Abstract Body (Do not enter title and authors here): Background: Current consensus guidelines emphasize the importance of achieving 150 minutes or more of moderate to vigorous physical activity (MVPA) per week to promote cardiovascular health but give little guidance about sedentary behavior.
Research Question: Is sedentary behavior associated with cardiovascular (CV) disease in a manner distinct from insufficient physical activity?
Aims: Examine associations between accelerometer-measured sedentary behavior with risk of specific CV outcomes, including potential interactions with MVPA.
Methods: Using 89,530 individuals providing one week of accelerometer-based physical activity data from the UK Biobank, we fit Cox models adjusted for demographic and lifestyle factors to assess associations between sedentary time (as a spline term) and incident atrial fibrillation (AF), myocardial infarction (MI), heart failure (HF), and CV mortality. We assessed the potential effect of MVPA on these associations by including MVPA as an adjustment variable, as well as performing subgroup analyses stratified at the guideline-recommended MVPA threshold.
Results: Among 89,530 individuals (age 62±8 years, 56.4% women) undergoing accelerometry, median sedentary time was 9.4 hours/day (quartile-1: 8.2, quartile-3: 10.6). In multivariable models, using the second quartile (8.2-9.4 hours/day) as a referent, sedentary time in the top quartile (>10.6 hours/day) was associated with greater risk of HF (hazard ratio [HR] 1.45, 95% CI 1.28-1.65), and CV mortality (HR 1.62, 95% CI 1.34-1.96), with evidence of a threshold effect at 10.6 hours/day. Higher sedentary time was also associated with greater risk of incident AF (HR 1.11, 95% CI 1.01-1.21) and MI (HR 1.15, 95% CI 1.00-1.32), with an approximately linear relation. Associations with HF and CV mortality persisted after adjustment for MVPA, as well as among individuals both above and below the guideline-based activity threshold of ≥150 minutes MVPA/week.
Conclusions and Relevance: Sedentary behavior is broadly associated with future adverse CV outcomes. For HF and CV mortality, associations appear distinct from insufficient MVPA, and sedentary time in excess of 10.6 hours/day conferred an increased risk.