The Science of Sweat
Join T N T (Our own Taylor & Thang) for a look at the science of hydration and how to keep healthy even in an extremely hot climate.
After the video you can check out the documents that support the science, and Taylor's experiences with both Nix and Hdrop.
Taylor's Data:
To continue in depth on what we touched on in the video, I was spurred on to look into sweat sensors after a rough experience riding the Dirty Pecan, up in Tallashassee. The day started out nice, but got quite hot and you can see on the graph around 6 hours in, i utterly fell apart. My heart rate dropped a lot but it felt like i was redlining, and same for my power output.
I had stayed on top of my calories, so this wasn't a traditional bonk- I began to feel slow, weak, and a bit nauseous, too. I managed to limp back in, but was motivated to find out what went wrong.
Looking for a solution
The symptoms i had felt led me to wonder if i was not properly keeping up with my hydration needs, so i looked into sweat sensors. I came across a few- the gatorade patches, Nix, and Hdrop. I decided to try Nix because at the time it was immediately available. It also had the ability to record longer workouts.
The Nix unit was pretty new at the time, and the physical unit really appeared well made and solid; the unit itself clicks into one-time use patches. The app that it connects to was a bit buggy, at best- thankfully it seems like they have now made the app a good bit more reliable nowadays. I began to use it for some rides and i was getting some great data. Right away it confirmed my suspicions- i was a sweaty, sweaty dude. Both my fluid loss and my sodium content was quite high.
This is a screenshot from the Nix app. On a fairly cool spring day, i was sweating 31oz an hour and losing 2080mg of sodium/hr. Meanwhile, i was drinking around 30 oz of fluid per hour- so that was good- but was using skratch hydration, which was only supplying 380mg. So not too big a surprise that eventually i would be faced with a bad experience on a longer ride!
I haven't had much luck finding out what kind of 'sodium storage' the human body typically has- for instance, it's generally agreed that we have around 2.5 hours of glycogen stores. But I wasn't able to find what our 'sodium stores' are; i surmise it's different for everyone, but apparently for me, it's around 6 hours.
No Fluke
After a number of further rides wearing the Nix, I was able to find those high numbers weren't a fluke- and once we got into the really hot days, my numbers went even higher. That is one advantage to the sensors- you can tune your hydration to what you need in different climates, which i definitely need to do. As an example, here's the numbers from a ride we had on the fourth of July- 93 degrees with humidity of 87% and a 'feels like' of 111:
With big numbers like that, it's pretty hard to keep up with your hydration at all.
Head to Head Trials
When i began to see such big numbers, I wondered just how accurate these devices can be. The fluid numbers seemed accurate when I compared against the weigh-in weigh-out method (assessing total fluid loss through weight loss during an exercise) but what if these wildly high electrolyte losses were totally wrong? Just because it confirmed what I hoped was the issue didnt necessarily make it true.
So, I invested in the Hdrop unit to see if it measured similarly to the Nix. The Hdrop unit is a bit different than the Nix in that is straps on to your upper arm similarly to an armband heartrate sensor. It originally was limited in internal memory, but now has been updated to be able to record up to 10 hours of data. Not having to dispose of one-time use patches is certainly a plus over the Nix unit, but in practice I have found the Nix to be substantially more comfortable. The strap on system with Hdrop is a bit cumbersome, and I found myself fairly constantly moving it around to stay comfortable.
The Hdrop app, though, was pretty solid compared to the Nix app. And the data i was getting backed up the data from the Nix. So unless two different sensors read equally incorrectly, I feel like these are reliable numbers. Here are some screen caps from two different rides (one in winter, one in summer) that pretty closely match up to the Nix measurements.
My Take Away
These units have helped me immensely. I've been able to properly stay on top of my electrolyte needs using products like LMNT, which has been a lifesaver on those hot, humid days. One ride in particular was nearly 14 hours, and i took in 15,000mg of sodium! It's daunting to think i'm taking in basically 7 times the recommended maximum daily amount of sodium, and i did bring this up to my doctor, who pointed out if i know i'm losing that much, then i know i need to replace it.
If you would like to know more about my experiences, or about the hydration sensors, stop in anytime. I love talking about this stuff!