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Carb loading before endurance events

Updated: Jan 17

Nutrition plays a very important part in our lives. Healthy foods provide us with the essential nutrients our body needs to work properly.

When preparing for a competition following the right nutrition plan is as important as following a training regime. Without it our performance could be jeopardised and we may not achieve the results we want, therefore we need to ensure that this element is not neglected.

In this blog I will focus on carb-loading in preparation for events that involve endurance (e.g. running a marathon, cycling, rowing, competing in a long distance triathlon) and bouts of explosive energy during short periods (e.g. tennis, rugby, football). Hopefully at the end of this you will have a better understanding of what carb-loading is, how it improves performance and how to plan a carb-loading diet.

1. What is carb-loading?

In the week before a competition it is possible to manipulate your daily carbohydrate intake to increased endurance and performance. This can make a huge difference during the event.

The main goal of carb loading is to increase the stores of glycogen in the body before a competition. This requires precise calculations to ensure that the carbohydrates don't get stored as fat but as fuel in muscles instead.

It is essential that the carb-loading strategy is combined with plenty of rest and tampering. Tampering is a reduction in training, intensity and duration which is crucial in the days before the event for the best performance.

A 7-day carb-loading strategy can be advantageous for endurance events lasting longer than 90 minutes or events involving heats over a short period. If the event lasts less than 90 minutes or it doesn't involve several heats over a short period, it is unlikely to be beneficial. For those events a glycogen top-up for the final 3 days may be more suitable.

2. How does carb-loading improve performance?

Our bodies need carbohydrates as fuel for exercise. Carbs are stored as glycogen in your liver (about 100g) and muscles (about 400g) and must be topped-up each day. The purpose of liver glycogen is to keep the blood sugar levels stable whereas muscle glycogen is to fuel physical activity.

A carb-loading regime increases time to exhaustion ratio by about 20% and improves performance by about 2-3%.

Increasing your muscle glycogen levels pre-competition will give you the energy to complete the event with less fatigue and help you to enhance endurance, skill execution, power output and rate of speed, and to lower the perceived effort rate during the event.

3. How to plan a carb-loading diet?

Below you will find an example of a carb-loading programme:

Day 1 (7 days before the competition date):

  • taper your training by carrying out endurance exercise for about 1 hour to reduce the glycogen in your liver and muscles;

  • eat your normal training diet that day.

For the following 3 days:

  • taper/reduce your training;

  • eat a moderate carbohydrate diet (5 to 7 grams of carbohydrate per kilogram of body weight).

For the final 3 days before the competition:

  • taper your exercise or rest;

  • eat high carbohydrate diet (8 to 10 grams per kilogram of body weight).

4. Common mistakes when carb-loading

Some people fail to achieve their goal when they attempt to carb-load. Below are the most common mistakes:

1) Not tapering an exercise when necessary - this can compromise carbohydrate loading and performance on the day of the event

2) Not eating enough carbohydrates - it is important to have a good understanding of the amount of carbohydrates required in order to fuel the muscles with glycogen before the event

3) Eating too much food high in fibre - this can result in upset stomach or finding the food too bulky to consume. Make use of compact sources of carbohydrate such as sugars, soft drinks, sport drinks, jam, honey, jelly and canned fruit.

4) Not sticking to the carb-loading diet because of fear of weight gain - carb-loading will most likely cause body mass to increase by approximately 2 kg. This is because for every 1 g of glycogen your body will also store around 3g of water.

5) Eating too much fat - this will make it difficult to consume sufficient carbohydrates and can result in gaining body fat. It is important to follow a high-carbohydrate, low-fat diet while carb-loading.

In order to help improve your performance before a competition your dietary requirements need to be carefully calculated and analysed and trialled before the day. If you are unsure about how to create a carb-loading plan consult it with a qualified nutritional advisor who can coach you along the way.

Use "Contact me" section above if you have any queries or would like a personalised carb-loading plan to follow.

References: The Health Sciences Academy - Sports and Exercise Nutritional Advisor Certification course

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