Human bodies are composed of roughly 60-70% water, and water plays an essential role in nearly every bodily function. It helps regulate body temperature, excrete waste, moisten bodily tissues, protect organs, lubricate joints, and deliver nutrients to various bodily systems. This is why proper hydration is crucial to the smooth functioning of these processes.

Fluid is lost in a variety of ways during exercise. Sweat is the biggest contributor to this during exercise. Sweat helps cool the body by getting the skin wet and taking heat with it when it evaporates. However, you are also losing fluid via respiration and through normal bodily functions as well.

Environment is hugely influential too. As a consequence of hotter, more humid conditions, more sweat will be lost, whereas a cold environment will result in an increase in the amount of water lost through respiration.

So how much fluid do we need before, during or after exercise? The amount of fluid an individual needs depends on a number of factors, including sex, body size, and the propensity to sweat. There are other influential factors additionally to the environment such as clothing, physical fitness level, intensity and duration of the activity itself.

Without considering these factors, making a fluid recommendation can be challenging. There are, however, some general recommendations that can serve as a starting point. One common suggestion is to consume 0.5 to 1 fluid ounce per pound of body weight.

In the most basic sense, your urine color is a good indicator of hydration status. Urine does not need to be clear but should be light yellow. You should step up your hydration game if your urine is dark yellow or brownish.

What is Dehydration?

Dehydration can be extremely detrimental to performance. During exercise, dehydration and losing water reduces the amount of blood pumped by your heart to the rest of your body. It negatively impacts almost every aspect of performance, both physically and mentally when you dehydrate 2 percent of your body weight or more. Dehydration, in contrast to other nutrition habits, has almost immediate negative effects. 

Symptoms of dehydration include the following:

Increased thirst

Dry mouth and throat

Dark yellow or amber-colored urine

Muscle cramps

Fatigue and weakness

Dizziness or lightheadedness

Loss of appetite

Headache

Fluid Intake Timing

Similar to other nutrients, water also has some important considerations regarding timing around your workouts. Approaching hydration purposefully can help maximize training and promote good performance. The following recommendations will help you time your hydration before, during, and after training or competition.

Before the Workout

You should ultimately aim to be adequately hydrated when heading into training or competition. Sawka and colleagues (2007) recommend drinking 5 to 7 milliliters per kilogram of body weight at least four hours before exercise and, if needed, 3 to 5 milliliters per kilogram of body weight two hours before exercise. 

During the Workout

During training, it’s generally recommended to drink every 15 to 20 minutes, especially if it’s hot or humid. However, many athletes must rely on their coaches to provide breaks with that frequency. If your coach does not, you might consider talking to them about it. If they are still reluctant to give frequent breaks, or if the environment for any reason makes it hard to do so, make sure to maximize your intake at breaks you do get. If it is especially hot or humid or if breaks are limited you may not be able to afford to just sip water. Although you don’t want to chug fluid and upset your stomach, you can try to take gulps to ensure you’re getting enough.

Some other practical considerations can also be the temperature of the fluid: Most people enjoy colder fluids when it’s warm, but if it’s so cold that it’s hard to drink quickly you may be deterred from getting enough. Anything that can help increase total fluid intake is a positive and ensures hydration.

After the Workout

Hydration does not stop even after you finish your training session. After completing exercise, athletes should continue to drink fluids for an hour or two. It is important to keep in mind that the body absorbs fluid only at a certain rate, so there is no need to drink a lot at once. You can aim to drink until your thirst is quenched, plus a little bit more, specifically 2 to 3 cups of fluid per pound that you lost during exercise. It is important to remember that you have more options than just water when it comes to your post-workout beverage choices. Choosing beverages such as protein shakes or chocolate milk can help you hydrate and support recovery.

Header photo by Ketut Subiyanto