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Replenishing muscle glycogen for maximal, faster recovery
By Dr. Luke Bucci & Jeff Feliciano
The post-exercise glycogen two-step can help you bounce back overnight.
Carbs are fuel, and fuel drives the machine that is the human body. That’s endurance athletics 101. But our carb need doesn’t end when the workout does, because when the tank is empty, the only way to fill it up is to, well, fill it up.
In this blog post, Dr. Bucci and Jeff Feliciano explain the post-exercise process of getting enough carbohydrates into your body to restore muscle and liver glycogen as quickly as possible. They’ll also install some signposts and guardrails along the way to indicate what you should – and shouldn’t – do in order to recover faster and realize bigger gains from your efforts.
CARBS AND RECOVERY
After a very long, grueling endurance workout, race, or event, you need to bounce back as quickly as possible to keep your exercise capacity at full strength. That means recovery starts immediately after exercise stops. Immediately!
Although you are fatigued mentally and physically, your muscles are just beginning to get the internal signals to start the Pain-For-Gain process of DOMS/EIMD for recovery – but for that to be successful, your body still needs energy first and foremost.
Before the post-exercise antioxidant/signaling storm gets cranked up there is a narrow window of opportunity to start the process right so you can shorten the recovery cycle. Taking advantage of this nutritional window is extra-critical for repeated days of strenuous exercise. It can forestall a steady decline in performance and recovery and prevent overtraining.
The trick is to replenish your muscles’ glycogen levels, re-upping the supply of fuel that you burned up during exercise. If you do post-exercise glycogen repletion right, you can restore muscle glycogen levels to normal in 24 hours.
KICKSTARTING THE CHO WINDOW OF OPPORTUNITY
OK, for a sec, BE your exhausted muscles at the end of a grueling exercise bout. FEEL your muscles screaming for energy to replace the depleted glycogen they used to get you to the finish.
As soon as exercise stops, there is a very short lull of about an hour before the rapidly increasing, dramatic energy needs for the DOMS/EIMD recovery process (detailed in another blog post) start signaling a massive renovation, repair, and rebuild requiring all the energy you can get to muscles. And on top of that heavy demand, your muscle glycogen needs to be repleted ASAP – evolutionarily-speaking, your body never knows if and when you need to keep going, so it defaults to filling up muscle glycogen as fast as possible. Both processes pull from the same pool of resources: the carbs you feed yourself. How do your muscles keep up with all this enormous extra energy demand?
A very large amount of human research on post-exercise glycogen repletion has been published, and the results show that – done properly – rapid muscle glycogen replenishment improves recovery and makes your next exercise bout easier with less diminution of performance, if any. Recommendations are entrenched, universally-agreed, and should be standard practice for exercise over two hours in duration, even if you have been fueling and staying hydrated throughout the exercise event.
The importance of getting carbohydrates into your muscles as soon as possible after exercise is finished cannot be reinforced enough. Your intense, long-duration exercise has already set the wheels in motion for repair and recovery, and soon the wave of molecular signaling throughout your body will take over and control glucose for those processes rather than for replenishing muscle glycogen. Having replenished muscle glycogen gives your muscles the energy to enhance and accelerate the entire recovery process compared to not having enough glycogen, which slows the process.
THE MUSCLE GLYCOGEN TWO-STEP
Just like your gut cells move GLUT4 receptors to their gut-facing surface in order to absorb more glucose during exercise, your muscles use the same trick to grab more glucose when glycogen levels drop during exercise. This GLUT4 translocation is furiously increased in the 30-60 minutes after exercise for a duration of 30-60 minutes (Jentjens 2003), and represents the first stage of rapidly replenishing your muscle glycogen. That window is critical, because if you don’t replenish glycogen while it’s open, it becomes much harder to do so, and your overall recovery will be impeded.
The translocation of glucose receptors is triggered by low muscle glycogen levels, which are typical near the end of an exhaustive, long-duration exercise bout. Your muscles are very hungry for glucose at this time and smart enough to use several ways to increase glucose content to finish the workout/race/event and also to kickstart glycogen replenishment. By translocating glucose receptors, depleted muscles become glucose sponges, taking up as much as they can without needing insulin.
After 30-60 minutes, the DOMS/EIMD recovery process gets rolling, and insulin becomes more important for flooding muscles with glucose and amino acids. This is the second step of replenishing your muscle glycogen, and – like the first – it requires, simply, carbs. But how much? Well, we’re glad you asked.
HOW MUCH CARBOHYDRATES IMMEDIATELY AFTER EXERCISE?
Much research has clearly shown that the highest muscle glycogen synthesis rates are achieved by CHO intakes of 0.8-2g carbs/kg body weight/hour – 50-120 grams of carbs. This is close to what you should be doing hourly during exercise, but to satisfy the First Step of muscle glycogen replenishment, it also needs to be done by 30 minutes after you finish, during the glycogen window.
n practice, 60 grams of glucose is easily accomplished in the first 30 minutes without GI intolerances. Liquid drinks are the best way to get glucose to hungry muscles in the first 30 minutes. A second serving can be ingested at an hour, but even better is to eat a high-carbohydrate meal.
WHICH CARBOHYDRATES IMMEDIATELY AFTER EXERCISE?
Again, much research over the past 40 years has shown that glucose is still the preferred form of carbohydrate for immediate post-exercise glycogen replenishment – it’s what your muscles are primed to look for and use the fastest way, courtesy of those migrating receptors. There are other options, of course, so let’s take a detour down Alt CHO Avenue before arriving at our destination.
Sucrose (table sugar) and fructose are also able to replenish muscle glycogen, but not any better than pure glucose itself, and pure fructose even delays muscle glycogen repletion by shunting some glucose to replenish liver glycogen, which necessarily cuts into the supply going to those desperate, depleted muscles.
Short glucose polymers like the maltodextrins in EFS, EFS-PRO, and Liquid Shot are similar to glucose for glycogen repletion, but because glucose itself is still hanging around your bloodstream when Step Two kicks in, insulin works better with glucose.
So ultimately, glucose was our destination all along. The metabolic signaling milieu of muscles simply favors glucose in the Glycogen Two Step. Ever the capable dance partner, Ultragen follows the considerable research and successful practice findings by supplying 60 grams of glucose per serving. If you are truly glycogen-depleted, the surge of glucose can be felt quickly as a decrease in fatigue. Your brain also runs on glucose and is revived too, helping your post-exercise mood – and reducing the risk of an intense Saturday morning session blowing half your weekend off the rails.
ANYTHING ELSE TO HELP CARBS GET INTO POST-EXERCISE STARVED MUSCLES?
This won’t be a surprise, but hydration is critical. Fortunately, hydration is also satisfied if you use liquid drinks like Ultragen. Ultragen is complete, there’s no need to add anything else, so we recommend mixing it with water only because any other additions will only slow absorption.
Consensus recommendations also insist that vitamins and minerals accompany glucose to the dance, and you can always ensure adequate status of each and every essential vitamin/mineral beforehand by consistently using a comprehensive, high-potency MVM like MultiV. A chain is only as strong as its weakest link, and there is a long chain of events for muscle glycogen repletion and exercise recovery.
The final non-glucose addition is protein and/or protein hydrolysates (peptides) plus certain amino acids, which – along with glucose sources – increase the replenishment of muscle glycogen after depletion.
SUMMARY
After long-duration, strenuous, exhausting exercise, starting recovery immediately – immediately! – after you finish cannot be stressed enough. (IMMEDIATELY!) Maximizing glucose intake after exercise with consistent and continued intakes of carbohydrates can replete muscle glycogen to normal in 24 hours. That’s an overnight turnaround if you play it right, and the research evidence is deeply rooted and widely agreed-upon. Furthermore, results for recovery and overall health are also better with starting recovery quickly.
References for Glycogen Window for Recovery
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Literature Quotes for Glycogen Window for Recovery
“In conclusion, the present results indicate that glucose and sucrose are the carbohydrates of choice to restore muscle glycogen deposits after exhaustive exercise.”
Blom 1987, p.496
“As an evidence-based framework, a 4R's approach to optimizing post-exercise recovery was identified: (i) Rehydration-a fundamental process that will depend on the athlete, environment and sports event; (ii) Refuel-the consumption of carbohydrates is not only important to replenish the glycogen reserves but also to contribute to the energy requirements for the immune system and tissue reparation; ... (iii) Repair-post-exercise ingestion of high-quality protein and creatine monohydrate benefit the tissue growth and repair; and (iv) Rest-pre-sleep nutrition has a restorative effect that facilitates the recovery of the musculoskeletal, endocrine, immune, and nervous systems.”
Bonilla 2020, Abstract
“Rapid recovery after training session or multi-day competition, especially when there is less than 8 hours until next session. Recommended carbohydrate intake. Intake of 1-1.5 g/kg every hour in the early stages of recovery after exercise, contributing to a total intake of 6-10 g/kg over 24 hours.”
Bosch 2011, p.162
“Benefits from rapid and full replenishment of glycogen levels by post-exercise dietary carbohydrate intake include faster recuperation, faster return to training, and maintenance of exercise performance (prevention of impaired performance) in strenuous daily events (such as Tour de France cycling races).”
Bucci 1993, p.13
“Ingestion of drinks containing glucose has shown to increase blood glucose, improve endurance running performance, and decrease plasma cortisol levels and circulating leukocyte subsets. Carbohydrate ingestion attenuates the inflammatory response to acute exercise through reduced levels of IL-6, total anti-inflammatory IL-1RA, and cortisol.”
Buonocore 2015, p.64
“Rapid resynthesis of muscle glycogen stores is aided by the immediate intake of carbohydrate (I g.kg-1 BM each 2 hours), particularly of high glycemic index carbohydrate foods, leading to a total intake over 24 hours of 7-10 g.kg-1 BM.”
Burke 1997, Abstract
“...early intake of carbohydrate after strenuous exercise is valuable because it provides an immediate source of substrate to the muscle cell to start effective recovery, as well as taking advantage of a period of moderately enhanced glycogen synthesis.”
Burke 2004, p.28
“Availability of carbohydrate as a substrate for the muscle and central nervous system is critical for the performance of both intermittent high-intensity work and prolonged aerobic exercise. Therefore, strategies that promote carbohydrate availability, such as ingesting carbohydrate before, during and after exercise, are critical for the performance of many sports and a key component of current sports nutrition guidelines.”
Burke 2010, Abstract
“The role of dietary carbohydrates (CHO) in the resynthesis of muscle and liver glycogen after prolonged, exhaustive exercise has been clearly demonstrated.”
Costill 1985, Abstract
“The most sensitive period for glycogen resynthesis is within the first few hours after exercise.”
Costill 1991, Abstract
“Carbohydrate ingestion at a rate of ≥1.2 g carbohydrate per kg body mass per hour appears to maximise post-exercise muscle glycogen repletion rates. Providing these carbohydrates in the form of glucose–fructose (sucrose) mixtures does not further enhance muscle glycogen repletion rates over glucose (polymer) ingestion alone.”
Gonzalez 2017, Abstract
“Consumption of small amounts of CHO (1.0–1.2 g/kg BW) and protein immediately after exercise and during recovery is generally recommended to replenish body glycogen stores [49], to stimulate muscle protein synthesis [94] and to enhance training adaptations [95].”
Gunzer 2012, p.1197
“4. Ingest a good postexercise carbohydrate/protein drink. After exercise, the body is primed for muscle glycogen resynthesis and the repair of muscle damage. A carbohydrate/protein drink based on the principles of the Nutrient Timing System can improve muscle glycogen recovery and muscle protein status.”
Ivy 2004, p.132
“Thus CHO availability at the correct time during exercise recovery is critical for replenishing muscle glycogen.”
Millard-Stafford 2008, p.194
“The most effective nutritional countermeasures, especially when considered from a metabolomics perspective, include acute and chronic increases in dietary carbohydrate and polyphenols. ... Carbohydrate supplementation has the strongest scientific support, and reduces post-exercise stress hormone levels, inflammation, fatty acid mobilization and oxidation.
Nieman 2017, Abstract & p.18
“The main factor determining the recovery time is the glycogen synthesis rate, which is particularly important when the repletion periods are short, such as during periods of intensive training, stage races, and tournament-style competitions.”
Orru 2020, p.6
“Current evidence continues to support mandatory high carbohydrate intakes ... after the event to optimize post-event repletion of endogenous carbohydrate stores.”
Peters 2003, Abstract
“Energy and macronutrient needs, especially carbohydrate and protein, must be met during times of high physical activity to maintain body weight, replenish glycogen stores, and provide adequate protein to build and repair tissue.”
Rodriguez, American College of Sports Medicine, American Dietetic Association 2009, Abstracts
“For maximal glycogen resynthesis, carbohydrate intake must be high enough to ensure sufficient blood glucose for muscle glucose uptake and sufficient insulin to keep a high percentage of glycogen synthase in the active form. However, there appears to be both insulin-dependent and insulin-independent phases of post-exercise human muscle glycogen resynthesis.”
Wilkinson 1998, p.88
Comments
Jeffrey said:
Well said. For about the last 15 years, Ultragen has been my go to. Ultragen allows me to play hard in the mountains on weekends AND still be of some use to my family, instead of laying on the floor all day.