Fit young adults have a higher IQ and are more likely to go to university than those who aren’t physically active, according to a new study from the University of Gothenburg in Sweden.

The research, carried out by the university’s Institute of Medicine, involved 1.2 million Swedish men doing military service who were born between 1950 and 1976. The research group analysed the results of both physical and IQ tests when the students enrolled at age 18.

The study shows a link between good physical fitness and better results in the IQ test, with the strongest links in logical thinking and verbal comprehension. However, it is only fitness that plays a role in the IQ results, not physical strength.

Michael Nilsson, professor at the Sahlgrenska Academy and chief physician at the Sahlgrenska University Hospital, said: “Being fit means that you also have good heart and lung capacity and that your brain gets plenty of oxygen. This may be one of the reasons why we can see a clear link with fitness, but not with muscular strength."

The researchers also analysed data for twins and concluded that it is primarily environmental factors and not genes that explain the link between fitness and a higher IQ.

The results of fitness tests during national service were also compared to the socio-economic status of the men later in life. Those who were fit at 18 were more likely to go into higher education and many secured more qualified jobs.