Tuesday, May 15, 2012

Dr. Hydration or How I Learned to Stop Worrying and Love Water & Electrolytes!

1 week to go!!!  By now you’ve tested your stomach and working on those love handles (click to check out my blog from 4/26).  Have you thought about your hydration plan?  Water, Electrolytes, Hponatremia, oh my!  It's a lot to review, but have no fear, your dietitian is here!
Salt, fluids, outside temperature, wind, humidity, clothing, and how hard you’re pushing all affect hydration needs.  Your body excretes water and salt in your sweat; you lose about 12 g salt in six hours of cycling at 86 degrees F and 30% relative humidity.  The rule of thumb is drink 8 oz of water every 15-20 minutes.

You can calculate your *Sweat Rate below to determine exactly how much water you should drink (see below). You can also CHECK YOUR URINE!  If your urine is clear and barely yellowish, then you’re keeping up with your fluids well.  If you’re urine is dark yellow, then drink more WATER!  If you don’t drink enough water and become dehydrated, your blood becomes thick, making it more difficult for your body to pump oxygen to you while you’re cycling. Remember, if you’re thirsty, then you’re already dehydrated!

In addition to fluids, sodium content in your body regulates your blood pressure and blood volume.   This is because sodium is one of four blood electrolytes that affects the function of our cells and organs.  Other blood electrolytes are potassium, bicarbonate, and chloride.   A serious and life-threatening condition called hyponatremia can result when your blood sodium level falls below normal.  Symptoms include headache, muscle cramps, weakness, disorientation, apathy and lethargy. Sweat is about 1000 mg sodium/quart; a typical sports drink has 440 mg sodium/quart.  You need more than just water and sports drinks during the century ride.

Remember, even if you feel dry, you are sweating!  Consider a granola bar has 75-160 mg sodium; a banana has 1-2 mg sodium (you want the banana for the potassium!).  Typical sports gels have 40 mg sodium per 1 oz packet (remember these require you to drink 15-20 ounces or about 1 water bottle of water with every packet to help you absorb all the carbs and electrolytes quickly).

4 Things to Remember

  1. Drink BEFORE you’re thirsty.  "Drink, Pee, no IV"
  2. Drink 8 oz of water every 15-20 minutes (you should go through more than 1 water bottle every hour).
  3. Eat a snack at EVERY pit stop and carry sports gel to get your sodium between pit stops.
  4. You’re riding 140 miles...don’t worry about the calories!

*What is my sweat rate?
Sweat Rates range from 0.75 - 2 Liters/hour, depending on outside temperature, humidity, pace, clothing, and individual heat acclimation.
Calculating Personal Estimate of Sweat Rate:

1) Weigh yourself immediately prior to a training ride.
2) Weigh yourself immediately following the end of the training ride.
3) Calculate the number of lbs. lost during the ride and multiply it by 16 oz.  (1 lb of weight loss = 16 oz of fluid.)
4) Add the number of ounces of fluid you drank during the ride.

5) Divide the total ounces by total number of hours you rode.  Remember, this is NOT true weight loss - just body fluid loss.

1) Alex weighed 150 lbs at the start of the 5 hour ride.
2) Alex weighed 145 lbs at the end of the ride.
3) 150 lbs - 145 lbs = 5 lbs lost during the ride; 5 lbs x 16 oz. = 80 oz.
4) 80 oz. + *120 oz. = 200 oz.  (*Alex drank 120 oz. during the ride)
5) 200 oz./5 hours = 40 oz/hour (or ~1.18 Liters/hour)
*Thus, Alex is loosing fluids at the rate of 40 oz. per hour.
So, when riding, Alex should plan on drinking 2 1/2 water bottles  (aka 40 oz) each hour.

150-145 = 5 lbs lost
5 lbs x 16 oz = 80
80 + 120 oz = 200 oz
200 oz / 5 hours = 40 oz/hour
Therefore, Alex should plan on drinking 2 ½ bottles of water every hour.

If you need someone this week, please email Sara at smcclean@MFeast.org or Elana at ekanter@mfeast.org

Good luck!

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