>Short answer: No, but with a HUGE caveat.
Long answer: Here we go…
Carbohydrates are needed as fuel for muscle contraction. A typical human can store enough muscle glycogen for roughly 60-90 minutes of strenuous exercise. After that, your stores of readily available glycogen will be very low. You’ve gotta either seriously back off the intensity, or run a serious risk of bonking (no longer enough blood sugar for the brain – dizziness, jelly legs, and disorientation are common symptoms of a bonk). How do we combat this? By consuming carbohydrates during exercise. There are countless choices for your CHO source, but time and again, I advise my athletes to consume gels, specific sports drinks, bars, and blocks. (disclaimer: I always roll with Clif products, but I do recognize that other companies out there are also making some good products, specifically Gu, EFS, and Power Bar).
So what do we want in a CHO source? Multiple studies have shown that a mixture of sugar types is the way to go. A glucose:fructose blend has been shown to promote higher carbohydrate oxidation rates than glucose alone. The blend, when compared with pure glucose, is associated with improved performace, increased fluid delivery and lower probability of GI distress (Jeukendrup). O’Brien et. al., showed that an approximately equal mixture of fructose:maltodextrin had similar benefits when compared to a blend that was predominantly maltodextrin.
Why the benefits? It is suspected that different sugars are going through different transport pathways, and therefore, the sugars are more readily digested and delivered to muscles. Consuming only one type of sugar can cause a specific transport pathway to get “backed up”, and thus CHO delivery hits a bottleneck, and your performance suffers.
This is where the gels/drinks/bars/blocks come into play. Surprise (surprise!) but some of the people at sports nutrition companies actually know what they’re doing and they want to produce good products. It’s easy to find the carbohydrate blends in sports nutrition products – just look at the ingredients and nutrition info. Any reasonable product will tell you exactly what carbohydrates they use. Some will go so far as to tell you the ratio, and some don’t. If no ratios are listed, then just look at the nutrition label. It should have “Carbohydrates” and “Sugars” listed. All of the sugars will likely be some combination of glucose and fructose. Any remaining carbohydrates will likely by maltodextrin (i.e. if there are 25 g of carbohydrates, and 10 g of sugars, then that means there are 15g of maltodextrin).
I advise all of my athletes to use these specially made products (although I generally only recommend Gu, Power Bar, or Clif) because these companies produce carbohydrate blends in desirable ratios, have different caffeine levels in various products (so you can closely control caffeine intake), and they come in packaging that is convenient to carry and use during exercise.
Could you use other carbohydrate sources (bread, bananas, etc…)? Sure, they’re cheaper, and in some cases, they can work well. But you have to be very careful. “Normal” foods will often come along with excess nutrients that may hinder performance (fiber, fats, excess protein, etc…), and you will have to put some effort into getting a good carbohydrate blend. Something like white bread with jelly on it comes to mind as a decent CHO source, but really… who wants to carry a bunch of bread and jelly with them while running? Not me. I’ll keep using my Clif Shot gels and Clif Bloks, thanks. (also- where are you getting your sodium from if you’re relying on bread/jelly/bananas/etc…?)
The most important thing to remember is, when in intense activities, you only want to give your body exactly what it needs at that moment. You can worry about vitamins, protein, fats, etc.. when you’re sitting around eating dinner.
1) Jeukendrup, AE “Carbohydrate and Exercise Performance: the role of multiple transportable carbohydrates”
2) O’Brien WJ, Rowlands DS “Fructose-maltodextrin ratio in a carbohydrate-electrolyte solution differentially affects exogenous carbohydrate oxidation rate, gut comfort, and performance”
Until next time… keep training hard, and resting harder,