Last week on the blog, we discussed hydration needs, sweat rate and how to use your sweat rate data to meet your hydration needs. Now, we’re on to the next level – sweat composition – why do we care about it, and how can we use our sweat composition data to improve our hydration & performance.

Why should I care about my sweat composition?

Sweat composition tells us the breakdown of electrolytes that we lose in our sweat. Our sweat contains water, sodium, chloride, potassium, and calcium. Sweat composition is genetic and it is fairly consistent throughout your training. Sodium is the electrolyte lost in the greatest amount via sweat, followed by chloride. Sodium losses & dehydration can lead to detrimental performance outcomes. The average athlete loses around 900 mg sodium per liter of sweat, with ranges from 200 mg – 2000 mg per liter reported. We also lose potassium, magnesium, and calcium in much smaller amounts, however, these electrolyte losses do not hinder performance & we typically consume adequate amounts in our daily diet. This is why we focus on sodium intake before, during, and after training and races.

Sweat composition varies dramatically as well. Understanding personal sweat composition has been a game-changer for many endurance athletes.

How do I know if I'm an average sweater or a heavy sweater?

Are you more sweaty than your running friends? Do you sweat through your clothes and look like you took a shower after every run? Then you might be a heavy sweater. As a general rule, if your sweat rate is >32 oz/hr, you are a heavy sweater (use our sweat rate calculator to figure out your sweat rate if you haven’t done so already).

How do I know if I'm a salty sweater?

Have you ever noticed white crusty stains on your clothing or gritty white residue on your skin after training? This is the salt in your sweat drying as the sweat evaporates. As your sweat dries, if you notice minimal salt on your skin and clothes you likely have a low sodium concentration in your sweat. If you notice some salt on your skin and clothes, you likely have an average sodium concentration in your sweat. If you see very noticeable lines on your clothing and skin, you likely have a very high sodium concentration in your sweat. Other signs, along with salty streaks, that indicate you may have a high sodium loss in sweat are frequent muscle cramps after heavy sweating, intolerance to training in the heat or feeling awful after, dizziness or lightheadedness at the end of training, your sweat stings your face and eyes, and cravings for salt. Salty sweaters may experience GI issues, cramping, decrease in performance, and intolerance to training in the heat more easily than peers.

How can I stay on top of my hydration as a salty sweater?

The CDC recommends that we eat less than 2300 mg sodium per day. A salty sweater loses this in an hour of running. As you can see, salty or heavy sweaters may need to add significantly more sodium into their day when training. It’s not uncommon for a heavy, salty sweater to need 2 – 4x the daily recommended amount of sodium. Add salt to your food. Try higher sodium electrolyte drinks. Choose saltier foods. And notice how you feel and recover.

In addition, salty sweaters training in the heat can benefit from taking a very high sodium supplement the night before big workouts and long workouts to hyperhydrate. This means our body holds onto extra sodium and fluid to act as a buffer to our hydration when we begin sweating in our next training session.

How do I know what my sweat composition is?

There are several options to help you determine your sweat composition:

#1 – Trial & Error 

Use this post & our hydration resource page & think through if you have symptoms of a heavy or salty sweater. If so, try incorporating more sodium before/during/after runs and see how you feel. Adjust as needed.

#2 – Wearable Hydration Monitor

Calling all nutrition nerds/number nerds – this device is for you. With a wearable hydration monitor (like the hdrop), you will strap the device to your arm, complete your run or workout, and all the data will upload to the app on your mobile device. It will tell you how much sweat & sodium you lost and rates per hour. Super cool if you ask us. This device is also reusable. The Gen 2 just dropped – get it with our discount code here.

#3 – Hydration Sensor or Patch

Levelen is a patch you can wear and send back into the company, who will email your results of sweat loss & a breakdown of electrolytes lost (use code Featherstone for 20% off – order Single Sport for 1 use, Multi-sport for 2 uses). Nix is hydration sensor, in which fluid & total electrolyte loss (you will not receive a breakdown of each electrolyte just yet) will show up on the app after use. These options are not reusable, but you can order multiple patches.

If you need help with your fuel & hydration plan, Meghann can create a Customized Race Fuel & Hydration Plan for you! Plan ahead so you can practice your plan during your long runs -please allow 14 business days for your plan to be emailed to you. 

What hydration & sports fuel products are right for me?

Find the right hydration and sports fuel products that will meet your hydration & fueling needs. Choose what you like and what you will consume. You can play around with hydration the night before, the day of, sports fuel, salt tabs/chews, etc. to find the right combination for you.

Hydration Products

Sports Fuel Products

Low Sodium: 

Skratch chews

Spring Awesome Sauce



CLIF Bloks

Higher Sodium: 

Huma Plus

Never Second

CLIF Bloks (2x sodium)

Check out our Hydration resource page for more details on hydration, sweat rate & sweat rate calculator.

If you need help with your fuel & hydration plan, Meghann can create a Customized Race Fuel & Hydration Plan for you! Plan ahead so you can practice your plan during your long runs -please allow 14 business days for your plan to be emailed to you. 

Disclaimer: The content in our blog articles provides generalized nutrition guidance. The information above may not apply to everyone. For personalized recommendations, please reach out to your sports dietitian. Individuals who may chose to implement nutrition changes agree that Featherstone Nutrition is not responsible for any injury, damage or loss related to those changes or participation.