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Running in Singapore: How much water do you need for exercise?

By: Verne Maree

In our regular running column, we share favourite routes and talk about shoes, gadgets, treadmills, nutrition, racing, hashing, children’s running and more. This month, Verne Maree taps into the water debate.

My favourite East Coast drinking fountain – the one near Changi Sailing Club – wasn’t working this Sunday morning. Blazing from a blue sky, the sun delivered its usual 33°C (real feel 44°, said accuweather.com). Luckily, having to run three or four kilometres to the next water point isn’t a problem. We can thank evolution for bodies that are perfectly designed to run in the heat – and on much smaller amounts of water than previously thought.

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The dehydration myth
Yes, runners need water, and yes, we should drink enough of it. But drinking too much water can be more dangerous than not drinking enough, as explained below.

Why I think it’s still worth addressing the point here is that popular wisdom often lags way behind scientific research. In fact, the health and fitness industry is still urging eight or more large glasses of water a day.

“If you wait till you’re thirsty to drink,” they say, “it’s too late – you’re already dehydrated.” They’re dead wrong, as it turns out. Your body knows best, and thirst is the mechanism it uses to tell you when to drink; and that’s as true for an ordinary day at the office as it is when you’re out there pounding the pavements.

Quoted in runnersworld.com, “The eight glasses a day is totally arbitrary,” says Susan Yeargin, PhD, assistant professor of athletic training at the University of South Carolina. “Everybody, especially athletes, has different needs.”

We’re born to run, declares Tim Noakes, the acclaimed South African sports scientist. He argues that our species, Homo sapiens, having evolved on the arid African savannah, is perfectly designed to run long distances in the heat.

Four main adaptations gave us the evolutionary edge: bipedalism (walking on two feet rather than on the hands and feet) reduced our exposure to sun and heat, and made us more effective runners; our prodigious sweating capacity kept us cool during exercise; so does being furless; and our brain protects us from heat injury by making sure that we only ever exercise at an intensity or for a duration that won’t allow our body temperature to rise to a dangerous level.

Until the 1950s or so, elite runners drank according to thirst. In fact, not drinking at all during a marathon was regarded as an ultimate aim! Jim Peters, perhaps the greatest marathoner of all time, wrote: “In the marathon… every effort should also be made to do without liquid.” And American Matthew Maloney, who set a marathon record of 2:36:26 in New York in 1908 said: “As to what I use when in a marathon race, I only chew gum. I take no drink at all.”

Now, it would be unthinkable to suggest that runners shouldn’t drink while training or racing. But how did we go from pre-1950s practice to believing we had to glug down as much as humanly possible in order to avoid death from dehydration or heatstroke?

The running boom
The big change happened in the 1960s, when the running scene exploded, millions of Americans took to the road, and – surprise, surprise – big business saw the vast opportunity in this huge new market.

Gatorade, first marketed in the 60s, became the main sponsor of international sports bodies like the ACSM in the US. It’s also the first platinum sponsor of the Australian Institute of Sport (AIS), one of the provisions being that AIS-sponsored athletes may not promote the drinking of water over the drinking of sports drinks – and that Gatorade is the only sports drink they may promote. This little nugget only came out after legal action in terms of the Freedom of Information Act in Australia.

It wasn’t long before a slew of sponsored scientific studies purported to prove exactly what would send Gatorade sales through the roof: that any level of dehydration would impair performance and even lead to death.

Tim Noakes spills the beans in his book Waterlogged: The Serious Problem of Overhydration in Endurance Sports. Amongst other findings, his own studies in the early 1980s showed that those who became the most dehydrated during performance (more than minus three percent) also ran the fastest – and that it did them no harm.

Noakes and others kept up the pressure, but it took the ACSM 25 years to acknowledge the error in its 1976 guidelines – that in order to optimise performance and avoid catastrophic heat injuries, athletes should “drink as much as is tolerable” – and instead to encourage them to drink according to the dictates of their thirst.

How too much water can kill you
Exercise-associated hyponatraemia, or EHA, happens when the body retains too much water, Tim Noakes explains. Most people simply excrete the excess fluid, but around 30 percent of those who over-drink will retain it. This happens because their brains continue to secrete a hormone called ADH (anti-diuretic hormone) when its production should have been turned off. Excessive fluid accumulates in the blood, sodium levels fall and the brain swells, with disastrous effects that can include sudden death.

And so?
For an average runner like me (and possibly you), the facts are really good news. I don’t have to carry a bottle of water around MacRitchie Reservoir, because the sole drinking fountain en route will do the trick. Before a race, I won’t have to queue for the porta-loo after drinking too much water. Even better, I won’t be wasting time stopping at every water-point along the way.

And finally, most elite runners still drink according to their thirst, as elite runners have always done. That’s good enough for me.