The relation between critical power and neuromuscular fatigue as estimated from electromyographic data

Abstract

The purpose of this study was to define the relation between ‘critical power’ (CP) and the onset of fatigue (fatigue threshold or FT) as estimated from electromyographic data taken from representative leg muscles during cycling. The rate of rise in integrated EMG (IEMG) activity as a function of time (IEMG slope) was calculated at each of three or four constant power output ergometer bouts for 11 subjects. The IEMG slopes so obtained were plotted against workload resulting in linear plots (0-88 <R² <0.99( which were extrapolated to zero slope to give an intercept on the power axis which was interpreted as the fatigue threshold (FT). The mean workload at CP was 169-5 +12-8 W compared with 1905 ± 14-0 W at FT (p<O 05) though the two measurements were highly correlated. Power output at anaerobic threshold (AT) was not significantly different from FT at 187-1 + 15-9W. The correlation between these two variables was 0-903. It is suggested that the IEMG estimation of FT may provide an attractive alternative to the measurement of anaerobic threshold.

Additional information

Notes on contributors

TOSHIO MORITANI

Present address: Bio-dynamics Laboratory, Department of Physical Education, University of Texas at Arlington, Texas, U.S.A.

AKIRA NAGATA

On leave from the Bio-dynamics Laboratory, Faculty of Science, Tokyo Metropolitan University, Tokyo, Japan.

KENT MAGNUSSEN

Present address: Aviation Physiologist, Marysville, California, U.S.A.