Scientists looked at over 1.2 million men born in Sweden between 1950 and 1976. All had physical fitness and intelligence tests at age 18. The researchers compared this information to academic and lifestyle data in national databases.
They found that physical fitness in the 18-year-olds was strongly linked to scores on intelligence tests. Muscular strength, though, showed little connection to intelligence.
”Being fit means that you also have good heart and lung capacity and that your brain gets plenty of oxygen,” says study co-author Dr. Michael Nilsson of the University of Gothenburg. “This may be one of the reasons why we can see a clear link with fitness, but not with muscular strength.”
To see if genes and upbringing were responsible, the researchers looked at a subset of twins in an NIH-funded database. The link between fitness and intelligence held even in identical twins.
Fit teens were also more likely to get a university degree later in life, and they landed better jobs—with higher pay or management responsibilities—up to 36 years later.
These findings point to the importance of encouraging physical fitness in teens. “This being the case, physical education is a subject that has an important place in schools,” says the study’s lead author, Dr. Maria Åberg of the University of Gothenburg.