Triathlon Hyrdration Facts and Advice

Triathlon hydration can be a complicated subject. This article by Kerry Sullivan covers many facts that make it easier to understand. Do you know how much your speed decreases as you dehydrate? How much water should you be drinking during a triathlon? Did you know you can drink too much water? Read

Triathlon Hyrdration Facts and Advice

Curious how important triathlon hydration is? How about how much you should actually be drinking during your triathlon? This article from the Rock Star Triathlete Academy will teach you everything you need to know about triathlon hydration. (Video below)

Consider the following  triathlon hydration facts:

  • Your cycling and running speed decreases about 2% for each 1% of body weight lost through dehydration.
  • By the time you feel thirsty, you can already be at 2% body weight loss.
  • A 3% weight loss indicates dehydration has occurred.
  • Loss of fluid during exercise varies, but averages about 34 ounces per hour (and can be 3x that much in hot and humid conditions!).
  • Hyponatremia, which is just as dangerous as dehydration, is a term used to describe “water intoxication” and can occur with excess water intake above 30oz of water an hour.
  • Acclimatised individuals who are used to training in hot climates or hot rooms can reduce fluid loss by up to 50%.

Based on these facts, it would pretty important to make sure your  triathlon hydration is properly planned. Here is how to do it:

  • Divide your weight in half to determine the ounces of water you should drink per day for adequate triathlon hydration. So a 160 pound triathlete would consume about 80 ounces of water, or 10 8 ounce servings. While some nutritionists will recommend drinking even more if you exercising, you need to remember that you’re also getting water from all the food you eat about 20% of your daily fluid intake is typically from food.
  • During exercise, your triathlon hydration goal should be to consume about 17-25 ounces per hour, or around 4-8 ounces every 15-20 minutes. A typical large water bottle is 20-25 ounces. During hot and long races such as Half-Ironman and Ironman, you can shoot for closer to 28-30 oz of water per hour although smaller individuals will need to take caution with this level of fluid intake.
  • Before a long exercise session, such as a multi-hour workout, race or trip to the gym, your goal should be to consume 17-25 ounces per hour for 2-3 hours leading up to event (but always taper off fluid consumption about 20 minutes before to eliminate “stomach sloshing”).
  • Over 30 ounces of fluid per hour can cause water dilution in the blood, which disrupts normal cellular metabolism and physiology, often with dangerous consequences, such as swelling around the brain. High-end intake above these values should only occur during exercise in hot and humid conditions.

There are a few other good  triathlon hydration tips you need to take into account:

  • To avoid taking in too much water, you can combine your triathlon hydration with doses of external water to control heat stress, such as squirting some cold water over your head, putting ice in your jersey or uniform, or using ice sponges.
  • For people who tend to sweat and cramp excessively, glycerol supplementation can help maximize water storage, but this is illegal in some events so use caution!
  • Cold water is absorbed more rapidly than warm water giving you a good excuse to use thermal water bottles and freeze them overnight.
  • Pay attention to your urine color “pale to light yellow is optimal. If you’re still peeing dark yellow a couple hours after an event or training session, continue to re-hydrate.
  • You can lose up to a pound in glycogen, fat and muscle tissue during a 3+ hour training session, so account for this when re-hydrating, or when weighing yourself after exercise to see how much you ¹ve lost.
  • Remember…you still evaporate water in cooler training environments, so if you’re training in cold weather,  triathlon hydration is still important!

No discussion of water would be complete without emphasizing that liquid compounds that are full of fructose, glucose or artificial colorings and sweeteners are not to be considered normal  triathlon hydration methods, and should only be consumed when completely necessary, such as during a multi-hour training session during which calories are necessary, or when no form of pure water is handy.

Finally, whenever possible in your triathlon hydration, choose clean, filtered water, and avoid heavy consumption of water from plastic bottled sources, especially those that have been exposed to heat.

Kerry Sullivan is a triathlon coach. To read more about Kerry click here.

Feature image from