Expiratory Musculature Targeted Resistance Training Modulates Neural Connections During Swallowing Tasks: Preliminary fMRI Evidence.

Purpose: Strength gains and synergistic muscle group activations due to expiratory muscle strength training (EMST) lead to beneficial changes in several upper aerodigestive functions, including swallowing; however, there may be a potential top-down influence through neuroplasticity. The current study investigated changes in brain activation patterns during swallowing tasks before and after 4 weeks of EMST. Methods: Five right-handed, healthy young adult men aged 19-35 (mean = 28.8, SD = 2.68) participated in 4 weeks of EMST. All participants performed a swallow task, and blood-oxygen level-dependent (BOLD) responses were obtained at baseline and post-training conditions using functional magnetic resonance imaging (fMRI). Results: We observed a significant increase in activation across 12 regions, including the left primary somatosensory cortex (S1), left primary motor cortex (M1), bilateral supplementary motor areas (SMAs), bilateral cerebellum, right middle frontal gyrus, insula, anterior cingulate, and thalamus, following 4 weeks of EMST. While activations in several regions implicated with swallowing were expected, we also observed strong activation in areas associated with motor learning and cognitive functions. Conclusion: Our study's results provide preliminary evidence that EMST can modulate neural networks associated with swallowing. We speculate that enhanced sensorimotor excitability and cortical representation, motor learning, and improved cognitive-sensorimotor integration contribute to EMST's multidomain benefits. Furthermore, our findings suggest that EMST may offer potential cognitive and neuroprotective benefits beyond improving upper aerodigestive functions.