Although I’ve been running for four years and doing triathlon for three, I still am not confident in my fueling strategy. It has been an ongoing experiment for me to figure out what my body needs to fuel itself for workouts and races. Trial and error has been my only method and I have been anything but consistent in tracking it.
Every run and race is under different conditions and our body reacts differently depending on many factors – temperature, humidity, altitude, your heart rate, the amount of sleep you got the night before, what you ate for dinner or breakfast, how much caffeine you have in your system, if you had a drink or two (or more) the night before, how rested you are, and even for women, where you are in your cycle. One method of fueling one day may not work the next so it’s very hard to know what will work.
Lately, I have been training based on heart rate and a lot of my heart rate training is in Zone 2. When we are working in this zone, our body uses more fat for fuel compared to glycogen. When we work in higher zones, for example while doing a tempo run or during a race, we burn more glycogen and less fat. Our bodies have limited glycogen stores and when we dip too low, our energy levels can plummet and never return to normal (in a marathon this is hitting the wall). For endurance athletes, knowing when to fuel can be the difference in a PR or age group podium and a bad race. Unfortunately due to the aforementioned factors that can change how much fuel we need during each run, it’s hard to know how much we really need.
A product called Fuelstrip can help athletes take the guesswork out of fueling. When your body begins to run out of glycogen and use muscle for fuel, your body produces metobolites. Fuelstrip has created a technology that can detect metobolites and therefore indicate how much glycogen you need to refill your stores. To read more about the science behind Fuelstrip, read here.
The technology takes form in small strips that are easily stored in pockets, water bottle cases or bento boxes and can be used during activity to test your sweat. It is recommended that for hard efforts until 1 hour to test your sweat every 15 minutes and for efforts over 1 hour to test every 30 minutes. The strips contain a tiny square which when swiped on your sweat will change colors – orange for a full glycogen tank, yellow for 3/4 depleted, yellow for 1/2 tank and blue for 1/4 tank. Corresponding with these colors are suggestions on how many Fuelstrip chews or how much Fuelstrip carbohydrate sports drink to consume (30 calories each – 1, 2, 3 or 4 respectively).
I tried the Fuelstrips twice – first during my 2 hour long run last weekend and second this morning during my 90 minute trainer ride which was followed by a 60 minute aqua jog (thank you ankle sprain). One of my fueling concerns during my Zone 2 long runs is when to take fuel. I’ve notice that since I’m in the “fat burning zone” I definitely don’t need as much as I used to take (which was 1 Gu every 35-40 minutes). Fuelstrip confirmed this by indicating at 30, 60 and 90 minutes that I only needed 1 chew for a total of 90 calories for a 2 hour run. However, on a more intense run, I would likely have tested for higher caloric needs. Not all long runs are created equal.

This morning on the bike I first tested orange, meaning only 1 chew, but by the end of my 90 minute ride, I tested yellow, meaning I needed 2 chews now to sustain myself for my aqua jog. I took an extra chew knowing I wouldn’t be testing my sweat in the pool and had high energy throughout the workout. I’m really looking forward to using this on a harder effort run to see how my caloric intake increases with intensity. I’ll have to wait until the ankle heals for that one though unfortunately!

Fuelstrip has recognized a need by endurance athletes and has successfully met it. It takes the guesswork out of fueling and puts the power in our own hands. If you’re curious about Fuelstrip and want to give it a try, I’d recommend the starter pack at only $12.
Do you have a tried and true nutrition routine for training and racing? Would you try something like Fuelstrip?
I was compensated for this post but all opinions and stories are truthful and my own. I would not write about a product I don’t believe in and never do.
Hmm- very interseting product. And kind of crazy how little fuel you need when not running hard.
I never know if I’m fueling properly, and unfortunately never do the same thing or even remember what I did the previous time so have to totally go by fuel. So far, it’s worked ok for me, but I’m sure I could get better or at least scientific!
How’s your ankle doing? How are you feeling about it all? Is it kind of nice to bike?
The ankle has made a lot of progress! The swelling is way down and the bruising (which appeared on day 3) is going away and there is little to no pain. However I’m not allowed to run on it until its been 2 days since the swelling, bruising or pain is gone … Hoping for a run next weekend but we will see. We haven’t talked about what will happen to Phoenix yet – bracing myself for the worst because I don’t want to race it if I’m not in the right shape for a BQ so we will see. I still got in nearly 8 hours of workouts last week but only 3 miles of running so I’m not sure how that will affect my fitness. Boo!
I have never heard of Fuelstrip. I would definitely be interested in trying it. Sounds like it is working for you and will be interesting to see when you start running again!! I feel like I used to not take in as much and that was a problem but now I take in more but maybe that is bad!! Fueling is harder than training! 🙂
Hope your ankle is feeling better!!
Had no idea such a product existed. Very interesting.
I had some testing done on a New Leaf Metabolic system. It created a custom profile that I could upload to my Garmin. It shows me (almost) exactly how many calories I’m burning, including how many are fat calories. It’s been a very helpful tool for avoiding under/over fueling.
Wow that sounds awesome! My Garmin tells me calorie burn but I never assume its right. What a great tool!
Does it help you stay in front of what you need? I mean, if it says you need two chews, how much does it know to process by the time you are behind in nutrition? Does that make any sense? lol
I think the goal is not to ever need 4 chews by keeping up with the testing so you don’t fall behind… But I’m not sure! I think it’s also good bc it keeps you thinking about it!
Very interesting product! I’m intrigued…