2017 Sweat Rate and Fluid Intake at Unbound Gravel

Tomorrow is THE DAY!  The day where Graveleurs will inundate the sleepy cow town of Emporia Kansas to test their mettle against the flint rock and weather elements of central Kansas.  We’ve heard many a strategy when it comes to rider support but one thing we’re going to address is how much fluids a rider needs to persevere in the Flint Hills.

First, how much do you really sweat? In this 2015 study by Karlsen (above), sweat rate of athletes who are heat trained can eclipse 2.5L/ hour, while non heat trained athletes max out at 1.5L/ hour.  That’s a lot of sweat!  But how much is a liter or two liter container? The best answer is to show you an image that is ingrained in nearly every American’s mind.  The soda bottle…  
These two containers are 1 and 2 liters, respectively.  
Okay, so that’s how much you CAN sweat.  What about real sweat rates as expected on the road?  Well, that’s an issue of heat stress and the body’s adaptability to it.  It’s well established that the more heat trained you are, the more you sweat. That makes it imperative you drink, lots.  But to measure heat stress, you’ll need this hour by hour guide of the local weather…. Right here:

Based on this, it’s looking like the temperatures will be warm, but not hot after 9am with the humidity contributing significantly to the heat stress.  My conservative estimate is that, assuming sunny weather and a 12-hour finish, an Unbound Gravel athlete will need about 20 liters or about 5.25 gallons of fluid to replenish sweat throughout the day.  All the fluids should be a sports mix of some sort, depending on each individual’s tolerance and taste.  That’s a lot of fluids.  But how much, exactly?
Someone like Camelback makes 1.5L and 3L packs (14 and 7 total).
If water bottles are your choice, you’re looking at 28 of the 24oz water bottles or 34 of the 20oz water bottles on the day.
Okay so that’s it. Warm and muggy means more fluids are needed.  Good luck everyone!
Check out our recorded webinar on Racing and Training in the Heat. 
Check out some of our other articles on Gravel Riding and Racing. 

About the Author: Adam’s true talent comes with his ability to combine his vast experience with his knowledge of sport. He is indeed a student of science, sport, athletic performance, strategy, and tactics. He continuously educates himself by keeping up to date with current trends and methods in sport. Adam is able to incorporate these attributes to help his clients reach and exceed their goals whether they are a beginner or a seasoned professional. Learn more about Adam and Source Endurance here.