Sex differences in genioglossus muscle response to changes in pharyngeal resistance.

The genioglossus (GG) muscle's response to partial oropharyngeal occlusion was studied in age-matched, healthy awake men (n = 16) and women (n = 15). A miniature balloon was placed in the retroglossal pharynx, and the GG's electromyographic (EMG) reflexive response was evaluated in different body postures. We assumed that inflating the pharyngeal balloon and changing the body posture from upright to supine would increase pharyngeal airway resistance. Our hypothesis was that the change in airway resistance would elicit a different response in the GG muscle depending on sex. Our results showed that GG activity during natural breathing was higher in women than in men. GG EMG activity did not change upon inflation of the balloon in women. In contrast, when the balloon was inflated in the men, the GG's basal activity increased (P <.01) in both the upright and the supine positions. Women appeared to show a higher GG baseline EMG activity during spontaneous breathing at rest, while men were more responsive to the partial occlusion of the pharyngeal airway.