How Sweat Testing Made Me a Better Athlete Overnight

March 23, 2026•3 min read

How Sweat Testing Made Me a Better Athlete Overnight

Before I knew anything about sweat testing, I was a normal runner who hadn't started doing really long races yet. The longest races I had ran were half marathons on the roads and trails. I would be so drained of energy after long runs and races and it took me many days to recover from the soreness and to be able to run again.

I then started to run longer races and you can guess how well that went. Every race beyond two and a half hours was a blow up. It always started with cramps in my legs and trying to play catch up with electrolytes and water. There was always some level of GI distress and I couldn't crack the code to having a really solid race.

Enter thePrecision Fuel and Hydration Sweat Test.I selfishly tested myself as soon as I got it to find out what I was doing wrong. I thought for sure that I may be the saltiest sweater alive, or so I felt. I strapped the test on my arm and sat there for 15 minutes until the test tube filled with enough sweat to test. My results popped onto the screen and baffled me. 747 mg/liter of fluid. This is considered a low sodium amount compared to the average person's 1000 mg/liter.

I knew immediately that I had been fighting fire with kerosine. I was trying to take more electrolytes to solve my cramps but electrolytes weren't my problem at all, hydration was. You see, there are 4 important variables to understanding your hydration:

Electrolytes- how much sodium you lose per liter of fluid that you sweat out
Water- how much fluid you sweat out
Time- how long are you training for
Conditions- how hot or cold is it, how humid, etc.

I was overdosing electrolytes which leads to hypernatremia. This causes cramps, fatigue, GI distress, and nausea. No wonder I was bonking so hard.

Getting electrolytes right is not about taking a certain amount per hour though. It's about taking the proper ration to keep your electrolytes in constant balance. If the balance is off in one direction or the other you will have similar symptoms.The ratio of sodium to water that is specific to you is the gold standard.

Once you know your ratio you just need to dial it in for your bottle size. Since mine is 747 mg/L and I use 20 oz bottles, I need exactly 453 mg per bottle. Since you don't have to be perfectly exact I use 500 mg per bottle.

Since removing that variable from my race brain (which typically doesn't operate well at math) I only had to worry about how much water I need to drink and how many carbs I need to take per hour. For hot days and harder intensities I drink more. For cold days and less intensity I drink less. Simple, right?

Race results followed and I was finally able to race to the ability I knew I was capable of. I have been able to recover faster from races and long runs and that has improved my training more than anything else.

If there is one test that I recommend people to have done to improve endurance sports, it is this one.

Want to book a test or have more questions? Call or text us at 256-513-9525 or click the link below to book a phone consult with us today.

Happy running,

R2S Team

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