One of the first pieces of advice given to novice runners is to drink more. But as most of us find, drinking gallons of water every time we run is neither practical nor effective.
You have probably been told that you should always have a bottle of water on you at all times and should be sipping regularly when you exercise to avoid dehydration, which will not only damage your health but impede your performance. To an extent, this is sound advice. Getting hydration right is essential for comfortable, safe running.
The often-quoted fact that even a tiny drop in hydration, just one or two percent of your body weight leads to a much greater drop in performance is also true. However, drinking as much as you can, as often as you can is not necessarily the answer. During an hour of running you might lose up to 2 liters of fluid, but your body is incapable of replacing that amount over the same time period.
Effectively Monitor Your Hydration
Instead of thinking about hydration in terms of filling up with liquid before and after a run, think about staying well hydrated generally. It is easy to monitor your hydration using one of these simple methods:
- Weigh yourself (naked). Do this before and straight after a run. Every kilogram lost equates to one liter of fluid.
- Monitor the color of your urine. It should be very pale yellow (almost clear) most of the time. If it is very dark, you are dehydrated.
- Pay attention to your thirst. The old wisdom of drinking before you are thirsty is overly cautious, but it is certainly true that as soon as you feel thirsty your body is telling you to take in some fluid.
Although some level of dehydration is inevitable after a long run or race, it should not severely hamper your session. In fact, studies have shown that elite athletes regularly perform at modest levels of dehydration, and may even benefit from being slightly lighter as a result of carrying less water. However, it is important to be aware of the symptoms of severe dehydration, particularly if you are running in very hot or humid conditions, as in extreme cases this can be fatal. Signs to watch out for include, severe thirst, headache, lack of sweating, and confusion.
Beware of Drinking Too Much
While dehydration is still one of the biggest problems facing runners, particularly over longer distances, drinking too much water can be just as dangerous. Your body needs a certain level of sodium to function properly, and filling up with plain water without losing it through sweat or urine can lead to a condition called hyponatremia, which means lack of sodium but is often known as water poisoning or over—hydration. This condition is increasingly common in larger mass races, where runners are slower and more likely to be overly conscientious about taking on water. The slower you run, the less fluid you lose through sweat, and the more opportunity there is to take a drink. Taking ibuprofen or aspirin will increase a runner’s risk of developing hyponatremia. The symptoms are very similar to dehydration, headaches, nausea and confusion usually develop, along with bloating. Many runners are rightly very reluctant to reduce the volume of ﬂuid they drink, as it can be difficult to judge how little is too little, so the simplest way to avoid hyponatremia is to drink sports drinks instead of water. These drinks contain electrolytes which replace those lost through sweat and they maintain your sodium levels. They also have the added benefit of containing carbohydrates, which will improve your running performance and fight off fatigue.
Generally speaking, any ﬂuid can be used to stay hydrated, but some are more beneficial than others, and some have side effects.
What is Good
- Plain water: for runs up to one hour’s duration, if required.
- Sports drinks: for long runs over one hour. Diluted fruit juice: for long runs.
- Coffee or cola: just before hard or fast sessions, to increase alertness and speed.
What is Bad
- Fizzy drinks: the gas in carbonated drinks makes them hard to take on the run, so many runners can’t take on enough liquid to stay hydrated.
- Thick drinks: some smoothies and shakes contain food that needs to be digested, so are absorbed slowly into the body.
- Alcoholic drinks: any drink which contains more than 4 per cent alcohol speeds up the body’s urine production, causing dehydration.
Exactly How Much to Drink?
You will need to use trial and error to a certain extent to find a comfortable and beneficial amount of fluid for your training, but here are some good general hydration rules to follow:
- Drink 500ml of fluid during the two hours directly before your run
- Aim to drink 2-3 liters each day (depending on your size and exercise level)
- Drink little and often rather than large volumes at once
- For every kilogram of body weight which is lost during a run, drink approximately 1.5 liters of water
- On short runs (up to one hour) there is no need to drink during exercise