Purpose: The aims of this study were to: 1) describe the development and utility of the open mouth-maximal isometric press (OM-MIP), a tool designed for the quantitative assessment of suprahyoid-infrahyoid muscle
strength; 2) examine the effects of age and sex on OM-MIP; and 3) establish age- and sex-based OM-MIP
norms.

Method: Two hundred-sixteen healthy male and female volunteers were recruited. Participants performed OM- MIP, and the maximum of three trials that were within 10% of each other was recorded. Rest between each trial was allowed to avoid fatigue. Multiple regression examined the influence of age and sex on OM-MIP. Descriptive statistics outlined normative OM-MIP values for young adult (18-39 years), middle-aged adult (40-59 years), old adult (60-79 years), and very old adult (≥80 years) males and females. Two-way ANOVA determined if normative data differed significantly between the age and sex groups.

Results: Age and sex significantly influenced OM-MIP, though no significant interaction effect was identified. Females had lower mean OM-MIPs when compared to males (p < .0005), and very old adults had lower mean
OM-MIPs when compared to young (p = .001), middle-aged (p < .0005), and old adults (p = .013).

Conclusions: This study establishes age- and sex-based OM-MIP norms and outlines its potential utility during clinical swallowing evaluations and treatment. By providing these norms, clinicians can begin to quantitatively
measure suprahyoid and infrahyoid strength, individualize resistance training programs to patients’ OM-MIP one repetition maximum, and track strength changes over time in response to therapeutic interventions.