Sato Kohei, Kamoda Tatsuki, Sakamoto Rintaro, Katayama Keisho, Neki Toru, Katayose Masaki, Iwamoto Erika
Graduate School of Health Science, Sapporo Medical University, South-1 West-17, Chuo-ku, Sapporo 060-8556, Japan.
Graduate School of Health Science, Sapporo Medical University, South-1 West-17, Chuo-ku, Sapporo 060-8556, Japan; Japan Society for the Promotion of Science, Kojimachi Business Center Building, 5-3-1 Kojimachi, Chiyoda-ku, Tokyo 102-0083, Japan.
Respir Physiol Neurobiol. 2025 Aug-Sep;336:104422. doi: 10.1016/j.resp.2025.104422. Epub 2025 Mar 26.
This study aimed to clarify the effects of inspiratory muscle metaboreflex on cerebral circulation at rest and during exercise.
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).
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.
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.
