What is the rate of muscle glycogen (glycogen stored in muscle tissue) replenishment?

From the Guidelines

Muscle Glycogen Replenishment Rate

Muscle glycogen replenishment occurs at a rate of approximately 2-3% per hour after exercise-induced depletion. The optimal replenishment is achieved through consumption of ≥ 1.2 g kg−1 h−1 carbohydrate intake for 4–6 h following the conclusion of a glycogen-depleting exercise session 1. Additionally, co-ingestion of protein, such as in a 4:1 carbohydrate:protein ratio, can aid in recovery and will not harm glycogen repletion 1.

• Key factors influencing replenishment rates include:
  • Carbohydrate intake: 1.0-1.2 grams of carbohydrates per kilogram of body weight within 30-60 minutes post-exercise
  • Protein co-ingestion: 20-30 grams of protein, such as whey protein, can enhance glycogen replenishment by 10-20% when combined with carbohydrates
  • Timing and frequency of meals: meals and snacks should be scheduled to achieve intakes of 20–25 g of (high-quality) protein at 3–4 hour intervals 1
• The replenishment rate can be further influenced by the type and intensity of exercise, as well as individual factors such as muscle mass and overall nutrition. For example, elite football players may require 6–8 g/kg BM of daily CHO intake in the 24 hours following a game to replenish glycogen stores 1. It is essential to consider these factors when developing a personalized nutrition plan to optimize muscle glycogen replenishment.

From the Research

Muscle Glycogen Replenishment Rate

The rate of muscle glycogen replenishment is influenced by various factors, including diet, exercise, and individual variability.

• The study 2 found that muscle glycogen levels can be maintained for at least 3 days in a resting athlete when a moderate-CHO diet is consumed, with muscle glycogen remaining near 1.79 times baseline levels.
• Another study 3 demonstrated that muscle glycogen can be elevated to high levels with a moderate exercise-diet regimen, but the initial muscle glycogen levels influence the amount subsequently utilized during exercise.
• The review 4 suggests that elevated starting muscle glycogen content will postpone fatigue by approximately 20% in endurance events lasting more than 90 minutes.

Factors Affecting Glycogen Replenishment

Several factors can affect the rate of muscle glycogen replenishment, including:

• Carbohydrate intake: A high-CHO diet can help replenish muscle glycogen stores 2, 3.
• Exercise intensity and duration: Endurance exercise lasting 30 min or more can deplete muscle glycogen stores, while high-intensity exercise may not benefit from elevated muscle glycogen levels 5, 4.
• Individual variability: Gastrointestinal problems and other factors can affect an individual's ability to replenish muscle glycogen stores 5.

Replenishment Strategies

Strategies for replenishing muscle glycogen stores include:

• Consuming a high-CHO diet after exercise 2, 3.
• Avoiding dehydration and minimizing body mass losses through sweating 5.
• Using an individualized nutritional strategy to deliver carbohydrate to the working muscle at a rate dependent on exercise intensity and duration 5.