A LONGITUDINAL STUDY ON THE EFFECT OF INCREASED ARTERIAL STIFFNESS ON MUSCLE MASS REDUCTION IN MIDDLE-AGED AND OLDER ADULTS: THE WAKAYAMA STUDY

Objective: The molecular mechanisms underlying arteriosclerosis, including insulin resistance, inflammation, and oxidative stress, are hypothesized to contribute to both qualitative and quantitative changes in skeletal muscle in older adults. This study aimed to evaluate the longitudinal effects of increased arterial stiffness on skeletal muscle mass reduction in middle-aged and older adults. Design and method: This study analyzed data from 663 community-dwelling individuals (mean age; 65±8 years) who participated in health examinations conducted at intervals of at least three years between 2014 and 2023. Participants with a history of treatment for cardiovascular, renal, or orthopedic disease were excluded. Appendicular skeletal muscle mass (ASM) was estimated using bioelectrical impedance analysis. ASM values were normalized for height and expressed as the ASM index. Arterial stiffness was assessed by measuring brachial-ankle pulse wave velocity (baPWV) using an automated oscillometric device with an appropriately sized cuff. Results: During a follow-up period of 3.0 to 6.3 years (mean, 4.2 years), the ASM index slightly decreased from 4.41±0.77 kg/m2 at baseline to 4.39±0.68 kg/ m2. Participants were divided into three groups based on baseline baPWV: low (<1600 cm/s), moderate (1600–1999 cm/s), and high (=>2000 cm/s). The ASM index at follow-up and its change from baseline (d) were as follows: low group, 4.45 kg/m2(d = 0.016); moderate group, 4.38 kg/m2(d = 0.002); and high group, 4.17 kg/m2(d = -0.179). Significant differences in changes in the ASM index were observed among the groups. Multiple regression analysis revealed that baseline baPWV was a significant determinant of follow-up ASM index (beta = -0.222, p < 0.001), independent of age, sex, HbA1c, systolic BP, antihypertensive medication, alcohol consumption, smoking, regular exercise, and baseline ASM index. Conclusions: This longitudinal study demonstrated that higher baseline baPWV was significantly associated with greater reductions in ASM index during follow-up, even after adjustment for potential confounders. These findings suggest that increased arterial stiffness may contribute to skeletal muscle mass decline in community-dwelling middle-aged and older adults.