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Hydrate! or Suffer the Consequences

December 09, 2017

Hydrate! or Suffer the Consequences

by Mike Wood, CSN

Close your eyes and imagine the worst muscle cramp you’ve ever had. Pain shoots through your muscles like a lightning bolt and completely paralyzes you.

It’s a common experience.

I hear stories all the time of athletes getting awful muscle cramps while competing at obstacle course racing. The sad thing is most of these instances could have been easily prevented with some proper training.

Do you know what all athletes who cramp up have in common?

Low sodium levels in their blood caused by dehydration.

We’ll get into how to prevent cramps and stay properly hydrated in a bit. But before we do, let’s talk about the math and science behind hydration. Keep reading. I promise I’ll make this interesting.

The definition of dehydration is a loss of 2% of your body weight as water. The average human burns through 2.25 liters of water per day, about 4.96lbs. In order for a 180lbs person to become dehydrated, they’d only need to lose 3.6lbs/ 1.5L of water.

Think about how much water you’ve had today. Enough?

By the way, there are 33 ounces in a liter. So start refilling those 16oz Dasani bottles.

2.25 liters is just the baseline for water burn. For obstacle course racers and other really active people, the need for water is even greater because your body burns another 1-2L per hour while exercising. If you’re not properly hydrated and not replacing what you lose while exercising, you’re destined for some muscle cramps.

To illustrate how vital proper hydration is, let’s take a look at a breakdown of body weight lost through dehydration over time for a 180lbs athlete during a 5 hour obstacle course race. In the first graph, you can see how quickly the athlete reaches a level of dehydration when only consuming 1L of water per hour during the race:

Dehydration when drinking

1L/hr of water  

As you can see, the athlete reaches dehydration (illustrated by the red dotted line which represents 2% of body weight) after less than 2 hours of activity.

Now let’s look at how our athlete fares when hydrating with 1.5L of water per hour:

Dehydration when drinking

1.5L/hr of water

TL:DR- Hydrating properly during exercise can significantly extend an athlete's ability to perform at optimum levels for over twice as long.

But the real question is,

How much water should you drink in the week leading up to the race?

The simplest way to figure this out is to divide your bodyweight in half.

If you weigh 180 pounds, then you should be drinking 90 ounces (2.72 liters) of water per day.

If you don’t want to measure 2.72 liters, your urine can tell you if you’re properly hydrated. (Sorry to get graphic on you, but it’s for your own good!) If your urine is clear or very pale yellow, you’re good to go. If it’s yellow or dark yellow, grab a glass, fill it up, slam it and repeat.

Lastly, I wouldn’t do my Certified Sports Nutritionist designation justice if I didn’t warn you about diuretics and hypertonic drinks.

Let’s start with diuretics, which can cause dehydration even though you’re drinking. The most common things we drink with diuretic compounds in them are coffee and alcohol. I know it sucks, but lay off of both indulgences for at least a week before your next race. You’ll thank me at mile number six.

On to hypertonic. This is where the sugar content of what you are drinking is greater than that of your blood. This dehydrates you by drawing water out of your blood and into your gut through the process of osmosis. Watch out for sports drinks because a lot of them are loaded with sugar. If you absolutely must have a sports drink, pick one that has 6g or less of sugar per 100g of fluid.

Drinking enough of the right fluids isn’t just about race day, and it isn’t always fun, but with the proper preparation you’ll still be running while those less prepared “competitors” are doubled-over with cramps.