For years, doctors have been telling their patients that, by the time you feel thirsty, you've already lost water and are on the way to dehydration. But new research indicates that might not be the case.
In a study published in the Scandinavian Journal of Medicine & Science in Sports, Brock University physiologist Dr. Stephen Cheung found that losing even three per cent of body mass through dehydration has no discernible effect on cycling performance for high performance cyclists.
The CBC's Dr. Peter Lin says research by Cheung and others is changing the understanding of the relationship between thirst and dehydration.
"Instead of striving to replace every drop that you sweat out, it now appears that a little thirst isn't the end of the world," Dr. Lin said.
The findings don't mean drinking during your workout is a waste of time, but that how much you need may depend less on the fluid levels in your body than on what's going on in your brain.
Elite athletes vs. regular people
Dr. Lin says that, despite the new findings, regular folks should continue to follow their thirst in pursuit of hydration. But the best way to measure hydration levels is by monitoring urine.
"If it's nice and dark, it means that you need lots of liquid to dilute that out," he said.
"If you haven't gone to the bathroom for five hours or something crazy like that, then it means that you are dehydrated."
With the scorching summer months coming soon, Lin says people should be hydrated before they head out into the warm weather.
Coffee and tea should be avoided when possible, he says, because they're mild diuretics that can lead to the loss of up to one litre of water.
To hear the full interview with Dr. Peter Lin, listen to the audio labelled: Dr. Peter Lin debunks thirst myths.