How much should I drink while cycling?

Understanding how much you should drink while cycling may be more complicated than you think
20/05/2020

The answer to the question ‘how much should I drink?’ isn’t as straightforward as many riders would like it to be.

While hydration isn’t necessarily a complex topic, there’s a tendency to oversimplify hydration for exercise in one of two ways:

  1. By setting yourself targets - i.e. replacing an arbitrary percentage of your estimated fluid losses or by drinking ‘X’ millilitres per hour.
  2. Or by ignoring any type of planning and relying solely on ‘drinking to thirst’.

While these approaches have merit for some athletes, they shouldn’t be treated as binary options.

You don’t have to choose between ‘drinking rigidly to a plan’ or ‘drinking entirely to thirst’.

In most cases, there’s a middle ground, and that’s where the guys at Precision Hydration like to reside. We teamed up with Precision Hydration for a deep dive into how much you should be drinking while you ride.

1. Measure your sweat rate

When trying to understand how much you should be aiming to drink, it can be useful to start by looking at how much fluid you lose when sweating.

Conducting some simple sweat rate testing can help you get a handle on your sweat losses. Precision Hydration has created a guide on how to measure your sweat rate to improve your hydration strategy.

Unlike sweat sodium concentration (i.e. how salty your sweat is) - which is relatively consistent because it is largely genetically determined - an individual’s sweat rate is much more variable, as it’s affected by environmental conditions, intensity, and many other factors.

Measuring your sweat rate gives you an estimate of how much fluid you lose during a certain period of time, at a certain intensity of exercise, and in particular environmental conditions.

Repeating the process under different conditions will provide you with a catalogue of data to consult and learn from.

2. Why you shouldn’t aim for 100%, ‘like for like’ fluid replacement

Once you’ve measured your sweat rate, there’s a temptation to think: ‘Right, so that’s what I gotta put back in’.

Instead, when getting an understanding of your fluid losses and putting your hydration strategy in place, one of the most important factors to bear in mind is that aiming for a 100%, ‘like for like’ replacement isn’t something which is necessary or advisable.

There are several confounding factors which make the 100% ‘like for like’ approach impractical:

  • The fact that different athletes can tolerate different levels of dehydration
  • The rate of sweat and sodium loss can outpace your gut’s absorption rate
  • Your pre-exercise hydration status and the availability of drinks before, during and after exercise
  • Whether you are hydrating to get through the current session, or setting yourself up for another bout of exercise later that day or the next day.

Striving for a 100% fluid replacement also makes you susceptible to hyponatremia, which in extreme cases, can be fatal.

3. A flexible hydration strategy

The most successful athletes Precision Hydration has worked with have a basic framework for their hydration strategy, which they’ve perfected through training and competition. However, this framework is flexible enough to allow them to make adjustments on the fly.

This ‘best of both worlds’ approach is very common amongst elite performers because they tend to be in tune with their bodies and can rely more heavily on their instincts and experience.

Becoming more reliant on your instincts over time will allow you to use your intuition to guide your fluid intake.

Less experienced athletes, or athletes who struggle with remembering to drink, may benefit from a pre-planned approach, with some flexibility.

Some simple signs to look out for when it comes to over-drinking include feeling bloated or experiencing ‘sloshing’ in the stomach.

On the other hand, indicators that you may be under-hydrating are feelings of thirstiness, dry mouth or difficulty swallowing.

Conclusion

The answer to the question ‘how much should I drink?’, does not have a simple answer.

Sticking to the standard fluid intake guidelines (e.g. 500-750ml for runners and 750ml-1L for cyclists) may be oversimplifying a complicated issue. For example, a person’s size will play a big part in how much fluid they can tolerate, so recommending 500ml (16oz) across the board fails to consider individual differences.

While the guidelines are a good starting point, a personalised approach is always best.

In collaboration with Precision Hydration and Andy Blow.

Andy Blow founded Precision Hydration to help athletes solve their hydration issues. He has a degree in Sport and Exercise Science and was once the Team Sports Scientist for Benetton and Renault F1 teams. He also has a few top 10 Ironman/70.3 finishes and an Xterra World Age Group title to his name.

To get some personalised hydration advice for your Haute Route training, take PH’s free online Sweat Test. Plus, use the code HAUTEROUTE to get 15% off electrolyte drinks that match how you sweat at precisionhydration.com.