The influence of breathing mechanics on the development of the slow component of O2 uptake

Abstract: We examined the influence of operational lung volumes and mean inspiratory flow on the amplitude of the slow component of O2 uptake () during constant-load cycling performed below and above the respiratory compensation threshold (RCT) in young (24±1yr), healthy individuals (n =10). Subjects demonstrated a significantly greater rise in expiratory reserve volume (ERV) and mean inspiratory flow over the period during exercise performed above compared with below the RCT (P <0.05). Inspiratory reserve volume (IRV) was, on average, smaller for trials performed above relative to below the RCT (P <0.05). The difference in the magnitudes of change in ERV and mean inspiratory flow, but not IRV, were positively correlated with the increase in amplitude between work rates (R 2 =0.86, P <0.01). These findings suggest that dynamic hyperinflation and mean inspiratory flow (by increasing inspiratory resistive work) contribute to the development of the , particularly when exercise is performed above the RCT. [Copyright &y& Elsevier]