Being able to train multiple days in a row heavily relies on your ability to recover. Everyone knows the basics of recovery: eat, sleep, and rest.
However, taking a closer look into the nutrition aspect of recovery, carbohydrate post-exercise can be timed to further optimize recovery.
A brief review of the role of carbohydrate
One of the main roles of carbohydrate within the body is to provide energy to the muscles. Carbohydrate is stored in the muscles and liver as glycogen. The total amount of glycogen stored in the body equates to 380-710g of carbohydrate.
When glycogen stores in the body are depleted after activity, the body begins to re-synthesize glycogen when we ingest carbohydrate. The highest rates of glycogen synthesis occur after exercise.
The ability to quickly and efficiently restore glycogen is what helps support multiple days of training in a row (1).
With this knowledge in mind, a recent study investigated how delaying carbohydrates after HIIE (high-intensity interval exercise) affects a bout of HIIE the next day.
Diving into the Study
In this study, participants performed 10×2 VO2 max intervals two days in a row. During the 3 hours following the first workout, participants consumed either a carbohydrate drink or a flavor-matched placebo with no carbohydrates.
During the 24 hour period in between workouts, carbohydrate intake was matched between both groups. On the second day, participants repeated the VO2 intervals until failure (2).
The “immediate” group is represented with the white bars, the “delayed” group in red.
In summary, participants who were fed carbohydrate immediately after the first session were able to complete 5 more intervals than the delayed CHO (carbohydrate) group. RPE and heart rate were also lower in the immediate CHO group as well (1).
Delaying carbohydrate for just 3 hours caused a significant difference between the two groups. This is due to the CHO group taking advantage of increased glycogen synthesis immediately post exercise (2).
Glycogen synthesis rates
Immediately after exercise, glycogen synthase the enzyme responsible for glycogen synthesis is highly active. This high level of glycogen synthase allows for rapid glycogen synthesis.
If carbohydrate is ingested immediately after activity, glycogen can be rapidly synthesized. If carbohydrate isn’t ingested until hours later, glycogen synthase activity is decreased and glycogen synthesis rates significantly drop (2).
The image below illustrates this concept.
How to optimize the Rapid phase of glycogen synthesis
With the importance of immediately consuming carbohydrate post exercise established, here are some practical guidelines on how to implement this into your training.
- Ingest high Glycemic Index (GI) carbohydrate immediately after exercise- When optimizing recovery is the goal, the first few hours following exercise is the most important time to be ingesting high GI carbohydrate (2). For a more complete look at carbohydrates in training check out our Carbohydrate Fueling For Cycling Guide.
- The glycemic index- GI describes the increase in blood glucose and insulin when a standard amount of food is consumed. The greater the GI, the faster a carbohydrate can be readily available to the body. Consuming high-GI carbohydrates is found to increase muscle glycogen more than 50% compared to low-GI foods (1). Here are some common foods with GI scaled from high to low
| High | Moderate | Low |
| Pancakes: 102 | Bagel: 69 | Potato Chips: 54 |
| Baked Potato: 86 | Doughnut: 67 | Banana: 52 |
| Cornflakes: 81 | Coke: 63 | Orange Juice: 50 |
| Rice: 72 | Power Bar: 56 | Spaghetti: 49 |
| Watermelon: 72 | Snickers: 55 | Tomato or Broccoli: 15 |
- 1g/kg of high GI carbohydrate each hour for 4 hours after exercise- This carbohydrate intake per hour is found to be the optimal rate of carbohydrate to synthesize glycogen as fast as possible. For example: if you’re 68kgs you would aim to eat 68g of high GI carbohydrates each hour for 4 hours after exercise.
References
- Javier Díaz-Lara, Elizabeth Reisman, Javier Botella, Bianka Probert, Louise M. Burke, David J. Bishop, Matthew J. Lee. (2024a, September 12). Wiley. Delaying post-exercise carbohydrate intake impairs next-day exercise capacity but not muscle glycogen or molecular responses. https://onlinelibrary.wiley.com/doi/pdfdirect/10.1111/cas.14215
- Jeukendrup, A., & Gleeson, M. (n.d.). Sports Nutrition (4th ed.)