Carbs for 1 hour workout - a conundrum

I forget the exact episode, but there was a question a while back about CX riders with gels taped to their top tube to take during the race. And the gist of the discussion was that it was no help, and @Jonathan even brought up his continuous glucose monitor data while taking in carbs and showed that it took anywhere from 30-45 minutes to hit your blood. So the conclusion was that taking a gel for a 1-hour race had no benefit.

So what’s the deal with 1-hour workouts? How is that any different? If I hop on the bike, are they saying that taking in carbs is no use? If it had a recovery benefit, wouldn’t that be the same for the CX racers? I’m just a little confused why taking a gel for a 1-hour race has no benefits but taking carbs for a 1-hour workout does.

And I’m specifically talking about 1-hour rides, not longer. Obviously things change for long rides. The talk was specific to 1-hour CX races.

Edit: For the record, I’m of the opinion that carbs always help. And the crew usually are, too. Which is why I thought it was odd they were saying that there weren’t any benefits of taking it during the race.


Most cx racers take the gel at the start row


N=1 but for any one hour effort I would always make sure I’ve eaten well before but wouldn’t take in carbs on the bike, although in exceptional circumstances eg v hard workout I might but it feels to me like a bit of a placebo really.


Usually have 3 scoops of Gatorade endurance for a couple reasons. First is there is an effect where even swishing carbs in the mouth can lower RPE, this helps during vo2 and other hard intervals. Second, I try to train my gut to digest carbs and get used to having carbs move through the system while under load. I don’t “need” the carbs tk do the work, but i feel the benefits are worth it


I’ve heard this before. And to tell the truth, I carry a bottle in CX races. In nearly every race, there is a portion of the course that I can get a big swig. If nothing else I get the sugars in my mouth and may makes things feel ever so slightly easier.

Agree. I always try. But sometimes I can’t and have to hop right on the bike and rely on whatever I ate that day. I still usually take in carbs during the workout.

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The difference is with training you’re always trying to stay on top of the nutrition for the rest of the day and the next workout and the next week. If I do a 1hr threshold workout, and take in nothing I’ll be around 1200 calories behind on fueling that day. If I eat 400 calories during, then I’m only 800 behind and my bodies slightly less depleted 2hrs later, 4hrs later…etc

With a race, it might be okay to end up in a deficit by the end if you have enough carbs on board to finish strong. The downside of being in a 1k+ calorie deficit by the end might be outweighed by the convenience of NOT having to drink during the event, not having to carry a bottle, not having to take your hands off the bars, not having to open and suck down a gel while potentially missing the race winning move.


Having to think about nutrition during your race, may also have a nagative impact

Well I TT not cx but in a flat out 25 I wouldn’t take anything…that said I would have had a big bowl of porridge 3 hours before and a protein shake or big piece of cake after - cake is what it’s all about in the UK TT scene :laughing:


This is very individual, and depends on the form of carbohydrate. I have worn a CGMs several times as part of research. My blood glucose levels rise within 5-10 minutes after eating straight sugary food with no fiber, fat, or protein. My glucose curves after eating gummy bears and donuts are very clearly different. I barely see a rise from 40g sugar in donuts. If I eat 10g of sugar in gummy bears it spiked up to 140ish within 15 minutes and is back to normal in 30. Also, if you are depleted of glycogen and then have carbs, it doesn’t rise as much either, at least in my experience. I once did a fasted ride and then had oatmeal after and it barely moved (I did this for fun while I was wearing CGM, I don’t do fasted rides ever).


I train early in the morning and don’t have time to eat beforehand. For Z2 and SS workouts I typically just have a bottle with a scoop of Scratch, mostly because I prefer the taste over plain water. For threshold and Vo2 workouts I’ll add a couple tablespoons of pure maple syrup to the bottle, and usually drink most of it during the warmup. I also like to munch on gummy bears. I can definitely tell a difference if I don’t drink that mixture and eat gummy bears. Whether that is RPE or not, it makes the workouts “easier.”

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1 hour conundrum? I’m an afternoon rider so my carb stores are topped up before riding. No need to take carbs for a 1 hour ride, and depending on breakfast/lunch carb consumption, and the timing of post-ride dinner, I often don’t bother to take carbs for 2 hour workouts or fast group rides. I’ve tried drinking carbs, and no change in RPE or performance. Again these are afternoon rides/workouts. If there is a big gap between lunch and the ride, I’ll eat two bananas while headed to the garage. Big post-ride gap to dinner and I’ll eat 90g late into a 2 hour ride.

Mornings are a completely different story. At an absolute minimum wake up and slam 8 ounces of tangerine juice. I’ve gotten lazy, and see a performance gap between morning/afternoon, so I avoid morning workouts except on Saturday.


There is a classic series of studies performed on cyclists doing 40k time trials. First, they gave one group carbohydrate and the other placebo. Carbohydrate cohort outperformed but that didn’t make sense because everybody has enough stored glycogen for an hour effort.

Then, they gave one group carbohydrate and the other placebo. This time they INFUSED the carbohydrate & placebo. No difference in performance.

Finally, they gave just a mouth rinse. Carbohydrate outperformed again. Of course, you know this story.

The lesson I take away from all that is that yes, consuming carbohydrate during an hour effort can help performance…but not because of the impact of digested carbohydrate. There is something else going on and you’re just as well to use a sweetened rinse.


Something else going on… I tell myself a story - a mouth rinse primes the body to burn carbs. No idea if thats true or not, but thats my story. So I figure snarfing a handful of blueberries as I walk out the door is good enough. Or a banana. Because who has time to use tangerine juice to rinse the mouth? And the wife would kill me for wasting precious tangerine juice.


:joy: I was gonna say…


It would be interesting to see if mouth rinse results could be replicated with artificial sweetener.

I have 100% performed better in 30-45 minute crits when having a carb drink. I’ll typically take 3-4 sips as I get a chance. It can’t be more than 10mg. I told my brother one day “it is like a signal to my brain that I have energy readily available so I can burn as much rocket fuel as I need”.

Alternatively, sugar releases dopamine when you eat it. Dopamine has all sorts of effects on performance that are well documented. Potentially, the infusion did not facilitate a release in dopamine, while ingestion or mouth rinse does.

edit: affects to effects


Just like Timon said.

thats right, tell the body to bypass the fat and go straight to the rocket fuel!!!

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They aren’t. (PLA=saccharin)


thank you!

I think that the theory with mouth rinsing (but not digesting carbs) is that the body gets a signal that carbs are available to ingest if needed. From this signal it’ll free up stored carbohydrate it might have otherwise tried to conserve, if stores were low. The body trying to ensure you never completely exhaust available carbs.