Exercise May Reduce Negative Effects of Excessive Sitting

From IDEA Fitness Journal, Volume 11, Number 10: Lately, several research reports have shone an unfavorable spotlight on the impact of prolonged sitting on health and mortality rates.  However, a new study from the American Cancer Society, The Cooper Institute and the University of Texas suggests that while extended bouts of sitting can lead to health problems, regular exercise may soften the impact. The primary focus of the study, published in Mayo Clinic Proceedings (2014; 89 [8], 1052–62), was to “examine the association between sedentary behavior and cardiometabolic risk.” Study participants were 1,304 sedentary men who had visited The Cooper Institute between 1981 and 2012. Each subject offered self-reported data on how much time he spent watching television and driving in a car. The men also described their exercise habits and completed a treadmill protocol to determine cardiorespiratory fitness. This information was then compared against blood pressure, lipid and glucose levels; height and weight; waist circumference; and body fat percentage. On average, the men reported around 16 hours of sedentary behavior - television viewing and time in a car - each week. A control group accrued no more than 9 hours a week. Not surprisingly, more sedentary time—at least 10 hours per week—was associated with poorer health scores: specifically, higher triglyceride levels, a higher triglycerides-to-HDL-cholesterol ratio, and higher body mass index, waist circumference and body fat percentage.

The study authors did learn, however, that regular physical activity and higher levels of cardiorespiratory fitness seemed to protect against some of these health risks. When data were adjusted for “fitness and covariates,” prolonged sitting was significantly associated only with the higher triglyceride-to-HDL-cholesterol ratio, and prolonged sedentary behavior was not linked with increased incidence of metabolic syndrome. The authors added that “taking fitness into account, prolonged sedentary time had a markedly less pronounced effect on cardiometabolic risk and adiposity.” While these data are promising, the researchers noted that further study is warranted to accurately determine the benefits of exercise and fitness levels on health scores among sedentary individuals. “Furthermore, our findings underscore the need to encourage achieving higher fitness levels through meeting physical activity guidelines to decrease disease risk factors,” they concluded.