A comparative study comparing Americans in the 19th and 21st centuries found that their daily physical activity was reduced by half an hour.Today, Americans seem to have endless ways to exercise, huge gyms, and even high-end home exercise equipment like Peloton. Despite this, new research estimates that the average American spends about 30 minutes less in physical activity every day than its ancestors 200 years ago.
This is the conclusion drawn by evolutionary biologist Daniel-E-Lieberman’s laboratory researchers after using data on American body temperature drops and changes in metabolic rate to measure the decline in American physical activity levels since the Industrial Revolution. This work is described in “Contemporary Biology”.
Scientists have found that since 1820, Americans’ resting metabolic rate (or the total number of calories burned when the body is completely at rest) has dropped by about 6%, which means that moderate to vigorous physical activity per day has decreased compared to 200 years ago. About 27 minutes. The author said that the main reason is technical.
Andrew K. Yegian, a postdoctoral researcher in the Department of Human and Evolutionary Biology and the lead author of the paper, said: “We no longer walk to work, but take cars or trains; we no longer do manual labor in factories. , But using machines. We have allowed technology to do physical activities for us…. Our hope is that this will help people think more about the long-term changes in activities that come with changes in our lifestyle and technology .”
In the past two centuries, although the profound technological and social changes that have reduced the overall level of physical activity have been well documented in the scientific literature, people have never calculated how much physical activity has decreased.
This paper provides a quantitative figure for the literature and shows that the historical record of resting body temperature may be used as a thermometer for population-level physical activity.
A new study by scientists at Stanford University last year showed that the average body temperature of Americans dropped to about 97.5 degrees Fahrenheit during that time-one block lower than the accepted 98.6 degrees Fahrenheit. Researchers believe that the decline in body temperature and reduced physical activity are related, and may be related to human metabolism. Metabolism produces body temperature, which is partly driven by people’s performance in physical activity.
Scientists searched the previous research of other researchers to find a quantitative answer to this question. If there is a change in body temperature, what does this mean in terms of metabolism and activity? They extracted data from the two papers, calculated their correspondence, and used this to estimate the degree of reduction in physical activity.
In the paper, the researchers pointed out that in addition to reduced physical activity, other factors also affect resting metabolic rate and body temperature, complicating their estimates.
They also said that the future work is to improve the relationship between metabolic rate, body temperature and physical activity, which can more accurately investigate the trend of physical activity and serve as a way to understand how the decline in physical activity affects the health and morbidity of Americans in the industrial age. A pillar.
Physical activity is a major determinant of health,” said Edwin M. Lerner II Professor of Biological Sciences Lieberman. “Understanding how inactive Americans have become in the past few generations can help us evaluate 2 To what extent the increase in the incidence of chronic diseases such as type diabetes, heart disease and Alzheimer’s can be attributed to the decrease in physical activity. “