Nutrition X Nutritionist Danny Webber Reveals the Secret to Effective Carbohydrate Loading
For the past 50 years it’s been an accepted fact that carbohydrates are the major source of energy to fuel exercise as it is stored in the muscles and liver as glycogen. As glycogen content is linked to endurance performance, if you start your race with a lower concentration of glycogen, you will suffer from premature fatigue. But don’t worry, simple nutrition strategies to increase muscle and liver glycogen before a competition are easy to do. Here we answer some common questions and provide a strategy to ensure you get the most from your diet and fuel your next event properly.
When should I start to load?
Sufficient muscle glycogen levels can be achieved from just 24-48 hours of carbohydrate loading. Events lasting between 90 minutes and three hours require just 24 hours of loading, and then anything longer than that should be applied for 48 hours before.
How much carbohydrate?
Again this will depend on the duration of the event, but training status should also
be considered. For example an elite Tour de France cyclist will consume on average 10-12g carbohydrate per kg body mass per day, but somebody running their first half marathon will not need this much. So for a 90 minute race, six to eight grams per kg body mass of carbohydrate is adequate the day before. For marathons and ultraendurance events 8-10g per body mass is advised. A 70kg athlete running a marathon will require at least 560g (8g per kg of body mass) carbohydrate. This is the equivalent to nine large potatoes, 750g raw pasta or 17 ½ 500ml bottles of Lucozade Sport.
What type of carbohydrates?
As you can see a lot of carbohydrate needs to be consumed, and eating that amount of pasta or potatoes is not recommended. It’s important to eat foods that can be better absorbed by the muscles and will not cause gastrointestinal discomfort. Not all carbohydrates do this. The glycaemic index (GI) determines the effect a certain food has on blood glucose with high-GI foods being broken down much quicker during digestion than low-GI foods, and are absorbed by the muscles more easily. Foods with a high glycaemic load (GL) have a greater quantity of carbohydrates for a given weight of food, and together with GI allow your muscles to efficiently obtain more carbohydrates. Eating a large amount of fibrous (typically low-GI) foods such as vegetables can lead to gastrointestinal discomfort so it may also be wise to focus on simple, low fibre foods to alleviate digestive issues. White potatoes are high-GI and GL, and removing the skins reduces the fibre content, making mashed potatoes an ideal choice when carb-loading.
Your pre-race meal is typically breakfast and you should make sure it consists of easy to digest carbohydrates with ample protein and plenty of fluids. This can be personal preference, but a bowl of porridge with honey and banana is a good choice. Choosing lower-GI foods may actually be better in the hours before a race to help keep you feeling full, and research also suggests that it may enhance performance compared to high-GI carbs. Timing and quantities are down to the individual, however it would be practical to eat one to four hours before your race ensuring your meal contains 1-4g of carbohydrate per kilogram of body mass for each hour.
Foods to avoid:
As well as fibre there are other nutrients to limit to allow for the increased calorie intake from carbohydrates. Dietary fat is very calorie dense and you should be eating significantly less of this. Protein also needs to be limited to approximately 1.2g per kilogram of body mass. This is because fat and protein slow down the digestion of carbohydrates. You should avoid spicy food as this can cause major gut problems like bloating and wind, which you do not want while racing. Keep in mind high levels of fructose (fruit sugar) can also do funny things to your stomach, so downing a large glass of orange juice might not be a great idea.
Hydration is fundamental during carb-loading because carbohydrates require water to get into the muscles. Drink plenty of fluids throughout the day especially with meals to aid absorption, but also to boost your performance on race day.
Practise your strategy:
Any athlete should practise their nutritional strategy before a major competition. This is the same for carbloading. Consuming foods that your body is not used to can have a negative effect. If you normally have porridge with skimmed milk before training, it’s not then a good idea to switch to a bowl of chocolate cereal with full fat milk before a race? Stick to foods you know and have practised with before in the days before a race to prevent unexpected digestive complications.
Performance Nutritionist Danny Webber is one of the expert team at Informed-Sport approved sports nutrition brand Nutrition X.
First published in Triathlon Plus Magazine, Issue 98