Hydration for cyclists and the benefits of sports drinks

Water is life. And even more so during exercise. For the body to function properly during a bike ride, it may not be enough to fill the gaps. This is where exercise drinks come into play. Here are our recommendations for fluid consumption for cyclists.

By Jean-François Tatard – Photos: Frédéric Poirier, Pixabay.com, Kask

Your body contains a lot of water. Sure! But how much of this vital fluid is it exactly? And how is this water distributed in the human body? Why is it essential? How do its variations change when you ride?

Water represents on average 60% of body weight. It is the main constituent of the human body. It is essential for life. In fact, we cannot live more than a few days without water. In fact, it has many functions in the body: it is used in the production of cells and body fluids; and it plays a role as a reaction medium, solvent and reagent. It also carries nutrients and promotes the elimination of waste from the body through urine. It is essential for controlling body temperature through sweat evaporation. To function optimally, it is therefore not surprising that we need not to disturb this balance too much. Moreover, professional cycling teams take hydration very seriously and in stage races or during tough training blocks in stage, the staff weighs the runners daily. They also regularly check urine.

The risks of dehydration

Whether you are training, tackling a high-flying competition, let today be your D-Day or you're riding a multi-day epic, if you don't stay hydrated you will compromise your performance! Indeed, if you throw that 60% out of whack, you will significantly limit the benefits of your training. You will also take longer to recover. Performance will decline rapidly. In fact, studies have shown that surprisingly small amounts of fluid loss can significantly affect your ability to ride. It is said that a 2% loss of body weight due to sweating (1,6 kg for an 80 kg cyclist) will significantly reduce performance, 4% will reduce your muscular work capacity, and at 5%, heat exhaustion can become a problem and your work capacity will decline by up to 30%. Beyond 7%: you will start to experience hallucinations, and at 10%, circulatory collapse, heat stroke, and even death become possibilities.

Why this drop in performance?

The physiological reasons for performance losses due to dehydration are:

1. A reduction in blood volume
2. A decrease in skin blood flow
3. A decrease in sweating rate
4. A decrease in heat dissipation
5. An increase in body temperature 
6. An increase in the rate of muscle glycogen utilization
7. Decreased digestive function

How to monitor hydration?

Finally, it is quite simple to monitor hydration. Two easy techniques to implement. Weigh yourself daily and, especially if you're already quite lean, sudden, large weight drops probably suggest you should increase your fluid intake. You can also monitor the color of your urine.

Drinking daily 

Before considering what, when and how much to drink on the bike, make sure you stay well hydrated at all times, even off the bike! This means you need to maintain optimal hydration levels when you’re out riding. Monitor your hydration levels off the bike and aim to drink 2-3 litres of fluids per day, whether you’re riding or not. Fruit or vegetable juices, sports drinks and water all count towards this goal, but not soda-type drinks or drinks loaded with alcohol, tea, coffee and sugar.
If you monitor and keep control of your hydration on a day-to-day basis, it should not be necessary to drink excessively the day before or in the hours leading up to a bike ride. Drinking excessive amounts in a desperate attempt to catch up on hydration will only ensure early and frequent pee breaks. In the two hours before a long ride, training session or tough race, sip 500 to 750 ml of isotonic sports drink to ensure optimal hydration and fully stored energy reserves.

On the bike

The best way to get an estimate of how much fluid you need is to do a test 60 minute sweat session. After you have hydrated well during the day, weigh yourself naked and record your weight. Go out and ride at your normal sport or running intensity for 60 minutes and do not drink during the ride. As soon as you get home, undress, wipe any sweat from your skin and weigh yourself again. The difference between the two weights in grams will be your total fluid loss in milliliters.

Most cyclists will find that they will typically lose 500-1000ml per hour.

Obviously, results will vary depending on weather conditions and the intensity you put into your ride and you may want to do several tests to get a wider range. But it will still give you a good idea. Most cyclists will find that they will typically lose 500-1000ml per hour. And especially if you are at the higher end of this range, it may not be practical or necessary to try to replace it all, but you should aim for a minimum of 75%.

How and what to drink on the bike

The key word is " don't wait until you're thirsty to drink". Drink little and often, and early in your ride. Aim to take 2-3 sips from your bottle every 10-15 minutes. Also, don’t forget your recovery drink at the end of your ride. No matter how careful you’ve been with your hydration, especially on a hot day, you’re likely to become dehydrated, and in addition to providing the protein and carbohydrates to kick-start your recovery, the fluids and electrolytes provided by a recovery drink are essential.

For outings of less than 60 minutes, plain water is fine., but for longer rides I recommend adding electrolytes and carbohydrates. Why? Plain water won't provide you with any energy, it can make you feel a bit bloated, and it will reduce your desire to drink before fluid losses have been replaced.

Electrolytes and Carbohydrates 

Electrolytes are salts that include: sodium, potassium, calcium, and magnesium. They are lost in sweat. They are essential for normal cellular function and must be replaced. Most commercially available sports drinks have a good balance of electrolytes and, if you don't want to drink to gain calories, carbohydrate-free effervescent electrolyte tablets are also available.

Remember that for a long ride you will want to aim for 0,5-1g of carbohydrate per kilogram of body weight per hour and you should also try to spread out more than 2-3 micro-foods every 20-30 minutes. 500ml of sports drink will give you about 36g of carbohydrates, which for an 80kg cyclist requiring 40-80g per hour is a decent and easy proportion to assume in proportion to this energy requirement.The composition of sports drinks

Most sports drinks contain a mixture of simple sugars, such as glucose, fructose and sucrose, which release their energy quickly and also more complex carbohydrate polymers such as maltodextrin that provide longer term energy. Like all sports drinks, they contain slightly different ingredients, so it is important that you try them during training to find one that works well for racing or cycling. Don't get too gambler! TestWash the products well before D-Day ! Beware: there is more than one who has already ruined his performance by venturing to try his new drink on race day.

Osmotic concentration

In the somewhat barbaric names: Have you ever heard of osmolarity? This is a measurement! The measurement of the number of molecules dissolved in a solution, including electrolytes and carbohydrates. Blood typically has an osmolarity of about 300 mOsm/kg and so a solution with a similar osmolarity is said to be isotonic, iso meaning the same. If the osmolarity is higher it is hypertonic and lower it is hypotonic.

• Isotonic drinks 

It is more relevant to use isotonic drinks for endurance sports, because they are formulated with a perfect balance of fluid replacement, carbohydrate and electrolyte supply, and thirst stimulation. If you follow the mixing instructions on most sports drinks, the 6-8% solution will usually be isotonic.

• Hypotonic drinks

Ordinary water for example is hypotonic. It will replace lost fluids very quickly but will not provide energy or important electrolytes. Also, as mentioned earlier, hypotonic drinks will often reduce your desire to drink more before you have replaced adequate fluids and will make you feel bloated.

• Hypertonic drinks

These are carbohydrate-loaded solutions that can be used for higher caloric intakes.. Many long distance triathletes will have a bottle loaded with an extremely strong carbohydrate solution and will use this in conjunction with plain water in their other bottle for example. Also great for low intensity winter rides where you won't be sweating much, stronger carbohydrate solutions can be experimented with. However, they will leave your stomach quite slowly and as they can also cause gastric upset they should be tried carefully in training first.

The consequences of drinking too much fluid

Out of fear of running out or failing, you may sometimes drink too much water, and if you don't also take adequate electrolytes alongside it, you will dilute and affect your body's fluid balance. This can lead to a feeling of bloating, decreased performance, and in extreme cases hyponatremia or even death. This is no joke! We have seen this in recent years at major marathons where runners, alerted by fairly constant external reminders about the importance of staying hydrated, have over-drank before the event and chugged plain water at every aid station.

And remember, in addition to replacing lost fluid, you also need to replace lost electrolytes.

The cramp 

Many cyclists who experience cramps during a race or even during training immediately make the connection to poor hydration and a lack of electrolyte intake. Yet recent studies have indicated that this is not always the case. For such a common occurrence, you might be surprised to know that the exact reason for cramps is still unknown.

Many people blame inadequate hydration or electrolyte levels and while some studies have shown that drinking a 6% carbohydrate sports drink can help prevent them, other studies have failed to confirm this. Recent work with triathletes in Ironman races has found no link. Some studies of people with long-term cramps have shown that magnesium supplementation is already more helpful. Another factor is a sudden increase in exercise intensity.

So if you suddenly ride harder or longer than usual, you can expect cramps. However, exercise intensity cannot be the only factor as it does not explain nighttime cramps for example. Anecdotal evidence suggests that stretching can help relieve cramps and that regular stretching can help prevent cramps in muscles that are prone to them or have already been injured. If you regularly suffer from cramps while riding, we suggest an approach that covers all the bases:

1. Relax a little on your pace and distance. You're overdoing it. 
2. Check your power, threshold or heart rate,
3. Find your training zones and ride strictly within those ranges
4. If you are going out for a long ride, this should mean that you will stay in the endurance zone for the majority of the time. 
5. Do not suddenly increase time, distance or intensity.
6. Follow a structured training plan that builds progressively.
7. Continuously drink fluids containing electrolytes throughout your ride. Even in cooler conditions, aim to drink 500 to 750 ml per hour.
8. At the same time, remember to eat foods rich in magnesium and calcium and, if necessary, consider magnesium supplementation.

To conclude

Whether you are a professional cyclist or an amateur runner, hydration is a crucial factor that influences performance. In the end, drinking regularly and when you're thirsty is not a detail. It's a point that you absolutely must not neglect! Don't forget, however, that excess is just as harmful. So in the end, don't try to replace the exact amount of water that you've lost, or even to try to compensate for more than you've lost. Just think about drinking, before, after and during exercise. Especially according to the needs that you feel and according to the level of effort that you're making... Come on, cheers!

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