Associations of sedentary time patterns and TV viewing time with inflammatory and endothelial function biomarkers in children

Abstract

OBJECTIVE: The relationship between cardiovascular disease-related biomarkers and sedentary time in children is currently unknown. Thus, our objective was to investigate the associations of TV viewing time and accelerometry-derived sedentary time with inflammatory and endothelial function biomarkers in primary school aged children. METHODS: A cross-sectional analysis based on the Transform- Us! study in 164 (87 girls), 7-to 10-year old children, attending primary schools in Melbourne, Australia. Weekly TV-viewing time was assessed by parental proxy-report and total sedentary time and patterns of sedentary time accumulation (e.g. prolonged bouts) were assessed by accelerometry. The cardiometabolic biomarkers assessed were: C-reactive protein (CRP), homeostasis model assessment of insulin resistance (HOMA-IR), interleukin-2 (IL-2), -6 (IL-6), -8 (IL-8), -10 (IL-10), tumor necrosis factor alpha (TNF-a), adiponectin, resistin, brain derived neurotrophic factor (BDNF), soluble intercellular and vascular adhesion molecule 1 (sICAM-1, sVCAM-1), plasminogen activator inhibitor 1 (PAI-1) and soluble E-selectin. Generalized linear models with standard errors accounting for clustering at the class level were used to assess the associations of sedentary time with biomarkers, adjusting for sex, waist circumference, moderate-to vigorous-intensity physical activity (MVPA) and diet density. RESULTS: Each additional hr/wk of TV viewing was associated with 4.4% (95% CI: 2.1, 6.7) greater CRP and 0.6% (0.2, 1.0) greater sVCAM-1, independent of confounders. The association of the frequency and duration of 5-10 minute bouts of sedentary time with CRP was positive and approached statistical significance (p=0.056-0.084). CONCLUSIONS: This study indicates there is a detrimental association between prolonged bouts of sedentary time with markers of inflammation in healthy children, which adds to the wealth of research supporting a reduction in TV viewing during childhood to benefit health. Given recent recommendations that state children should break up prolonged periods of sedentary time, public health policies would benefit from further work directed at understanding how the accumulation of sedentary time influences health outcomes early in life.