The Ultimate Guide to Hydration for Runners

Hydration for Runners is an essential topic for performance, and understanding the importance of hydration, electrolytes and the body’s need during long runs can really transform how you feel.

man in green shirt drinking water on side of road

You may have realized that you feel a lot better when you’re adequately hydrated, but do you know what proper hydration for athletes looks like, and why?

This post will review the basic core concepts of hydration. It will cover:

  • How much water should an athlete drink?
  • Importance of adequate hydration
  • Calculating your individual sweat rate
  • Developing a hydration plan for athletes
  • Hydration around workouts
    • Pre workout hydration
    • Hydration during exercise
    • Post workout hydration
  • Dehydration in runners
    • Signs and symptoms of dehydration

How Much Water Should An Athlete Drink?

The human body is around 60% water. As a person acquires more lean muscle mass, their water percentage actually increases, which highlights the importance of proper hydration to maintain optimal performance. Water is incredibly important, especially for the brain, heart, and muscles.

A general rule of thumb for the recommended water intake for athletes is to start by calculating daily water needs. It’s usually recommended to drink half their body weight in ounces of water or other noncaloric beverages per day.

For example: a 160 pound athlete will need to drink a minimum of 80 oz. per day. Additional fluids will likely be needed before, during, and after exercise, and/or in hot, humid conditions, or altitude.

glass pitcher with water and cucumber and limes

Staying adequately hydrated is not just a matter of drinking enough fluids. Consider that nearly 20% of water intake comes from food sources, with fruits and vegetables containing 80 to 98% water.

You may also want to use an app to alert you when you need to drink water throughout the day, or use a water bottle that can keep track.

Importance of Adequate Hydration 

Staying hydrated is important to just about every system in the body. And no, drinking just coffee or pre workout doesn’t count.

Here are some ways that hydration impacts the body.

  • Provides moisture to the eyes, nose and mouth
  • Assists the body in thermoregulation through sweat
  • Provides lubrication to the joints
  • Transports nutrients, oxygen and waste through the blood (yes hydration is important for training your gut)
  • Replenishes the muscle stores, as muscles are 75% water
  • Helps with mental clarity and focus
  • Minimizes fatigue, which can help minimize the risk of marathon bonking

woman in sports bra drinking from water bottle with mountains in background

Calculating Your Individual Sweat Rate

Each person has a different sweat rate, which is dependent on gender, body weight, genetics, heat acclimatization, and metabolism.

Hydration needs can be practically determined by measuring body weight.

After you wake up in the morning and after urinating, weigh yourself with as little clothing as possible. Do this for three consecutive mornings and monitor your average weight of the three days.

Be sure to be eating adequately and drinking regularly to achieve an accurate reading.

For women, a few more measurements might be helpful to determine an average, as menstrual cycles can influence body water status by increasing total body weight.

After finding your average body weight, you can then determine how much fluid you lost in sweat by weighing yourself after an exercise bout. Step on the scale without clothes as they may have sweat trapped in them.

Alternatively (and perhaps, in a much easier fashion), hydration status can also be determined by checking your urine color. Urine can range from light yellow to dark yellow or almost brown.

Leaning towards a light yellow indicates proper hydration; whereas, a darker yellow indicates dehydration and the need to consume more fluids.

This 8 scale urine hydration chart from the study, “Development of Urine Hydration System Based on Urine Color and Support Vector Machine,” provides a helpful visual.

8 color scale urine chart


Hydration Plan for Athletes

Overall, a hydration plan for athletes means focusing on hydration over the course of the day, not just around workouts, for optimal benefits.

On average, a physically active individual should consume 3 to 4 liters of fluid per day. Individuals who train more than two hours per day should be consuming more than 7 or 8 liters per day.

man in green shirt drinking water on side of road

Proper hydration for athletes before, during, and after exercise helps sustain cardiovascular function and body temperature.

Exercise, especially in warm and humid environments, increases fluid needs and consuming enough fluids must be taken seriously to prevent dehydration that may lead to heat exhaustion, decreased performance, increased perceived exertion, and muscle cramps, to name a few.

While sweating in hot environments can increase sweat rates and fluid loss, fluid consumption must also be maintained when exercising in colder environments.

For during exercise hydration, you may want to carry your own liquids with you using a handheld water bottle or a fluid belt or backpack.

These are also great for races because you can just stop at 1-2 of the water stops to refill your bottle versus having to stop more often for water or sports drinks.

water bottle belt on back of runner

Fluids include water but also chocolate milk, regular milk, Propel, Gatorade, tea, and coffee. Sports drinks provide energy in the form of sugar and are more appropriate for exercise that lasts longer than 60 to 90 minutes.

Electrolytes for runners, such as sodium, potassium, magnesium, and chloride, also play a key role in maintaining proper hydration.

Carbohydrates also help maintain fluid status. Therefore, incorporating carbohydrate-containing foods and salty snacks throughout the day along with fluids is highly suggested for active individuals or those struggling with hydration.

Here’s a helpful post all about carb loading for running

Some easy salty snacks include:

inforgraphic of hydration before, during, after exercise

Hydration Around Workouts

Just as you should practice your nutrition for fueling before a long run, you should practice hydrating as well.

Let’s review what hydration should look like in and around workouts.

Pre Workout Hydration

Let’s review the importance of hydration before exercise.

  • 2-3 hours before activity drink 20 oz. water or sports drink
  • 10-20 minutes before activity drink 10 oz. water or sports drink
  • Have a variety of fluid options to choose from
  • Pre-hydrate to produce a light-colored urine
  • Designate a place or source where you will access water during your exercise, especially on warmer days or when exercising for over 30-45 minutes
  • Know the warning signs of dehydration (thirst, light-headedness, dark urine, dry mouth, rapid heartbeat)

Hydration During Exercise

  • Begin exercise in an adequately hydrated state (see above tips!)
  • Drink before you get to the point of feeling thirsty
  • Drink a couple sips or gulps (approx. 4-8 oz. water or sports drink) every 15-20 minutes
  • Train yourself to drink during exercise if this is new to you (try these tips to train your gut to take in carbs)
  • Sports drinks will also provide carbohydrates and electrolytes
  • Estimated to consume 500 to 1000mg sodium per hour
  • Consider fueling with carbohydrates for activity lasting more than an hour, such as long-distance running

closeup of running hydration pack on man with blue shirt

Post Workout Hydration 

After a workout, remember that your everyday hydration status and habits will be impacted tomorrow based on how you hydrate today. Keep up with the fluid intake!

  • Continue to drink after exercise on a regular basis
  • Aim to drink 16-24 oz. water or sports drink for every pound of body weight lost during exercise. The best way to estimate this is to weigh yourself naked before and after runs.
  • Consume salty snacks or foods
  • Notice if you have white residue spots on your clothes or skin from sweat; this means you are a ‘salty sweater’ and may require more electrolytes

For every pound lost during exercise, the athlete needs to drink at least 16 ounces of fluid to replenish it.

Hydration Refueling Chart

Weight lost (lbs.)Fluids lost (ounces)Sodium lost
116500 mg
2321000 mg
3481500 mg
4642000 mg
5802500 mg
6963000 mg

Dehydration in Runners

It takes a loss of only 1% – 2% of your body’s ideal water content to cause dehydration. It can be dangerous if a runner is not hydrating adequately before, during, and after exercise.

Exercising in a dehydrated state can impair performance and increase the risk and susceptibility to injury. An athlete could be under-hydrating if they are working out in hot or humid conditions, working out in cold weather with multiple layers, or having excess amounts of sweat, due to long or intense training sessions.

Dehydration Can:

  • Decrease Performance
  • Increase Risk of Muscle Injury
  • Increase Risk of Illness
  • Impair Recovery Between Workouts

Signs and symptoms of dehydration

Some signs of dehydration while running or after running include:

  • Headache / Dizziness / lightheadedness
  • Fatigue
  • Moodiness / irritability
  • Dry mouth or skin
  • Thirsty
  • Poor appetite
  • Nausea
  • Muscle cramps
  • Decreased or dark urine
  • Decreased endurance performance
  • Rapid heartbeat or breathing (seek immediate medical help)
  • Lack of sweat production (seek immediate medical help)

If you are constantly experiencing some of these symptoms, or constantly feel thirsty or dehydrated, your fueling and hydration plan are likely not working for you. 


Alexander A S Gunawan, David Brandon, Velinda Dwi Puspa, Budi Wiweko, Development of Urine Hydration System Based on Urine Color and Support Vector Machine, Procedia Computer Science,
Volume 135, 2018, Pages 481-489, ISSN 1877-0509.

Fluid Loss Calculator. (n.d.). Retrieved May 13, 2021, from

Susan M. Shirreffs & Michael N. Sawka (2011) Fluid and electrolyte needs for training, competition, and recovery, Journal of Sports Sciences, 29:sup1, S39-S46, DOI: 10.1080/02640414.2011.61426 

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