Effects of inspiratory muscle metaboreflex on cerebral circulation at rest and during light-intensity exercise in healthy males.

PURPOSE: This study aimed to clarify the effects of inspiratory muscle metaboreflex on cerebral circulation at rest and during exercise.

METHODS

Twelve young males randomly completed two trials (rest and exercise [leg cycling at 40 % peak oxygen uptake] trials) on separate days. In each trial, the internal carotid artery (ICA), an index of cerebral circulation, was measured using Doppler ultrasound 2 min after inspiratory loading breathing (IL condition) or non-loading breathing (control condition). During ICA assessments, participants engaged in 3 min of spontaneous breathing (SB), followed by 3 min of isocapnic hyperventilation (IHV).

RESULTS

ICA conductance was lower in the IL condition than in the control condition in both rest and exercise trials. Inspiratory muscle metaboreflex did not reduce ICA blood flow during SB but decreased it during IHV in both trials.

CONCLUSION

Our findings suggest that inspiratory muscle metaboreflex could decrease cerebrovascular conductance from rest to light-intensity exercise and attenuates cerebral blood flow with increased respiratory muscle work.