Relationship between leisure-time physical activity and metabolic syndrome using varying definitions: 1999-2004 NHANES

Purpose: To examine the relationship between leisure-time physical activity (LTPA) and the metabolic syndrome in the U.S. adult population. Methods: The sample (N=5,620) in this cross-sectional study included adults aged 20 years and older. Physical activity was measured in two ways: a six-level measure based upon those reporting no LTPA and quintiles of LTPA, and a three-level categorical measure, according to participants who were found to be inactive, insufficiently active, and those meeting the current public health PA recommendation. SAS and SUDAAN were used for the statistical analysis. Results: When utilising the AHA/NHLBI criteria, adults acquiring between 736 and 1,360 MET-minutes per week (MET.min.wk(-1)) of LTPA were found to be 35% (OR 0.65; 95% CI 0.48, 0.88) less likely to meet the metabolic syndrome diagnosis criteria compared with those reporting no LTPA. However, protection (OR 0.70; 95% CI 0.51, 0.96) started earlier when utilising the WHO criteria (393-737 MET.min.wk(-1)). Significant inverse associations (OR 034; 95% CI 0.44, 0.66) and (OR 0.61; 95% CI 0.48, 0.77) for WHO and AHA/NHLBI criteria respectively, were also found for the metabolic syndrome when examining LTPA by the current public heath PA recommendation. In addition, the overall age-adjusted prevalence of the metabolic syndrome among U.S. adults was estimated to be 21.9% and 36.3% for the WHO and AHA/NLHBI definitions respectively. Conclusion: Our findings estimate that adults engaging in a level of LTPA similar to the current public health recommendation may have a decreased risk of developing the metabolic syndrome. Also, depending on the definition used, between one in three and one in five U.S. adults are estimated to have the metabolic syndrome.