Relationships of occupational and non-occupational physical activity to abdominal obesity

Hypothesis: Physically active occupations may protect against the risk of abdominal obesity. Objectives: This study assessed the interaction between non-occupational physical activity (NOA) (leisure-time, transport and domestic activity) and occupational activity (OA) in relation to abdominal obesity. Methods: A total of 3539 adults over the age of 20, with no work limitations, employed in one of the 17 occupations classified as low OA (LOA) or high OA (HOA) were identified in the 1999-2004 National Health and Nutrition Examination Survey. Waist circumference (WC) was used to categorize individuals into either non-obese or abdominally obese (WC > 88cm in women and > 102cm in men) categories. NOA was divided into three categories based upon physical activity guidelines: (1) no NOA; (2) insufficient NOA; and (3) sufficient NOA. Logistic regression was used to examine possible associations between NOA, OA and abdominal obesity. Results: In those who are sedentary outside of work, a high-activity occupation reduces the odds risk ratio of being categorized with abdominal obesity to 0.37 in comparison with those who work in low-activity occupations. For people working in low-activity occupations, there was a clear association with activity outside of work and the odds risk ratio of being categorized with abdominal obesity. In these adults, a reduced odds ratio was found only among those who met the physical activity guidelines through NOA (odds ratio = 0.55; 95% confidence interval (CI) = 0.40-0.75). Conclusion: HOA is associated with a reduced risk of abdominal obesity. Thus, it is important to include OA in studies seeking to understand the association between physical activity and abdominal adiposity. International Journal of Obesity (2012) 36, 100-106; doi:10.1038/ijo.2011.50; published online 22 March 2011