If crosswords are too easy and Sudoku a touch boring, why not go and climb a tree?
A study found that childish pastimes such as climbing trees, running barefoot and crawling dramatically boost memory.
Working memory - the type of memory we use every day to remember phone numbers, follow directions and use a shopping list - improved by 50 per cent.
Those who don’t want to find their inner child will be glad to hear that squash, tennis and football are likely to have a similar effect.
Like climbing a tree, they feed the brain with information about everything from balance to orientation and give it a good workout.
The University of North Florida researchers put 72 men and women aged between 18 and 59 through a test of working memory, in which they had to remember lists of numbers in reverse order.
Some then spent two hours doing a range of obstacle course-like activities.
These included climbing trees, running barefoot and crawling along a narrow beam.
Others listened to a lecture or did a yoga class, before working memory was tested again.
Only those who had done the obstacle course did better, the journal Perceptual and Motor Skills reports.
Given that those who did yoga didn’t benefit, this suggests that it is the type of exercise that is important.
Climbing a tree and balancing on a beam hone ‘proprioceptive’ skills – the brain’s ability to sense where the legs, arms, hands and feet are in space without looking.
The brain also has cope with fast-changing information, as a creaky branches and wobbly beams.
A spokesman for the researchers said: ‘Proprioceptively dynamic training may place a greater demand on working memory because as the environment and terrain changes, the individual recruits working memory to update information to adapt appropriately.
‘Though the yoga group engaged in proprioceptive activities that required awareness of body position, it was relatively static, as they performed yoga in a small space, which didn’t allow for locomotion or navigation.’
Ross Alloway, one half of the husband and wife team that did the study, said: ‘This research suggests that by doing activities that make us think, we can exercise our brains as well as our bodies.
‘By taking a break to do activities that are unpredictable and require us to consciously adapt our movements, we can boost our working memory to perform better in the classroom and the boardroom.’
Dr Tracy Alloway added: ‘Improving working memory can have a beneficial effect on so many areas in our life, and it’s exciting to see that proprioceptive activities can enhance it in such a short period of time.’