Carbohydrate is the main fuel for high intensity and prolonged endurance exercise. Although fat may provide more energy, it is used slowly. Carbohydrate yields more energy per litre of oxygen consumed and is a more efficient fuel, providing energy quickly to be used by the working muscles. Although an athlete can enhance the way they use fat a fuel source, potentially sparing muscle glycogen stores, race-winning performance is fuelled by carbohydrates.
Where carbohydrate comes from?
Carbohydrate comes in a variety of forms. While they contain similar calories, they are all metabolised differently, thus affecting our performance output:
- Must be converted into glucose in the liver before they can be metabolized
- Is oxidized at a much lower rate during exercise
- May cause gastrointestinal issues (stomach cramps/ sickness)
- A chemical combination of glucose and fructose
- Has been shown to digest quickly
Maltodextrin (made up of chains of glucose molecules):
- Has a high glycemic index (GI), meaning that energy is available quickly
- Digested quickly during exercise
- Reduce the risk of developing gastrointestinal complaints during prolonged exercise
How body digests carbohydrates?
The digestion of carbohydrate for fuel begins when it first enters your mouth until it is absorbed into the bloodstream from the small intestines. The first organ to receive the broken down carbohydrate (glucose, fructose and galactose) is the liver. Here, glucose is either stored (as glycogen) or leaves the liver to be delivered by bloodstream to the muscles so that it may be used for energy . However, the type of carbohydrate that is ingested can determine the speed at which your muscles can use it for energy.
How SiS gels are different?
The source of carbohydrate, the amount and the concentration of the gel can all vary greatly. You really need to consider this to make sure you get the best performance out of your gel. SiS uses maltodextrin which is broken down into glucose and which is the base of nearly all products. SiS have been using a type of maltodextrin with a particular size of molecule, known as its’ molecular weight. This allows to balance the amount of energy delivered versus how quickly it empties from the stomach. This means that you will feel the performance benefits of taking on a SiS GO Isotonic Energy gel far more quickly than when a non-isotonic gel is consumed. The risk of upsetting your stomach is also much less. Energy gels with an osmolality close to the gastric content (i.e. isotonic) may promote high carbohydrate delivery to the small intestine compared to thick, concentrated hypertonic gels. SiS gels have been shown to get working in 15 minutes.
WHAT is the best way to keep sugar levels up?
Chronically – a healthy diet and training. Acutely – taking 60-100g of mixed energy substrate carbohydrates in divided doses for each hour of exercise, and using a good pacing strategy. In practice, this is down to ensuring you use energy products tailored to the amount of exercise you’re doing.
Tim Noakes is very much advocating very low carbs unless it’s during competition. A good diet for an endurance athlete? Any thoughts?
Noakes’s work has some limitations. Even if you train low and then race high carb, your metabolic pathways for metabolising carbohydrate will not be well developed and you won’t be able to race at as high an intensity. It’s a bit like only training at 65% of VO2 max and then expecting to be able to race at 85%.