Athlete Empowerment Tip: Learn about your Sweat

Calling all endurance athletes in the northern hemisphere who are starting up (or are in the midst of) their base training…Run through the list below and see whether you identify with any of the following:

  • Are you a heavy sweater during exercise?

  • Are you a long-course triathlete, ultra runner, ultra cyclist, or other type of endurance athlete whose competitions exceed 4 hours in duration or more than 1 day in a row?

  • Do you train (or compete) in hot and/or humid environments?

  • Do you frequently have salty, white residue on your skin and clothing after workouts?

  • Have you struggled with knowing what to do regarding your hydration and electrolyte planning for previous competitions? Or ended up with suffering from over- or under-hydration? (perhaps you do not even know this!)

If you answered ‘yes’ to one or more of the above questions, I’ve got a To Do for you:
Get a sweat sodium composition assessment.

This form of assessment doesn’t require you to exercise or apply sweat patches all over your body. In fact, here’s a picture of a recent sweat test I did for the founder of OrangeMud, to show how easy your part is:

Josh (looking so comfy) during his sweat sodium assessment

Josh (looking so comfy) during his sweat sodium assessment

The test itself is fairly quick to do, taking about 20-25 minutes of your time. If you want to see a bit more of the steps involved, this ~1 minute video shows an abbreviated test.

What does the test tell you?
The short answer is: how much sodium is in one liter of your sweat.

The test does not tell us about how much you sweat (your “sweat rate”), as this is quite variable depending on exercise intensity and environmental conditions. As a part of the service I offer, you do learn how to monitor your sweat rate throughout the season and apply your sweat rate(s) and sweat sodium loss together to aid in your hydration planning for optimal training and recovery.

Why should you care about sodium? Let me give you 3 quick reasons.

  1. Sodium is the primary electrolyte lost in sweat. Knowing more definitively your personal sodium losses helps to fine-tune selection of hydration/electrolyte products to minimize risk of over- or under-consuming needed fluids and sodium. You save money, or spend it more wisely by making smarter product decisions. You minimize your risk for exercise-associated hyponatremia.

  2. Sodium balance, along with your hydration level, plays a role in maintenance of blood plasma volume. If plasma volume drops too low due to high sweat and/or sodium losses during exercise (combined with improper hydration and sodium intake), your performance will take a hit. This can be due to negative effects on cardiovascular functioning, cognition and focus, and thermoregulation.

  3. We’re not all the same. Did you know there can be about a 10-fold difference between athletes for sodium lost per liter lost of sweat? This is largely independent of what your daily dietary sodium intake is. You can thank your sweat gland physiology for this fact. And it speaks to the need to find out where you are on the spectrum (low, moderate, high level).

How do you get the test done? If you’re in Colorado, contact me or my colleague, Ryan, to schedule an appointment in Boulder at Colorado Multisport. We also offer remote testing clinics and workshops locally and nationally, which is a great service for training camps and clubs to offer their athletes.

In summary, the test has been a game changer for many endurance athletes. I encourage you to prioritize this piece of the learning puzzle. It is well worth your investment and time. And you only need to do it once to have the data apply for the remainder of your athletic lifetime!

Thanks for reading,


P.S. The header photo was taken after my friend and I volunteered at the Ironman World Championships (Kona) this past year. We worked a midday shift as bike catchers, running bikes to their proper rack position as quickly and efficiently as possible, in the blazing sun. Our sweat and fluid losses were extremely high during this 4-hour period, as you can get a sense of by our drenched t-shirts. Good thing we had plenty of fluids with us… and extra deodorant.

P.P.S. If you are a doubter (or need more information to see the importance of giving attention to personalizing your hydration and electrolyte strategies), check out these recent podcasts with Andy Blow of Precision Hydration: Purple Patch Fitness and HVMN.