The inclusion of carbohydrate supplementation post-workout and/or during strenuous training sessions has repeatedly been shown to increase muscle glycogen levels, enhance protein synthesis, and increased exercise performance. Strength, power, and fitness athletes should understand the positive (performance-enhancing) effects increase muscle glycogen has on their ability to increase lean muscle mass, recover from stranger training sessions, and increase muscle growth.
Therefore, in this article we will discuss what you need to know about muscle glycogen, how it can help you build new muscle tissue, and the steps you need to take to ensure you are maximizing its effects.
What is Muscle Glycogen?
In short, muscle glycogen can be defined as the primary fuel source for skeletal muscle tissue during prolonged strenuous exercise, such as training for sports like powerlifting, weightlifting, strongman, and competitive fitness. Low levels of muscle glycogen has repeatedly been shown as one of the key physiological factors that contribute to increased perceived rates of fatigue, increased rate of exhaustion during strenuous exercise, and even plays a role in one’s ability to maintain rigour levels of anaerobic capacity. Simply put, muscle glycogen is the preferred energy source of all your muscles, and without it your peak physical performance most likely will be inhibited (1).
How Does Muscle Glycogen Build Muscle?
When we train hard, our muscles used muscle glycogen to fuel muscle contractions that promote force necessary for movements like deadlifts, squats, presses, cleans, and other muscle building exercises. Without adequate stores of muscle glycogen, you will leave you body unprepared to fuel the challenging task of training, ultimately limit your ability to move higher intensity loads and perform more work (volume); both of which have been shown to increase muscle hypertrophy and strength.
We also know that exercise itself is a destructive process, resulting in muscle breakdown due to high amounts of eccentric loading. Research suggests that post-workout carbohydrate ingestion (specifically fast-acting carbohydrate sources (simple carbs, often lacking fats and fiber, which slow down absorption) has been shown to significantly increase plasma insulin levels (one of the most anabolic hormones in the body) and in turn increase protein synthesis 36% when compared to exercise alone (2). Lastly, urinary nitrogen (and other compounds suggesting muscle breakdown) levels were significantly lower following carbohydrate supplementation after strenuous exercise, further supporting increase muscle growth (by decreasing muscle damage/atrophy).
More importantly, however, is that when carbohydrates are paired with a protein (such as amino acids) and ingested post-workout, research has found an increased amount of protein synthesis (anabolic muscle building process) when compared to a meal only containing carbohydrates (3). This was also supported by a study that found a complete meal consumed post-workout of carbohydrates and a protein source stimulates mRNA translation (important protein synthesis)(4).
What Happens When Muscle Glycogen Drops?
As one may have guessed, decreased levels of muscle glycogen is not preferable for optimal performance (in either aerobic or aerobic sports), strength and power training, and/or for the creation of new muscle tissue. During times of decreased muscle glycogen, you can expected to experience the following:
Increase Muscle Fatigue
Increased muscle fatigue be due to lack of adequate stores of muscle glycogen coming into a training session (failure to replenish with carbohydrates after your previous training session) or after prolonged periods of strenuous exercise, often during longer training sessions/events).
Decreased Power Output
Carbohydrates are the preferred source for skeletal muscle, which are responsible for forceful muscular contractions during explosive movements like jumping, cleans, snatches, and jerks. With drops of muscle glycogen comes increased muscle fatigue and the inability to promote fast, forceful muscle contractions (power).
Lack of Recovery
After hard training, it is important to replenish used muscle glycogen within skeletal muscle to (1) boost insulin sensitivity and stimulate muscle protein synthesis, (2) prepare for upcoming training sessions in the day/week, and (3) to limit the amount of muscle damage caused by training. Without properly addressing low levels of muscle glycogen, you run the risks of depleting energy reserves within muscle tissues (decrease performance and inhibit improvements in strength, power, and fitness) and limiting protein synthesis necessary for muscle growth.
How Can You Increase Muscle Glycogen?
The research is pretty clear that increased carbohydrate and protein consumption after strenuous training sessions/events can significantly improve muscle function and aerobic performance in subsequent bouts of training (in some studies only a few hours apart). Research suggests consuming 0.8g of carbohydrate per kilogram of body mass post exercise, with a further increase in glycogen synthesis with the ingestion of an additional 0.4g of carbohydrates per kilogram of body mass taken every 30 minutes during strenuous exercise. To maximize glycogen and protein synthesis, it is suggested to also ingest 0.4g of protein per kilogram of body mass after strenuous training sessions (5).
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- Ivy, J. (2005). Regulation of Muscle Glycogen Repletion, Muscle Protein Synthesis and Repair Following Exercise. International Society of Sports Nutrition Symposium. Retrieved May 2, 2018, from https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3905295/#ref33.
- Tarnopolsky, M. A., Bosman, M., Macdonald, J. R., Vandeputte, D., Martin, J., & Roy, B. D. (1997). Postexercise protein-carbohydrate and carbohydrate supplements increase muscle glycogen in men and women. Journal of Applied Physiology, 83(6), 1877-1883. doi:10.1152/jappl.19220.127.116.117
- Levenhagen, D. K., Carr, C., Carlson, M. G., Maron, D. J., Borel, M. J., & Flakoll, P. J. (2002). Postexercise protein intake enhances whole-body and leg protein accretion in humans. Medicine & Science in Sports & Exercise, 34(5), 828-837. doi:10.1097/00005768-200205000-00016
- Gautsch, T. A., Anthony, J. C., Kimball, S. R., Paul, G. L., Layman, D. K., & Jefferson, L. S. (1998). Availability of eIF4E regulates skeletal muscle protein synthesis during recovery from exercise. American Journal of Physiology-Cell Physiology, 274(2). doi:10.1152/ajpcell.1998.274.2.c406
- Loon, L. J., Saris, W. H., Kruijshoop, M., & Wagenmakers, A. J. (2000). Maximizing postexercise muscle glycogen synthesis: Carbohydrate supplementation and the application of amino acid or protein hydrolysate mixtures. The American Journal of Clinical Nutrition, 72(1), 106-111. doi:10.1093/ajcn/72.1.106