Abstract
Introduction: Sleep, sedentary behavior, and physical activity are each independently associated with cardiovascular health (CVH). However, many studies have investigated these relationships in isolation even though a change in any one given behavior will affect the time spent in the others. It is unknown how reallocating time in sedentary behavior with sleep or physical activity effects overall CVH in a diverse cohort of men and women at risk of cardiovascular disease (CVD). Hypothesis: Reallocating 30 minutes of sedentary time with sleep, light (LIPA), or moderate to vigorous physical activity (MVPA) is associated with more favorable overall CVH due to improvements in risk factors for CVD. Methods: Data for this analysis were taken from the Multi-Ethnic Study on Atherosclerosis (MESA) Sleep Ancillary Study. Eligible participants (n= 1718) wore Actiwatch accelerometers for 24 hours a day, and had at least 3 days of valid accelerometry. Time spent in sleep, sedentary behavior, LIPA, and MVPA was determined based on an established algorithm. The American Heart Association’s life simple 7 was used to represent the CVH score after excluding the physical activity component, with higher scores indicating more favorable CVH. All components were ascertained from MESA exam 5. Isotemporal substitution modeling was conducted to examine the effect of substituting 30 minutes of sedentary time for an equivalent amount of sleep, LIPA, or MVPA. Results: The mean age of participants was 68.3, 54.0% were female and 38.6% were white. The mean CVH score was 5.9 (95%CI: 5.8-6.0). On average, participants spent 499.3 minutes/day in sedentary time, 415.3 minutes/day in LIPA, 26.0 minutes/day in MVPA, and 388.2 minutes/day sleeping. Reallocating 30 minutes of sedentary time to sleep, LIPA, and MVPA was associated with a significantly higher CVH score [β(SE): 0.077(0.023), 0.039(0.017), and 0.485(0.065) respectively]. Reallocating 30 minutes of sedentary time to sleep was associated with lower BMI. Reallocating 30 minutes of sedentary time to LIPA was associated with higher diastolic blood pressure and total cholesterol, and lower BMI. Reallocating 30 minutes of sedentary time to MVPA was associated with lower systolic and diastolic blood pressure, and lower BMI. Conclusions: Our study demonstrates that sleep, LIPA, and MVPA are all positively associated with more favorable overall CVH and several key CVD risk factors. These findings underscore the importance of lifestyle modifications in improving CVH.
