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How much fluid should you drink when cycling?


Oct 9, 2021

Emma Cole 8 Oct 2021

Hydration is important even in the winter months and it all comes down to the individual cyclist

The importance of hydration is most typically associated with summer, since that's when the body sweats most to control its core temperature, but keeping an eye on hydration throughout the year is paramount, whatever the weather.

Staying hydrated may seem like common sense but a study on over 400 athletes found that 31% of them turned up to training sessions or competitions dehydrated, which had a negative impact on performance.

Why is hydration important for cyclists?

Hydration is a key element of any cyclist's training, and one which plays a crucial role in overall performance and recovery.

When you exercise, you lose water, sodium and calories in the form of carbohydrate and glycogen which can lead to dehydration and an electrolyte imbalance.

‘Hydration requirements are driven by sweat losses, which are usually increased in summer because of the hotter weather,’ explains Andy Blow, sports scientist and founder of Precision Hydration.

‘When it’s cold, it is easier to lose excess heat, but this doesn’t mean you don’t sweat at all and it is also worth bearing in mind how hard you are working, as intensity is a major factor in sweat loss.

‘Cyclists can overlook hydration in winter as it’s not seen to be as critical compared to in summer but small things such as overdressing for a ride can mean a cyclist sweats heavily’.

Pre-ride hydration: ‘preloading’

After a long day at work, many of us might be dehydrated so starting off a heavy session by preloading with hydrating fluids can be beneficial.

‘Before a long, hard session, a lot of athletes will preload by drinking 500ml of a very strong electrolyte drink which tend to be about three times the strength of a normal one,’ says Blow.

‘The sodium in the drink pulls into the blood stream and increases blood volume, helping an athlete retain and hold onto liquid a lot better.’

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Hydration during a ride

Over the cooler months, when those wintery rain clouds roll in, the temptation to get off the bike and move indoors increases.

When training indoors, riders can sweat huge amounts as there isn’t the same airflow as outdoors especially during a two-hour Zwift session, which amplifies the importance of keeping on top of your fluid intake.

‘If you are doing a higher volume of indoor training, which can lead to serious sweat loss, you are going to need to replace a reasonable proportion of this’, explains Blow.

‘For some riders who are big sweaters, for a 90 minute or two-hour session they will need to drink between 2 to 3 litres of fluid.’

According to Blow, indoor training can be fantastic opportunity to learn more about sweat output and sweat loss.

‘A rider could weigh themselves before and after training, take out how much fluid they drank, and the difference will show how much sweat they have lost.

‘Repeating this exercise over a few sessions will give a clearer picture of how much a rider is losing and how much they should be replacing.

‘If hydration is right, it can be a good sign seeing your heart rate more stable during an indoor session.’

For a short, easy ride, indoors or outdoors, Blow recommends just drinking water, but for rides over an hour riders may benefit from an electrolyte replacement or an isotonic drink for a race or a hard interval session.

Post-ride hydration

The importance of hydration doesn’t peter out once a ride finishes.

Drinking fluids after exercising can help regulate the body’s temperature and helps make up for fluid loss.

According to Blow, depending on how hard the ride has been it could be beneficial to pace rehydration out over a few hours post-session.

Using a urine colour chart can be a good indicator of hydration levels however he adds that there isn’t a simple and linear relationship between actual hydration status and the colour of urine as there are many factors which can affect urine colour.

Can a cyclist drink too much?

Drinking too much water can lead to hyponatremia, when the sodium level in the blood is diluted to below normal, which can undermine performance and in worse cases, lead to serious illness.

Symptoms include nausea, cramps and headaches.

‘Drinking too much water is more common than anything else as an athlete can become paranoid about not drinking enough, and then they run the risk of hyponatremia,’ explains Blow.

‘Another issue could be taking too many electrolyte capsules as this can lead to nausea and diarrhoea, but you would have to take a lot in order to give yourself a major problem.’

Bradley Wiggins drinking champagne after winning the 2012 Tour de France

Bottom line: It’s all about the individual cyclist

There is no one-size-fits-all hydration strategy. In reality, there is a huge variability between athletes.

Some cyclists in the pro peloton will only drink 200-300ml an hour on cold days, whilst in stage races during the summer some athletes drink 1.5 litres an hour, but the range is everywhere in between, according to Blow.

‘The two factors, how much and what you need to drink, are extremely variable between riders,’ explains Blow.

‘Ultimately figuring out what works for you is the most important thing and not getting too caught up on what other people do.’

Precision Hydration offer a free online sweat test and have sweat testing locations all around the UK.


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