Hydration: Should you Trust Your Thirst?

Proper hydration during endurance events will not only improve your performance, it may also save your life!

Finding that just right balance between drinking enough but not too much does not have to be a complicated equation – just pay attention to your thirst. For many years we heard that thirst is a poor indicator to help regulate fluid intake but it turns out there was little research to back up this claim. Many runners took these guidelines to heart and drank up to the point of over-hydration which can lead to low levels of sodium in the blood. This condition called hyponatremia can be very serious and even fatal. It is more common in slower, less trained runners who may be on the race course for many more hours and also exposed to the mid-day heat that can cause even more sodium loss.

Because of these health risks and a renewed interest in the evidence behind hydration recommendations, the International Marathon Medical Directors Association (IMMDA) advises marathon runners to listen to their body and drink when thirsty. While running in the heat it may also be beneficial to drink sports drinks to replace sodium lost in sweat.

After 60 minutes of running, sport beverages are beneficial as they provide energy in the form of easily digested and absorbed carbohydrate.

So are you listening to your thirst? Often times we get distracted and out of touch with our internal cues. Even a 2% loss of weight (3 pounds in a 150 pound runner) from fluids can hinder your performance. Because of this many athletes determine in training their sweat rate in order to know how much they need to drink each hour and divide that up every 15 minutes. Small frequent sips tend to be tolerated better than less frequent gulps of fluids.

The bottom line is: everyone is different so practice hydration in training to find the balance that is right for you!

Jacque Maldonado, MS, RD, CDE

Jacque has a B.S. and M.S. in Nutrition and is an avid endurance athlete having finished several full Ironman® Triathlons and over 25 marathons including qualifying for Boston. She is also a USA Triathlon coach Level 1.