Hydration for runners: The new rules

There is an underlying fear of dehydration, compounded by billboard reminders not to neglect fluid intake, that mean it is rare to spot a recreational runner who is not clutching a drinks bottle. Such is the preoccupation with drinking enough that research from Loyola University in Chicago reported how almost one in ten of the ‘fun-running’ brigade drink as much as possible and before they are thirsty while 36.5% of them sip fluid according to a preset schedule or to maintain a certain body weight.

Their practices are at odds with the drinking habits of more serious athletes, the majority of whom would not consider consuming fluid on the run unless in training for a marathon or beyond. Yet, even at club level and above, the mixed messages about drinking for sport – from scientists and manufacturers – have diluted our reasoning and caused a mild state of fluid confusion.

What should athletes be drinking and when? Here we present the latest findings:

Rule 1: Don’t fear mild dehydration

John Brewer, professor of applied sport science at St Mary’s University, Twickenham, says it’s a little-known fact that some fluid loss can help rather than hinder performance, and that “tactical dehydration” is a growing phenomenon among endurance runners, triathletes and cyclists, at club and elite level.

“Think about it,” Brewer says. “Each litre of fluid lost equates to approximately 1kg of body weight. Carrying around less weight has a positive impact on endurance performance, so people train their bodies to cope with dehydration, rather than fighting to prevent it.”

A report by New Zealand sport scientists suggests that a 3% drop in body weight through fluid loss doesn’t slow down athletes, while a 2012 paper in the Clinical Journal of Sports Medicine found that elite runners in the heat of the Dubai marathon recorded fluid losses of almost 10%, yet still their finishing times were unaffected.

Rule 2: Listen to our body

A few years ago, I took part in a sweat analysis organised by the sports drink company Gatorade, overseen by experts in fluid research from Loughborough University’s school of sport, exercise and health sciences. I was put through my paces, completing a sweat-inducing 40-minute bike ride in a warm and airless room while scientists probed the hi-tech sticking plasters dotted around my body, designed to assess the quality and quantity of my sweat.

The result was an eye-opener to the scientists, but not to me. Years of running had taught me that I could get by without frequently sipping fluids and my results proved it: I lost just …

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