If you are an experienced, performance athlete, or just a person trying to start a workout routine and stick to it, proper hydration is crucial for your performance, mental acuity, and also muscle and organ function. But getting the right amount of water may be confusing: how much water you need depends on the air temperature, length of the workout, intensity of the exercise, your own adaptation to heat, and how or how much you sweat. Here are some things to keep in mind when exercising in different situations.
During challenging athletic events, it is common for athletes to lose 6-10% of their body weight in sweat loss. They can become easily dehydrated, leading to lower performance if they don't rehydrate enough during or after the workout; and research shows sports performance can be affected when the body is even 2% dehydrated. These effects are magnified at the beginning of a sports season, and also in hotter weather.
It’s estimated that 1 kg of body weight loss equals around 1 L of sweat loss, and to compensate for that sweat loss, around 0.4 to 0.8 L of fluid per hour of exercise may be necessary depending on how you sweat.
How Do I Describe My Sweat?
The American College of Sports Medicine joint position guidelines suggest that athletes who have the following attributes may need either more water or more electrolytes (or both). How would you describe your sweat?
I sweat more than normal (>1.2 L/hour)
I have “salty sweat,” often having a salt residue on my skin and/or clothes during and/or after exercise
It is important to know how you sweat, to either plan your workouts to include more water, more electrolytes, or both. If you are a salty sweater, you may need a little electrolytes before even a small workout to help with fluid retention.
The Rules of Hydration Before, During, and After Exercise
Under normal circumstances, physically active people who consume a nutritious, plant-rich, well-balanced diet should not need to add specific ingredients to their fluids before, during, or after exercise.
Make sure you are properly hydrated before a workout, and have an optimal body water content. You'll know it, because during will be a pale yellow color. If you're not in this state,
drink 11 to 22 mL of fluids for each pound of your body weight within two to four hours before activity
The National Strength and Conditioning Association (NSCA) has similar guidelines: 5 to 7 mL/kg at least four hours before exercise
During a workout, you may need between 3-8oz of fluids every 10-20 minutes depending on how much you sweat.
Plan ahead: If it is a hot day, or you plan to exercise for longer, take more water.
If you are planning to exercise for longer than 60 minutes, you may need an electrolyte supplement.
After exercise, the goal is to fully replenish any fluid and electrolyte deficit from the exercise bout.
Weigh yourself before and after. Ingest 20 to 24 ounces (600 to 720 ml) of fluids for every pound of body weight lost.
Rehydrate within 6 hours after a workout.
To rehydrate fast, avoid caffeine and alcohol in the first 3 hours after the activity ends (especially after an intense workout lasting over 60-90 minutes)
If exercising for 45 minutes or less, the risk of electrolyte imbalance is quite low, and electrolytes are not needed unless you are a salty sweater.
When to Add Electrolytes:
As part of a big industry, many energy drinks and electrolyte products are promoted with intense marketing efforts, even when they’re not needed. It may appeal to people looking for a competitive edge and/or more energy. But these beverages are sold at high prices and may contain additional sugar, calories, and caffeine, which may be either unnecessary or, in the case of caffeine, more dehydrating. Some brands of bottled waters that claim to be electrolyte-enhanced don’t actually contain any more electrolytes than are found in typical household tap water, approximately 2% to 3% of daily needs.
Supplement your water with some sodium, or other electrolytes if:
You participate in intense exercise
It is hot outside
You sweat a lot
You're exercising for more than 2 hours
You typically have "salty sweat"
The workout will be shorter, but it's a very hot day outside
For most people who exercise moderately for less than an hour are better off drinking plain water without electrolytes. Having typically "salty sweat" is the only exception.
What Electrolytes to Use
If you don't have sports drinks or electrolyte tablets around, or you just don't want to feed that growing billion dollar industry —a salty snack such as a pickle with your water may be warranted for pre-exercise hydration. The sodium in the drink will help the body absorb and retain the fluid and use the carbohydrate.
If sodium is consumed in a beverage, the recommended amount is 460 - 1,150 mg per liter. - Swaka et al. 2007
For the fluids to be effectively retained and hydrate your workout, drink your water with foods that contain sodium and other minerals. Snacks containing plenty of sodium like salty nuts, crackers and tomato juice can help recover fluid loss, but if these aren't available to you, an electrolyte replacement is a fine substitute in-a-pinch.