Sitting too much may negate benefits of exercise

Cardiologists at the Medical College of Wisconsin (MCW) and University of Texas (UT) Southwestern Medical Center have found that sedentary behaviors may lower cardiorespiratory fitness, and sitting for several hours may negate a brief period of exercise.

The findings are published in today’s online edition of Mayo Clinic Proceedings http://www.mayoclinicproceedings.org/.

Sedentary behaviors include low-energy behaviors such as sitting, driving and lying down. Researchers in the study evaluated data from men and women (and children) between the ages of 12 and 49 with no known history of heart disease, and measured their daily activity levels, as well as the amount of time spent in sedentary behaviors. Fitness was estimated using a treadmill test, adjusted for age, gender and body mass. Ultimately, the findings demonstrate that six hours of sitting negates the benefit of one hour of exercise.

“We knew that sedentary behavior is associated with an increased risk of cardiovascular disease, but we haven’t fully understood the mechanisms at work. Our findings suggest that sedentary behavior may influence cardiovascular risk through lower fitness levels,” said Jacquelyn Kulinski, M.D., assistant professor of cardiology at MCW. “Therefore, avoiding sedentary behavior throughout the day may represent an important companion strategy to improve fitness and health outside of regular exercise activity.”

“Further, we now have evidence that any movement is beneficial during a period of sedentary activity. For example, if your job keeps you restricted to a desk for many hours of the day, it may benefit your health to stretch and shift positions frequently,” she added.

Corresponding author of the study is Jarett Berry, M.D., assistant professor of internal medicine and clinical science at UT Southwestern. Other study authors, all from UT Southwestern, include Amit Khera, M.D.; Sandeep Das, M.D.; James de Lemos, M.D.; and Colby Ayers.

This study was funded with support from the National Heart, Lung and Blood Institute, the American Heart Association, and an unrestricted endowment provided to Dr. Berry by the Dedman Family.