Exploring the Relationship Between Cerebral Blood Flow and Oral Exercise Using Head-Mounted Near-Infrared...

Swallowing activities have been increasingly recognized as relevant to cognitive function, yet the physiological pathways linking these functions to the brain remain incompletely understood. One proposed mechanism involves changes in cerebral blood flow. This study examined whether a standardized oral exercise program could alter prefrontal cerebral blood flow, measured by near-infrared spectroscopy. This single-center prospective study enrolled 52 healthy adults (mean age 33.1 ± 10.4 years; 67.3% female). Participants performed a 12-min exercise protocol consisting of 15 guided tasks classified into neck and shoulder relaxation, swallowing muscle strengthening, and vocalization practice. Cerebral hemodynamic responses were recorded continuously with a head-mounted dual-wavelength spectrophotometer. Hemoglobin difference (HbD), defined as oxygenated minus deoxygenated hemoglobin (HbO₂ - HbR), was used as a surrogate marker of blood flow, and task-related changes (ΔHbD) were calculated relative to baseline. Category-level effects were evaluated with Bonferroni correction, and task-wise comparisons were treated as exploratory and adjusted using Benjamini-Hochberg false discovery rate correction. Swallowing muscle strengthening tasks demonstrated a significant category-level increase in ΔHbD (0.34 ± 0.96 µM; p = 0.01), whereas the other exercise categories did not show significant overall effects after correction. In exploratory task-wise analyses, tongue protrusion (p = 0.0098, q = 0.049), lateral tongue movements (p = 0.0003, q = 0.0045), and chewing and swallowing action (p = 0.0095, q = 0.049) remained statistically significant after false discovery rate adjustment. No differences were observed by age or sex. In summary, swallowing-related oral exercises were associated with acute increases in prefrontal cerebral blood flow. These results suggest a possible physiological link between oral motor activity and cerebral perfusion, which warrants further investigation in larger and more diverse populations.