Author(s): VLOET, J., VAN DER SLUIJS, K., SITEUR, E., THIJSSEN, D., EIJSVOGELS, T., BAKKER, E., Institution: RADBOUD UNIVERSITY MEDICAL CENTER, Country: NETHERLANDS, Abstract-ID: 2050

INTRODUCTION:
Previous research demonstrated a positive relation between sedentary time (ST) and the risk for adverse health outcomes, including diabetes, cardiovascular diseases, and mortality. This detrimental impact of ST gradually attenuated with increasing levels of moderate-to-vigorous physical activity (MVPA). However, these studies relied on questionnaires which are prone to various forms of bias. Therefore, we used objective accelerometry data to examine the joint association between ST and MVPA in relation to markers of cardiometabolic health.
METHODS:
Participants of the Nijmegen Exercise Study cohort were invited for simultaneous assessment of free-living ST and MVPA using thigh-worn accelerometery across 8 consecutive days. Body composition (body mass index and % body fat), cardiometabolic risk factors (systolic blood pressure (SBP), diastolic blood pressure (DBP), total cholesterol, low-density lipoprotein (LDL), high-density lipoprotein (HDL), triglycerides, and estimated glomerular filtration rate (eGFR)), and glucose metabolism (glucose, insulin, and homeostasis model assessment of insulin resistance (HOMA-IR)) served as measures of cardiometabolic health. Participants were allocated to tertiles (low/moderate/high) of ST and MVPA, which created 9 (3x3) groups to assess joint exposures. Multivariate linear regression was performed to estimate the effects of the joint exposures, with the high ST - low MVPA group as reference. Age, sex, alcohol consumption, smoking status, education level and antihypertensive, antidiabetic and cholesterol-lowering medication use served as confounders.
RESULTS:
2,002 participants were included (age 64±11 years, 42% female, BMI 24.8±3.5 kg/m2). All joint exposures of increasing MVPA and reducing ST were associated with lower BMI, % body fat, insulin and HOMA-IR compared to individuals with high ST and low MVPA. Joint exposures of ST and MVPA related to cardiometabolic outcomes (i.e. SBP, cholesterol, LDL, and triglycerides) and glucose showed less strong associations, with only significant effects in some subgroups. Additionally, stratified analyses revealed that low ST was associated with an improved BMI and % body fat, improved kidney function, lower insulin and lower HOMA-IR compared to high ST (all P<0.05), but no differences were found across MVPA categories.
CONCLUSION:
Based on our large cohort including objective accelerometry to assess ST and MVPA, we confirmed the health benefits of lower volumes of ST in relation to various cardiometabolic risk factors, especially body composition and glucose metabolism outcome measures. More importantly, these effects of ST on body composition, eGFR, and glucose metabolism were consistent across groups of lower, moderate, and high volumes of MVPA, suggesting that MVPA cannot fully attenuate the negative effects of ST. These results highlight the relevance of reducing ST, even in individuals with high MVPA.