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CAMBRIDGE, Mass. — Today, there are an almost infinite number of ways to exercise and stay healthy. From working out in a gym to riding a bike to work, staying active may have never been easier. Despite all this, a new study finds Americans are actually much less active than their ancestors 200 years ago. In fact, researchers from Harvard University say the average American stays physically active for 30 fewer minutes than people did in 1820.
The team came to this conclusion after examining historical data which shows that body temperature among Americans has been falling for years. They also looked at changes in metabolic rates, which measure how physically active people are.
Since 1820, researchers found that the resting metabolic rate — the total number of calories the body burns while completely at rest — has declined by six percent. That's the equivalent of someone getting around 27 fewer minutes of moderate to vigorous physical activity.
Blame technology for this sedentary lifestyle?
So what's the cause of all this? Study authors say the main culprit of this sedentary lifestyle is the growth of technology since the industrial revolution.
“Instead of walking to work, we take cars or trains; instead of manual labor in factories, we use machines,” says lead author Andrew K. Yegian, a postdoctoral fellow in the Department of Human and Evolutionary Biology, in a media release. “We’ve made technology to do our physical activity for us. Our hope is that this helps people think more about the long-term changes of activity that have come with our changes in lifestyle and technology.”
Countless studies have shown a link between the growing use of technology (such as smartphones) and drops in physical activity throughout society. Until now, however, researchers say there has never been a study that calculated how many fewer minutes of exercise people are getting.
“This is a first pass estimate of taking physiological data and trying to quantify declines in activity,” Yegian adds. “The next step would be to try to apply this as a tool to other populations.”
People are literally colder today
Study authors started their investigation after seeing the results of a Stanford University report, which found that the average body temperature of Americans has dropped from the age-old 98.6 degrees Fahrenheit to about 97.5 degrees.
The Harvard team speculated that falling body temperature has a connection to less physical activity and the two could have a link to changes in human metabolism. Researchers say metabolism plays a key role in producing body heat and much of this depends on how active a person is.
The team pulled data from two other studies to come up with an estimate of how much exercise Americans got in 1820 in comparison to today.
“Physical activity is a major determinant of health,” says evolutionary biologist Daniel E. Lieberman. “Understanding how much less active Americans have become over the last few generations can help us assess just how much increases in the incidence of chronic conditions like type 2 diabetes, heart disease and Alzheimer’s can be attributed to decreases in physical activity.”
The study appears in the journal Current Biology.
