Influence of sex and resistance training status on orofacial muscle strength and morphology in healthy adults between the ages of 18 and 40: A cross-sectional study

Objective To compare the orofacial muscle strength and facial muscle thickness between resistance-trained and non-resistance trained men and women. Methods Resistance-trained (25 men and 22 women) and non-resistance trained (21 men and 30 women) adults (18-40 years) had standard measurements of orofacial muscle strength (ie, anterior tongue elevation, cheek compression, and lip compression) and ultrasound measurements of facial muscle thickness. Body composition (percent fat, etc.) was estimated using ultrasound prediction Equations. A Bayesian analysis of variance (ANOVA) with between subject factors of training status (yes/no) and sex (man/woman) were used to determine differences in muscle size and strength. Results Body mass, height, and percent fat were similar between resistance-trained and non-resistance trained individuals, while appendicular lean mass was higher in resistance-trained. There were no differences in orofacial muscle strength between resistance-trained and non-resistance trained. However, men had greater strength in every task except for anterior tongue strength which was similar between sexes (men: 66 vs women: 64 kPa). Handgrip strength was greater in men and in those who were resistance-trained. The frontalis muscle was greater in women than in men and in those who were non-resistance-trained than those resistance-trained. None of the other muscles differed by training status, however, all were greater in men. Conclusion Results from our cross-sectional study would suggest that exercise-stimulation to the facial muscles during resistance training of the limbs and trunk did not reach a level where orofacial muscle strength could be changed. Sex differences in facial muscle thickness are very unique, although the reasons are unclear.