Consuming a carbohydrate rich snack or meal before exercise helps to improve performance by providing an energy source and preventing fatigue. However, a small number of athletes respond negatively to carbohydrates consumed before exercise. This is due to an exaggerated response to these carbohydrates, which leads to symptoms of low blood sugar at the start of exercise such as fatigue, dizziness, shaking, racing heart etc.

As mentioned above, only a small number of athletes experience this negative response to carbohydrates consumed pre-exercise. You don’t need to measure your blood sugar levels, but will know if low blood sugar symptoms are experienced. For those who experience symptoms, carbohydrates should still be consumed pre-exercise in-addition to preventative actions, such as:

  • Experiment to find the ideal time before exercise to consume a carbohydrate rich meal or snack. Food consumption further out from start of exercise (more than 45-75 minutes) is associated with greater prevalence of low blood sugar
  • Consume a substantial amount of carbohydrates rather than a small amount. Aim to consume 1 gram of carbohydrate per kg of body weight. For instance, a 70 kg athlete should aim for 70 grams of carbohydrate. Oatmeal made with ½ cup dry oats, 1 cup milk, and 1 banana would be approximately 70 grams of carbohydrates.
  • Select lower glycemic index foods. Foods with lower glycemic index cause a lower rise in blood glucose. Low glycemic index foods include steel cut oats, sweet potatoes or quinoa. For more information on glycemic index, click here.
  • Include high-intensity sprints during warm-up. This helps glucose stored in the liver to be secreted into the bloodstream.
  • Follow guidelines for the amount of carbohydrates consumed during exercise. For exercise lasting 1-2.5 hours, aim for 30-60 grams carbohydrates per hour. For exercise over 2.5 hours, aim for 60-90 grams carbohydrates per hour.

To perform at your best, adequate fuelling is vital. Ensure that your pre-event meal or snack is going to help you reach your performance goals.

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Categories: Megan Kuikman

Megan Kuikman

Hello! I’m Megan Kuikman. I’m a Registered Dietitian with specialized training in sports nutrition. My goal is to help athletes and active individuals achieve a healthy attitude towards health, training, and food. I empower athletes to fuel properly for training in order to restore their health and enhance performance. You can get in touch with me at:


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