Hey everyone!
I’ve been amazed and a little caught off guard by the carb craze going on in the endurance community. And at first, I was somewhat averse to the idea that we should be choking down immense volumes of carbs even during easy aerobic training – intervals and racing I understand, but all the time? In the past year I’ve started getting targeted instagram ads and emails from endurance fuel brands preaching that more sugar equals more power and performance. To me, that seems like a good message to spread if you’re selling sports gels.
On a physiological level, I was curious whether loading one’s system with carbohydrates during exercise where the primary stimulus is fat oxidation (aerobic respiration) would be wise. By loading your system with simple carbs during aerobic training, would we not accidentally train our bodies to use glycolysis and metabolize sugar even at lower efforts? Obviously in cross country skiing, where most of our races are <60 minutes, having good anaerobic metabolism is paramount; but it seemed counterintuitive to me to push carbs so much during aerobic training.
I took my questions to a local sports physiologist and coach in Tom Cuddy. He has done metabolic testing for us over a couple years and has a great understanding of this stuff. And in short, my doubts were wrong! Tom talked me through energy expenditure and replenishment during aerobic training, using my own metabolic data, to show that consuming 40-60g carbs per hour makes up for less than 30% of the energy I’m expending during easy training (likely more like 15-20%). This level of intake during easy training wouldn’t nearly override the aerobic system with glycolysis. Rather, under a typical training load for a professional athlete, the benefit of exogenous carbohydrates is to help the upkeep of blood sugar levels; low blood glucose during training can lead to high levels of cortisol, increasing overall stress on the body. This can result in the breakdown of muscle tissue to be used as fuel, and increases the load and recovery time from the training session (harder to absorb gains).
While this is positive, high carb intake isn’t necessary or beneficial for every session or every type of athlete. My conversation with Tom was in the context of my summer training, where I have a high chronic stress load from the high volume of training and am frequently depleting muscle and liver glycogen. High carb intake isn’t as important for sessions lasting less than 60-90 minutes. And for athletes training less frequently and with less volume, the body doesn’t have that same stress background and caloric demand that high carb fueling can ease.
Long story short, I’m convinced that supplemental carb intake is, more often than not, beneficial for my training. I still bring real food snacks like fig bars and granola bars. But now I’ll typically supplement with 30-50g/hr of carbs in a more digestible form – more for interval and race days.
If you’re still with me here, all this brings us to the more fun part of this blog: what’s the best carb source during training?
Through high school and college I was all in favor of chews: think Clif Shot Bloks and the likes. One time in college I had a good race using Probar Bolt Chews, and so that was the pre-race ticket for the next 4 years. Five to six Bolt chews during warmup (totaling ~23g of sugar) and the occasional Gatorade in the drink belt was all I was working off. I was turned off to gels because I didn’t like the consistency of the Gu brand. This summer, however, I had a bit of a gel renaissance. I “discovered” other brands that were much tastier and lighter feeling in my stomach. I found it was much easier to get more carbs down and far easier on the stomach. Before getting into my gel review, I’ll say that I recently went full convert and started making my own high carb drink mix, as Reid, Simon, and Noel have been for a while now. The concept is similar to theirs in that I mix maltodextrin and fructose to the ratio I desire, except I spent a little more money to add sodium alginate and pectin in small quantities to my mix. These are the ingredients Maurten uses as gelling agents in their industry-revolutionizing $100 million hydrogel innovation. When these ingredients meet the acidity of the stomach, they create a gel that is fast tracked to the small intestine where carb absorption is most efficient. (A tip: grocery store jam/jelly pectin contains some citric acid which will cause the gelling agents to thicken the drink mix before being consumed.)
I used my new mixture regularly for the first time at our training camp in Canmore and loved it. I’d mix 80 grams with half an LMNT stick for the 2-3 hour distance sessions, and 100g for the interval and race days.
Sometimes in races and workouts you need a carb boost without all the liquid. So what gel would I take during a 60 min threshold session, or a 4 hour trail race, or the Birkie, for example?
The bottom line for me comes down to carb density and flavor/eatability. Most of these gels are engineered to deliver carbs quickly and minimize gastro intestinal stress (not gu roctane) (i mention a few other exceptions later on). Here’s my thoughts on every gel I’ve tried since my gel renaissance began:
Gu:
Only 23g of carbs, which doesn’t feel like enough for the struggle of getting it down. I don’t like the texture. Won’t be using these. And - never ever ever ever using a Gu Roctane again. I've been hurt one too many times.
SIS isotonic:
Unlike other gels on this list, the only carb source in these gels is maltodextrin, so they're 100% glucose. This among other reasons is why I haven't gone back to them. To my own dismay I have not tried SIS Beta Fuel yet, but these isotonic gels were 10 for $10 on the feed which was way too good of a deal. They pack about 22g of carbs, and despite a slightly higher volume they’re quite thin/liquidy and light – I feel like I could easily take two at a time. The consistency is a little odd though, and the green apple flavor is gross. Cheap at <$1.50
Enervit:
Comes with 30g and 40g; I’ve only used the 30g (screw top version). I tried these in Sweden during our training camp and liked them. The flavor is a bit tangy which might surprise some, but goes down pretty well.
Maurten:
(1:0.8)
25g of carbs and all the science you’d ever want. The hydrogel is pretty thick but also doesn’t freeze easily (+++birkie). It is unflavored, and ironically I find the flavor aversive– if it’s going to be sweet (which all gels will be) I need some sort of flavor acidity to help. While every other gel on this list has a 2:1 glucose to fructose ratio (except the sis isotonic), Maurten proudly has a scientifically optimized 1:0.8 ratio. And the gel is way overpriced.
Precision:
Similar to Maurten - unflavored and a bit bland and sweet but a little more pleasant and easier to swallow due to the thinner consistency. This one has 30g of carbs that sit lighter than that. This is Erin’s favorite gel.
CARBS FUEL:
Best carb/$ on the list, and about as basic as it gets. No flavors, fancy hydrogels or gelling agents, nothing, just maltodextrin, fructose, water, and a bit of salt. These have been awesome for training because they’re so cheap and have such high carb density. I did opt to use these heavily during the Rut 28k trail race this year while I experimented with forcing higher carb intake, however, I've found I liked them better during long, tough ODs. I crushed 5 of these along with Skratch and some stroop waffles to get through a 5 hour gravel ride without any sign of bonk. I think some of the science-y features are better for race day performance though.
Never 2nd:
In full transparency I’ve tried one of these but it was amazing. A very thin and light consistency, so easy going down. Super pleasant light citrusy flavor, and packs 30g of carbs that sit in the stomach like half that. Definitely recommend especially in the citrus flavor. The only reason I haven’t bought more yet is that they’re as expensive as any gel at $3.50.
There you have it. A little bit of nerd out and some good old fashion product review! Hit me up if you have questions about fueling etc, I love chatting about it.
✌️ Willson
