Updated 02 October 2015

High and dry

You’re two thirds H2O, so when thirst speaks, listen carefully. Dehydration is unpleasant, but water intoxication is no fun either.


The overriding memory is just feeling desperately, desperately thirsty... I'd fall over a lot and I'd hear water and I'd start digging around searching for it. Couldn't find it, couldn't get it. And it was driving me mad, to be able to hear water. - Joe Simpson, Touching the Void.

A memorable moment in this survival classic is when mountaineer Simpson, exhausted, delirious, dragging his shattered leg, finally reaches a small stream. He describes the transformative effect of drinking as "fuel" entering his body, giving him the strength to crawl the last torturous stretch to safety.

But it isn't necessary to go to Void extremes to get a taste of what this kind of thirst is like. If you haven’t ticked Dehydration off on your list of life experiences yet, then simply follow the steps in this handy guide, as tested by myself:

1. Have nothing for breakfast except a strong cup of coffee and a handful of dry muesli.
2. Go on a stiff hike in warm weather for a couple of hours, chatting and ignoring the state of your body, except to sing out periodically that you’re "a bit thirsty but fine and don’t need to stop thanks".
3. Drink nothing.

With any luck, you will soon develop various interesting symptoms, including: dizziness, nausea, weakness, and (especially dramatic) painful muscle cramps - classically in the calf muscles, but they may strike elsewhere.

You will be unable to continue or to successfully hide your pathetic condition from your hiking companions.

You may also throw up, pass out, become delusional, or, as was the case a couple of weeks back with an American tourist on Platteklip Gorge, Table Mountain - a dehydration and heat exhaustion hot-spot according to Wilderness Search and Rescue - need to be airlifted.

I was spared the latter mortifications, but things were embarrassing enough. Especially as I go around calling myself “Health24’s EnviroHealth Editor”, and especially as I was hiking with an expedition doctor, a top woman mountaineer, an outdoor guide and members of the Volunteer Wildfire Services (on the Chapman's Peak leg of the Mountains of Hope project).

These sorts of people are well-versed in wilderness survival, and are just dying to flaunt their knowledge and pounce on anyone who shows the slightest sign of weakness.  Which they did.

My brother firefighter refused, as I requested and would have much preferred, to leave me to die on my own in dignity. Instead they made me rest in the shade and take in fluids, primary among these a truly disgusting draught of blackcurrant Rehidrat, an electrolyte solution which helps replenish lost salts and fluids. Fortunately you generally only drink it when you're really thirsty.

Stiv Samuel of Volunteer Wildfire Services prepares an electrolyte potion for the author. (Photo: Craig Barker)

They also tried to get me to eat something, but at that stage I was too focused on not regurgitating Rehidrat.

When we caught up with the rest of the group waiting at the summit, expedition medic Dr Charlotte Noble approved the firemen's first aid, and encouraged me, Rehidrat or no Rehidrat, to keep drinking, and to have a small snack.

She also asked, in front of the assembled group: "Have you urinated yet?" Another symptom of dehydration is, not surprisingly, low or no output of urine, and you can tell you're sufficiently rehydrated when this important bodily function is back to normal.

The "Dehydration Myth"

After this episode, I resolved to always knock back loads of non-diurectic fluids before exercise, and to stay tanked up to overflowing every step of the way.

But hydration is a complex matter, and it's not simply the case that if too little water is bad, then a lot must be excellent.

Medics, exercise gurus and sportspeople themselves disagree on exactly how much, when and what you should drink. In fact, a few years back there was something of a rebellion among sports scientists, Prof Tim Noakes, Director of the UCT/MRC Research Unit for Exercise Science and Sports Medicine, notable among them. These researchers challenged the widely-held tenet: "Drink before you get thirsty".

Dr Ross Tucker, Health24's Fitness Expert, belongs to the Noakes "Drink when you get thirsty" school of thought, which does not consider exercise-induced dehydration to be quite the threat we've previously been lead to believe. In fact, some scientists have gone as far as to dub this the "Dehydration Myth", which they claim has been popularised by the sports drink industry.

It's OK, says Ross, to get a bit dehydrated during endurance exercise. It's not uncommon for athletes to finish long-distance events 3-4% lighter than when they started, without dire consequences. Thirst, even quite bad thirst, is not the same as dehydration, he points out, and even seemed a bit dubious that dehydration was the correct diagnosis in my case – which was annoying because it was the entire premise of my article.

Ross considers hyponatremia (also referred to as over-hydration or sometimes "water intoxication"), the excessive intake of water, to be a graver risk to endurance athletes than dehydration. The misguided notion that any loss of fluid during exercise is bad, he says, has lead to marathon athletes over-drinking to the extent that they feel bloated and ill, with sometimes serious consequences.

At its most severe, hyponatremia can lead to seizures and death from cerebral oedema (swelling of the brain tissue).

Hydrate, don't super-saturate

The "drink when you're thirsty" proponents' most convincing argument to my mind is the fact that our thirst mechanism is so delicately tuned. It lets you know in no uncertain terms when it's even minutely disturbed. As long as you pay attention to it, and keep enough water around to slake (but not drown) it, you really shouldn't run into trouble.

Hydration may be physiologically complex, but getting it right is not mentally taxing.

You don't ever need to force yourself to drink, says Ross. The only way you'll become seriously dehydrated from exercising is if you just don't have access to enough water.

Ross reckons that about 2 litres for a 4-hour hike should be fine, and doesn't advise tanking up beforehand if you aren't thirsty. "You can't 'waterload'," is how he puts it. He also recommends taking along some savoury snacks to help balance the intake of water and the sometimes nauseating effect of sweet drinks.

A "camel" pouch with a tube (available at most outdoor and sports stores) is an excellent investment, because you don't have the hassle of stopping, scratching around for your water bottle and holding up proceedings – and you'll be more inclined to keep hydrating steadily.

Veteran hiker Rosemary Colenso demonstrates correct use of the drinking tube. (Photo: Olivia Rose-Innes)

Another classic symptom of dehydration is the splitting headache, which may set in some time after exercise. So organise something tall, cool and non-alcoholic to take with a mild pain-killer once you get home; GnT (another diuretic) might be tempting, but, and again I refer to recent personal experience, it is ultimately not helpful.

More on hydration, dehydration and over-hydration

A selection of expert opinions on the topic:

Proper hydration during exercise
Too much water could be dangerous
How much should we drink?
8 glasses a day a myth


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