Let's Talk About Sweat
Institute Performance Dietician, Jenna Moore, RD
We are in the midst of one of Colorado's hottest summers on record - you may have just gotten done with your Total Body Conditioning Class feeling more like you just got out of the shower. All of that perspiration is a great reason to talk about hydration - how much fluid do you really need during the day? Are you considering factors like weight and activity? What about fruits and vegetables, does watermelon count toward hydration?
Water is the foundation for all of the reactions happening inside of your body. At it's foundation, water is a source of oxygen that is carried through your blood to deliver it to your muscles. Water also happens to be one of the main ingredients for the creation of energy in your body, especially when you can't breathe in enough oxygen to power you through your workout.
Now let’s talk hypothetically about what happens when you don’t hydrate well. If you don’t drink enough water, there is not enough water in your blood, meaning your heart has to pump even harder during a workout just to deliver what little oxygen is there to the muscles! Research shows dehydration impairs performance outcomes. Not only does water deliver oxygen to the muscle, but it also acts as a carrier to transfer out heat created inside your body during a workout. If you overheat and can’t cool off, your heart takes the largest hit.
How much water should I be drinking?
The Institute of Medicine gives broad recommendations at 91 ounces of fluid for women and 125 ounces for men. The Recommended Daily Amount for fluid is a bit more specific: it is anywhere from 1-1.5 milliliters fluid per day for each calorie that you burn. If this seems overwhelming, here is the translation: on a rest day where you are not sweating much, 1 ounce of fluid per kilogram (your weight in pounds divided by 2.2) of body weight should keep you hydrated. This is a great baseline of overall fluid for each day. Fluid comes in many forms- meaning that the fluid in fruits and vegetables does count - so enjoy that watermelon for hydration!
What about when you are sweating? Your fluid needs on workout days can vary greatly compared to every other day or time. Some adults sweat as little as 0.5 liters per hour and others can sweat as much as 4 liters per hour. With all of this variability, you will want to understand your own needs, especially if you are a serious athlete, talk with your favorite trainer or nutritionist to find out what sweat-rate test options are best to help you monitor your specific hydration needs.