Nonexercise physical activity and inflammatory and oxidative stress markers in women

Background: Leisure time exercise has been linked to lower circulating levels of inflammatory markers. Few studies have examined the association of nonexercise physical activity with markers of inflammation and oxidative stress. Methods: This cross-sectional analysis included 1005 Chinese women aged 40-70 years. Usual physical activity was assessed through in-person interviews using a validated physical activity questionnaire. Plasma proinflammatory cytokines and urinary F₂-isoprostanes were measured. Multivariable linear models were used to evaluate the association of inflammatory and oxidative stress markers with nonexercise physical activity and its major components. Results: Nonexercise physical activity accounted for 93.8% of overall physical activity energy expenditure. Levels of nonexercise physical activity were inversely associated with circulating concentrations of interleukin (IL)-6 (P _trend=0.004), IL-1β (P_trend=0.03) and tumor necrosis factor-alpha (TNF-α) (P_trend=0.01). Multivariable-adjusted concentrations of these cytokines were 28.2% for IL-6, 22.1% for IL-1β, and 15.9% for TNF-α lower in the highest quartile of nonexercise physical activity compared with the lowest quartile. Similar inverse associations were found for two major components of nonexercise physical activity, walking and biking for transportation, and household activity. No significant associations were observed between nonexercise physical activity and oxidative stress markers. Conclusion: Daily nonexercise physical activity is associated with lower levels of systemic inflammation. This finding may have important public health implications because this type of activity is the main contributor to overall physical activity among middle-aged and elderly women.