Purpose: The aim of the study was to compare the kinetics responses of heart rate (HR), pulmonary (V’O2pulm) and predicted muscular (V’O2musc) oxygen uptake between two different pseudo-random binary sequence (PRBS) work rate (WR) amplitudes both below anaerobic threshold. Methods: Eight healthy individuals performed two PRBS WR protocols implying changes between 30W to 80W and between 30W to 110W. HR and V’O2pulm were measured beat-to-beat and breath-by-breath, respectively. V’O2musc was estimated applying the approach of Hoffmann et al. (Eur J Appl Physiol 113: 1745-1754, 2013) considering a circulatory model for venous return and cross-correlation functions (CCF) for the kinetics analysis. Results: HR and V’O2musc kinetics seem to be independent of WR intensity (p > 0.05). V’O2pulm kinetics show prominent differences in the lag of the CCF maximum (39 ± 9s; 31 ± 4s; p < 0.05). Conclusions: A mean difference of 14 W between the PRBS WR amplitudes impacts venous return significantly, while HR and V’O2musc kinetics remain unchanged.
Respiratory Physiology & Neurobiology / Vol. Article in press