This blog investigates certain carbs are metabolized faster than others. The best carbohydrates for exercise are those that are quickly emptied from the stomach, do not require digestion or are digested extremely fast, are absorbed quickly, and may be utilised right away by the muscle.
A brief summary
Since the 1980s, it has been known that eating carbohydrates while exercising can increase performance for workouts lasting two hours or more.
Following this finding, it was quickly determined that not all carbs are created equal and that they can be metabolized differently depending on the type of activity. Additionally, it has recently been shown that there is a dose-response link between the quantity of carbohydrates consumed and oxidized and exercise capacity. Therefore, it's crucial to discover carbohydrate sources that undergo fast oxidation.
The best carbohydrates for exercise are those that are quickly emptied from the stomach, do not require digestion or are digested extremely fast, are absorbed quickly, and may be utilised right away by the muscle. The review papers indicated at the bottom of this blog, which are completely free to download, are recommended to readers who are interested in further information because this blog is based on several research and references.
A drink can only contain 60 g of carbohydrates every hour
Regardless of the kind of carbohydrate consumed, the rate of oxidation during exercise cannot exceed 1 g/min (60 g/h). Therefore, even if you ingested high amounts of glucose, like 100 g/h, only 60 g/h would be used. This is supported by guidelines issued by the American College of Sports Medicine (ACSM) between 2007 and 2009, which suggested that athletes should ingest between 30 and 60 grams of carbohydrates every hour of activity. In one research, even when carbohydrate was consumed up to 3g/min (180g/h) (a "don't attempt this at home" consumption), the rate of oxidation was only 1g/min (60g/h).
Exercise-related carbohydrate ingestion can only be oxidized at a rate of 1 g/min (60 g/h).
Distinctive characteristics of carbs
All carbs can be oxidized at rates of around 60 g/h, while some are quicker than others. The quicker carbohydrates are maltodextrins, certain starches, glucose (grape sugar), sucrose (table sugar), maltose (milk sugar), and sucrose. Additionally, certain starches have a very high rate of oxidation. Galactose, trehalose, fructose (fruit sugar), and certain starches are examples of carbohydrates that digest more slowly (those that are not very well soluble in water).
It appears that neither the breakdown of the extremely long chain of glucose molecules in certain starches, which is seen in maltodextrins (a chain of 10–20 glucose molecules), nor the digestion of these molecules is limited. Galactose and fructose, on the other hand, are taken more slowly and must first undergo hepatic conversion before they can be used by the muscle. The conversion of fructose, for instance, into glucose or lactate, both of which are excellent providers of energy for the muscle, slows down the process.
While certain carbohydrates can be metabolized more quickly than others (at rates up to around 60 g/h), no one carbohydrate can.
It is known that eating large amounts of fructose—without consuming any other carbohydrates—can cause gastrointestinal discomfort. Galactose has shown the same behavior. It is advised to pick a carbohydrate that is quickly oxidized during exercise to prevent gastrointestinal bloating.
The majority of commercially available carbohydrate beverages marketed at endurance athletes mostly contain glucose and sucrose as sources of energy; some products have maltodextrins or quickly absorbed starches. In terms of providing carbs, each of these carbohydrates is equally advantageous.
The taste of carbohydrates varies as well; examples of extremely sweet carbohydrates are glucose, fructose, and sucrose (sugars). Maltodextrins and starches don't have any discernible sweetness, or rather very little sweetness. This might be crucial when making a homemade beverage that is tailored to your preferences.
Advice for real life
These studies' straightforward recommendations for action are as follows:
- Use a carbohydrate that can be metabolized quickly, such as glucose, sucrose, maltodextrin, or soluble starches. You may purchase or manufacture your own beverages using one of these carb sources (and even some solid sources if carefully selected).
- If you utilize a carbohydrate source that consists mostly of one kind of carbohydrate, consume no more than 70 g/h (30–60 g/h is recommended).
- Refrain from drinking beverages that are solely fructose, galactose, or other slowly oxidizing carbohydrates.
- The 60 grams per hour cap can be exceeded, and employing specialized carbohydrate mixtures, it is really feasible to increase the amount of carbohydrates ingested by the body. I'll go through this in my upcoming blog.
Deep dive sources
- Jeukendrup A. A step towards personalized sports nutrition: carbohydrate intake during exercise. Sports Med. 2014 May;44 Suppl 1:S25-33.
- Jeukendrup AE. Nutrition for endurance sports: marathon, triathlon, and road cycling. J Sports Sci. 2011;29 Suppl 1:S91-9