Nutrition During Exercise

by Dietitian Clare Wood

As well as eating before exercise (see pre-exercise nutrition) and after exercise (see post-exercise nutrition), it is also very important to make sure where appropriate, that food and fluid is ingested during exercise, in both training and competition.

During moderate to high intensity exercise the body uses predominantly carbohydrate as a fuel source, as well as some fat storage. Carbohydrate fuel comes in the form of muscle glycogen and blood glucose. Depending on many factors, many sports can adequately be completed with focus on nutritional preparation. Our carbohydrate (and fat) storage covers most fuel needs, if well prepared. Fluid however is vital for during exercise for majority of activities, as sweat rate begins so does the bodies need for fuel intake.

Food

Consuming food during exercise has the number one aim to improve performance in a competition, and also to lift work rate, or the ability to do the given work load during a training session.

Benefits of Intake

Specific benefits of consuming carbohydrate during exercise are to firstly keep blood glucose levels high during prolonged moderate-high intensity events. Blood glucose provides an alternative fuel source for the muscle when glycogen storage levels are getting low. Carbohydrate during exercise also provides a fuel source for the brain to maintain skills and decision making, and reduce the perception of fatigue. Lastly, intake of glucose can spare or replenishing muscle glycogen. It is believed that during low intensity work, carbohydrate consumed during exercise can be burned to save glycogen stores or can replenish glycogen stores for use later.

Should I Eat During Exercise?Refueling

Identifying factors that determine the appropriateness of consumption during exercise, is crucial in deciding if carbohydrate is needed for you.

1) Generally, the longer the event, the greater the amount of carbohydrate that is utilized. As a rule of thumb, if your sport or training is longer than an hour, you may benefit from consuming some carbohydrates during sport in addition to fluid.

2) Higher intensity exercise will burn more glycogen, or fuels stores more quickly during your game or session. So if your exercise session is roughly an hour and consists of predominantly high intensity work, then taking in some carbohydrate may be beneficial.

3) Temperature will also play a role, in that the hotter it is, the quicker glycogen will be used. However, in these situations, it is more likely that overheating and dehydration will be the limitation to performance

4) Pre-exercise eating has an impact on glycogen storage. The better ones pre-exercise meal is, the higher the stores of carbohydrate will be, and hence the more fuel that will be available for conversion during that event or session.

How Much?

This will depend on exercise intensity, weather conditions and glycogen storage at the start of the event. However, a good starting point is about 50g of easy to consume carbohydrate foods for every hour of exercise.

What Should I Consume?

Food intake during exercise should be easy to swallow with limited chewing. Liquid options are often the best options, however this will depend on personal preference and ability to stomach certain foods. Each of the following options provides about 50g carbohydrate:

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