Association of objectively measured sedentary time with central and local arterial stiffness
Authors: Van Der Sluijs K M , Bakker E A , Kerstens T P , Stens N A , De Koning I A , Thannhauser J , Malik A E F , Reesink K D , Raj K V , Nabeel P M , Joseph J , Eijsvogels T M H , Thijssen D H J 
Published: June 2024

Abstract

Background/Introduction
High volumes of sedentary time (ST) may affect arterial stiffness (AS), which precedes the development of cerebrovascular and cardiovascular disease. However, the association between ST and AS remains inconclusive as most previous studies assessed ST with subjective measures and/or focused on relatively small sample sizes.

Purpose
We investigated the associations of objectively measured ST with central and local AS measures in a Dutch cohort, and we determined which factors affected these associations.

Methods
We recruited adult volunteers from a prospective Dutch cohort study. We collected demographics via annual questionnaires and performed physical examinations at our research centre. ST was measured 24 hrs/day for 8 consecutive days using thigh-worn accelerometery and expressed as daily sitting time (hrs/day). AS was measured using carotid artery ultrasound. Central AS was expressed as carotid-femoral pulse wave velocity (cfPWV, m/s), and local carotid AS was expressed as stiffness index Beta (dimensionless). The associations of ST with AS measures were evaluated using linear regression adjusted for age, sex, employment status, smoking behaviour, cardiovascular health group, body mass index, systolic blood pressure (SBP), total cholesterol and C-reactive protein concentrations, and time spent in moderate-to-vigorous physical activity (MVPA). Interaction terms of these variables with ST were added separately to investigate which factors affected the association of ST with AS.

Results
We analysed 666 subjects (64.8±11.0 yrs old, 398 (60%) male) with complete covariate data. ST was 9.1±1.6 hrs/day, and AS levels were 8.6±3.0 m/s for cfPWV and 6.4±3.0 for Beta. The association of ST with cfPWV was not significant (β=0.04 95% confidence interval [-0.11, 0.19], p=0.60) and not moderated by any of the variables (p&gt;0.05 for interactions). The association of ST with Beta was moderated by SBP and time spent in MVPA. Stratified analyses with SBP and time spent in MVPA split at the median revealed a significant association of ST with Beta in subjects who had SBP values greater than 134 mmHg (β=0.29 [0.05, 0.52], p=0.017) or who spent more than 103 min/day in MVPA (β=0.23 [0.03, 0.43], p=0.025). In subjects who had SBP values less than 134 mmHg or who spent less than 103 min/day in MVPA, the association of ST with Beta was not significant.

Conclusion
In a cohort of 666 subjects, we found no significant association of ST with central AS. Conversely, we found a significant positive association of ST with local AS in subjects who had the highest SBP or who were most physically active. These findings suggest that in certain subgroups, larger volumes of ST are associated with stiffening of the carotid arteries, which may contribute to the relation between ST and the development of cerebrovascular disease. Further research is needed to understand the underlying physiological processes and their implications.