Conventional wisdom among runners is that dehydration is to be avoided at all costs. After all, doesn’t dehydration cause overheating? Doesn’t dehydration often result in heat distress? Doesn’t dehydration severely impair performance? Aren’t runners who collapse near or at the end of a race severely dehydrated and should be treated with rapid hydration?
Most of the running community will answer these questions with a resounding “yes”. This all seems very logical and commonsense……….but it is not true!
Over the past several years, the “dehydration is evil” theory has been disproved by Dr. Tim Noakes, one of the most eminent exercise physiologists. (Incidentally, Dr. Noakes is probably the only researcher in his field to have his own Wikipedia entry).
Dr. Noakes tested South African marathon and Ironman finishers in a series of studies over the course of several years. He determined that: