Arterial stiffness and the reallocation of time between device-measured 24-hour movement behaviours: A compositional data analysis

Background and aims: Arterial stiffness predicts cardiovascular morbidity and mortality. We aimed to quantify the differences in arterial stiffness associated with reallocating time between 24-h movement behaviours. Methods: This observational cross-sectional study included Luxembourg residents aged 25-79y who each provided ≥4 valid days of triaxial accelerometry (n = 1001). Covariable adjusted compositional isotemporal substitution models were used to examine if theoretical reallocations of time between device-measured sedentariness, the sleep period, light physical activity (PA), and moderate-to-vigorous PA (MVPA) were associated with the percentage difference in carotid-femoral pulse wave velocity (cfPWV). We further investigated if replacing sedentary time accumulated in prolonged (≥30 min) with non-prolonged (<30 min) bouts was associated with arterial stiffness. The results are presented as 30 min time exchanges (β (95% confidence interval)). Results: Beneficial associations with lower cfPWV were observed when reallocating time to MVPA from the sleep period (−1.38 (−2.63 to −0.12) %), sedentary time (−1.70 (−2.76 to −0.62) %), and light PA (−2.51 (−4.55 to −0.43) %), respectively. Larger associations in the opposite direction were observed when reallocating MVPA to the same behaviours (for example, replacing MVPA with sedentary time: 2.50 (0.85–4.18) %). Replacing prolonged with non-prolonged sedentary time was not associated with cfPWV (−0.27 (−0.86 to 0.32) %). In short sleepers, reallocating sedentary time to the sleep period was favourable (−1.96 (−3.74 to −0.15) %). Conclusions: Increasing or at least maintaining MVPA appears to be important for arterial health in adults. Extending sleep in habitually short sleepers, specifically by redistributing sedentary time, may also be important.