The aim of this study was to determine the effect of inspiratory loading on limb locomotor (LM) and respiratory muscle (RM) deoxygenation ([deoxy (Hb+Mb)]) using NIRS during constant-power cycling exercise. Sixteen, male cyclists completed three, 6-min trials. The intensity of the first 3-min of each trial was equivalent to ∼80% V̇O2max (EX80%); during the final 3-min, subjects received an intervention consisting of either moderate inspiratory loading (Loadmod), heavy inspiratory loading (Loadheavy), or maximal exercise (LoadEX). Loadheavy significantly increased LM [deoxy(Hb+Mb)] from 12.2±9.0μm during EX80% to 15.3±11.7μm, and RM [deoxy(Hb+Mb)] from 5.9±3.6μm to 9.5±6.6μm. LM and RM [deoxy(Hb+Mb)] were significantly increased from EX80% to LoadEX; 12.8±9.1μm to 16.4±10.3μm and 5.9±2.9μm to 11.0±6.4μm, respectively. These data suggest an increase in respiratory muscle load increases muscle deoxy(Hb+Mb) and thus may indicate a reduction in oxygen delivery and/or increased oxygen extraction by the active muscles.
- Muscle oxygenation
- Near-infrared spectroscopy
- Resistive breathing
ASJC Scopus subject areas
- Pulmonary and Respiratory Medicine