Basics of Hydration for Cycling
Drinking sensibly for performance, comfort and health
by Jon Sparks

Mar 23, 2007

Exploring the importance of hydration for recreational cycling as well as racing. Looking at reasons to drink sensibly, and what to drink.

Back in the 1960’s, it was common for riders in races like the Tour de France to stop off at roadside bars for a glass of wine or something stronger. This seems hardly believable now, but there were some marathon stages in those days and a more laid-back attitude prevailed, at least in the early part of a long hot day. The death of Tom Simpson in the ‘67 Tour is generally blamed on a cocktail of amphetamines and cognac (for more on this see his biography, in the Top Ten Cycling Books article).

Sports science hardly existed in those days. Today, there is much better understanding of proper nutrition and, specifically, proper hydration. This is vital for endurance racers, but should not be neglected by anyone setting out on longer rides - certainly if you will be riding for more than a couple of hours, even at a moderate pace, hydration is important.

Put it another way: de-hydration can have all sorts of unpleasant consequences. Cramp is the most obvious, and real heat exhaustion can follow, which can even be life-threatening. But dehydration can impair concentration or judgement, which could also be life-threatening on a tricky mountain bike trail or if you’re riding among traffic.

Low-level, sub-critical dehydration may have no obvious symptoms, but still makes riding less comfortable, less efficient and less pleasurable. If you tend to gulp down several glasses of water or soft drinks at the end of a ride, you’ve probably reached this point.

What to drink?

Plain water is good, up to a point: it’s certainly loads better than nothing. When exercising you lose fluid partly through breathing and partly through sweating. What you breathe out is mostly water vapour but sweat contains chemicals, often referred to as salts or electrolytes, which also need to be replaced. The more you sweat, the more important this becomes. This is where special electrolyte drinks come in; these are designed to match the chemical balance of what you lose.

Commercial soft drinks are usually loaded with sugar - something you don’t need so urgently for most rides - and generally do little to replenish electrolyte levels. Some - especially so-called ‘energy’ drinks - also contain caffeine. Caffeine is a diuretic (it makes you pee) and so doesn’t help hydration.

Dilute fruit juices are an economical and healthy choice. If it’s hot, you could add a little common salt. The operative phrase is ‘a little’. Remember that the total recommended daily intake of salt is just 6 grams (about 1 teaspoonful), though this is a guideline for sedentary people. Those who are taking a lot of exercise, particularly if they sweat heavily, can use more. But even so, the quantities needed are small, just a couple of milligrams per litre, so drinks should not taste obviously salty.

Alcohol also promotes dehydration - after all, that’s most of what a hangover is. Tea and coffee are not particularly helpful either as they are also diuretics. Coffee is probably worse than tea in this respect, though it’s hard to make comparisons as strengths vary and coffee is often drunk in smaller volumes.

This is not to say that you can’t have a ‘cuppa’ or even a beer at a stop during a ride: just think of it as extra to your basic hydration needs, not a replacement. During long rides, especially if it’s hot or you’re pushing yourself, it is certainly wise to avoid strong drinks or excessive consumption of coffee.

Further advice on hydration for recreational cycling as well as racing, focusing on when and how much to drink.
The importance of proper hydration - drinking enough, but drinking sensibly - has already been explored. This article takes a closer look at when to drink, how much to drink and also a couple of ways to judge if you are drinking enough.

When to drink?

Pre-hydrate: Make sure you’re well hydrated before the ride. Most people are chronically dehydrated because they simply don’t drink enough water. Keep a bottle on your desk and sip frequently all day. For an energy as well as fluid bonus, down 16 ounces of a sports drink about an hour before the ride.

One of the key points that is now understood is that you can begin to dehydrate before you feel thirsty. Rule One of hydration is: Drink before you think you need it. And, as with many things, little and often is usually the best way. When you feel thirsty, it’s already too late. Make it a habit to reach for your bottle every 15 minutes and slug down a couple of big swallows. The great advantage of modern hydration systems is that they make it easy and convenient to drink on the move and without upsetting your balance.

Practice Drinking On the Bike: If you aren’t comfortable taking one hand off the bar to pull the bottle from the cage, practice while riding in an empty parking lot or lightly traveled road with a wide shoulder. Hold the bar with your other hand near the stem to limit swerving as you reach down.

Hydrate After the Ride: No matter how much fluid you drink while riding, in hot weather you’ll finish the ride depleted. Your stomach doesn’t empty fast enough to keep up with the demand.

Weigh yourself before and after the ride. Compare the figures. If you’ve lost weight, drink 20 ounces of fluid for each pound of bodyweight you’re down. Keep drinking until your weight has returned to normal and your urine is pale and plentiful.

How much to drink?

How long is a piece of string? How much you need to drink is one of those questions. There is no precise answer; it depends on body mass, metabolic rate, how hard you are working, how hot and/or humid it is, how prone to sweating you are (and this can also be a function of your broader diet and hydration regime), and so on.

A figure that is often bandied about is one litre per hour. This sounds like a lot and as it’s often quoted by those who are trying to sell you a hydration product, you might view it with suspicion. It is probably a realistic figure for cyclists - and other athletes - in endurance competitions, but may be on the high side for those riding recreationally. On the other hand, if your idea of a recreational ride is one of Moab’s mountain bike trails in the desert heat, a litre an hour is probably a reasonable guide.

It is possible to drink too much, and become hyper-hydrated. This has been reported among endurance athletes taking their hydration to extremes, and can also be dangerous to health. It is unlikely that this will be a problem for recreational riders as few are going to want to carry excessive volumes of water.

Ways to tell if you are drinking enough include:

• Feeling thirsty. Yes, this is obvious, but you need to remember that you can be in early stages of dehydration before you have any sensation of thirst. A raging thirst after a ride is a sure sign of under-hydration. If the ride is only an hour or so then this is unlikely to be dangerous, but it’s still better to forestall it. Waking up with a ‘hangover’ the next morning is also a sign that you haven't taken on enough liquid during the ride.
  
• The ‘pee test’. If you feel the need to urinate at about the same interval when riding as you do when not exercising, you’re probably adequately hydrated. If the intervals get longer and longer, or the volume is reduced, you should up your fluid intake. And if what’s coming out is significantly darker in colour than normal, this is a real warning sign.
  
• Headache, dizziness, 'hungover' feeling. All are likely symptoms of dehydration.
  

How to drink.

You know how to drink; you've been doing it since you were born. This is really about how to carry the required voulme of fluid on the bike and the best way to get it to your mouth while riding. If you have to stop every time you want a drink, you almost certainly won't drink enough. Once upon a time it was just a bottle mounted on the bike frame; now there are all sorts of hydration systems, which really deserve an article to themselves (coming shortly).