David Roche is back with something we wish we had read 10 years ago. David breaks down the exact mistakes that are costing you watts, minutes, and breakthrough performances and, more importantly, he tells you how to fix them.
The Top 3 Fueling Mistakes I See Athletes Making (and How to Fix Them)
Every part of training theory has been subsumed by the fueling revolution. I've never seen anything like it in coaching, and I think you could live 20 athletic lifetimes without experiencing a moment like this.
What training sessions work? What training week structure is best? How fast and hard can someone go? All of those questions have become nuanced ways of asking "How much can an athlete fuel sustainably in training and racing?"
I lived it as an athlete too. For 15 years, I had notoriously bad fatigue resistance. In our field tests involving hard efforts after 2 hours of moderate running (measuring the offset between fatigued and fresh performance), my scores were deep in an abandoned well hanging out with the girl-demon from The Ring.
My fresh numbers were solid before high-carb. Riding the high-carb wave first made my fatigued numbers get closer to matching up. But then, the most important thing happened: in my mid-30s, my fresh numbers skyrocketed because I was able to adapt better to training.
The best time to start high-carb fueling was 15 years ago. The second-best time is tomorrow. Here are 3 mistakes to avoid as you get going, modeled after how I learned the hard way.
Mistake One: Failing to buy into high-carb fueling during quality training.
I was a high-carb coach before I was a high-carb athlete. I saw athletes explode with breakthrough performances at 90+ grams of carbs per hour, but I was still slow on the uptake personally. In retrospect, I am full of regret at all of that wasted time. I guess I was subject to the same messaging about "fat oxidation" and "blood glucose" that holds back so many athletes even now.
I wish I could go back and re-live my 20s with the high-carb acceptance. When you're training, the burn rate is much higher than you'll be able to consume outside of wildly easy training. If you're fueling the work you're doing, it won't mess up your Hemoglobin A1c. And if you're training adequately, your fat oxidation rates will be sky high. Instead, fueling the work will increase metabolic rate and enhance performance, while also improving health outcomes.
Here are my 8 rules to apply for high-carb fueling:
During purely easy training days (defined as days in Z1/Z2) under 1 hour, there is no need to take mid-exercise carbs
On purely easy training days between 1 and 2 hours, 45-60 grams of carbs per hour is plenty
On purely easy training days above 2 hours, 60-75 grams of carbs per hour is ideal.
On easy/moderate long runs where the effort is not purely easy (like in an ultra), try to fuel at 75-90 grams of carbs per hour no matter what the duration
On moderate/hard training days (with Z3+ work) under 90 minutes, 60 grams of carbs per hour is ideal
On moderate/hard training days above 90 minutes, aim for 75-90 grams of carbs per hour.
Once an athlete is experienced and finds benefit from 75-90 grams per hour, they can experiment with 105-120+ grams of carbs moderate/hard training days above 90 minutes and easy/moderate training days above 2 hours.
In races, apply the lessons learned in Guidelines Six and Seven to determine carb intake, trying to max out totals (while doing gut training)
Mistake Two: Expecting fueling plans to work without gut training.
After our first kid Leo was born in 2022, my wife and coach Megan told me it was now-or-never. No more defense mechanisms allowed, where I'd call myself a "coach only" and refuse to race big events as a result.
Going all-in on ultras meant I had to go all-in on carbs. But I didn't go all-in on gut training right away. I am writing an article on mistakes, so you might be able to guess where this is going.
At mile 45 of the Canyons 100k in 2023, a gel hit my tongue and I did my best uncapped-blender impression all over the beautiful California trails. It was a BIG and POWERFUL explosion that some are calling "the most impressive vom session since The Exorcist."
I think that gut training is the most overlooked part of ultra-endurance. The principles are backed up in tons of studies that generally have these findings:
Carb-specific gut transporters can be trained in a very short time
The sensation of "fullness" can be trained rapidly
However, there are no set protocols, and the studies usually end with "do what you're going to do on race day." I think that's falling a bit short, though. Just like intervals train harder efforts than race day, gut training should train greater stress than race day.
Here are 2 levels of gut training:
Level One: Fuel a few moderate long runs with more carbs per hour than you will on race day, while fueling like race day on the other long runs. Studies show that gut transporters get more efficient at processing specific carb ratios with practice.I think this method only gets 50% of the way there, since it's impossible to simulate the demands you will feel late in longer races.
Advanced Level Two: Consume your hourly fluid needs within a shorter window several times, combined with Level One. Since the studies on gut training show that the "bloat" feeling can go down quickly, this method may prevent rejection later in events. Just make sure you have the need for hydration (don't do this prior to running), and that electrolytes are dialed in to prevent hyponatremia.
Mistake Three: Winging it with electrolytes.
While carb needs are relatively stable across the population (higher output or larger-bodied athletes need a bit more, but generally carb needs are tied to effort), hydration needs vary wildly. Heavy sweaters might have a few times higher sweat rate than light sweaters, and heavy salters might be 10 times above light salters.
What happens if you miscalibrate sweat rate? I have somewhat salty sweat, just over 1000 mg per 1 L fluid, and I used to violently cramp when I didn't supplement. (Anyone who tells you that sodium intake isn't tied to cramping does not live in the real world.) Meanwhile, athletes with lower sodium rates usually have terrible stomach issues when going too high.
And the hardest part? It's impossible to tell who is a heavy or light salter without testing (the salt rings on your clothes aren't good data, since everyone has those at times). I recommend that every athlete get a sweat test. Instead of aiming to see a precise number, the goal is to categorize yourself into one of 3 cohorts:
Light sodium: generally 200-700 mg per L of fluid, where sodium is less of an emphasis, but some athletes might need to specifically avoid salted sports drink
Medium sodium: around 700-1100 mg per L of fluid, where sports drink is the primary hydration option, usually with salt supplements at the upper end of the range
Heavy sodium: 1100-2200 mg per L of fluid (or higher), where sports drinks and salt supplements need to be a lifestyle during training and racing
Maintain a holistic view of the numbers, since sweat numbers change over time and even within events.
And that's a good takeaway message: general principles are good because they can adapt to new information, but strict belief systems usually aren't good because they are inflexible to evolve over time. In your fueling journey, you will make mistakes. Those mistakes will be essential for your breakthroughs... as long as you learn from them.
You all are amazing. Thank you for reading!
Want to start fueling like you know you should? A great way to start is with our Packs. Here you can find anything from high-carb gels and hydration mix packs to sport-specific ones like the Runner Box.
Matt's P.S.
The only thing I would add here is the importance of taking care of your gut when high-carb fueling. Happy Tummy is a simple one-sachet solution to do just that.
SwissRX Happy Tummy is what keeps your digestive system cooperating when you're pushing those high-carb intakes David's talking about.
10 billion CFU of targeted probiotics plus gut-soothing ingredients like Slippery Elm and 3g of L-Glutamine to fortify your gut lining.
Whether you're training your gut to handle 120g per hour or dealing with bloat from yesterday's long run, this repairs your gut. Mix one stick daily, and your gut will actually adapt to the fueling demands instead of fighting you.
Photo Credits: Peter Maksimow
