B-15 Free Communication/Slide - Sedentary Behavior: MAY 27, 2009 1:00 PM - 2:45 PM ROOM: 619
Many studies had showed that time spent in sitting while watching television or playing computer games was associated with obesity. However, for many people, most of their working days are spent sitting in front of a computer screen. Is it inevitable for these people to get obesity?
PURPOSE: To investigate the relationship between sitting time, physical activity level and obesity in Chinese adults
METHODS: A total of 4,225 Hong Kong Chinese adults were included in a citywide fitness survey in 2005-2006, which included the measurement of body weight, height and waist circumference (WC). Daily sitting time (<3h, 3-6h, 6-9h, 9-12h, ≥12h) and physical activity level were assessed by a self-rated questionnaire and weekly Physical Activity Rating (PAR=0 to 10). Obesity was defined as a BMI >=25 or a WC >= 90 cm for men and ≥ 80 cm for women Chi-square test was used to compare the prevalence of obesity in short sitting time (SST) group (<3h) and long sitting time (LST) group (≥12h) as well as lack of exercise (LE) group (PAR≤3) and sufficient exercise (SE) group (PAR≥7). Logistic regression, using obesity as dependent variable and sitting time group, age group, gender, education level and family income as independent variables, were conducted to determine the odds ratio of having obesity likelihood for the LST group as compared to SST group. The same strategy was used to examine the odds ratio of having obesity likelihood for the LE group as compared to SE group.
RESULTS: Chi square analysis found that prevalence of obesity in LST vs. SST were 17.7% vs. 35.1% (P<.05) in men and 19.5% vs. 35.4% (P<.05) in women, respectively; prevalence of obesity in LE vs. SE. were 37.2% vs. 26.7% (P<.05) in men and 28.4% vs. 32.6% (P>.05), respectively. Logistic regression revealed no increased obesity risk in LST as compared to SST (OR = 0.79, 95% CI: 0.47-1.32), but significantly increased obesity risk in LE as compared to SE (OR = 1.43, 95% CI: 1.14-1.80).
CONCLUSION: Long sitting time is not associated with obesity. Lack of exercise rather than long sitting time is the risk factor associated with obesity. Regardless the duration of daily sitting time, keeping physical activity would be beneficial for preventing obesity