Association between obesity and craniofacial muscles sensitivity: an experimental study in pain-free subjects

The objective of this study was to investigate if any association exists between obesity and muscle sensitivity in the craniofacial region of healthy individuals with different body mass index (BMI). The study was designed as a parallel single blinded investigation approved by the North Denmark Region Committee on Health Research Ethics (N-20180029). Written informed consent was obtained from all participants. Subjects were divided into normal BMI (18.5-24.9 kg/m²) and high BMI (≥25.0 kg/m²). Measurement of body composition parameters was followed by pressure algometry applied on skin overlying masseter and temporalis muscles before and after a cold pressor test (CPT). Deltoid muscle was used as a reference point. Statistical analysis was carried out to investigate the difference in mean pressure pain threshold (PPT) values and the conditioned pain modulation (CPM) effect. Forty subjects were included (20 normal BMI and 20 high BMI). No significant difference was found in mean PPT values or mean CPM effect between the BMI groups (PPT: masseter P=0.763, temporalis P=0.425, deltoid P=0.595 and CPM effect: masseter P=0.396, temporalis P=0.463, deltoid P=0.484). Mechanical muscle sensitivity and CPM effect were sex-independent. No influence of BMI was identified on mechanical muscle sensitivity in the craniofacial region of healthy individuals.