Relationship between physical activity, sleep quality, and frailty in middle-aged and older adults: a cross-sectional study Running title: The correlation between physical activity, sleep quality, and frailty

Abstract

Background: Frailty is linked to numerous negative health consequences, with past research indicating that physical activity (PA) and sleep quality play a role in influencing frailty among older adults. As societal norms evolve, middle-aged adults are faced with time constraints that may result in differences in PA and sleep compared to older adults. Despite this, there is a limited amount of research focusing on middle-aged and older adults. This study seeks to examine the prevalence of frailty among middle-aged and older adults in the region, as well as investigate the connection between sleep quality, PA, and frailty. Methods: This cross-sectional study involved 1,265 middle-aged and elderly permanent residents from a region in Shaanxi Province, China. Participants were selected randomly for a physical examination and questionnaire survey. The questionnaires covered sociodemographic information, the Frailty Scale, the Pittsburgh Sleep Quality Index (PSQI) Scale, and the International Physical Activity Questionnaire (IPAQ). Statistical description and correlation analysis between variables were conducted using SPSS software. Results: A total of 1042 study participants were ultimately included in the analysis, with 74 classified as frailty and 444 as non-frailty. Adjusting for relevant covariates revealed that middle-aged and older adults engaging in light PA were more likely to be frailty compared to those with high PAL during non-frailty (CI 0.149-0.682; P < 0.01) and pre-frailty stages (CI 0.098-0.425; P < 0.001). Conversely, individuals without sleep disorders were less likely to be frailty (CI 1.241-3.720; P < 0.01). Occupational MET values were highest during the pre-frailty period in the presence of substantial PA (P < 0.001). Sleep quality not only directly predicted frailty but also acted as a mediator in influencing the role of age on frailty, with a mediating effect of 12.43%. Conclusion: Both PA and sleep quality play a role in frailty. The impact of PA on frailty is influenced by the nature of the individual's occupation. Sleep disorders can heighten the risk of frailty, with sleep quality acting as a mediator in the relationship between age and frailty.