Arterial stiffness, total sedentary behavior, and fragmentation of sedentary behavior in physically active individuals

It has been documented that levels of sedentary behavior (SB) are related to elevated cardiovascular disease (CVD) risk. However, details regarding the association between arterial stiffness (AS) and SB, along with breaking and prolonging of SB, remain unclear among individuals meeting physical activity (PA) guidelines. PURPOSE: To determine the relationship between total amount of SB and fragmentation (FI) of SB per day and AS in individuals who meet the PA guidelines as established by the ACSM. SUBJECTS: A total of 54 (32 females, 22 males) participants with an average age of 43 ± 7 years, meeting physical activity guidelines. METHODS: An ActivPal accelerometer was worn for 7 days to monitor SB. SB is defined as sitting or reclined position ≤1.5 METs during waking hours. FI is defined as the average number of sit-to-stand transitions completed during sedentary periods, when total hours of SB are controlled for. Measurement of pulse wave velocity (PWV) was completed as an estimation of AS. RESULTS: Participants averaged 8.6 ± 1.6 h/day of SB, and 3.7 ± 1.2 sit- stand-transitions/seated hour, and PWV of 7.9 ± 1.4 m/s. SB explained 4.5% of the variance in AS. With covariates of age and gender controlled for, the explained variance of FI by the regression equation was 1.1% and was not a significant predictor. CONCLUSION: SB is a significant predictor of AS, a preclinical marker of CVD. Individuals who meet PA guidelines should make a conscious effort to reduce SB to further reduce their risk of developing premature CVD