Hydration for Runners

A personal view by Alan Pritchard. alanpritchard18@hotmail.com. 24th May 2020

When I was asked to contribute an article to Coaches Corner, after an initial moment of panic (I’ve never done an article as such before) I picked up on Dewi’s expression that he had enjoyed his research, so I thought I would research the answer to a question that I’ve certainly got wrong myself in the past, and that I’ve noticed a wide disparity between my running friends, and beginners and experienced runners.

The question is How much should I drink when running/racing? I had hoped that I might be able to find some science based numerical answers and guidelines, and although some numbers do exist it seems that different sources dispute the findings given. Having consulted several books on training, googled for BARR guidelines, NHS guidance, UK athletics, Healthline, Dr Phil Maffetone (the Heart rate Training GURU) amongst others, and asked some very experienced friends, including a very successful lady Ultra Runner, and another who has run every-day for more than 1000 days, and run marathons in Africa, I can offer the following personal guidance.


1) Pay attention to your hydration (fluid intake) generally but especially the day before and the day of a race. The best guide is the colour of your urine. There are colour charts available, but simply “clear is probably over hydrated, pale straw colour is good, Dark towards brown is dehydrated.” Other colours are possible normally due to diet. Beetroot can cause red/pink, some food dies also go straight through. If blood is present its probably best to seek medical advice.

2) Drink early on the day of a race but avoid drinking too much, one visit to race toilets is enough for most people!

3) For races up to an hour (possibly 90 minutes for some people) there should be no need to drink during the race.

4) For races over an hour, Individuals requirements are different, but generally the bigger you are the more you will need to drink, the best way to know how much you are likely to need is to practice in training under conditions as close as possible to race day. The best guidance figures I could find were a suggestion of between 300 and 800ml per hour, however there’s some strong guidance given to avoid drinking predetermined amounts as conditions vary so much. **

5) Repeated advice through the sources is to drink to thirst, however during races where you are probably reliant on drink stations, be aware where they are, and drink slightly ahead of thirst, even if it’s just to swill your mouth out. It’s better to drink little and often.

6) If using water to pour over your head to cool down, check first that it is water and not a sports drink or squash!!

7) If you’re working harder or the temperature is higher you will sweat more, so need to drink more, but thirst is still the best guide. (faster, hills etc)

8) Try to avoid drinking energy or isotonic drinks or use gels unless you have trialled the same brand in training. (a number of runners myself included seem to find caffeine gels upset their stomache remarkably quickly)

9) For longer events where you carry your own water/drinks, its best to have more than one source. With the backpacks you can’t tell how much you’ve drunk, so it’s good to use either the smaller soft bottles (many packs use 500ml containers) or carry a separate bottle to top up and avoid running out. Having a good idea of the minimum amount you have left means you know when to top up if you have the chance, without having to carry too much.

10) Post- race/run its important to rehydrate, drink plenty of fluid over the course of the next 24hrs, aim for straw coloured pee.


Some additional advice from my friend who has raced in Africa, (that’s sometimes relevant in the UK.)

11) Check if there are enough drinks stations en-route (especially if it’s a hot day) if not or you have concern that drinks may have run out by the time you get to a station, take your own with you.

12) In the heat adjust your race goals, it’s better to adjust your pace rather than struggle for hydration later on, also run in the shade if its available, it’s more important to keep cool than to gain a few seconds on a race line.


Further reading

** A few years ago the advice was to drink, drink and then drink some more, unfortunately this then lead to some deaths from Hyponatremia, particularly amongst women (apparently they are more likely to follow advice!) Over-drinking can also lead to underperformance from feeling uncomfortable, and or needing the toilet during a race. Your kidneys can only process 0.8 to 1.0 litre per hour, so drinking significantly more than this can be harmful (even fatal).

Further reading. (Please use your own judgement as to how much you trust these sources!)

The Runners Body By Ross Tucker PhD, and Jonathan Dugas PhD

Runners World Complete Guide to Running and Hydration. https://www.runnersworld.com/uk/nutrition/a761780/rws-complete-guide-to-hydration/

Dr Phil Maffetone https://philmaffetone.com/tag/hydration/

NHS. https://www.nhs.uk/live-well/eat-well/water-drinks-nutrition/

To my surprise several other sources don’t mention the subject at all as far as I could see..