Does being in peak physical condition ensure higher IQ levels? A study involving 1.2 million Swedish soldiers born between 1950 and 1976, shows a clear link between fitness and mental calibre.
The strongest links are for logical thinking and verbal comprehension. But it is only fitness that plays a role in the results for the IQ test, not strength.
"Being fit means that you also have good heart and lung capacity and that your brain gets plenty of oxygen," says Michael Nilsson, professor at the Sahlgrenska Academy and chief physician at the Sahlgrenska University Hospital, Sweden.
"This may be one of the reasons why we can see a clear link with fitness, but not with muscular strength. We are also seeing that there are growth factors that are important," adds Nilsson.
By analysing data for twins, the researchers have been able to determine that it is primarily environmental factors and not genes that explain the link between fitness and a higher IQ.
"We have also shown that those youngsters who improve their physical fitness between the ages of 15 and 18 increase their cognitive performance," says Maria