So I ordered a test from Levelen. A couple days later a package showed up in the mail containing my sweat test kit - an alcohol swab, cotton swab, a little plastic vile, tweezers and info card.
|The cotton swab on my arm....ready to start sweating.|
You're supposed to replicate race conditions so I rode indoors and cranked the heat and humidity and got the temp up around 80 with 70% humidity. I didn't use a fan (mistake) because I wanted to make sure I'd sweat enough to get good results. I rode for an hour at Ironman power, but the heat, humidity and lack of a fan made for a pretty intense workout. I was burning up and ready for the hour to end so I could drink something and cool down.
As soon as I finished I used the tweezers to remove the swab and put it in the vile and I weighed myself. I had lost 3.8 pounds - 60 oz. Ouch.
I dropped everything in the mail the next day and a few days later they emailed results...
I was and wasn't happy to see these results. This does help explain why I keep ending up in the med tent, especially the significant electrolyte losses. This will definitely help me prepare for races, but losing a lot of fluid and electrolytes can definitely make long course races more challenging than they already are, especially hot races.
But now I have some real numbers to work with.
- 53 mmol of sodium per liter of sweat
- 8.1 mmol of potassium per liter of sweat
- 51 mmol of chloride per liter of sweat
That comes to about 1200 mg of sodium per liter of sweat (34 oz). I've done a few sweat tests in the past and on hot days outdoors I tend to lose between 40-50 oz per hour. That's about 1400-1750 mg of sodium lost per hour.
They recommend replacing 60-70% of fluid and electrolytes lost. So I need to drink around 30-36 oz per hour and take in about 850-1200 mg of sodium per hour for a hot race. I'm probably getting about 300-400 mg of sodium per hour right now...maybe.
I asked them if electrolyte losses stay the same per liter of sweat lost regardless of sweat rate and they said yes, so now that I know how much I'm losing I can adjust my intake based on conditions and how much I think I'll sweat.
I got my results back about a week ago, so about 3 weeks before IMTX. It's a little late in the game to make changes, but what I'm currently doing isn't working so I'm taking a chance and more than doubling my electrolyte intake.