Memory letting you down? Hit the gym!

Performing physical exercise four hours after learning has been shown to boost long term memory.

Successfully solidifying a new memory is thought to depend on the presence of particular chemicals in the brain. Known as neurotrophic factors, these chemicals support the growth of brain cells.

Physical exercise has been found to stimulate the release of such chemicals, and now researchers at the Donders Institute for Brain Cognition and Behaviour in the Netherlands believe they have found a direct link between exercise and the incorporation of facts into long term memory.

In the study, 72 participants spent 40 minutes learning a series of pictures of everyday objects. The participants were split into three groups and after the learning session, one group performed exercise straight away, one after a four hour delay, and the third group did not exercise at all.

Two days later, the participants were tested on how well they could remember the location of each object on the screen. Interestingly, the group that exercised four hours after learning performed better than the other two groups, which performed much the same.

This result, which is published in this week's Current Biology journal, came as a surprise to Prof. Guillén Fernández, head of the research team performing the study. It was expected that the group who exercised immediately after learning would have more efficient memory recall than those who exercised after a four hour delay, however their findings showed quite the opposite.

They speculate that for the group who exercised straight away, there will have been both beneficial and detrimental effects. The exercise would indeed stimulate the release of the neurotrophic factors that promote memory consolidation, however this would then be counter balanced by the detrimental effect.

"If you learn new things one after the other, learning the second thing interferes with the memory of the first," explains Prof. Fernández. "That's a well established psychological effect called interference." Performing the controlled exercise test will have also created a host of new memories for the participants, and for those who exercised straight after learning, these memories are likely to have interfered with the pictures they had been asked to study just beforehand.

Instead, for the group who waited four hours to exercise there was more time for the original 'picture' memories to be consolidated, without interference from the new 'exercise' memories.

These findings are particularly promising for the field of education, where appropriately timed exercise could be incorporated into the daily timetable to assist students with high workloads and revision.