DURING THE COMPETITION: HOW MUCH CARBOHYDRATES?

Consuming additional carbohydrates during your Ironman has a number of positive effects that combine to result in better performance and a faster race time. During the race there is no need for other macronutrients (protein, fat) as only carbohydrates are present in limited quantities and are the best source of energy.

The recommendations for how much carbohydrates you should consume vary between 60g and 120g per hour. For most people, a moderate carbohydrate intake of 60g per hour is sufficient to enhance performance, and although this is a moderate intake, these amounts should be practiced before competition.

You should avoid delaying your carbohydrate intake until you feel tired and should begin early in the competition with regular meals every 20 to 30 minutes, as desired. For anyone competing at a very fast pace and high intensity, an intake of up to 90g or even 120g per hour may be useful, as the higher speed requires more carbohydrates for energy. High carbohydrate intake is not for everyone and should be reserved for relatively experienced triathletes who compete relatively quickly.

What is the best source of carbohydrates?

There are a wide range of foods and drinks to consume carbohydrates during an Ironman - including drinks, gels, chews and bars. All sources are similarly effective at providing carbohydrates, although each has different specific considerations.

Drinks are very popular and can be available ready to drink or as a powder that you can mix yourself. Carbohydrate concentration is worth considering because drinks with very high carbohydrate concentrations can slow gastric emptying, causing discomfort and also limiting carbohydrate absorption. If the concentration is too low, very large amounts of fluid have to be consumed in order to obtain enough carbohydrates, which increases the urge to urinate. An ideal sports drink should have a carbohydrate concentration of 6-7%.

Energy gels have a very high carbohydrate content (+/- 30%), which means that if consumed without water they can cause stomach upset and bloating. Because they are so compact, it is important to consume liquids in addition to gels. Gels have the advantage of being quite easy to consume compared to large amounts of carbohydrate-containing drinks or foods that require chewing.

Bars are very different and can contain very different amounts of carbohydrates, fat and fiber. Therefore, it is important to check the nutritional information before choosing bars. Choose energy bars that are low in fat, fiber and protein and are quick and easy to digest. Bars have the advantage of preventing the feeling of hunger or empty stomach that often occurs towards the end of a race.

However, they can be difficult to chew and swallow during competition. Some bars have a very high carbohydrate content (e.g. 60g), which can meet your carbohydrate needs for an entire hour. Therefore, it may be best to divide the bar into regular portions every 15 to 30 minutes to ensure consistent carbohydrate intake. This high carbohydrate content makes them an efficient way to transport lots of carbohydrates.

Chews offer some of the benefits of gels in that they are high in carbohydrates with minimal or no protein, fat or fiber and must be consumed with liquid due to their high carbohydrate concentration. Like bars, they require chewing, which can be difficult during competition.

The key when choosing carbohydrate sources during competition is to choose options that are comfortable for you and that you have practiced.

LIQUIDS AND HYDRATION

Dehydration is a potential cause of fatigue during an Ironman - as water is lost through sweat to maintain normal body temperature and through breathing. A more intense effort leads to greater heat production - and therefore more sweating. This is exacerbated in hot conditions as the body tries to lose more heat.

Losing too much water can cause dehydration, making it more difficult to maintain a normal body temperature. Some degree of dehydration is not a problem, but a loss of 3% of body weight or more can negatively impact performance. It is important to stay hydrated at the start of the competition, and staying hydrated after the start is also important.

Aiming to consume slightly less fluid than you lose through sweat is good exercise, as longer races are closer to your sweat rate. Most carbohydrate drinks contain sodium and other electrolytes that are lost with sweat. Consuming these electrolytes can support fluid absorption. Because later in the competition, your gastrointestinal tract is less able to absorb carbohydrates.

If you drink a lot of fluids, it's best to start with fluids and carbohydrates at the beginning of the competition. You should expect to lose some weight over the course of the competition (perhaps 1 to 2 kg), which is a mixture of glycogen and water. It is important not to drink too much fluid during competition as this can lead to a potentially fatal condition called hyponatremia.

If you experience gastrointestinal symptoms such as bloating, we recommended you to stop fluid and carbohydrate intake and temporarily reduce running speed to allow the stomach to empty and absorb the fluid and carbohydrates.