Sedentary behavior and stroke risk in US adults: The mediating role of central adiposity.

Prolonged sedentary behavior is a modifiable risk factor increasingly linked to cerebrovascular disease. Using 4 National Health and Nutrition Examination Survey cycles (2007-2014), we conducted a nationally representative cross-sectional analysis (N = 37,385) to examine the relationship between daily sedentary time and self-reported stroke, considering effect modification by physical activity and potential mediation through adiposity- and metabolism-related indices. Survey-weighted logistic regression showed that each additional hour of sedentary time was associated with a 5% higher odds of stroke (fully adjusted OR 1.05, 95% CI = 1.02-1.08, P = .002). Participants with severe sedentary behavior (≥8 h/d) had a 53% higher odds of stroke compared with those sitting <8 h/d (OR 1.53, 95% CI = 1.20-1.96). Moderate-to-vigorous physical activity attenuated this relationship across sedentary levels. Mediation analyses indicated that central adiposity, particularly the weight-adjusted waist index (WWI), partly explained the association between sedentary time and stroke. Restricted cubic spline modeling suggested a threshold beyond which stroke risk increased sharply. These findings indicate that prolonged sitting raises stroke risk through metabolic pathways related to central obesity, while regular physical activity may offset these effects. Reducing sedentary time and improving central adiposity should be integral components of stroke prevention in modern sedentary lifestyles.