What is Sweat Testing and should you do one?

Nov 04, 2021

What is Sweat Testing?

Sweat testing is a way to measuring your sweat sodium concentration during exercise. Simply, we put patches on your skin, you exercise for a defined period of time and then take them off and analyse them. Combine with measuring your body weight pre and post, we can also calculate your sweat rate in ml/hr and then calculate sweat sodium concentration in mg/L of sweat.

In the field, we use sweat patches at certain sites on the body to calculate your sweat sodium concentration and then use mathematical equations to calculate total body sweat sodium.

Many things impact your sweat rate; genetics, your fitness level, intensity, the environmental conditions of the day, your pre-test diet – there are many things we want to try and control for to give you the most accurate results.

Who is sweat testing best suited for?

  • Athletes competing in endurance events 10hrs + e.g. ironman, ultra-marathons, 24hour mountain bikers
  • Shorter events if having issues
  • If you’ve ever suffered from hyponatremia (low sodium)
  • If you suffer from gut issues (nausea, vomiting, bloating)
  • If you’re collapsing in events

What to look for when you're doing a sweat test?

  • Do it outside in environmental conditions that are likely to match your race conditions
  • Exercise while you’re wearing a sweat patch. Not just sitting still as this is unlikely to reflect what your sweat sodium concentration is during exercise
  • The practitioner is qualified and across the research in this space to conduct an accurate, evidence-based test
  • Don’t try and do testing yourself at home – there are too many variable to control for and you are more likely to contaminate your sample, giving inaccurate results.
  • THE MOST IMPORTANT thing to consider, is how to apply your data to you and your specific situation. A number is just a number, it’s what you do with it that’s key

How can sweat testing help you?

  • It will help you understand your specific sweat rate and sweat sodium concentration at testing conditions
  • This helps you understand how much fluid you need available for your events
  • It also helps you understand how much sweat you’ve lost during exercise to then work on rehydrating effectively. As we know dehydration effects performance
  • It also helps you to understand if/what gut training you may need to do to meet your hydration needs

If you need more information about sweat testing or want to register your interest in getting a test, head to

To go deeper, listen to the Triathlon Nutrition Academy Podcast Episode 15: ‘What is Sweat Testing and should you do one for more!

Listen in wherever you listen to your podcasts 🎧



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