Sports Nutrition

The Ultimate Guide to Carbohydrates for Training and Racing

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Are you confused when you go to your favorite sport store as to which type of powder, gel, liquid or bar you are going to buy for your next endurance event? Do you prefer to use real food instead? This guide is for you, so you can make a sense of what is being sold and don’t get too caught up in the latest hype.

The simple sugar


At the bottom of the food chain there is the simple sugar glucose or also called dextrose which is the simplest form of carbohydrate. Glucose is in regular table sugar (also called sucrose or cane sugar) that we have in our household to add in our coffees or when baking. It is actually glucose and fructose linked together (scroll down for more on fructose). However, glucose alone has made a comeback in the Sports Nutrition industry and I’ve seen many athletes jumping on a product called *Glukos, which is basically what the name says: glucose (original right?). Other products such as *Skratch  and *Osmo have been on the market for longer and also contain glucose. These are more meant for re-hydration and I’ll explain why below.

Advantages: We have a lot of glucose receptors in our gut and this molecule gets easily absorbed in the blood stream giving a quick boost of energy. Glucose gets readily used by muscles during exercise and that’s a bonus.

Disadvantages: Here is the short list

-You can’t pack a lot of glucose in a solution without affecting the osmolality of the solution. The higher the osmolality the longer it takes for the stomach to empty its content. The stomach must draw more water in to dilute it. As a result, it takes longer to empty and can lead to GI distress, endotoxemia and inflammation. Not good. Product like Skratch and Osmo are designed so that their osmolality is just right so it does not affect the emptying. But what if you decide to eat some solid food on top of that? Then it all goes haywire and slows down everything.

-It can make you crash. Yes, your body sees a high concentration of blood sugar, it reacts by bringing it way down via insulin and the working muscle and leaves you with an empty feeling. The only way to remediate is to have another dose, again and again and again leading potentially to GI distress.

-In theory, it can shut down lipid metabolism. Your body won’t be able to use this endless reserve now that you have that much sugar on board, again leaving you with that crashy feeling.

When to use: Given what I just mentioned the best time to use something with glucose would be at the end of a long race to give you a final kick, or before short very hard races such as a < 5K.

The other simple sugar

Another commonly used simple sugar is fructose. Fructose is often added in gels and is naturally present in fruits and vegetables. Fructose does not raise insulin as much as glucose therefore is lower on the glycemic index. But it also does not regulate appetite as well and can lead to over-consumption, so beware.

Disadvantages: Fructose enters the body via a difference receptor which is less dominant than the glucose receptor. That is why one has to be careful when eating fructose. Eating too much fructose can lead to gastro-intestinal discomfort as fructose will not be absorbed as much in the gut.

Advantages: for the same reason, since fructose and glucose do not enter the body via the same receptor fructose is a good addition to a sport nutrition strategy. It will enable absorption of more carbohydrates and therefore could result in enhanced performance.

When to use: during long events when more carbohydrates need to be ingested, fructose is a good complement. Make sure that the ratio of fructose to glucose does not exceed 1 to 3 to be safe.  Most fruits and other sweetener will have a ratio of 1:1. Check here for more info.

Question: What is coconut sugar? Is that a good option?

Coconut sugar is sugar! And very close to table sugar with maybe a little bit more nutrients. But marketers want you to believe that it is a healthy alternative to sugar. Well unfortunately not…So beware and look on the labels.

A notch above the simple sugar


A more complex carbohydrate is maltodextrin. Maltodextrin is a starch that has been slightly broken down. Read below to know more about starches. It is often used in gels and digest more slowly than simple carbohydrates

Disadvantages: it doesn’t empty the stomach that quickly but still better than simple sugars for same amount.

When to use: Maltodextrin should be use in my opinion like glucose more for short efforts and at the end of long races to give a final kick.  It could be used during if the dose is divided, so one doesn’t have too much at a time. A whole gel has 22 g of maltodextrin, clearly too much. Divide it in half for a more sustainable effect.

Question: I heard that cyclic maltodextrin is a better option?

Cyclic maltodextrin is a maltodextrin that has been branched via an enzymatic reaction so that the osmolality is lower for similar amount of maltodextrin. Therefore, it is easier on the stomach. Worth trying if maltodextrin is not for you. EFS-Pro* by First Endurance contains a mix.



Simply put, a starch is a chain of glucose found in plants. The chain can be highly branched, we call it amylopectin or more in a straight line, we call it amylose. The higher the amylopectin, the faster it will be converted to glucose in the blood. Did you know that glycogen is the animal equivalent of starches in plants?  Starches can be found in the Sports Nutrition market. UCAN super starch* is one of them. It has been modified to make it even harder to digest and as a result glucose from this starch takes much longer to appear in the blood.  Another example is Vitargo*, a starch that digest very quickly and is a little bit the opposite of the previous one. Of course, you can also get starches from real food such as potatoes and rice. Notably sushi rice and waxy maize are very high in amylopectin and therefore readily accessible by the body

Advantages:  Starch are usually slower to digest and depending on the brand you buy, it can be very slow or faster. Because they are slower to digest it will enable the body to keep burning fat as fuel which can definitely be in advantages for longer events but again it will depend on the type of starch and the dose. Also, since starches are more compact, they don’t rise osmolality and they will empty the stomach much more quickly than maltodextrin and glucose

Disadvantages: Since these starches are digested more slowly it can be at a disadvantage depending on the type of event that you are doing.

When to use: As you might’ve guessed starches are very useful for longer events. Since the intensity is a little lower you won’t need as much glucose a once but need to sustain a certain level.  Starches will enable you to keep burning fats. But remember, not all starches are created equal and some starches are actually designed to digest more quickly such as Vitargo, so try before.

There are a ton of carbohydrate forms out there and these are some of the basic ones.  It’s always good to experiment with different kinds either alone or in combination to make sure your body will be able to utilize them when it needs it. Consult with a good sport nutritionist to fine tune what will work for you!

*I’m not sponsored by any of these and will never be. Well, never say never. I would not say no to a million dollars.


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