Strength and morphology of a suprahyoid muscle and their relationship to forward head posture in healthy older adults

<jats:sec><jats:title>Aim</jats:title><jats:p>Forward head posture, an abnormality in head and trunk positioning, adversely affects suprahyoid muscle activity. Jaw‐opening force, which reflects suprahyoid muscle strength, is a useful index of dysphagia. However, the relationship between forward head posture and strength and morphology of suprahyoid muscles remains unclear. This study aims to clarify the relationship between forward head posture, jaw‐opening force and morphology of suprahyoid muscles.</jats:p></jats:sec><jats:sec><jats:title>Methods</jats:title><jats:p>During October 2018, we enrolled older adults aged ≥65 years. The craniovertebral angle was measured, and an angle <49° was defined as forward head posture. Jaw‐opening force was also measured. The geniohyoid muscle (GHM) was selected to represent the suprahyoid muscles, and its cross‐sectional area and length were measured using ultrasonography. Sarcopenia was also determined based on the criteria of the 2019 Asian Working Group for Sarcopenia. Multiple regression analyses were conducted to determine the association between morphological characteristics of the suprahyoid muscle and jaw‐opening force as well as the association between the former and forward head posture.</jats:p></jats:sec><jats:sec><jats:title>Results</jats:title><jats:p>Data of 87 participants were analyzed. Sex, cross‐sectional area and length of the GHM, and sarcopenia were significantly associated with jaw‐opening force. In addition, sex and forward head posture were significantly associated with the length of the GHM.</jats:p></jats:sec><jats:sec><jats:title>Conclusions</jats:title><jats:p>Our study demonstrated that an overextended length of suprahyoid muscles mediates the relationship between forward head posture and jaw‐opening force. Forward head posture is easily visualized and can be a useful indicator of decline in suprahyoid muscle strength. <jats:bold>Geriatr Gerontol Int 2022; 22: 779–784</jats:bold>.</jats:p></jats:sec>