Effects of oropharyngeal exercises on orofacial function and corticomotor excitability in healthy individuals.

Oropharyngeal exercises/myofunctional therapy (OE/MT) offer complementary benefits for obstructive sleep apnea. However, the complex nature of the intervention impedes the understanding of the underlying mechanisms related to sensorimotor function and corticomotor control of involved muscles. This study explored the sensorimotor rehabilitation effects of OE/MT tasks in twenty-two healthy adults (24.1 ± 3.1 years) using a cross-over design to better understand the normal physiology of the tongue before and after these different tasks. Sessions involved breathing training (BT), tongue training (TT), or a no-training control (CT). Transcranial magnetic stimulation (TMS) evaluated motor-evoked potentials (MEPs) of the tongue and first dorsal interosseous (FDI, internal control) muscles before and after each session. Secondary outcomes included orofacial muscular pressure/force, peak expiratory flow rate (PEFR), oral stereognosis ability, and subjective ratings. Results showed TT significantly increased tongue MEP amplitude (P < 0.001) and volume (P < 0.001) compared to BT and CT. Conversely, FDI MEPs were unaffected by any task (P > 0.050). No significant differences were observed in orofacial pressure, PEFR, stereognosis, or subjective ratings (P > 0.050). These findings demonstrate that TT elicits unique corticomotor excitability in tongue motor control, which may represent early-phase neurophysiological adaptation rather than established neuroplastic change, providing mechanistic insight into the neurophysiological effects of OE/MT. BT may need further development and be tested longer before functional effects can be observed.