Influence of Central Obesity on Associations Between Physical Activity, Sitting Time, and Metabolic Syndrome Among Middle-Aged and Older Adults in Urban China: A Cross-Sectional Study.

ABSTRACT

Objective: This study assessed possible associations among physical activity (PA), sitting time (ST), metabolic syndrome (MetS), and the individual components thereof. We analyzed the entire study sample and subpopulations stratified by visceral fat area (VFA). We hypothesized that individuals with elevated VFA might respond differently to modifiers of metabolic health, including PA and ST. Methods: This cross-sectional study, conducted between March and May 2010, enrolled 957 adults with abdominal magnetic resonance imaging (MRI) aged 40-65 years living in the urban communities in Hangzhou, China. PA and ST were recorded using the standard International Physical Activity Questionnaire (IPAQ) and categorized into three levels. The ethnicity-specific cutoff for central obesity was VFA ≥ 80 cm2 on MRI according to Chinese population-based research. Multiple logistic regression models were used to analyze the associations between PA, ST, MetS and its components. Results: In the total subject population, participants reporting high level of PA were at a lower risk of MetS (OR = 0.46, 95% CI 0.25, 0.86) than those declaring low PA. In the subgroup population with VFA ≥ 80 cm2 (ie, with central obesity), moderate-to-high PA levels were associated with a lower risk of MetS (p for trend < 0.05) and a lower risk of decreased high-density lipoprotein cholesterol (HDL-C) concentrations (p for trend < 0.05). In addition, ST > 3 h/day was a risk factor for both MetS (p for trend < 0.05) and hypertriglyceridemia (p for trend < 0.05) in the total subject population. While in the central obesity subgroup, ST > 3 h/day was found a stronger risk factor. Conclusion: Our study suggests that moderate-to-high levels of PA may have a role in prevention of MetS, and ST > 3 h/day was associated with a higher risk of MetS, particularly in individuals with central obesity.