Joint associations of sedentary behavior and domain-specific physical activity on C-reactive protein in Korea

Sedentary behavior (SB) and physical activity (PA) exert opposing effects on inflammatory markers. This study examined the associations of a more subdivided combination of PA and SB with high-sensitivity C-reactive protein (hs-CRP). Using the 2014-2019 Korean National Health and Nutrition Examination Survey, this cross-sectional study analyzed 20,541 adults. The independent variables were SB, defined as ≥10 h of sitting per day, and three domains of PA: occupational PA (OPA) during work, leisure-time PA (LPA) during leisure time, and transportation PA (TPA) or active commuting. The dependent variable was hs-CRP ≥ 1.0 mg/L. Besides exploring the individual association of SB and each PA with hs-CRP, the combined association of SB and each PA with hs-CRP was also examined using multiple logistic regression. The analyses indicated that concurrent exposure to SB and OPA (odds ratio [OR] 1.36, 95% confidence interval [CI] 1.02-1.80) significantly raised the likelihood of increased hs-CRP, while SB without LPA (OR 1.26, 95% CI 1.11-1.41) or TPA (OR 1.19, 95% CI 1.08-1.31) significantly increased risk of higher hs-CRP, compared to their respective reference. The absence of non-occupational PA such as LPA or TPA combined with SB was associated with the increased hs-CRP risk, whereas OPA increased the risk when present concurrently with SB. Reducing SB and OPA while increasing LPA and TPA, is necessary to reduce inflammatory conditions.