V O 2 kinetics in subjects differing in aerobic capacity: investigation by spectral analysis

Abstract

The power-V_O2 transfer functions of 38 subjects differing in aerobic capacity have been determined on the basis of breath-by-breath total oxygen uptake (V_O2.1) measurements during light cycle ergometer exercise (lactic acid concentrations below 2 mmol · l⁻¹). At constant pedalling frequency (1 Hz) pseudorandom binary sequences (PRBS) of workload were used as the testing signal. TheV_O2.1 response was analysed by autocorrelating the ergometer power input and crosscorrelating the power input andV_O2.1 output. From the spectra of these functions the amplitude ratios and phase relationships were computed for the first six harmonics of the PRBS fundamental (14 mrad · s⁻¹). We found that differences in aerobic capacity are associated with significant differences in the amplitude plots of theV_O2 transfer function.