Cycling Hydration

David’s Nutrition Question:

I read that I should drink 2 litres of water during a normal day and that I should drink 500 ml to 750 ml per hour if I am exercising. Is the 500 ml to 750 ml consumed during exercise extra to the 2 litre daily minimum? In other words if I am cycling for 4 hours and drink 500 ml per hour is that my 2 litre daily allowance met or do I need to still drink another 2 litres?

Kelli’s Answer:

Hi David,

Thanks so much for the question.  Short & sweet, the answer is “yes,” you need this Training fluid in addition to your daily 2 liter minimum.  The 2 liters per day stems from needing approximately 1 ml fluid per calorie consumed for optimal metabolism of foods.  So, a 2000 calorie diet = 2 liters.  If you need more calories than this (again, daily calories and not extra for training), you need more water.  Many athletes need 3000 calories per day, and therefore 3 liters water.  This is every bit as important to a cyclist as the Training fluid, as any chronic dehydration going into a ride will negatively affect performance, and there’s really no way to make it up during the ride since you’ll be actively losing more.  Then, for training, I recommend 500-1000 ml per hour – this largely depends on how much you sweat due to your climate, size, and genetics.  It’s fine to go with this estimate, or you can weigh yourself immediately before and after training to see how much you lose.  Every bit of loss is fluid.  I typically see the 500 ml loss in someone 150 lbs or less, in cool weather (humidity + temperature (F) =<140) at moderate intensity.  Anything more than this and you need more fluid.  Try to replenish your losses, as much as possible and at least 500 ml per hour, during any ride that is more than 60 minutes and make up for the difference immediately after.  For shorter rides, go into them hydrated and consume everything you lost immediately after (there’s not enough benefit during the ride to carry the weight of the fluid for these short rides).  For training fluid, it’s a good idea to consume fluids that also contain electrolytes – you’ll find all the reasons why in the free document “Hydration Report: Why not just water” @

Ride hydrated & strong!

Kelli, RD

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