Accepted for/Published in: JMIR Aging
Date Submitted: Jun 1, 2025
Date Accepted: May 28, 2026
(closed for review but you can still tweet)
Warning: This is an author submission that is not peer-reviewed or edited. Preprints - unless they show as "accepted" - should not be relied on to guide clinical practice or health-related behavior and should not be reported in news media as established information.
Circadian rhythm syndrome exacerbates the adverse effects of solid fuel use on physical function and muscle strength: Evidence from a nationwide cohort study in China
ABSTRACT
Background:
The relationships between circadian rhythm syndrome, physical function, and muscle strength remain unclear.
Objective:
This study aimed to demonstrate the separate and combined deleterious effects of solid fuel use and circadian rhythm syndrome on physical function and muscle strength.
Methods:
We used data from the China Health and Retirement Longitudinal Study cohort. The study population consisted of participants who underwent comprehensive assessments of metabolism, circadian rhythm, indoor air pollution, physical function, and muscle strength at the initial evaluation. Muscle strength was assessed using repeated grip strength measurements, and physical function was assessed using a composite score of muscle strength, physical performance, and balance. Circadian rhythm syndrome was derived from the five diagnostic components of metabolic syndrome, combined with sleep duration and depression. Logistic regression and linear mixed models were used to assess the relationships between solid fuel use, circadian rhythm syndrome, physical function and muscle strength. Furthermore, we analyzed the mediating role of circadian rhythm syndrome and its combined effect with solid fuel use on physical function and muscle strength.
Results:
A total of 7954 participants were included in the study, most of whom used solid fuels. solid fuel use was positively associated with circadian rhythm syndrome (OR: 1.078; 95% CI: 1.031–1.125). Circadian rhythm syndrome was found to be a significant risk factor for impairment of physical function and muscle strength. Participants who used solid fuels and had circadian rhythm syndrome needed to pay more attention to changes in physical function (β: -0.698, 95% CI: -0.813, -0.584) and muscle strength (β: -0.332, 95% CI: -0.387, -0.277). Circadian rhythm syndrome partially mediated the association between solid fuel use and physical function.
Conclusions:
Circadian rhythm syndrome exacerbates the adverse effects of solid fuel use on physical function and muscle strength. Fuel cleanliness and regular work and rest habits are crucial for the health of middle-aged and older adults. Clinical Trial: Not applicable
Citation
