Smart Carbohydrates for Athletes: What the Science Says Today (A 2026 Update)

For athletes, carbohydrates remain the most reliable fuel for training and competition. That core message has not changed over the past decade. What has evolved is how sports nutrition research refines the amount, timing and form of carbohydrate intake to support performance, recovery and long-term health.

Modern evidence continues to show that carbohydrates are the primary substrate for moderate- to high-intensity exercise. Muscle glycogen and blood glucose strongly influence endurance capacity, repeated sprint ability and perceived effort. When carbohydrate availability drops, fatigue rises and output declines.¹

Latest Update on Carbohydrate Recommendations

1. Before and During Exercise: Matching Fuel to the Work

Pre-exercise fueling

Current consensus guidelines recommend 1 – 4 g of carbohydrate per kg body weight consumed 1 – 4 hours before exercise, depending on session duration and intensity. This approach supports muscle glycogen availability and improves endurance performance.²

For most recreational athletes, this may be as simple as a carbohydrate-rich meal several hours before training, followed by a light snack closer to exercise if tolerated.

Fueling during exercise

For sessions lasting longer than 90 minutes, carbohydrate intake during exercise helps maintain blood glucose and delays fatigue. Evidence supports 30 – 60 g of carbohydrate per hour for most endurance athletes.³

Higher intakes, up to 90 g per hour, are typically reserved for well-trained endurance athletes and require combining multiple carbohydrate types such as glucose and fructose to improve absorption. These strategies should be practiced in training to minimize gastrointestinal distress.

For shorter or lower-intensity sessions, water alone is usually sufficient.

2. Recovery Nutrition: When Timing Matters Most

Carbohydrate intake after exercise supports glycogen re-synthesis, particularly when recovery time between sessions is limited. Research consistently shows that consuming carbohydrates soon after exercise accelerates glycogen restoration compared with delayed intake.

That said, the idea of a narrow “recovery window” has softened. Rapid carbohydrate intake is most critical when athletes train more than once per day or on consecutive days. For individuals training once daily, total carbohydrate intake across the day matters more than immediate timing.

Combining carbohydrates with protein after exercise may further support muscle repair and reduce soreness, particularly after resistance or high-impact training.

3. Emerging Research: Timing & Metabolism

Recent studies are exploring how when carbohydrates are consumed may influence metabolism beyond immediate performance.

The same Mattsson’s study found that carbohydrate intake after evening exercise impaired next-morning glucose tolerance, while increasing carbohydrate oxidation during subsequent exercise. These findings are preliminary and do not yet warrant changes in athlete fueling recommendations, but they highlight the complex interaction between exercise timing, metabolism and carbohydrate use.⁴

Another area of interest is carbohydrate mouth rinsing, where athletes briefly rinse a carbohydrate solution without swallowing. A controlled trial⁵ show small performance benefits from carbohydrate mouth rinsing during high-intensity exercise, without changes in blood glucose, suggesting mechanisms other than direct energy provision.

These effects are modest and inconsistent. Mouth rinsing may be useful for athletes who cannot tolerate carbohydrate ingestion during intense efforts but it does not replace fueling during longer events.

4. Practical Guidance for Everyday Athletes

For most athletes, carbohydrate strategies should balance performance, gut comfort and overall diet quality.

Before training

• Use carbohydrate-rich, low-fat foods before long or intense sessions.
• Adjust portions based on body size and tolerance.

During training

• Fuel only when duration and intensity justify it.
• Practice race-day fueling in training.

After training

• Prioritize carbohydrates when training sessions are close together.
• Include protein for muscle recovery.

Food quality matters
Outside competition windows, emphasize whole-food carbohydrate sources such as grains, legumes, fruits and starchy vegetables. These provide fiber, vitamins and minerals that support long-term health and gut function. Highly refined carbohydrates can be useful around training but they should not dominate the overall diet.

Individual needs vary. Athletes differ widely in carbohydrate tolerance, sweat rate, and metabolic response. The best strategy is one that supports consistent training, stable energy levels, and good digestive comfort.

The Bottom Line

Carbohydrates remain a cornerstone of athletic performance. Modern sports nutrition emphasizes strategic carbohydrate use, not blanket high intake. By matching carbohydrate amount and timing to training demands, athletes can improve performance, recover more effectively and support long-term health.

Smart carbohydrates are not about eating more. They are about eating with purpose.

1. Amawi, Adam et al. “Athletes’ nutritional demands: a narrative review of nutritional requirements.” Frontiers in nutrition vol. 10 1331854. 18 Jan. 2024, https://doi.org/10.3389/fnut.2023.1331854
2. Jiménez-Alfageme, Rubén, et al. “Nutritional Intake and Timing of Marathon Runners: Influence of Athlete’s Characteristics and Fueling Practices on Finishing Time.” Sports Medicine – Open, vol. 11, no. 1, 16 Mar. 2025, article 26. https://doi.org/10.1186/s40798-024-00801-w
3. Jeukendrup, Asker E. “Carbohydrate Intake During Exercise and Performance.” Nutrition, vol. 20, no. 7–8, 2004, pp. 669–677.
   https://pubmed.ncbi.nlm.nih.gov/15212754/
4. Mattsson, Stig, et al. “Impact of Carbohydrate Timing on Glucose Metabolism and Substrate Oxidation Following High-Intensity Evening Aerobic Exercise in Athletes: A Randomized Controlled Study.” Journal of the International Society of Sports Nutrition, vol. 22, no. 1, 2025,
   https://pubmed.ncbi.nlm.nih.gov/40259503/
5. Murray, Kevin O., Hunter L. Paris, Alyce D. Fly, Robert F. Chapman, and Timothy D. Mickleborough. “Carbohydrate Mouth Rinse Improves Cycling Time-Trial Performance Without Altering Plasma Insulin Concentration.” PMC Free Journal Article, 2018, https://pmc.ncbi.nlm.nih.gov/articles/PMC5844201/.