Advice to overdrink may cause fatal hyponatraemic encephalopathy

A recent report that a female participant in the 2002 Boston marathon died from hyponatraemic encephalopathy because she ingested excessive volumes of a sports drink before and during the race,1 exposes an emotive debate that has raged for more than a decade.2 At issue is how much should athletes drink during exercise.3

From antiquity to the late 1960s, athletes were advised not to drink during exercise since it was believed that fluid ingestion impaired athletic performance.2 The publication in 1969 of an incorrectly titled article, “The danger of an inadequate water intake during marathon running,”4 provided the impetus for change, even though the study neither examined a 42 km marathon race nor did it identify any dangers.2 Rather, the most dehydrated athletes won those 32 km races, as is usually the case.2 This article's incorrect title provided the intellectual incentive for numerous studies, many funded by a fledgling sports drinks industry, culminating …