Physical Fitness Associated with Less Pronounced Effect of Sedentary Behavior

http://pressroom.cancer.org/ShuvalSedentary

American Cancer Society
July 14, 2014

Physical fitness may buffer some of the adverse health effects of too much sitting, according to a new study by researchers from the American Cancer Society, The Cooper Institute, and the University of Texas. The study appears in the journal Mayo Clinic Proceedings, and finds the association between prolonged sedentary time and obesity and blood markers associated with cardiovascular disease is markedly less pronounced when taking fitness into account.

Sedentary behavior has been linked to an increase risk of obesity, metabolic syndrome, type 2 diabetes mellitus, cardiovascular disease, some cancers, and premature death. But previous studies of the association have not taken into account the protective impact of fitness, a strong predictor of cardiovascular disease incidence and mortality.

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The study showed that more sedentary time was significantly associated with higher levels of systolic blood pressure, and total cholesterol and triglycerides, as well as lower levels of HDL, the “good” cholesterol. It was also associated with BMI, waist circumference, and body fat percentage. But when researchers controlled for fitness, they found prolonged sedentary time was only significantly associated with a higher triglyceride/HDL cholesterol ratio (an indicator of insulin resistance). Sedentary time was not associated with metabolic syndrome (a clustering of risk factors). In comparison, higher fitness levels were associated with reduced adiposity and metabolic measures.

The authors say interpretation of their study’s findings should be tempered by its limitations. For example, sedentary behavior was based on self-report at one point in time, whereas fitness was assessed objectively during clinic visits.

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