J-shaped relationship between physical activity and frailty risk in adults with sleep disorders: the additional...

Frailty is a multifactorial syndrome associated with increased vulnerability to adverse health outcomes. Physical activity (PA) is widely recognized as a modifiable factor potentially related to reduced frailty risk; however, its association among individuals with sleep disorders remains unclear. Using data from 2706 participants with sleep disorders in the National Health and Nutrition Examination Survey (2007-2018), we examined the association between PA and frailty. PA was assessed using the Global Physical Activity Questionnaire and expressed as metabolic equivalent minutes per week. Multivariable logistic regression, nonlinear modeling, and subgroup analyses were performed. A nonlinear J-shaped association between PA and frailty was identified, with an inflection point at approximately 1,037 MET-min/week. Below this level, higher PA was associated with lower odds of frailty (OR = 0.50, 95% CI: 0.33-0.76), while no significant association was observed at higher levels. Participants in the highest PA quartile had lower odds of frailty compared with those in the lowest quartile (OR = 0.65, 95% CI: 0.46-0.91). The "weekend warrior" pattern was inversely associated with frailty compared with inactivity (OR = 0.49, 95% CI: 0.25-0.96). These findings suggest that moderate levels of PA may be associated with lower frailty risk among individuals with sleep disorders. The "weekend warrior" pattern was associated with lower odds of frailty, suggesting that achieving recommended levels of physical activity through concentrated weekly accumulation may be relevant in this population.