A Runner’s Guide to Proper Hydration


We’ve all likely felt the effects of dehydration at some point in our lives, however as runners, proper hydration is especially important. Proper hydration does not mean going off a one-size-fits-all guide you found on Google, nor is it guzzling water a day before your race. Proper hydration requires time and effort from you, but it can also be the key difference that keeps you healthy, aids in your recovery, and helps you reach a new PR or distance. 

The issue around hydration is it’s hard to know what advice to trust. One thing that is certain is we are all different runners, with different needs. Everything from outside temperature, terrain, individual sweat rate, and beyond can affect the amount of fluid we need. Many experts recommend that runners find out what their sweat rates are which we’ll discuss further below. 


Our bodies are composed of roughly 60% water. A body water loss starting at 2 to 3 percent can result in serious cognitive and physical effects such as headaches, dizziness, nausea, loss of coordination, difficulty processing information and more. [1]

Weather – Weather variables include temperature, humidity and wind speed. Running in extra hot or humid conditions will require extra sodium and electrolytes from your beverages. Think about how weather can affect your sweat rate. A helpful tool for monitoring weather is the WetBulb Globe Temperature (WBGT). [2]

Water or Electrolytes – For distances longer than 6 miles, you should highly consider incorporating a mix of water and electrolytes. Remember that too much of only water can flush you of your electrolytes and can lead to hyponatremia.

Cumulative Dehydration – It’s a lot more common than one thinks to start your run off already dehydrated. This makes actively hydrating before, during, and after your runs equally important. For how much you should drink daily, multiply your weight by ⅔ (or 67%) and change that to ounces. For example, if you weigh 165 pounds, you multiply that by ⅔ which means you’d need to drink around 110 ounces of water daily.  [3]

NOTE: This does not substitute what you lose during a run, nor does it replace calculating your sweat rate. The water you lose during your run (sweat rate) is additional to what you should be drinking daily. 

Sweat Rate – One of the most important factors, if not the most, is sweat rate. Every runner should know what their average sweat rate is. This tells us how much sweat/water we’re losing during our run, the pace we’re losing it at, and how much we should be replacing. 

The way to calculate sweat rate is (access online calculator):

  1. Pre-Run Weight – Post-Run Weight = Weight Lost (in kg) (also known as Sweat Loss) 
  2. Multiply weight loss by 1000 to convert your loss to grams
  3. Add the amount of liquid you drank during your run in mL 
  4. Subtract urine volume (if applicable) 
  5. This equals your total sweat loss 
  6. Divide sweat loss by your total exercise time in hours to get your sweat rate per hour 
  7. To get your average sweat rate after tracking for several days, add up your daily sweat rate and divide by the number of days tracked 

Sweat rate will fluctuate with weight, weather, diet, exercise intensity, and more so it’s recommended to track this at least twice a year (winter and summer). Aim to record your sweat rate over 14 days to get a total average.

By finding your sweat rate per hour, you now know how much you should be replenishing during and/or post-run. Experts recommend replenishing 80 to 100 percent of that loss to maintain optimal hydration during your run. For example, if you lose 1165 mL of water per hour (39 oz), you should aim to drink between 932 mL to 1165 mL of liquids. [4]

Once you have that target amount that you should be drinking during your run per hour, think about how you will be carrying that water on your runs? Will you need to stop and refill? 

Then while you’re running, aim to drink your beverage of choice in small but frequent sips rather than all at once to avoid cramping. For example, if you know you lose 39 oz of water per hour and you’re running for 50 minutes, you should drink anywhere between 26 oz to 32.5 oz by the end of your 50 minute run. This means you should drink 2.6 to 3.25 oz every 5 minutes.

Remember that what you replenish from your sweat loss during your run, is separate from the daily recommended amount of what you should already be drinking.

Don’t wait till the week of your race to get adequately hydrated or to calculate your sweat rate. Prioritize hydration today and you’ll be shocked at all the hidden benefits that will come from it. 

For more information on hydration and running, check out this free e-book and sweat rate calculator which compiles digestible information from top researchers including the International Society of Sports Nutrition, National Athletic Trainers’ Association (NATA), UPMC Sports Medicine and more – https://www.vesselathletics.com/hydration-ebook

Jasmine Sanchez is a runner and the Founder of Vessel Athletics The Hydroshirt™ is the first hydration shirt that allows runners to seamlessly carry water on runs without the extra weight, slosh and bottle. Her goal is to create a purpose-driven brand with Vessel by creating better hydration solutions, promoting healthy hydration for runners, and using Vessel’s profits, influence, and voice to help bring clean water to underserved communities. Connect with her at: 

Website: https://www.vesselathletics.com/
Instagram: https://www.instagram.com/vesselathletics
Personal Instagram: https://www.instagram.com/thejasruns/

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