5.3 Eating during exercise

Both intermittent high intensity exercise and prolonged moderate exercise can deplete muscle glycogen stores. If you consume carbohydrate during exercise this will help maintain your blood glucose levels, avoid muscle glycogen depletion and provide performance benefits. Figure 4 shows the guidelines for carbohydrate intake during exercise of increasing duration, from 30 minutes of exercise up to ultra-endurance exercise lasting over 2.5 hours (Jeukendrup, 2014).

Figure 6 Carbohydrate intake guidelines during exercise (adapted from Jeukendrup, 2014)

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The figure shows three columns (Duration of exercise, Amount of carbohydrate needed, and Recommended type of carbohydrate). The figure depicts that for 30-75 minutes of exercise small amounts of mouth rinse of single or multiple carbohydrates should be consumed. For 1-2 hours of exercise 30g/hour of single or multiple transportable carbohydrates should be consumed. For 2-3 hours of exercise 60g/hour of single or multiple transportable carbohydrates should be consumed. For exercise of greater than 2.5 hours duration 90g/hour of multiple transportable carbohydrates only should be consumed.

Figure 6 Carbohydrate intake guidelines during exercise (adapted from Jeukendrup, 2014)

The guidelines show that the amount of carbohydrate required per hour increases as exercise duration increases. For ultra-endurance events (i.e. over 2.5 hours) the recommendation is to consume a larger amount of carbohydrates to ensure an optimal supply into the bloodstream over time. Interestingly, for shorter duration exercise the guidelines suggest that just rinsing the mouth with a carbohydrate drink can be beneficial for exercise performance.

The carbohydrate intake guidelines can be achieved by consuming high GI drinks, gels and solid foods (e.g. bars low in fat, protein, and fibre). A mix-and-match strategy, based on personal preference, can be used to achieve carbohydrate intake goals. However, the carbohydrate intake should be balanced with appropriate fluid intake.