Even women who exercise regularly spend too many hours a day sitting, a new study led by a Northwestern University professor found.
The study, the results of which were published in the Oct. 4 issue of the International Journal of Behavioral Nutrition and Physical Activity, tracked the activity levels of 91 healthy women who ranged in age from 40 to 75. For one week, each of the women wore a monitor called the activPAL, which recorded the amount of time they spent sedentary, upright and moving, as well as the intensity of their physical activity.
The study found that there was no connection between the amount of time women spent working out and the amount of time they spent sitting.
"It's a very interesting finding. I think it will resonate with a lot of women who do exercise for their health to know that there's another behavior they need to work on that is important as well," said Lynette L. Craft, adjunct assistant professor in preventive medicine at the Feinberg School of Medicine at Northwestern University and lead author on the study. "It's the first study that has looked at this."
Although exercise is helpful, people should break up, or replace, extended sitting periods with light activity, Craft said. "Becoming aware of how much time you're sitting is a really important first step," she said.
The study, titled "Evidence that women meeting physical activity guidelines do not sit less: An observational inclinometry study," was done in collaboration with the Pennington Biomedical Research Center in Louisiana and the American Cancer Society.
Researchers also need to track how much time men and children spend sitting, Craft said.
"I think the study needs to be replicated in a larger, more diverse sample, to see if the finding has negative health consequences for others, such as men or children," Craft said.
She also plans to investigate how time spent sitting is related to the type of calories and food consumed, such as junk food, transfats or sodium.
Charles Matthews, a physical activity epidemiologist at the National Cancer Institute, praised the study.
"The study showed that women who walk at a moderate intensity for at least 2.5 hours each week were still highly sedentary; that is, they sat for 60 or more hours per week," Matthews said. "Importantly, the amount of walking the women engaged in did not appear to influence how much sitting they did. If we really want to increase overall activity levels in the population, we need to encourage adults to sit less and exercise more."