Combined Effect of Physical Activity and Leisure Time Sitting on Long-Term Risk of Incident Obesity and Metabolic Risk Factor Clustering
What is the combined effect of moderate to vigorous physical activity and leisure time sitting on the long-term risk of obesity and clustering of metabolic risk factors?
The duration of moderate and vigorous physical activity and of leisure time sitting was assessed by questionnaire between 1997 and 1999, among 3,670 participants from the Whitehall II cohort study. Multivariable-adjusted logistic regression models examined associations of physical activity (moderate to vigorous defined as ≥3 METs) and leisure time sitting (tertiles with odds of incident obesity [body mass index ≥30 kg/m2]), and incident metabolic risk factor clustering (two or more of the following: low high-density lipoprotein cholesterol, high triglycerides, hypertension, hyperglycemia, insulin resistance each with standard definitions for the metabolic syndrome) at 5- and 10-year follow-ups. Covariates included age, sex, socioeconomic status, occupation, health status, diet, alcohol, and smoking status.
Approximately 73% were male, and mean age was 56 years. Physical activity, but not leisure time sitting, was associated with incident obesity. The lowest odds of incident obesity after 5 years were observed for individuals reporting both high physical activity and low leisure time sitting (odds ratio [OR], 0.26; 95% confidence interval [CI], 0.11-0.64), with weaker effects after 10 years. Compared with individuals in the low physical activity/high leisure time sitting group, those with intermediate levels of both physical activity and leisure time sitting had lower odds of incident metabolic risk factor clustering after 5 years (OR, 0.53; 95% CI, 0.36-0.78), with similar odds after 10 years.
The authors concluded that both high levels of physical activity and low levels of leisure time sitting may be required to substantially reduce the risk of obesity. Associations with developing metabolic risk factor clustering were less clear.
The results support the recent craze of having sedentary workers (classically secretaries) walk on a treadmill or ride a stationary bike during work, and adults and children exercising while watching TV to both increase exercise and decrease time sitting.
Keywords: Odds Ratio, Hyperglycemia, Follow-Up Studies, Exercise, Risk Factors, Insulin Resistance, Social Class, Smoking, Metabolic Syndrome X, Cholesterol, Body Mass Index, Leisure Activities, Obesity, Diet, Confidence Intervals, Questionnaires, Triglycerides, Health Status, Lipoproteins, HDL, Hypertension, Logistic Models
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