Cycling is one of the most popular recreational and competitive sports nowadays, with the cycling industry and government reports suggesting record sales and participation levels respectively1 . From a scientific standpoint, cycling is also one of the preferred sports for measuring the effects of nutrition on performance. This is because of the ease with which studies on cyclists can be conducted. You simply pop the subject on a stationary bike; connect your electrodes, heart rate monitors, oxygen tubes or whatever you want and then easily measure your data while the subject exercises. Measuring the power output of a cyclist is also easy and commonplace, which makes for some very useful objective data on how hard the subject is exercising. Match this data with heart rate, lactate or VO2 output and you have an information rich tool by which to measure the effects of a given nutrient, protein or amino acid on performance.
Carbs For Cyclists
Because cycling is one of the preferred methods of measuring the effects of nutrition on exercise performance there is no shortage of research when it comes to supplements for cyclists2. For this reason, this article will focus on one specific category of sports nutrition supplements; namely carbohydrates.
In general sports nutrition terms carbohydrates stored in muscle (i.e. muscle glycogen) and carbohydrate in the blood (i.e. glucose) are the two most important fuel sources for exercising muscle3, with fatigue during endurance exercise directly linked to muscle glycogen depletion and reduced blood glucose concentrations4. So naturally, high pre-exercise muscle and liver glycogen concentrations are believed to be crucial for optimal performance of endurance exercise such as cycling. But to maximise pre-exercise levels of muscle and liver glycogen requires attention not only to pre-exercise carbohydrate intake but intake during and post-exercise.
Carbohydrate Intake For Cyclists
Carbohydrate intake needs for cyclists can be split into three categories, namely before, during and after exercise. The nutritional needs of the average competitive cyclist or endurance athlete for that matter are different in each of these periods and carbohydrate supplements are formulated to reflect these differences.
When it comes to pre-exercise carbohydrate intake, much of the debate centres on the amount, timing and type of carbohydrate. It is well established that high carbohydrate diets can increase muscle glycogen levels and in turn improve endurance performance5. This practice is popularly referred to as carbohydrate loading5. Traditional carb loading strategies involve reduced carb intake for three days followed by three days of very high carb intake6. However, the draw back with this approach is that it is quite cumbersome for the individual, given it takes 6 days of meal planning. Fortunately, more recent research has confirmed that high muscle glycogen levels can be achieved with just one day of very high carbohydrate intake in the order of 10-12g/kg per day7. Ingesting this amount of carbohydrate can be quite a challenge practically speaking, which is why many elect to use carbohydrate supplements to cover the bulk of their carb intake. Such supplements are generally the most convenient and practical way of ingesting large amounts of carbohydrates.
Carbohydrate Ingestion before Exercise
A number of studies have explored whether ingesting carbohydrates in the sixty minutes prior to exercise has any beneficial or negative effects on performance. Without going into great detail, the major conclusion from this line of research is that carbohydrate ingestion in the sixty minutes prior to exercise is unlikely to have any beneficial or negative effects on performance8.
Carbohydrate Intake during Exercise
Carbohydrate intake during exercise is one of the most important aspects of nutrition in cycling and also one of the most heavily studied. The whole purpose of carbohydrate intake during prolonged exercise is to offset use of the body’s own limited carbohydrate reserves in muscle and liver6. Muscle and liver glycogen are the preferred fuel sources for intense activity and therefore any strategies that can reduce their use during exercise should help to increase endurance.
Consuming Multiple Forms of Carbohydrate during Exercise
The most important scientific development in research on carbohydrate intake during exercise has been that it is possible to ingest more than 60g per hour if using multiple types of carbohydrates/sugars9. Researchers have discovered that the human small intestine has multiple carriers for different types of carbohydrates10. So to improve total carbohydrate absorption and use during exercise, it’s important to use different types of sugars; with the two most common being glucose and fructose10. Glucose can take the form of maltodextrin (glucose polymers) or dextrose, but as far as the body is concerned it is still glucose when it absorbed in the small intestine. So in this sense a product containing a mixture of maltodextrin, dextrose and fructose would still only constitute two different types of sugars for the gut to absorb. Sports and electrolyte drinks are the most common type of carbohydrate supplement used by cyclists during exercise. They offer the advantage that they address both fluid and carbohydrate needs of cyclists and can be carried easily by means of drink bottle holders on bicycles. Energy gels are a particularly popular carbohydrate supplement for cyclists because they can be carried conveniently in a back pocket and provide a concentrated source of carbohydrate that’s quick and easy to consume.
Carbohydrate Intake after Exercise
Carbohydrate intake after exercise is generally considered the most important time for carbohydrate intake when refuelling for the next training session or race is a major priority. Studies have conclusively shown that the body stores carbohydrate more efficiently immediately after exercise when compared to two hours following exercise11. The importance of post-exercise carbohydrate intake is increased when the individual is required to take part in another session or competition in less than 8 hours time. In such situations, the proven strategy for optimal refuelling is to consume 1.0 – 1.2g/kg/hr for the first four to six hours followed by normal daily fuel needs6, 12. This is considered the best strategy for maximising muscle and liver glycogen levels in a short period of time. The sport of cycling itself often requires that cyclists participate in multiple events within a single day so advanced carbohydrate refuelling strategies such as these take on great importance for optimal performance. Powdered carbohydrate supplements are particularly popular in such instances as athletes are required to eat every hour over a period of four hours.
When it comes to cycling, carbohydrate supplements can take the form of energy gels, sports/electrolyte drinks or carbohydrate powders. While many carbohydrate supplements simply offer plain carbohydrate or a mix of two or three carbohydrate sources, some also include added nutrients such as caffeine, electrolytes or amino acids such as leucine.
Common Types of Carbohydrate
Most of the research on carbohydrate supplementation during or after exercise has utilised glucose polymers, which is simply chains of glucose molecules, often referred to as maltodextrin. Maltodextrin also happens to be one of the cheapest forms of carbohydrate powder and therefore it is generally the most common form of carbohydrate found in energy supplements and the like. Waxy maize is another common type of carbohydrate found in carbohydrate supplements that has a lower GI than maltodextrin and is generally associated with reduced risk of gastrointestinal upset. However, when it comes to studies, waxy maize has not been studied anywhere near as much as maltodextrin. For more information on the different types of carbohydrates, see our advanced carbohydrate guide article.
Special Forms of Carbohydrate
Carbohydrate polymers are typically classified according to their chain length or molecular mass. Another form of terminology used is dextrose equivalents (DE). As far as special carbohydrate polymers go, there is a particular patented long chain carbohydrate polymer worthy of mention. Sold under the brand name of Vitargo, the carbohydrate polymer has been shown to result in higher glycogen levels when consumed post-exercise compared with normal carbohydrates and sugars13, 15. Vitargo is fractionated barley amylopectin and has a molecular mass between 500,000 and 700,000 which is thought to be the key reason it exits the stomach over twice as quick as maltodextrin and other sugars14. Expect to pay a bit more for such carbohydrate supplements though.
As a cyclist or any other avid endurance athlete for that matter, you simply can’t reach your potential if you don’t get your carbohydrate intake right. With the wealth of research that has been carried out on carbohydrate intake and performance in cycling, it’s the one area where there are some very specific guidelines that allow cyclists and endurance athletes to be very discrete about their carbohydrate intake and supplement use.
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