BLOOMINGTON, Ind. -- It may seem intuitive that greater amounts of exercise lead to less obesity, but an Indiana University study has found that this conventional wisdom applies primarily to white women. The findings draw attention not only to racial, ethnic and gender differences regarding exercise but also to the role work can play.
In his study involving more than 12,000 people in a nationally representative sample of U.S 20- to 64-year-olds, obesity expert Dong-Chul Seo found that obesity rates in general declined as the amount of weekly leisure-time physical activity (LTPA) increased. White women, however, saw the steepest decreases, particularly when meeting minimum national guidelines for weekly physical activity. This was not always the case for men and for women who were African American or Hispanic.
"For the majority of health professionals, even health researchers, they say the more leisure-time physical activity you engage in, the less likely you'll get obese," said Seo, associate professor in the School of Health, Physical Education and Recreation's Department of Applied Health Science. "This is true but it's probably only applicable to white women and some of the white men."
Surprised by the results, Seo looked deeper and found that job-related physical activity might have influenced obesity rates. Studies have found, for example, that men and Hispanic women are more likely to have manually demanding jobs than white women, which could affect the amount of LTPA they accumulate. For Hispanic women, their obesity rates dropped as their amount of occupational physical activity (OPA) increased. However, a different pattern was seen for men.
"This illustrates to me the importance of physical activity in the workplace," Seo said. "Workplace wellness programs should really be emphasized, especially for people who do sedentary work. To enhance their health, maybe employers could offer workout spaces and incentives to do physical activity during the work hours or right after. They can make it easier."
The study, published in the May issue of the Journal of Epidemiology and Community Health , is the first study that shows population-based evidence of a graded dose response relationship between the total volume of LTPA and obesity.
Here are more findings and information about the study:
National guidelines call for a minimum of 450-750 MET minutes per week. MET is a way of quantifying the total amount of physical activity in a way that is comparable across various forms of physical activity. Walking briskly for 30 minutes, for example, is around 100 MET. Running 6 mph for 30 minutes is around 300 MET.
Seo said the biggest decline in obesity rates was seen between women who met the guidelines and those who participated in LTPA but fell short of the guidelines. He said this supports the effectiveness of the minimum guidelines at least in terms of weight control -- and it was only applicable to women.
To speak with Seo, contact Tracy James at 812-855-0084 or traljame@indiana.edu .
For a copy of the study, contact Tracy James at traljame@indiana.edu or 812-855-0084.
Journal of Epidemiology and Community Health