Sweat Testing 101

Who Should Be Sweat Testing?

For our clients that plan to do any racing or events for a long duration (2+ hrs) at a high intensity, or for any clients who have goals of optimizing performance in those events, make sure to discuss sweat testing with your practitioner if you’re not already testing!

Why Do We Encourage Sweat Testing?

I’m sure it’s not news to you that we lose fluids from the body when we exercise through our sweat and respiration (breathing). The amount of fluid loss from the body will change based on our effort/intensity and the surrounding environmental conditions — For instance, is it 30F and very dry? Or is it 80 degrees and very humid? We guarantee your sweat losses in those two environments will be VERY different.

To be able to sweat test and gather sweat data in as many different environmental conditions as possible gives us more tools in our tool box to reference and pull from when preparing the gut for a race. If we can understand expected fluid losses in different types of race conditions, then we can calculate what your 2-3% dehydration finish will look like at different races conditions. This helps us then calculate your fluid and sodium needs for each individual’s race.

What are Some Ways to Sweat Test?

The simplest, most tried and true way to sweat test is to measure your bodyweight before and after your training session. If you are consuming fluids during this session, it’s important to account for anything consumed as this will add weight back to your body. This information is critical because it gives us the fluid loss variations in different temperatures, elevations, intensities, and humidities to reference back to when we are prepping for a race at a similar temp, elevation, or humidity. 

The second piece of the puzzle that we need to gather is your sweat sodium concentration. This information will tell us how many milligrams of sodium are lost per ounce of sweat fluid lost. There are a few ways to test your sweat sodium concentration these days that provide reputable and accurate data without going into a lab. See the below options for sweat sodium testing, sorted from least expensive to most expensive.

  1. GX Sweat Patches
    • Pros
      • Easy to get online
      • Can perform your test anywhere you want
      • Cheap ($25 for 2 patches)
    • Cons
      • Patches can easily be “over sweated” and data is lost/unreadable
      • Must be comfortable using the GX app to scan your patch, possibly mid session if you are a heavy sweater
    • Notes
      • If you are interested in using this form of sweat testing, you can click HERE to get started.
      • Additionally, please reach out to your practitioner because we have an entire protocol that details instructions and best practices when it comes to using GX Sweat Patches.
  2. NIX Biosensor
    • Pros
      • Easy to use app
      • Moderately priced
      • Continuous sweat measurements and suggestions during your workout
      • Can wear for as long as you want, without fear of “over sweating”
    • Cons
      • Their output equates to “total electrolyte” loss.
        • This means that this output value is not specific to sodium only. It will group ALL electrolytes into this calculation (potassium, magnesium, chloride, etc.), however, we have equations to calculate just your sodium loss from their output value.
      • Depending on session duration or where you sweat most, you may get told by the patch that you lost 0 fluid oz during a session because of the suggested placement location on the tricep.
  3. Precision Hydration Sweat Testing
    • Pros
      • Decently accurate information, reads similar to lab or GX patch results
      • Can test on a rest day or any day that you don’t have to train
      • Less room for user error since a professional runs the test
    • Cons
      • High price point of $300+
      • Must test in person
      • They try to upsell you to their products

Sweat Testing Next Steps

Reach out to your practitioner today if you would like to learn more about sweat testing and sweat sodium testing to see which method is best suited for you based on your training type and goals!

For those of you who are NOT currently clients, we highly recommend booking a FREE 15 minute call with a practitioner today to learn more!

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