Your Personal Hydration Needs: An Overview


Congratulations! You made it. You have survived another Iowa winter, or at least, like, 90% of it. It still might snow at the beginning of May, but we all can feel warmer temperatures lurking around the corner. It is only a matter of time before garage rides are a thing of the past and only a tiny spec in the future of “next season…”

Hold on. Sorry, I may have gotten a little carried away. Before we get too far ahead of ourselves, riding off into our magical 80-degree sunset, let’s chat about hydration. Although it may seem that hydration is more important to address when we are experiencing those 80-90 degree days, winter hydration is also a matter we must discuss. Luckily, we are in that confusing (and somewhat awkward) transition period where we don’t know if we should bust out the shorts or spare everyone the pain and agony of pale legs for a few more weeks. Fortunately the principles for maintaining hydration throughout the year are fairly consistent. Hydration is a pertinent topic that, as endurance athletes, we mistakenly overlook. We are all likely guilty of blaming a poor workout or race on a lack of fitness, fatigue, or other contributing factors, but did you ever stop and consider it could have been due to a lack of hydration?

A deficit of just 2% or more body weight during activity or competition is classified as dehydration. (For a 150# person, that would mean a 3# weight loss during a long workout or race. Have you ever finished a workout or race 3 pounds lighter than you were when you started? That, my friends, is dehydration.) A 3% deficit leads to significantly impaired aerobic performance. Dehydration can cause muscle cramps, nausea, headaches, dizziness, confusion, weakness, lack of balance, and can hinder your inability to concentrate. Dehydration causes your body temperature to raise, your heart to beat faster, more glycogen than fat to burn as fuel, and ultimately will make exercise seem harder than it would if you were sufficiently hydrated.

So how much fluid is necessary? As a general rule of thumb, I typically suggest taking your body weight divided by two and that number, in ounces, is the amount of fluid one should consume in one day. Of course, on long workout days that number should likely increase (keep reading, I’ll get to that). About 20% of one’s total fluid intake in a day may come from foods like fruits, vegetables, soups, or broth. Drinks like milk, coffee, soda, sports drinks and juice technically count towards your total, however, I would suggest a majority of your intake come from the good ole H20.

Water is essential for our body to function. In blood, water helps to transport glucose, oxygen, and fats to muscles and carries away things like lactic acid. Water absorbs heat from your muscles, dissipates it through sweat, and regulates body temperature. In urine, water eliminates metabolic waste products. The darker the urine, the more concentrated the wastes. Dark urine is bad, light urine is good. Got it? Good.

So what about hydration before, during, and after a workout?

Prior to exercise, the goal is to achieve water balance before you even begin your workout. It may take 8–12 hours to properly hydrate before a workout, depending on the intensity. If you hydrate with a drink containing sodium or eat a few salty snacks with your water or hydration of choice, your body may retain some fluid so it doesn’t go in one end and out the other. At the very least, shoot for 14-20 ounces of water within 2 hours of starting your workout.

For hydration during exercise, consume 6-12 ounces of water, or electrolyte drink, every 15-20 minutes as tolerated. For workouts lasting longer than 60 minutes, use a sports drink containing 6-8% carbohydrate concentration to help meet your fluid needs.

After exercise, for every pound of body weight lost, replace with 16–24 ounces of water or electrolyte beverage within 6 hours. If you choose to rehydrate with a sports drink or chocolate milk, then you can count the carbohydrate and/or protein towards your recovery nutrition needs. If you have found yourself severely dehydrated, it may take 24-48 hours to fully replenish fluid needs. Sip slowly and consistently to enhance fluid retention.

An individualized hydration strategy could be the difference maker in your race plan. Not only is the fluid itself important in the successful outcome of your performance, it also will enhance the absorption of any race fuel being used. For shorter races, being adequately hydrated before the race is just as important as it is for longer efforts. Contact me if you are interested in setting up your individualized plan.

Ellen Davis, RD, LD