Beat Dehydration

Dehydration will severely reduce your training and race performance, but you can stop it before it stops you. Paul Larkins keeps you on track…

Dehydration will severely reduce your training and race performance, but you can stop it before it stops you. Paul Larkins keeps you on track…
When it comes to the practice of good hydration, there are as many myths as there are hard facts. This results in a surprising amount of bad practice amongst the tri community. You can check this for yourself by conducting a quick-fire question and answer session with your training mates on this very subject.
We’re willing to bet that you’ll find some who never drink during races, those who swear by water over sports drinks, and a whole host of other variations on these themes. Some still believe that hydration ?has little or no effect on performance, ?while others can’t get enough of it. The simple fact is that dehydration can severely reduce your race performance.
Combating fluid loss
There are no two ways about it: sweat on a run without replacing what you’ve lost in terms of fluid and you’ll get slower. Scientists are in full agreement – fluid loss itself is the principal cause of performance deterioration. Argue all you want but for every kilogramme you lose in sweat, you need to take in something like 1.5 litres of fluid to replace it. If you don’t, performance will decline by around 2% and you’ll get slower.
The key is to learn to manage this and adapt it to your own needs and circumstances on race day. From an average point of view, sipping every 15 to 20mins during exercise is good, but that’s only an average – everybody needs to discover what works best for them personally. There’s plenty of science to back this up. Discomfort, raised heart rate and pace come into play here. Heat alone doesn’t affect aerobic performance, rather how you tackle performing in it. Work out what liquid intake works best for you while you’re training and use that strategy in a race.
So what should you rehydrate with? Water will understandably be top of many athletes’ list and it initially seems difficult to argue against such a philosophy. But, with a little understanding of science, you can. Water is a good thirst quencher but it isn’t the best rehydrator during activity due to the lack of sodium and flavour. Water may restore the volume of the blood plasma but it also inhibits the thirst mechanism before your sodium levels can be replenished.
Water vs sports drinks
For an athlete, water doesn’t provide your body with what it needs – fuel and electrolytes – for best performance. Carbohydrates are essential to fuelling working muscles, fighting fatigue and helping performance. Electrolytes, like sodium and other minerals lost through sweat, should be replenished to maintain body fluid balance.
It’s true that water drunk in normal quantities isn’t going to bother you, but neither is it necessarily going to help. A recent scientific study showed that cyclists drinking the sports drink Gatorade during fast-paced cycling had nearly twice the performance benefit during a subsequent trial than when consuming water or carbohydrate alone.
Salt is the next obvious area of debate; bypass that problem by drinking an electrolyte sports drink. That will more than compensate for the sodium loss sweating causes, and you won’t need to think about working out what levels of salt you should ?try and add to a drink (especially useful in very hot conditions). Sports drinks aren’t actually packed with salt but these ?low levels still provide a significant role ?in effective hydration.
Drink aware
The key in all of this is don’t go mad, be it loading with salt or even water. You may have seen stories about athletes dying because they drank too much water in a race. This has occurred, but like so many things, it’s the press that have created this alarm. ?It can happen, and forcing down several litres in a short space of time when dehydrated can create problems… as, of course, will not drinking anything!
So remember: controlled drinking will pay dividends. If you hydrate sensibly, your body will thank you with a faster time! 
Time for a drink?
Experience any of these symptoms and you’re ?in the realms of dehydration…
Dry mouth, loss of appetite, thirst, head rushes and dizziness, and mental fatigue.
Elevated heart rate, resulting in a reduction ?of oxygen being carried to the muscles.
Your body temperature rises faster during exercise when the body is dehydrated, meaning critical temperature can be reached far more quickly.
Increased sweating, skin flushing (otherwise known as ‘hot flushes’). Those who ?sweat a lot during exercise are at increased risk of dehydration. Weigh yourself before and after exercise to determine sweat loss.
Fatigue due to increased rate of muscle glycogen use. A runner capable of running 10km in 35mins when normally hydrated will slow by 2:48mins (8% of normal time) when dehydrated by 4% of body weight.
Special Issue 2009
Jargon Buster
Electrolyte drink
Contains sodium and potassium to help your body hydrate more effectively. Your sweat?contains a variety of electrolytes.
Required to regulate your body’s functions. Can be lost in sweat.
An essential mineral for the human body. It plays a vital role in nerve and muscle function, the absorption of major nutrients and maintaining water levels.
As triathletes, we appreciate accessiblity on the move so, with that in mind, consider these for your hydration requirements…
Nathan X Trainer Mutation £29.50
This waistpack design has proved extremely popular with marathon runners. It offers easy access to your bottle and doesn’t bounce too much. It’s light and offers good storage potential (
Drinking ?on the fly
Camelback Slipstream £35.99
This design is difficult to fault as it fits snugly on your back and doesn’t really move. But, in reality, we feel it’s more for long-distance endurance events and adventure races rather than shorter, ?pacier efforts (
Hilly hand-held bottles £3.99
These traditional hand-held bottles do exactly what they say on the tin. Hilly make a great range of accessories, specialising in producing easy-to-use products for runners. Great for regular training runs and half marathons (
Paul Larkins is a former 1,500m international athlete. He’s raced the Ironman 70.3 Worlds and has edited Running Fitness