Triathletes in Wilmington, North Carolina are getting ready for an event ranked second in the nation and fifth in the world, the PPD Beach 2 Battleship full and half triathalon. In one day, athletes competing in the full triathalon will cover a distance of 140.6 miles. Going the distance will require endurance, training, perserverance and proper nutrition. 

I don’t have hard facts on this, but I would bet most athletes are paying far less attention to the nutritional aspects of preparation than any of the other factors.

So I feel it is my obligation to be the advocate for good nutrition as a means to improve performance. Right now I want to focus on hydration. My next blog will be about fueling for the event.

Athletes are familiar with mantras, perhaps Nike’s “Just do it” is one of the most recognized. I remember when the mantra for fluid intake was,

“Don’t wait until you’re thirsty to get a drink.”

Well the new manta is, “Let thirst be your guide.”

Does this sound contradictory to you?

The old mantra was aimed at avoiding hypohydration (an insufficient amount of water for proper physiological function) and it was not considered likely that someone could drink too much fluid (hyperhydration). Now we know better! The new mantra reflects the goal of hydration being euhydration normal hydration (eu=normal); a normal or adequate amount of water for proper physiological functioning. Not too little, not too much.

Drink to thirst is considered the optimum  strategy, but this varies from individual to individual. Some athletes’ requirements will be equal to the general fluid recommendations of 8 ounces every 15 to 20 minutes. But this could be too much for runners who don’t sweat that much.

How do you know how much you sweat? It is a simple calculation and it will give you a more accurate idea of how much fluid YOU should be replacing. For every pound lost as sweat, you need to drink 16 to 24 ounces of fluid.

This “How to Calculate Your Sweat Rate” is from Runner’s World:

1. Weigh yourself nude right before exercise. This is your pre-exercise weight.

2. Exercise for one hour keeping track of how much you drink (ounces) during exercise.

3. At completion of exercise, strip down, towel off any sweat and weigh yourself again.

4. Subtract your weight from your pre-exercise weight and convert to ounces (multiply by  16). Then add that number to the ounces of liquid you drank during exercise. (For example, if you lost a pound and drank 16 ounces of fluid, your total fluid loss is 32 ounces).

5. To determine how much you should be drinking every 15 minutes during exercise, divide your hourly fluid loss by 4. In the above example it would be 8 ounces.

6. This test only determines your sweat rate loss for the environmental conditions you exercised in on that day. You should retest on another day when conditions are different to see how sweat rate is affected.

Once you have determined how much you should drink, the other part of the puzzle is to determine what fluids you will use for hydration, i.e. water, sport drinks. Water is always my first choice for exercise of short duration (<1 hour). But extended exercise requires more than just fluid, electrolytes (particularly sodium) need to be replaced and fluids can be a convenient way to get necessary carbs for muscle fuel. For this reason, inclusion of sport drinks is recommended. The limiting factor will be your gut. Again, know your body. Most athletes cannot tolerate the amount of fluid they need from a sport drink alone and have to rely on a combination of both sport drinks and water.

Practice your hydration strategy while you train. Know which combinations of fluids you tolerate best and use this combination for competition. Follow your thirst, have a personal hydration strategy and just do it!