In fact, more than 80,000 residents enrolled in the long-term Southern Community Cohort Study (SCCS) spent an equal amount of time — about nine hours or 60 percent of their waking day — in sedentary behaviors regardless of race.
"Our conclusion is that physical activity is not a significant factor in disparities that are observed in health between, for example, African-Americans and whites in this country," said senior author Mac Buchowski, Ph.D., research professor of Medicine and Pediatrics. Co-authors of the study are SCCS investigators from Vanderbilt, the International Epidemiology Institute, the National Institutes of Health and Harvard School of Public Health.
"Of course from this study we don't know what these reasons are but at least we could eliminate physical activity as a deciding factor in disparities, or even that it has much influence on disparities. But this does not diminish the role of physical activity in health, which is well known."
A major goal of the study, Buchowski said, was looking at sedentary behaviors, which are linked to health outcomes more than more active forms of physical activity in adults.
Sedentary behaviors are behaviors that usually do not require more than 50 percent more energy than lying down, such as sitting, doing office work in general and being engaged in screen time that includes viewing television, using tablets, smartphones or any other form of computer work.
Members of the cohort, residing in 12 southeastern states, were asked questions related to physical activity. In the cohort, only 16 percent of women and 25 percent of men were doing physical activity according to the guidelines for Americans, which is 150 minutes of moderate to vigorous physical activity per week.
"Perhaps for our cohort it may be more feasible to ask people to reduce the amount of time they spend sitting rather than do gym-based exercises," Buchowski said. "So if people would do a little bit more household or yard work it might be equally, or more, beneficial than vigorous exercise."
Sedentary and physically active behaviors were obtained from a validated physical activity questionnaire in 23,021 black men, 9,899 white men, 32,214 black women, and 15,425 white women (age 40-79) at enrollment into the SCCS.
The prevalence of obesity was 34 percent and 29 percent in white and black men, respectively, and 46 percent and 58 percent in white and black women, respectively.
With the exception of white males, nearly one-third of the participants had less than a high school education and the majority of participants reported household incomes of less than $15,000 annually.
"It has been shown in many studies that, in general, the amount of physical activity and fitness level are related to morbidity and mortality." Buchowski said.
"Regardless of our findings, we think that promoting physical activity is important. In addition to national programs and guidelines universally available to everyone, we need targeted interventions for vulnerable populations with specific needs."
"Our study suggests that interventions in older adults should focus on both reducing sedentary behaviors and increasing more active forms of physical activity," Buchowski said.