Hydration for Runners and Triathletes


Hydration for runners and triathletes is extremely important during workouts and races. Whether it’s summer or winter, fluids & electrolytes are lost during exercise and must be replaced in order to stay healthy and to be able complete your workout.

What are electrolytes? They are sodium, potassium, magnesium, and calcium and can be found in most sports drink and sports supplements.  When choosing how you’ll hydrate, think about what is used on the race course; will you use the same products the race offers or will you carry your own?  Either way, you’ll want to use in training what you plan to use on race day.

 Hydration for Runners and Triathletes

Are You a Salty Sweater?

The tell-tale sign that you’re a salty sweater is that you always have a white, salty residue on your skin and clothes after a run or workout. If this describes you, it means you are at risk of an electrolyte imbalance and focusing on getting enough electrolytes when exercising is very important.

Daily Hydration

Your daily hydration is important so that you don’t go into a workout or race already dehydrated. Starting a workout dehydrated will put you into further hydration “debt”, which means you will not perform as well during your workout and it will take you longer to rehydrate and recover after your workout.

An easy way of monitoring your daily hydration is with the pee test:
Monitor the color of your urine the first time you urinate in the morning.  If the color is more like apple juice than lemonade, you’re likely dehydrated. (Note: some medications & vitamins can cause the color of urine to change)

More Isn’t Better

There is such a thing a drinking too much.  Hyponatremia occurs when blood sodium levels are too low. This can occur in long distance racing and training when an athlete drinks too much water without electrolytes.

Symptoms include:

• Gastrointestinal discomfort
• Nausea and vomiting
• Throbbing headache
• Restlessness
• Lethargy
• Confusion
• Respiratory distress
• Seizures
• Brainstem herniation
• Death

To avoid hyponatremia:

• Consume enough electrolytes during exercise
• Avoid over-drinking. Drink according to the general guidelines or your sweat rate
• Limit pre-hydrating with plain water. Include high salt foods or drinks before racing & training.
• Don’t over-drink after training or racing

Some Guidelines:

Practice your nutrition & hydration plan during training so that you are accustomed to it.  If you’re not accustomed to food and fluid ingestion, it could result in gastrointestinal distress during exercise.

Your amount and rate of fluid intake depends on your own tolerance and the intensity of your exercise. Remember that fluids should be consumed slowly rather than all at once.

Before Exercise:

• Consume beverages with sodium and/or sports nutrition products and sodium-containing foods to help to stimulate thirst and retain the consumed fluids.
• Hydrate 4 hours before: 5-7 ml/kg (1oz per 10lbs of body weight)
• Hydrate 2 hours before: 3-5 ml/kg
• Hydrate up to race: to thirst

During Exercise:

• Consume 500 – 700 mg sodium per Liter or 32 fl. oz. (sports drinks typically contain 500mg–700mg sodium). Salty sweaters up to 1,000mg/Liter (or 32 fl. oz)
• Hydrate based on your sweat loss (see instructions below)
• If you don’t know your sweat rate, a general recommendation is 3-8 oz every 15-20 min.

After Exercise:

• Consume foods and fluids that contain sodium to facilitate rehydration. This results in less urine production and improved hydration.
• Consume fluids within 3 hours of exercise.
• Rehydrate by drinking 16 to 24 fluid ounces of fluid for every pound lost.

Calculating Your Sweat Loss:

1. Void all urine, then weigh-in wearing little to no clothing, in order to obtain the most accurate reading.
2. Following the weigh-in, exercise for at least one hour while keeping track of the quantity of fluids you consume.
3. After exercise, towel off and step onto the scale again, making sure to wear exactly what was worn before.
4. Your weight before and after exercise, as well as the amount of fluid that was consumed during the exercise, will be used to determine your sweat rate.
5. Subtract the post-exercise weight from the pre-exercise weight in pounds, and convert the difference to ounces of fluid loss.
6. Then add to that number the amount of milliliters of fluid that were consumed during the exercise. This will determine how much sweat was lost during exercise.
7. Divide the sweat loss by the duration of the exercise to determine total fluid loss during exercise.

*It is best if no food, or semi-solid fueling products are consumed when checking sweat rate, and that you are hydrated (not dehydrated) prior to conducting the test.

*Temperature plays a role in sweat rate, so calculations should be done for both summer & winter.

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