You know those days when you just don’t get around to drinking three glasses of water, let alone eight! On the average sitting-around kind of day, that wouldn’t be such a problem, but add more activity – especially intense and prolonged activity – and dehydration can become an issue.

Dehydration strikes when your body doesn’t have enough water, and can occur in just about any physical activity scenario. It doesn’t have to be hot and you don’t necessarily have to be dripping with sweat. In fact, you can become dehydrated in the water or skiing on a cold day.
So what does real dehydration feel like? 

Other than making you feel thirsty, common signs of dehydration include having a dry mouth, headache, dizziness, flushed skin, fatigue and muscle cramps. And of course there’s the concentrated dark-coloured pee.
If not treated correctly, severe dehydration can lead to mental delusion or unconsciousness and will require medical attention.
All of these symptoms are going to affect your exercise performance, too. Studies show that fluid deficits as little as 2 per cent of initial body weight (we’re talking 1.5kg for a 75kg athlete) are linked to significant reduction in sporting performance. As dehydration increases, blood pressure drops, breathing and pulse rate increase rapidly, and body temperature rises, resulting in early onset of fatigue and reduced exercise capacity.
The thing is, prevention is always going to be the best cure because hydration is a basic bodily necessity – your body will never get used to being dehydrated, and your body can’t be trained to handle it. 
Preventing dehydration is as simple as drinking regularly throughout the day before that thirsty sign hits. As a rule of thumb, 2 litres per day will suffice. As for athletes, fluid intake before, during and after exercise is important. It’s recommended to always start exercise well hydrated, which means drinking regularly throughout the day leading up to training or competition. Water is always your best bet, but when exercising longer than 60 minutes, the addition of sodium in a hydration beverage will help the body better retain water.
During exercise, athletes are encouraged to drink at regular intervals – ideally at a rate that matches sweat loss. And since thirst isn’t always a reliable gauge of your body’s need for water, developing good drinking habits during exercise based on sweat rates is recommended.
Monitoring weight immediately after exercise is a useful way of estimating fluid needs. During recovery, fluid loss via sweating and urine losses will continue, so replacing approximately 125 to 150 per cent of this fluid deficit over the next 2 to 6 hours will ensure optimal hydration. For example, if you lost 1 kg (1000mL), you will need to drink 1250 to 1500mL to fully rehydrate.
Bottom line: As far as avoiding dehydration, the proof is in the pee. You will be on the right track if your urine is clear or pale. If it’s darker, keep on drinking!
Kathleen Alleaume

Kathleen Alleaume is an accredited exercise physiologist and nutritionist and founder of The Right Balance