Swimming herself stupid? (Image: Steve Mason/Getty)

WOMEN who habitually take strenuous exercise might be at risk of damaging their cognitive function later in life.

Strenuous exercise is known to reduce oestrogen levels in women and girls. This can delay the start of menstruation, and can lead to irregular periods in adult women. Low levels of oestrogen in premenopausal women have been linked to impaired mental function in later life.

Mary Tierney at the University of Toronto, Canada, reasoned that strenuous exercise might therefore lead to impaired cognition in later life. She asked 90 healthy post-menopausal women to report their life-long exercise habits, and then tested their cognitive ability. The results, which will be reported in the Journal of Alzheimer’s Disease, showed a statistically significant decrease in performance in various cognitive tasks in women who said that they exercised strenuously compared with those that had exercised moderately.

The overall benefits of regular exercise are well established, but Tierney says the possible impact of strenuous exercise on cognition should be investigated further to see if it is significant.