Associations of Trunk Muscle Thickness and Muscle Strength in Healthy Male Adults

Background: Since the test of muscle strength needs a person’smaximumexertion, the objective assessment of muscle size is often used. Among the imaging techniques for assessing muscle size, muscle thickness is easy to measure by ultrasonography. However, little is known about the associations of trunk muscle thickness and muscle strength. Objectives: This study aimed to investigate the correlation between trunk muscle thickness and muscle strength. Methods: Seventeen healthymale university students participated in this study (20.80.6 years). Abdominal (rectus abdominis, external oblique, internal oblique, transverse abdominis) and low back (lumbar erector spinae, lumbar multifidus) muscle thickness were measured at rest using B-mode ultrasonography. Maximum voluntary isometric trunk flexion, extension, and rotation torque were measured using dynamometers. The relationships between all tested variables were investigated using the Pearson’s correlation coefficient. Results: A significant positive correlation was found between flexion and extension torque (r = 0.664, P = 0.004), flexion and right rotation torque (r = 0.565, P = 0.018), flexion and left rotation torque (r = 0.641, P = 0.006), extension and right rotation torque (r = 0.844, P < 0.001), extension and left rotation torque (r = 0.784, P < 0.001), and between right and left rotation torque (r = 0.982, P < 0.001). However, there was no significant correlation between trunk muscle thickness and torque. Conclusions: This study provides basic information about trunk muscle thickness and muscle strength in healthy male adults. The associations of trunk muscle thickness and muscle strength could not be identified through our measurements.