Staying well hydrated during training is key for athletes to maintain healthy cardiovascular function, muscle contraction, and regulate body temperature to enhance sports performance. How much you need to drink and what to drink is the question and it all depends on a number of conditions such as the humidity, temperature, duration of training, and sweat rate.
Effects of Dehydration
Look at Your Urine Color
Urine color is an easy way to figure out if you are well hydrated. Pre-workout, it’s optimal to have light yellow urine color, which indicates that you are well hydrated. The chart below explains the relationship between urine color and hydration.
Urine Color Possible Meaning
Clear Well hydrated to over-hydrated
Light Yellow Well hydrated to mild dehydration
Bright Yellow Mild to moderate dehydration or taking vitamins
Orange, Amber Moderate to severe dehydration
Tea-Colored Severe dehydration
What’s in your Sweat?
Sweating during exercise helps cool your body off, which is important for body temperature regulation. Most athletes can sweat up to 1-2 liters per hour (34-68 ounces), but this varies from person to person, depending on humidity, temperature, sweat rate, and duration of exercise.
Sweat contains water and electrolytes, sodium, potassium, chloride, magnesium and calcium. Sodium and potassium are the main electrolytes that are lost through sweat. On average, 200-600 milligrams (mg) of potassium and 500-1000 mg of sodium need to be replaced when exercising intensely for about 1 hour (which can vary by conditions). Replacing sodium during and after endurance training can help stimulate thirst as well as help retain fluid, to maintain proper hydration.
In general, if exercising less than an hour, water is typically your best choice; but when exercising longer than an hour (or in warmer temps), consider adding electrolytes. After training if you notice white streak marks on your skin or if your saliva tastes like salt, you may be a salty sweater and may need more sodium. Choosing the right electrolyte drink for your sport can be confusing, so test out different products during training to figure out which one works best for you.
Here are some examples of sports nutrition products that contain electrolytes. Endurance athletes training longer than 90 minutes may benefit from using a product with a higher amount of sodium.
Product Name Sodium mg Potassium mg
Tailwind Endurance 303 mg/1 scoop 88 mg/1 scoop Skratch 380 mg/1 scoop 39 mg/1 scoop Hammer Endurolytes Fizz 200 mg/1 capsule 100 mg/1 capsule Nuun Sport Tablet 360 mg/tablet 100 mg/tablet Nuun Endurance 380 mg/1 scoop 200 mg/1 scoop Gu Hydration Drink Tabs 320 mg/tablet 55 mg/tablet Clif Shot Bloks Margarita 150 mg/3 chews 20 mg/3 chews
Gatorade Endurance 300 mg/12 ounces 140 mg/12 ounces
Drink to Thirst or Hydration Plan?
There are two schools of thought on hydration for athletes, drink to thirst or having a pre-planned hydration schedule. Drinking only when thirsty (a.k.a drink to thirst) can help prevent over-hydrating, or exercise associated hyponatremia, which can be seen in novice endurance athletes. Drinking to thirst is less effective for preventing dehydration for endurance events, but can be beneficial for shorter activities.
Having a hydration plan is often recommended for athletes exercising longer than an hour and especially when training in the heat. Fluid needs vary depending on how length of exercise and level of sweat. In general, most athletes can use the following guidelines for a pre-planned hydration schedule, but these amount can vary depending on sweat rate. Your goal is not to replace every ounce you lose in sweat during training, but to focus more on balancing your hydration to prevent dehydration or over-hydrating.
Drink 24 ounces of fluid 2-3 hours before
Drink 8 ounces of fluid 15 minutes before
Drink 4-8 ounces every 15-20 minutes (approximately 1 big gulp = about 1 ounce of fluid)
Drink 16-24 ounces for every pound lost during training
If you want to tailor your hydration plan during and after training, consider calculating your sweat rate. Weighing yourself before and after training can also be helpful to determine how much fluid you have lost during exercise.
Take Home Message:
Start your training sessions well-hydrated. Take a look at your urine color to help determine your hydration level.
Add fluids containing electrolytes during and after training when exercising longer than 60 minutes and especially when training in warmer, more humid conditions.
Have a hydration plan for training sessions lasting longer than 60 minutes.
Practice your hydration plan during training so you know what works for competition day.
Determine your sweat rate if you want a more individualized hydration plan.