AHA Scientific Sessions 2026 Abstract · Nov 2, 2026
Reallocating 24-Hour Movement Behaviors and Predicting Risk of Cardiovascular Disease EVENTs (PREVENT): An Isotemporal Substitution Model from All of Us
By Lee S, Joyce C, Saban KL
Introduction: Sleep, sedentary behavior (SB), and physical activity are key behavioral determinants of cardiovascular health. These behaviors occur within a fixed 24-hour day, and time spent in one behavior necessarily displaces time spent in another. Isotemporal substitution modeling (ISM) provides a framework for estimating the potential health impact of reallocating time between 24-hour behaviors. The American Heart Association’s Predicting Risk of cardiovascular disease EVENTs (PREVENT) equations estimate 10- and 30-year cardiovascular risk using cardiovascular, kidney, and metabolic risk factors. However, the association between time reallocation among objectively measured 24-hour behaviors and PREVENT cardiovascular risk has not been examined. Objective: To examine associations of reallocating time among sleep, SB, light physical activity (LPA), and moderate-to-vigorous physical activity (MVPA) with 10- and 30-year PREVENT cardiovascular risk estimates in U.S. adults. Methods: This cross-sectional study used data from the All of Us Research Program Registered Tier v8 data. Adults aged 30-79 years with at least 7 valid consecutive Fitbit wear days and complete PREVENT risk data were included. Daily sleep, SB, LPA, and MVPA were derived from Fitbit data. PREVENT cardiovascular risk estimates were calculated using demographic, clinical, laboratory, and medication data (e.g., age, systolic blood pressure, total cholesterol, use of lipid-lowering medication) obtained within one year of the Fitbit wear period midpoint. ISMs estimated changes in 10-year cardiovascular risk among adults aged 30-79 years and 30-year risk among adults aged 30-59 years associated with reallocating 30 minutes/day among 24-hour behaviors. Models adjusted for age, sex, race/ethnicity, and Fitbit wear days. Results: Participants (N = 461) had a mean age of 57.3 ± 11.8 years (range: 30-79), 70.3% were female at birth, and 82.4% were non-Hispanic White. Participants contributed an average of 45.4 ± 66.5 valid Fitbit wear days and accumulated 691.7 ± 119.8 minutes/day of SB, 36.7 ± 33.2 minutes/day of MVPA, and 387.3 ± 62.1 minutes/day of sleep. Reallocating 30 minutes/day of SB to MVPA was associated with a 0.48 percentage-point lower 10-year PREVENT risk estimate (β = -0.0048, p = .016). Among adults aged 30-59 years, reallocating SB or LPA to MVPA was associated with 1.86 and 1.64 percentage-point lower 30-year PREVENT risk estimates, respectively (β = -0.0186, p = .003; β = -0.0164, p = .019). Conclusions: Reallocating time from SB or LPA to MVPA was associated with lower PREVENT cardiovascular risk estimates. These findings suggest that MVPA may be an important behavioral target for improving cardiovascular health, although longitudinal and intervention studies are needed to evaluate whether reallocating time toward MVPA can reduce future cardiovascular risk.