Development of a Jaw-Opening Sthenometer to Assess Swallowing Functions

First Report : Jaw Opening Muscle Strength of Healthy Volunteers

Abstract

Eating disorders and dysphagia are pressing issues in Japan, given its super-aging population. While simple assessment methods for eating and swallowing functions have been developed, they have consisted of observing the presence or absence of swallowing or a cough reflex. In other words, there has been no simple test to judge swallowing strength. Noting that the suprahyoid muscles that contract during swallowing are jaw-opening muscles, we created a jaw-opening sthenometer to assess the swallowing function and measured the jaw-opening muscle strength of 64 healthy participants (mean age, 44.7±12.6 years) as basic data. The mean jaw-opening muscle strength was approximately 8 kg (mean strength for men, approximately 10 kg; women, approximately 6 kg) . Muscle strength was significantly higher in men than in women, but no correlation with age was found. This result is consistent with previous studies that have measured jaw-opening muscle strength for different purposes. A significant correlation was found between jaw-opening muscle strength and handgrip strength, which uses different muscles. This indicates that the sthenometer provides meaningful measurements and is valid as a measurement tool. The suprahyoid muscles of healthy participants in their 60’s did not show reduced muscle strength due to age.