Abstract MP31: Diurnal Patterns of Physical Activity and Cardiovascular Risk Factors Over 10 Years: Results From the Coronary Artery Risk Development in Young Adults Study

Abstract

Introduction: Moderate to vigorous intensity physical activity (MVPA) is associated with lower cardiovascular (CV) disease risk. Cross-sectional studies has shown beneficial associations of morning MVPA with CV risk factors. We hypothesized that participants aged 38-50 yrs accumulating a greater proportion of MVPA earlier in the day will have lower risk of obesity, diabetes, and hypertension 10 years later. Methods: We included CARDIA participants with valid (≥4 of 7 days with ≥10 hr/d) accelerometer wear (ActiGraph 7164) at the year 20 exam (2005-2006) who performed at least 10 min/d MVPA (≥2020 counts per minute). Diurnal patterns were calculated from individual waking time, based on the first valid minute of wear after 4 AM. Diurnal patterns were operationalized as: 1) cumulative percent of MVPA counts within 4 hours after waking, and 2) time after waking when accumulating 50% MVPA counts. Logistic regression estimated odds of obesity, diabetes, and stage 2 hypertension and generalized linear models estimated the prevalence risk of stage 1 or above hypertension at the year 25 or 30 exam. Results: Participants (aged 45.2±3.6 yrs, 57.8% women) averaged 33.7±24.1 min/d MVPA, 34.1±1.3% MVPA was accumulated within 4 hours of waking, and 50% of MVPA was accumulated by 7.2±2.2 hours after waking. There were no statistically significant associations of diurnal patterns with obesity or hypertension (Table). However, every 10% greater MVPA accumulated within the first 4 hours was associated with a 20% higher odds of diabetes. Similarly, every 1 hour earlier accumulating 50% of MVPA was associated with 15% higher odds of diabetes. Total MVPA (min/d) was inversely associated with diabetes, obesity, and stage 2 hypertension. Conclusions: Total volume of MVPA is more important for cardiometabolic health than the time of day at which it is performed. In regards to diabetes risk, our findings showing higher odds with earlier accumulation of MVPA may be suggestive of a benefit in spreading activity throughout the entire day.