Factors Associated With One-year Changes In Skeletal Muscle Thickness And Echo Intensity In Healthy Young Adults

BACKGROUND: The quantity and quality of trunk skeletal muscles are related to risk factors for cardiovascular and metabolic disease. In general, loss of skeletal muscle quantity and quality occurs with age. To detect the early symptoms of cardiovascular and/or metabolic disease, it is important to elucidate factors associated with the quantity and quality of trunk skeletal muscles not only in elderly but also in young adults. However, factors related to longitudinal changes in the quantity and quality of trunk skeletal muscle in young adults are not clear. PURPOSE: The aim of this study was to investigate the factors associated with changes in trunk skeletal muscle thickness (MT, index of muscle quantity) and echo intensity (EI, index of muscle quality) in healthy young men and women over 1-year. METHODS: Twenty healthy young men (BMI:20.8 ± 2.0 kg/m2) and 16 women (BMI: 19.8 ± 2.0 kg/m2) were participated in this study. At the level of the 3rd lumbar vertebra, the thickness and EI of trunk skeletal muscle at the right side were assessed by ultrasound images of the following skeletal muscles: rectus abdominis, external oblique, and lumbar multifidus. The cardiometabolic risk factors were evaluated by blood properties such as total cholesterol, triglycerides, and fasting blood glucose. Nutritional intakes were assessed by a questionnaire (BDHQ). These measurements were performed twice with the interval of 1 year. RESULTS: In young men, stepwise regression analysis showed that change (Δ) in total cholesterol was a significant contributor of Δ trunk MT (adjusted R2 = 0.264). In addition, Δfasting blood glucose and Δ trunk MT were significant contributors of Δ trunk EI (adjusted R2 = 0.305). As for young women, Δ dietary fat was a significant contributor of Δ trunk MT (adjusted R2 = 0.325). There were no parameters which selected as a contributor of Δ trunk EI. CONCLUSIONS: In healthy young adults, changes in total cholesterol, fasting blood glucose, and dietary fat appear to be important factors in maintaining the quantity and quality of trunk skeletal muscle. MEXT KAKENHI Grant Number 20 K11602