Hydrating right is not just vital for your health, it’s also important for performance. But there are tons of myths about hydration, and about how and what you need to drink in order to stay fully hydrated.
Hydration status is best thought of as the level of water in your body. This can be estimated using equipment that measures the electrical conduction (or ‘bio-impedance’) of a small current. You can even get bathroom scales that use this technology for under £50.
But probably the simplest hydration indicator is urine colour. Clear and copious is the goal! However, vitamin supplemented bars, gels and antioxidant supplements can cause dark urine, so be warned. Vitamins B and C can turn urine yellow at even small doses but this does not necessarily mean you are dehydrated.
Obey your thirst
One of the major fallacies about fluid consumption is that you can teach yourself to survive without water. This probably stems from sports where fluid was restricted in order to minimise body weight, such as boxing and bodybuilding. Many old-school riders and coaches used to advocate this as a way to make riders harder and learn to survive without liquids. While it will make sessions harder and the rider (hopefully) mentally stronger, this is simply dangerous.
Fail to sweat effectively and your core temperature can start to rise, leading to complications such as heat stroke. So if you’re thirsty, drink. As a general rule, the larger the rider and the faster the speed, the greater the sweat rate, but in fit or larger individuals it is likely to exceed one litre per hour.
You need to drink, even when it’s cold
In the summer good hydration is particularly important because of the heat and faster riding speeds, meaning more and quicker heat build-up, but thinking about your hydration should not be confined to the hot months: exertion will lead to sweating, regardless of the ambient temperature.
Drinking to offset the loss of fluid and help cool your body’s core is vital. Yes, you can survive an hour without drinking but several hours’ sweating, gaining internal heat, with blood that is getting thicker and less effective, is a recipe for disaster. It is important for riders of all levels and abilities to see fluid replacement as part of riding and to learn how much they need to offset thirst and maintain energy levels.
Can’t drink? Make up for it afterwards
There will always be times when you can’t drink as much as you’d like and have to deviate from your normal drinking plan – whether because of the terrain, speed of riding or you’ve simply run out of liquids. You are likely to lose between one and two kilograms of bodyweight in average UK temperatures in a 25-mile time trial – but you will be able to complete it, just as marathon runners can run for more than two hours over a similar distance without drink.
Instead of worrying that you might be dehydrated, attend to your fluid replacement as soon as you can after the event. Your immediate post-ride hydration should constitute 150 per cent of the missed fluid intake. If you usually drink 600ml in an hour, then you’ll need to take in 900ml of a sports drink with electrolytes after riding. These are best absorbed after being chilled in the fridge.
You can improve on nature
Water. What could be better than pure, natural water? One of the biggest myths about fluid intake is that you can’t beat water for hydration; it’s not true, you most certainly can. Sports drinks and soluble tablets work better at maintaining hydration during rides and rehydrating you after, as the added electrolytes – sodium chloride, potassium, magnesium, and calcium – help your body maintain its optimum hydration status. Research shows that you absorb 35 percent more water, and rehydrate better, when consuming a 4:1 ratio carbohydrate and protein drink, than if you drink just water alone.
If ‘recovery-type’ drinks are too rich or expensive for you, down a bottle of your fluid replacement drink as soon as you get off your bike – you’ll still absorb three-quarters of what you drink.
What’s your sweat rate?
In order to get your hydration right, you need to calculate your own sweat rate. Start by weighing yourself without clothes on before riding for one hour. After the hour of exercise, return home, strip down and weigh yourself again. Assuming you did not use the toilet or consume any fluids during the ride, your weight loss is your sweat rate. For each kilogram of lost weight, you lost one litre of fluid, and this is the amount of fluid you need to replace per hour. For hotter or harder rides multiply by a factor of 1.2 to 1.6.
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