obtained at any time during the test) was 14.4 +/- 1.9 W/kg and w as achieved at a pedalling rate of 127 +/- 14 rpm. IsoW(peak) was significa ntly higher than NonisoW(peak) (p < 0.001) but there were no significant di fferences between NonisoW(peak) and IsoW(max) (maximal mean power for each full crank revolution) for the revolutions from 90 rpm to 140 rpm. Though, NonisoW(peak) and IsoW(peak) are significantly different, there was a stron g relationship between NonisoW(peak) and IsoW(peak) (r = 0.7158, p < 0.001) . There was also a strong relationship between NanisoW(peak) and IsoW(max) for the revolutions from 50 rpm to 120 rpm (p < 0.001) and at 130 rpm (p < 0.01).