Low carb training & exercise performance

Last week I discussed periodizing carb intake to training demands, and how carb needs will vary day to day (click here if you missed it). I also mentioned that carb needs should also take into consideration the goals of that training session.  If you want to perform at your best, then eating ample carbs is important. However, if the goal of your training session is not performance, then training with “low carbohydrate availability” may be an appropriate strategy. Read on to find out more.

Carbs stored in our body are used as fuel during training. The harder your training, the more your body is going to depend on carbs to fuel performance. Carbs are stored in our liver and muscle as glycogen, but these stores are limited. We can increase these stores by “carb loading”, but even then, there is still a limited capacity and they can easily be depleted during training. By consuming carbs during training, additional carbs are provided to help prevent the crash that occurs with depleted stores. When training is performed with depleted carb stores, this is known as training with low carbohydrate availability. This is a relatively new area of research, but there is some evidence that it can increase the adaptations that occur with training, and in turn improve exercise performance.  If you would like to try this out in training, there are multiple ways to do this:

1. Fasted training: Training before breakfast on an empty stomach
2. Twice per day training: The first training session is used to deplete carb stores. After this training session, carb containing foods are avoided before completing a second training session.
3. Sleep low, train low: Training is performed in the evening and carb containing foods are avoided after. The next morning, a fasted training session is performed.
4. Long training sessions without carb intake: Exercising for a duration that would deplete body carb stores (several hours) without the intake of carbs during this training session

Training low should not be used during competition or training sessions where performance is important. Rather, these sessions should be used during easy training sessions where performance doesn’t matter. Another thing to note is that training with low carbohydrate availability may not be appropriate for all athletes as it many increase the risk of illness and injury. Finally, while there is evidence to suggest that training with low carbohydrate availability enhances muscular adaptations to training, this does not necessarily mean that exercise performance will be enhanced.