The role of creatine in preventing muscular fatigue and boosting performance has preoccupied scientists for some time. But now it seems they are turning their attention to its potential for alleviating mental (or central) fatigue – an equally beneficial effect.

A team of Japanese researchers randomly assigned 24 young healthy volunteers (19 men and five women) to five days’ supplementation with 8g of either creatine monohydrate or placebo tablets per day. Before and after supplementation they completed a serial calculation task designed to reflect mental fatigue. At the same time oxygenation changes within the brain that are associated with mental fatigue were measured by a unique non-invasive technique known as near infrared spectroscopy (NIRS).

Analysis of the results showed that after supplementation the creatine group experienced less mental fatigue when repeatedly performing the simple mathematical calculations than the placebo group.

Study of the NIRS data showed that task-evoked increase of cerebral oxygenated haemoglobin in the brains of creatine-supplemented subjects was significantly reduced – a finding which is compatible with increased oxygen utilisation in the brain. ‘Because oral ingestion of creatine [has been] reported to increase creatine content in the brain… the effect of creatine on mental fatigue may be mediated by its effect on energy metabolism in the brain,’ report the researchers.

‘Although it cannot be totally ruled out that reduced muscle fatigue, rather than mental fatigue, contributed to the observed change in the performance of serial calculation task, haemoglobin oxygenation changes associated with creatine supplement suggested that this was mediated by its effect on the brain.

‘Although the interpretations are speculative and the data are not conclusive, our experiment may suggest a new line of approach to reduction of mental fatigue involving creatine.’

Neurosci Res 2002 Apr(4), pp 279-85

Isabel Walker