For a study, the researchers sought to find a link between objectively evaluated sedentary behavior and atrial fibrillation. For 1 week, a triaxial accelerometer was worn on a belt to track sedentary behavior. Medicare claims were used to determine the occurrence of atrial fibrillation. Cox proportional hazards models adjusted for demographic and clinical factors were used to investigate the associations between total sedentary time (or sedentary behavior patterns) and incidence of atrial fibrillation. There were 268 (10.0%) incidences of incident atrial fibrillation among 2,675 individuals (mean age, 78.2 years), with 31 incidents per 1,000 person-years. After adjusting for age, race and ethnicity, BMI, education, smoking history, hypertension, diabetes, stroke, heart disease, and other chronic conditions, a higher risk of incident atrial fibrillation was found (quartile 4 versus quartile 1: hazard ratio, 1.20, [95% CI, 0.81–1.78]; P for trend=0.05). However, this was no longer statistically significant after controlling for physical function and self-rated health. Longer mean inactive bout duration and more continuous sedentary times (vs frequent interruptions in sedentary time) were similarly linked to an increased risk of incident atrial fibrillation. Still, these links were weakened after serial adjustment. In future research on community-dwelling older women, total inactive time and protracted sedentary accumulation patterns were linked to a higher risk of atrial fibrillation. Still, these correlations were reduced after physical function and self-reported health were taken into account. It showed that overall function and health parameters could explain the link between sedentary behavior and atrial fibrillation.