Carbohydrates and Exercise Performance

Welcome to the latest edition of the Fueling Greatness Newsletter. Each week, I aim to decode the “science to application” of nutrition and related fields to help you optimise your performance, body composition and well-being. Be at the cutting edge of this knowledge, and subscribe to my newsletter.

This week, I discuss carbohydrate’s effects on exercise performance. As a sports nutritionist working with some of the greatest athletes and sports teams with high stakes regarding athlete performance and recovery, I must understand the facts and relevance behind the nutrition strategies I recommend to my clients. Perhaps one of the most important topics in sports nutrition is fueling optimally for the work required for peak performance, especially when it matters, such as competition day. And so, I have been particularly interested in the effects of carbohydrate intake on exercise performance and recovery for many years.

In this newsletter and blog post, I will provide a detailed overview of the key areas on this topic as I understand it. I will cover the major energy sources that fuel muscle during prolonged exercise, the benefits of carbohydrate intake during exercise, and the factors that contribute to these improvements. Based on the latest research findings and my experience, I will also provide practical recommendations for athletes and coaches.

The Major Energy Sources for Muscle During Prolonged Exercise

During prolonged exercise, the body relies on two major energy sources: glycogen and fat. Glycogen is stored in the muscles and liver and is the primary energy source for high-intensity exercise. Fat is stored in adipose tissue and is the primary energy source for low-intensity exercise. However, as exercise intensity increases, the body relies more on glycogen for energy. Therefore, maintaining adequate muscle glycogen stores is critical for optimal exercise performance.

To maintain adequate glycogen stores, athletes should consume a diet that is high in carbohydrates. Carbohydrates are broken down into glucose and stored as glycogen in the muscles and liver. The amount of glycogen stored in the muscles and liver is limited and can be depleted during prolonged exercise. When glycogen stores are depleted, the body relies more on fat stores for energy, which results in decreased exercise intensity and performance. So, if you want to win [the race or competition], Carbs are King!

The Benefits of Carbohydrate Intake During Exercise

Carbohydrate intake during exercise has been shown to improve endurance performance and capacity. As you now know, this is because carbohydrates are the primary fuel source for high-intensity exercise. Carbohydrate intake during exercise, such as from sports drinks or gels, can also spare muscle glycogen, which is important for maintaining exercise intensity and delaying fatigue. In addition, carbohydrate intake during exercise can also improve cognitive function and reduce the perception of effort, leading to improved performance.

The benefits of carbohydrate intake during exercise are dose-dependent. The optimal carbohydrate intake during exercise is between 30-60 grams per hour, depending on the duration and intensity of exercise. Consuming more than 60 grams per hour may not provide additional benefits and can lead to gastrointestinal distress. Therefore, athletes should consider the timing and amount of carbohydrate intake during exercise to optimise performance.

Factors That Contribute to Improved Performance with Carbohydrate Intake

Several factors contribute to the improved performance seen with carbohydrate intake during exercise. One factor is the stimulation of carbohydrate receptors in the mouth and gut, which can lead to improved exercise performance and reduced perception of effort. Another factor is maintaining blood (plasma) glucose concentration, which is important for maintaining exercise intensity and delaying fatigue. Carbohydrate intake during exercise can also improve hydration status, which is important for maintaining exercise performance and reducing the risk of heat illness.

The Optimal Amount and Timing of Carbohydrate Intake During Exercise

The optimal amount and timing of carbohydrate intake during exercise depends on the duration and intensity of the activity. Carbohydrate intake may not be necessary for activities lasting less than an hour. However, carbohydrate intake can significantly improve performance for activities lasting longer than an hour. The recommended carbohydrate intake during exercise is between 30-60 grams per hour, depending on the duration and intensity of the activity.

The timing of carbohydrate intake during exercise is also important. Consuming carbohydrates before exercise can increase glycogen stores and improve exercise performance. Consuming carbohydrates during exercise can spare muscle glycogen, delay fatigue, and improve cognitive function. The timing of carbohydrate intake during exercise should be based on the individual's tolerance and the type of activity being performed.

The Type of Carbohydrate for High-Intensity Exercise

The type of carbohydrate ingested during exercise can also affect performance. High-glycemic index (GI) carbohydrates, such as glucose and maltodextrin, are rapidly absorbed and can provide a quick energy source during high-intensity exercise. Low GI carbohydrates, such as fructose and sucrose, are absorbed more slowly and can provide a sustained energy source during prolonged exercise.

Recent research has also shown that ingesting multiple transportable carbohydrates (glucose with fructose) can improve exercise performance compared to ingesting a single carbohydrate source. This is because multiple transportable carbohydrates can increase carbohydrate absorption and oxidation rates, improving exercise performance.

Conclusion

In conclusion, carbohydrate intake during exercise can significantly improve endurance performance and capacity. The optimal amount and timing of carbohydrate intake during exercise depend on the duration and intensity of the activity. Consuming carbohydrates before and during exercise can spare muscle glycogen, delay fatigue, and improve cognitive function. The type of carbohydrate ingested during exercise can also affect performance, with high-GI carbohydrates providing a quick source of energy and low-GI carbohydrates providing a sustained energy source.

Take-Home Messages

1. Carbohydrate intake during exercise is critical for optimal exercise performance.

2. Carbohydrates are the primary fuel source for high-intensity exercise, and carbohydrate intake during exercise can spare muscle glycogen, improve cognitive function, and reduce the perception of effort.

3. Maintaining adequate glycogen stores is critical for optimal exercise performance.

4. Carbohydrate intake during exercise can improve endurance performance and capacity.

5. Several factors contribute to the improved performance seen with carbohydrate intake during exercise, including stimulating carbohydrate receptors, maintaining plasma glucose concentration, and improving hydration status.

6. Athletes and coaches should consider incorporating carbohydrate intake during exercise as part of their training and competition nutrition plan to optimise performance.

That’s it for today! I hope you found this of interest and value.

Have a great week, and see you next week for another edition of Fueling Greatness, in which we will continue to explore key topics in sport and exercise nutrition and unpack the “science-to-application” to help you achieve your performance, body composition and well-being goals.

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Have a great week!

Best regards,

Dr Laurent Bannock