Comparison of Suprahyoid Muscle Activation During Inspiratory Muscle Training and the Shaker Exercise: An Exploratory Pilot Study.

Inspiratory muscle training (IMT) has been discussed in the context of swallowing rehabilitation, yet its neuromuscular characteristics relative to established swallowing exercises remain unclear. This study aimed to compare profiles of muscle activation amplitude during IMT and the Shaker exercise, with a focus on task-specific recruitment of the suprahyoid, cervical, and respiratory muscles. In a single-center, prospective crossover study, healthy young adults performed IMT using a flow-resistive device and the Shaker exercise in randomized order. Surface electromyography (sEMG) was recorded from the anterior digastric, sternocleidomastoid, trapezius, and diaphragm-related respiratory muscles. sEMG amplitudes were normalized to maximal voluntary contraction (%MVC). Paired comparisons were conducted, with outlier handling, sensitivity analyses, and exploratory equivalence testing for digastric muscle activity. Twenty-four participants were analyzed. Digastric muscle activation differed significantly between tasks, with lower activation during IMT compared with the Shaker exercise. Sternocleidomastoid and trapezius activity also showed task-dependent differences, with higher sternocleidomastoid activation during the Shaker exercise and higher trapezius activation during IMT. Diaphragm-related activity did not differ significantly between conditions. Sensitivity analyses yielded consistent findings across datasets, and equivalence for digastric activation was not demonstrated within predefined margins. IMT and the Shaker exercise impose distinct neuromuscular demands despite partial overlap in the muscles involved. Whereas the Shaker exercise directly loads the suprahyoid muscles as primary movers, IMT engages them indirectly within respiratory and postural coordination. These findings support considering IMT as a complementary, rather than substitutive, approach to established swallowing exercises.