The Hydration Equation


For those in the thick of training for a spring race, high mileage just got very real. Long training runs have likely amplified weaknesses, making inadequate preparation very apparent as the miles (and hours) tick by.  When fuel and hydration are running low and the finish is still miles away, or a fueling/hydration combination of choice has turned a happy stomach gone bad, imminent suffering can sideline anyone. To avoid future pitfalls, here are some hydration basics that will help determine what works best when building up mileage.

We all know that replenishing fluids is crucial, especially during high mileage training.  Water goes in, sweat comes out.  Inside your body, blood volume is decreasing, which means your heart is working harder to deliver oxygen to your muscles. So re-hydration is essential to keep up blood volume levels.  As you sweat you’re also losing chloride, potassium, and sodium.  These major electrolytes (salts and minerals that conduct electrical impulses in the body) keep muscles from cramping by maintaining normal fluid levels throughout the body.  Classic sports drinks like Gatorade were some of the first products created to replace minerals, and quench the thirst of a dehydrated athlete.

Max King models a new hydration vest at Outdoor Retailer. Photo courtesy of

Max King models a new hydration vest at Outdoor Retailer. Photo courtesy of

Fortunately, newer tabs and powders have been formulated for more efficient absorption into the bloodstream, allowing glucose to come into direct contact with muscles.  The difference between these new mineral supplements compared with older sports drinks are the obvious king-size dose of sugar (or lack of) and artificial colors. When mixed with water, these hydration products create an electrolyte cocktail that is flavorful but not too sweet. Some are lower in calories and require a runner to consume additional fuel, while others guarantee a “one-stop-shop” of sorts that replenishes electrolytes, calories, and hydration in a single serving, and can be consumed without any additional fuel over the course of 10+ hours.

Method of delivery is also an important factor in the hydration equation.  While the convenience of handheld bottles is ideal for quick refills at aid stations, carrying a bladder of water in a vest means extra storage for fuel and supplies at your fingertips (which are free, because you’re not holding a bottle). Everyone is different, which is why a significant trial and error period should be implemented early in training.  Treat a hydration system as your lifeline throughout training – make sure it works and that you’ve got a backup plan on race day (pin-size holes in an H2O bladder can turn into a steady stream down your back).  Your body will be happy, and your stomach will thank you.


About Author

Amy Clark is the Editor of UltraRunning Magazine. She began her career at a small advertising agency in Bend, Oregon, where she enjoyed the fast pace and creative environment. For over 15 years, lunch hour runs were a ritual. Amy also joined the board of the local running club, became a race director and finished her first ultra. She has completed over 35 marathons and ultras combined, and continues to run long distances while encouraging both kids and adults to ignite their own passion for running.

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