David James and Catherine Coyle of the University of Ulster, Londonderry, tested 60 men aged 59 to 65 to find out whether there was a link between their exercise habits and their "working memory" - the ability to retain information and then use it to solve a problem.
All the men had blue-collar jobs with the same corporation and had very similar IQs. But their attitudes towards physical fitness were very different. Half were members of their company's "swim plus aerobics" club, which met twice a week, while the other 30 took absolutely no physical exercise, preferring to drive rather than walk to the local shops.
James and Coyle found that the two groups' performance in tests of crystalline intelligence (accumulated knowledge) were almost identical, but the exercisers did much better in a test which involved memorising words.
The men were asked to read a list of 12 nouns and commit them to memory without using mnemonic devices. They were allowed to take as long as they wanted, and then asked to recall the words two to three minutes later. The couch-potatoes managed to dredge up just four words on average, while the swimmers recalled eight.
"The results of our study and others suggest that encouragement to participate in regular physical exercise may, over a period of time, be one way of breaking out of the vicious circle of physical and cognitive inactivity and, possibly, depression," James and Coyle say.
"Physical Exercise, IQ Scores and Working Memory in Older Adult Men" appears in Education andAgeing, Vol.13, No 1, published byTriangle Journals, PO Box 65, Wallingford, Oxfordshire OX10 OYG.