On the Bike Fueling - Carbohydrates

Have you ever read the articles about 100 year old people saying their secret to longevity is smoking and a daily shot of whiskey? What worked for them probably would’ve killed most others decades earlier. I don’t believe there is ever a one sized fits all approach for everyone. However, I do believe that the one sized fits all approach is a great place to start and branch out from, if necessary. If branching out works for you then it works, no matter what the articles and science says! I try to keep an open mind but I think many times people branch out when it isn’t necessary and encounter unforeseen consequences. Even unseen consequences! What makes sense for someone like Pogacar might not make sense for you. I think this topic is a good example.

How many grams of carbohydrates should I consume while exercising?

When I first started racing twenty years ago the science suggested that 30-60 grams of carbohydrates per hour was tolerable for the stomach and improved performance. It said consuming more than 60 grams per hour was not necessary because the body was not able to absorb any more than that. It says still that past a certain point more carbohydrate consumption can lead to a decrease in fluid absorption. This obviously is one way to become dehydrated.

Nowadays there are articles everywhere that say 90-120+ grams or more improves performance. This specific study referenced doesn’t convince me that 90 grams is better than 30-60. The participants were split into three groups - a placebo group consuming water, a group that consumed 1.8 grams/hr of glucose, and a group that consumed 1.8 grams/hour of glucose/fructose. The glucose/fructose group performed the best (many studies show glucose/fructose is better so take that into account when choosing your drink mix), followed by the glucose group, followed by the water placebo group. The question I have is would a 1.8 gram/hour group perform better than a 1 gram/hour group? I hope to find that study one day. This study only reinforces what we already know, that carbohydrates improve performance and that 1.8 grams/hour can be tolerable.

There is quite a range of what experts suggest, companies are selling and what successful athletes consume.

Why have carbohydrates at all?

Let’s back up a moment. Carbohydrates are needed for high intensity exercise. When we run out we will go backwards when everyone else pushes hard up the hill or sprints to the finish line. Also, fat burns in a “carbohydrate flame.” When carbohydrates are broken down their byproducts are used to produce energy aerobically. So running out of carbohydrates even impairs our ability to burn fat. That’ll really slow us down!

Our body can store around 400 grams of carbs in our muscles and 100 grams in our liver (~2000 calories). We could go quite far on 2000 calories worth of carbohydrates. In theory we wouldn’t need any extra carbs for a one to two hour race. So why consume carbohydrates for shorter races? It turns out that consuming carbs before an activity actually increases the amount of carbohydrates our bodies will utilize during the activity. Consuming carbohydrates during our warm up for even short races will improve our performance.

Why not just start with 90+ grams and call it a day?

There are a few reasons already mentioned above. One is that it can lead to dehydration. Gatorade was one of the first sports drink to find that beyond a certain carbohydrate concentration fluid absorption decreased. That concentration is around 8% and above. If we dump a bunch of scoops of drink mix into our bottles we could be causing ourselves to prematurely dehydrate.

Another reason is stomach upset. It’s possible to poop your pants if you down a bunch of simple carbohydrates, especially in liquid form. This is one thing that does seem trainable over time. Tadej Pogacar thinks so too. He said, “and with our nutritionist he designed very good gels and drink that's easy on the gut. Since they created this product I don't have stomach problems. 5 years ago I always go shit my pants after the stage-races or long races and now even eating 120 grams no stomach problems." Even if consuming 90+ grams per hour is the right move for you, make sure you take small steps and build up a little slowly to get there.

*One important side note - speaking of professional athletes. Racing the Tour de France is probably way harder than what we are doing in our training. Pogacar not only has to worry about being fueled for each stage but for many stages to come. If he doesn’t fuel optimally and replace his muscle glycogen on stage 12 he may bonk on stage 16. He needs to make sure to get as much fuel in as possible, which is hard to do when you’re racing for six hours a day, sleeping for eight to ten, going on the post race podium for an hour, getting a massage, showering, and all the other stuff that he has to do. It’s probably hard for him to find the time to physically eat enough calories during a three week event like that. Even if he can’t absorb all the calories during the race they are in his stomach ready to be absorbed after the race. When you think about it, it makes a lot of sense that Pogacar would need to consume more during the Tour than you and me in our training and racing.

Back to another reason to consider. It might not be necessary for our training and racing. If we start with 2000 calories worth of stored carbohydrate and stick with 60 grams (240 calories) per hour, it’d take a very long race to “bonk (run out of carbs).” For me personally, I have been able to average 343 watts for three hours of continuous pedaling while consuming 60 grams per hour without bonking. Three hours of pedaling can be up to a four hour race. For an amateur like me four hours covers almost every race I do. That’s just me. For others, four hours may not even get them halfway, and they may benefit from more!

For most people I would recommend starting out with 30-60 grams per hour and see how it goes. If you can get away with 30-60 grams you could avoid these potential negatives associated with too many carbs.

One last thing to remember is that for most of us it’s not easy to get to or maintain race weight. If we are consuming more on the bike that we need or is even helpful then it’ll make things that much more challenging.

When you may consider 90+ grams/hour

• If you’re bonking all the time - if it’s not your fitness or off-the-bike nutrition, you may benefit from more on the bike.

• If your ride/race duration is very long.

• You train many hours a day and/or are a professional athlete.

• You have a hard time maintaining your weight.

Things to watch out for when trying out 90+ grams/hour

• Dehydration - if your heart rate increases at the same power output during a ride then you are probably experiencing dehydration.

  • Check out this video showing how to easily spot dehydration in your post ride data.

  • Another way to measure dehydration is weighing yourself pre and post exercise. Almost all of the weight lost during exercise comes from fluid loss. If you lost 2% or more of your body weight then dehydration decreased your performance! For every pound lost you’ll want to drink 16 ounces of water. Not too fast.

• Stomach upset, diarrhea

Either of these things are obviously worse than the risk of bonking. If these things are happening you may need to consume more water (if possible), decrease your rate of consumption for now and slowly build back up in training (allow your gut time to be trained), or consider that 90+ grams is not for you!

Long story short

Decide if going beyond 30-60 grams/hour is necessary for you and your goals. For many it won’t be. If it is then slowly build up to 90+ grams while watching out for dehydration and pooping your pants.