Americans are stuck in chairs and on the couch, spending eight hours a day with their metabolic engines barely idling, according to data from sensors that scientists put on nearly 2,600 people to see what they actually did all day.
The results were not encouraging: Obese women averaged about 11 seconds a day at vigorous exercise, while men and women of normal weight exercised vigorously (on the level of a jog or brisk uphill hike) for less than two minutes a day, according to the study published in Mayo Clinic Proceedings.
If you included moderate exercise, such as yoga or golf, folks of normal weight logged about 2.5 to 4 hours weekly, according to the data. In part, that's good news: federal recommendations for adults include 2.5 hours of moderate-intensity aerobic activity coupled with muscle-strengthening exercise.
Still, the data sketch a nearly supine population profile, with days marked by long hours of sedentary behavior, particularly for those who are overweight or obese.
"We've engineered physical activity out of our daily lives and that's causing the health disparities that we have in this country," said the study's lead author, Edward C. Archer, a nutrition and obesity researcher at the University of Alabama at Birmingham. "How you spend your day determines whether you store your food as fat or store your food in your muscle, healthfully."
The data part of a study testing whether an indirect measure of energy expenditure, based on metabolism of water, stood up to other measurements in the field -- or on the couch, as it turns out. It did, and depressingly so.
For the obese, the study confirms what has been known for some time -- they are stuck in a "vicious cycle" of inactivity and weight gain, said Archer.
The difference between those who were overweight and those with a normal range body mass amounted to four to six minutes of moderate to vigorous activity, the study showed.
Although socioeconomic data were not included in the paper, previous research has shown that low-income people, particularly single mothers, are most likely to falling into a low-exercise lifestyle, in part from the demands of work and from the condition of recreational facilities in their neighborhoods.
"Ultimately the greatest inequalities we have is in our health behaviors," he said.
Studies have shown that maternal obesity leads to obesity in children, he noted. But the lifestyle of all children could use some changes, to keep the cycle of inactivity and obesity from perpetuating itself, he added.