Why are carbohydrates important?

Carbohydrates are an important energy source for moderate-to-high-intensity exercise. Following digestion, they are primarily stored as glycogen in the muscles and liver.

As training duration or intensity increases, glycogen availability can affect the ability to maintain pace, power and repeated-effort performance.

Carbohydrates before exercise

Pre-exercise carbohydrate intake aims to provide sufficient energy without causing digestive discomfort. Suitable foods may include rice, oats, bread, potatoes, fruit or another easily digested source.

Evidence indicates that pre-exercise carbohydrates are more likely to improve longer-duration performance than very short exercise sessions.

Carbohydrates during exercise

For exercise lasting approximately 1–2.5 hours, recommendations frequently range from 30–60 g per hour. During very long endurance events, trained athletes may use up to approximately 90 g per hour from multiple carbohydrate sources.

Gastrointestinal tolerance should be trained progressively. Introducing a large amount for the first time during competition may cause bloating or digestive discomfort.

Carbohydrates after exercise

Post-exercise carbohydrate supports the restoration of muscle glycogen. Rapid restoration becomes more important when a second demanding session is scheduled on the same day or when recovery time is limited.

For someone training once daily, total daily carbohydrate intake is generally more important than consuming it within a strict window of only a few minutes.

Does everyone need intra-workout carbohydrates?

A short resistance-training session does not automatically require a sports drink. Carbohydrates during exercise are more relevant to prolonged sessions, endurance events, very high-volume training or multiple daily workouts.

Conclusion

Carbohydrate intake should be adjusted to the duration, intensity and purpose of training. Not every athlete requires the same amount, and intra-workout products are not necessary for every session.

References

• Burke LM et al. Carbohydrates for Training and Competition. Published: 2011.
• Jeukendrup AE. A Step Towards Personalized Sports Nutrition: Carbohydrate Intake During Exercise. Published: 2014.
• Rothschild JA et al. What Should I Eat Before Exercise? Pre-Exercise Nutrition and the Response to Endurance Exercise. Published: 2020.