Dangers of too much water for some athletes

Just a quick link to an abstract I saw which draws attention to the potential dangers of drinking too much water during exercise.

An important warning given the usual admonition to drink lots!

Exercise-Associated Hyponatremia and Hydration Status in 161-km Ultramarathoners

Exercise-Associated Hyponatremia incidence can be high in 161-km ultramarathons in northern California. In this environment, EAH is more common with dehydration than overhydration and is more common in hotter ambient temperature conditions. Because weight loss >3% does not appear to have an adverse effect on performance, excessive sodium supplementation and aggressive fluid ingestion beyond the dictates of thirst are ill-advised

It reminds me of elements of this advice given to those preparing for the West Highland Way ultramarathon

Notes / slides are here