Avoid GI Issues: How to Fuel Racing and Training

Updated: Jun 1

One of the toughest challenges faced by athletes is determining what to consume during exercise.

There is so much information out there.

The reality is there is no 'one size fits all'.

There are a number of guiding principles that you can use to help you pick a strategy.

In this video and article we are going to look at the following:

  • Explain the different types of carbohydrates in sports products

  • Show what the science and research says about using carbohydrates

  • Give some practical guidelines on how to fuel

During exercise we use fat and carbohydrates as sources of energy.

Depending on exercise intensity we utilise our fat and carbohydrate stores at different rates.

During long slow steady swims, cycles and runs we burn fat with a little carbohydrate.

For higher intensity work we will use more carbohydrate as fuel. The graph below shows this relationship. Here we see the impact of fuel utilisation as power output


At easy intensities the body uses more fat than carbohydrate as a fuel source, usually typical zone 2 training .

The breakdown of fat as fuel is a slower process than that of carbohydrates.

As intensity increases your body needs more energy fast, this is where carbohydrates come in.

Once you reach your FTP you will use mainly carbohydrates to fuel your performance.

Our body stores roughly 500g of carbohydrate (2000 kcal) in the liver and muscle as glycogen. During exercise you convert these stores into energy as the body requires it.

Fat stores are a lot more abundant. At the right intensity you can tap into up to 20hrs worth of energy using fat as the primary fuel source.

We have a limited supply of carbohydrates and an abundance of Fat.