Melatonin secretion and muscle strength in elderly individuals: A cross-sectional study of the HEIJO-KYO cohort

Abstract

Background: Decreased muscle strength is associated with functional limitation and disability and is a predictor of cardiovascular and all-cause mortality. Recently, oxidative stress and inflammation have been shown to contribute to the loss of muscle strength, and although melatonin has antioxidative and anti-inflammatory properties, the association between melatonin secretion and muscle strength remains unclear. Methods: In this cross-sectional study of 760 community-based elderly individuals (mean age, 71.0 years), we measured overnight urinary 6-sulfatoxymelatonin excretion (UME) and grip strength and quadriceps strength. Results: Median UME was 7.0 μg (interquartile range, 4.2-11.1), and mean grip and quadriceps strength were 27.5 ± 8.4 kg and 162.6 ± 80.1 Nm, respectively. On dividing participants into quartiles by their UME level (lowest-highest UME, Q1-Q4), higher quartiles were significantly associated with increased grip strength and quadriceps strength (p for trend