The following post is sponsored by Fuelstrip.

As I mentioned after NYCM, one of my major issues was fueling. I got pretty lucky that my fueling issues didn’t cause much more drama than a very quick trip to the medical tent for some salty goodness to battle my mild dehydration. It was cool enough that I couldn’t feel like I was sweating excessively. The signs of dehydration include dry mouth, feeling faint and a rapid heart rate. Thinking back, I did feel a bit of a rapid heart rate as I descended the hill on the east side of the park towards Central Park South.

You can do things like test your sweat rate, but what if there was a way to test how to fuel for a long run…while on the long run?

There’s a new company out there called FuelStrip that tests your sweat to do just that. And you don’t have to go to some fancy lab or pay a million bucks. Their starter pack is $12.00 for two vials of testing strips and a pack of their chews.

So, there’s three different types of fuel your body uses for endurance: glycogen, fat and muscle. Most marathoners are very familiar with “hitting the wall”: this is when your body has burned through all of your available glycogen and typically happens around mile 20. Some runners work to become more fat adaptive so that they rely less on glycogen without hitting the wall, which is when your muscles are starting to break down because they are being used for fuel.

But how do you know when you’re in each zone other than that massive hitting the wall?

With these FuelStrips, you divide your workout duration by 4, and it detects the metabolites to let you know where your body’s “tank” is.

I haven’t been doing any really long workouts because I’m not marathon training, but I’ve tried it on some treadmill runs. My runs have been short and sweet but hard and sweaty, and I’ve tested after about 30 minutes, and I’m right in that yellow zone.

You just swipe it on your forehead like that. It won’t remove your wrinkles or make your dark circles any better, but it will tell you your fueling needs.

You’re supposed to take 2 chews for the yellow zone, which works out to about 60 calories. With these shorter workouts, I haven’t had a chance to try the fueling and strips together because I don’t typically fuel for runs shorter than 9-10 miles, but I’m really interested to try these out for longer runs. You know, once it warms up a bit and I get my long-run mojo back.

Would you ever use something like this? How often do you fuel – and what kind of cues do you use to tell you when to fuel? I typically just do about 100 calories for every 5-7 miles or hour…ish.