Consuming 7-10g carbohydrate per kilogram of body weight after 90 minutes of exhaustive exercise resulted in greater muscle glycogen replenishment than consuming 5 g/kg of carbohydrate.
(Motonaga et al., 2022)
There is a strong relationship between muscle glycogen levels and endurance performance. Blood glucose and muscle glycogen are the primary source of energy to sustain brief (10–180 seconds) high-intensity exercise and are a major source of energy for events lasting longer than 2 minutes (Thomas et al., 2016).
In a randomized crossover trial, Motonaga et al., 2022, eight male Japanese collegiate endurance athletes (average age of 20, average VO2max of 56 millimeters/kilogram of body weight/minute) completed an approximately 90-minute incremental (increasing by 20 watts every minute) cycling test until voluntary exhaustion. They consumed one of three diets: 5 grams of carbohydrate per kilogram of body weight, 7 g/kg, or 10 g/kg during the 24-hour recovery period after the test. The three diets provided the same amount of energy and protein.
Muscle glycogen levels before exercise were not different between conditions, and exercise decreased muscle glycogen similarly in each state (27–33%).
Muscle glycogen recovery was greater in the 7 g/kg and 10 g/kg conditions compared to the 5g/kg condition. Muscle glycogen levels recovered to 81.7% with 5g/kg, 97.1% with 7g/kg, 100% with 10g/kg after 24 hours.
This study only included young Japanese men, so the results may not be generalizable to other populations since the metabolic response to carbohydrate intake varies between ethnicities, although these findings align with previous evidence.
Recommend carbohydrate intake for athletes (Thomas et al., 2016)
Low-intensity or skill-based activities; 3-5g/kg/day
Moderate-intensity exercise lasting about one hour; 5-7g/kg/day
High-intensity exercise lasting 1–3 hours; 6-10g/kg/day
Moderate-to high-intensity exercise lasting 4–5 hours; 8-12g/kg/day
Hi GI carb sources are faster absorbed and a better choice during short recovery periods (e.g., multiple bouts on the same day). Also, timing and feeding frequency become more important factors in short recovery periods. But during more extended recovery periods (24 hours or more), when athletes have time to consume adequate carbohydrates, the type of carbohydrate and the timing of intake can be selected according to personal preference.
Reference:
Namma-Motonaga, K.; Kondo, E.; Osawa, T.; Shiose, K.; Kamei, A.; Taguchi, M.; Takahashi, H. Effect of Different Carbohydrate Intakes within 24 Hours after Glycogen Depletion on Muscle Glycogen Recovery in Japanese Endurance Athletes. Nutrients 2022, 14, 1320. https://doi.org/10.3390/nu14071320
Thomas DT, Erdman KA, Burke LM. American College of Sports Medicine Joint Position Statement. Nutrition and Athletic Performance. Med Sci Sports Exerc. 2016 Mar