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

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Abstract
The power-VO2 transfer functions of 38 subjects differing in aerobic capacity have been determined on the basis of breath-by-breath total oxygen uptake (VO2.1) 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. TheVO2.1 response was analysed by autocorrelating the ergometer power input and crosscorrelating the power input andVO2.1 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 theVO2 transfer function.