This is because muscle tissue lacks the enzyme necessary to convert fructose to glucose. Therefore fruit is a bad carbohydrate choice for carbohydrate loading or supercompensation.

One of the earliest studies on the effects of muscle glycogen on endurance was conducted in by Ahlborg and colleagues 4. In this now classic study, he demonstrated a correlation between initial muscle glycogen concentration in the vastus lateralis muscle of the quadriceps and exercise endurance using a continuous bicycle ergometer protocol.

Since this study there have been numerous studies validating this effect see Conlee, for a review. In another classic study Bergstrom and associates 12 studied the effects of altering carbohydrate consumption for 3 days on exercise to exhaustion.

The researchers had the same subjects consume a mixed diet, a high low carbohydrate diet, and a high carbohydrate diet for three days. After each three-day period glycogen concentrations were measured and the subjects exercised to exhaustion on a bicycle ergometer.

The results are summarized in Figure 3. and performance Performance is also plotted on the y axis in minutes. from only 3 days of dietary manipulations. The order of the treatments was mixed diet, followed by high fat – high protein and finally high carbohydrate.

Not only did the high carbohydrate diet replace the carbohydrate stores that were depleted by the high fat – high protein diet, but it actually increased glycogen concentrations over baseline levels.

Bergstrom and colleagues concluded that the ability to sustain prolonged exercise depends on muscle glycogen concentration. The myriad of studies that followed firmly established the theory that sustaining performance in endurance events lasting longer than one hour is strongly dependent upon maintaining glycogen concentrations and that fatigue during these events is probably due to glycogen depletion 2.

Although glycogen depletion does not cause fatigue during high power events 13 , glycogen depletion has been shown to reduce the ability to produce a high power output. A standard power test involves pedaling as fast as possible against a fixed resistance for 30 seconds. Conlee 4 speculates that this reduction in power output occurs because some fibers are no longer capable of contributing because they are almost completely devoid of glycogen.

Since there are fewer fibers available to contribute, power output is reduced. Since every gram of glycogen is stored with approximately 3 grams of water 13 a doubling of glycogen stores due to glycogen supercompensation is likely to increase the apparent size of muscles.

Since exercise upregulates the body’s ability to store glycogen and bodybuilders have more muscle mass than the average person, we might expect that a bodybuilder stores considerably more than the grams of glycogen mentioned earlier as an average value for normal adults.

For the sake of argument let’s assume that a bodybuilder is storing grams not an unreasonable amount of muscle glycogen. By carbohydrate depletion and supercompensation to twice that level again, not unreasonable it would be possible to add grams of glycogen plus grams of water to the bodybuilder’s muscle tissue.

This amounts to a 7. Therefore a bodybuilder can potentially gain a significant amount of apparent mass with successful glycogen supercompensation. Beginning a typical 3-day depletion, 3 day loading supercompensation cycle just prior to a competition may not be the best strategy for an endurance athlete.

This is because glycogen depletion requires vigorous exercise and most endurance athletes refrain from vigorous exercise during the final week prior to a competition to ensure adequate recovery.

Fortunately glycogen levels stay elevated for at least 3 days following a glycogen supercompensation cycle 5. This allows the athlete to start the cycle 9 days prior to competition and still allow 6 days of recovery before the event. A typical glycogen supercompensation cycle would look something like this:.

The vigorous exercise should use the same muscles that are going to be used during the competition since it is these muscles that will be depleted and supercompensated. In other words, if you are a runner you carbohydrate deplete by running. If you are a cyclist you carbohydrate deplete by cycling.

Most of the carbohydrate consumption on day 1 of the high carbohydrate phase should be simple sugars and intake should not exceed 25 grams per hour or 75 grams every three hours.

Carbohydrates should be consumed at least every three hours so that continual glycogen synthesis is occurring. If, as Conlee speculated 4 , some muscle fibers are completely glycogen depleted by high power performances and subsequently are incapable of contributing, one might speculate that power athletes could benefit by glycogen supercompensation.

For many athletes, however, actual performance during competition would not be enhanced by supraphysiological levels of glycogen. For weightlifters, for example, performance is related to the ability to produce force and not the ability to maintain force output over time.

Although glycogen loading can delay the reduction in force output during repeated maximal contractions 14 , no study to date has shown that maximal force production can be enhanced by supraphysiological concentrations of glycogen.

The same logic applies to jumpers and throwers. For high power events lasting less than 10 seconds m sprint the majority of the energy comes from stored Adenosine Triphosphate and Creatine Phosphate with little contribution from carbohydrates Brooks and Fahey For high power events lasting longer than 2 minutes performance is limited by the cardiovascular system Based on these facts and the Heighenhauser study mentioned earlier 30 seconds of maximal pedaling , one might speculate that glycogen supercompensation might be useful for high power events lasting between 10 seconds and two minutes.

However, there is an important distinction between power tests and other 30 second events like a m dash. In a power test power peaks early because subjects are pedaling maximally from the start.

During all but the shortest sprinting events there is some degree of pacing. It is not known if pacing would affect the relationship of glycogen to fatigue during these events. In addition, no study to date has shown an actual increase in performance in sprinting events either bike, run or swim sprints due to glycogen supercompensation.

Also, in some power events, like weightlifting and sprinting, extra bodyweight can be a liability. Although they should maintain an adequate carbohydrate intake to prevent a decrement in performance, there is no strong evidence to suggest that power athletes would benefit from glycogen supercompensation prior to competition.

Since training can involve repeated high power performances repeated sprints, or sets one might speculate that glycogen supercompensation might be an effective training aid. While training performance might benefit from high concentrations of muscle glycogen, athletes cannot glycogen deplete and supercompensate prior to every training session.

An apparent increase in muscle mass is certainly a bonus for bodybuilders. Therefore, successfully glycogen supercompensating can certainly be a worthwhile process for these athletes.

Since bodybuilders have much more muscle mass than the average person, larger carbohydrate intakes are likely to be required to maximize glycogen synthesis. Since we are trying to maximize glycogen supercompensation in all muscles, we must glycogen deplete all muscles.

This is accomplished by performing high repetition, high volume workouts for all body parts while on a low carbohydrate diet prior to glycogen loading.

A typical regimen might look like this:. The bodybuilder should be training the entire body over the three-day period with a large volume of high repetition exercises to enhance glycogen depletion. It is the total volume of work that will determine the degree of glycogen depletion so rest between sets should be adequate to allow a large volume of work to be performed.

Bodybuilders should avoid lifting very heavy as high force eccentric contractions have been shown to interfere with glycogen synthesis 15 probably due to muscle microdamage. Urine color should be clear, and there should be a plentiful amount.

Coaches can keep track of fluid losses by weighing athletes before and after training. For every pound of fluid lost, athletes should consume 20 to 24 oz of fluid. Moreover, postworkout fluids or meals should contain sodium, particularly for athletes who lose large amounts of sodium through sweat.

Repair and Build In addition to fluid and electrolyte losses, training increases circulating catabolic hormones to facilitate the breakdown of glycogen and fat for fuel.

These hormone levels remain high after exercise and continue to break down muscle tissue. Without nutrient intake, this catabolic cascade continues for hours postexercise, contributing to muscle soreness and possibly compromising training adaptations and subsequent performance.

To repair and build muscle, athletes must refuel with high-protein foods immediately following exercise, especially after resistance training. They should consume 20 to 40 g of protein that includes 3 to 4 g of leucine per serving to increase muscle protein synthesis.

In addition, whey is an optimal postworkout protein because of its amino acid composition and the speed of amino acid release into the bloodstream.

What many athletes often overlook is the importance of carbohydrate intake for building and repairing muscle. Carbohydrate can decrease muscle protein breakdown by stimulating insulin release. Resistance training athletes benefit from consuming carbohydrates and protein after strenuous workouts.

Attenuating Excess Inflammation Athletes who get the required amounts of leucine-rich protein and carbohydrate immediately after exercise turn that crucial time period from a catabolic state to an anabolic state.

To help curb excessive inflammation and muscle soreness, researchers have examined various products and ingredients. In particular, tart cherry juice and ginger fresh or heat treated have been found to decrease eccentric-exercise—induced inflammation and delayed onset muscle soreness.

Specific Considerations While recovery nutrition has three primary goals, the manner in which these goals are achieved depends on the type of sport an athlete plays. Based on sports science research, nutrition recommendations for athletes are divided into two categories: endurance sports and resistance training.

A sports dietitian can develop individualized plans for each athlete, keeping in mind that plans may change based on training adaptations, changes in growth and body composition, injuries, illness, and training phase.

We educate them on their postlift needs during their individual nutrition consults. Many eat dinner postpractice at our training table or at the dining hall where a dietitian is available for live plate coaching as well.

Importance of Sports Dietitians Sports dietitians play an essential role in helping athletes recover from training. References 1. Ivy JL. Regulation of muscle glycogen repletion, muscle protein synthesis and repair following exercise. J Sports Sci Med. Casa DJ, Armstrong LE, Hillman SK, et al.

J Athl Train. Bishop PA, Jones E, Woods AK. Recovery from training: a brief review. J Strength Cond Res. Coyle EF, Coggan AR, Hemmert MK, Ivy JL. There is nothing inherent in carbs, glucose, or glycogen that increase your risk of gaining body fat.

When your glycogen stores are depleted through exercise or due to not consuming enough carbs, you will feel fatigued, sluggish, and perhaps experience mood and sleep disturbances. Murray B, Rosenbloom C.

Fundamentals of glycogen metabolism for coaches and athletes. Nutr Rev. Goyal MS, Raichle ME. Glucose requirements of the developing human brain.

J Pediatr Gastroenterol Nutr. doi: D'anci KE, Watts KL, Kanarek RB, Taylor HA. Low-carbohydrate weight-loss diets. Effects on cognition and mood. Winwood-Smith HS, Franklin CE, White CR. Low-carbohydrate diet induces metabolic depression: A possible mechanism to conserve glycogen. Am J Physiol Regul Integr Comp Physiol.

Adeva-Andany M, Gonzalez-Lucan M, Donapetry-Garcia C. et al. Glycogen metabolism in humans. BBA Clinical. Zajac A, Poprzecki S, Maszycyk A, et al. The effects of a ketogenic diet on exercise metabolism and physical performance in off-road cyclists.

By Laura Dolson Laura Dolson is a health and food writer who develops low-carb and gluten-free recipes for home cooks. Use limited data to select advertising.

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You need to maximize glycogen stores to have the energy you need. But too much glycogen can lead to an excess - and that surplus is stored as fat. Adenosine triphosphate ATP is a complex molecule used by all cells in your body for energy. It drives all our chemical processes and is vital for life. During exercise, the rate of ATP utilization increases proportional to the intensity.

In other words, the harder your workout - the more energy you use. At rest or at low intensities ATP is produced within a special organelle called the mitochondria - using both fatty acids and glucose. The journey that fat and glycogen take to generate ATP is long and complex. And when your body only requires a trickle of ATP at a constant rate, that long-winded process is worth it.

During anaerobic glycolysis, your cells use glycogen to generate the energy bond called ATP. If it switches from aerobic glycolysis which uses fat and glucose for energy and chooses anaerobic glycolysis instead, it can generate ATP faster. By skipping the use of fatty acids and bypassing the mitochondria.

Because the mitochondria provide much more ATP. Anaerobic glycolysis can only use glycogen for fuel. How much ATP you can produce is down to many variables - one of those is the glycogen content in the muscle.

In other words, glycogen is hugely important during high-intensity workouts. Your body gets glucose for energy, either from the food you eat or by tapping into stored glycogen. When you eat a carb-rich meal your cells take what they need and dump the rest into glycogen reserves ready for a rainy day.

According to a study published in the Journal of Physiology 4 the ability of muscle to exercise is seriously compromised when the glycogen store is reduced to low levels. Even when there is an abundance of other fuel sources.

Research has shown on several occasions that when athletes perform with low glycogen levels, both strength and endurance suffers. For example, a study of healthy participants experienced a loss in grip strength 5 after strenuous exercise. Another study showed a reduction in endurance.

The link between low glycogen and fatigue is due to several factors. One of the most important is the reduced calcium release from the sarcoplasmic reticulum that negatively impacts the ability to produce force.

Bonking is a phenomenon known all too well by marathon runners and other endurance athletes. It will make you feel weak, shaky and dizzy. And because your brain is using glycogen for fuel it leaves you feeling lightheaded, confused and drunk-like. Endurance training uses up a lot of glycogen due to the intensity and duration of exercise.

Overtraining is a condition where your athletic performance is significantly reduced, even when training has stopped. It can last weeks, sometimes months and is characterized by fatigue, low mood, reduced performance and poor sleep. As a multifactorial syndrome, overtraining has many underpinning causes.

Within this model, low glycogen is thought to increase the use of proteins for fuel. Which can lead to chronic central fatigue.

Risks of Low Muscle Glycogen Content Athletes with low muscle glycogen content will experience a decrease in exertion capacity as well as an increased risk for overtraining and muscle damage. Due to the high demand for glycogen as energy for exertion, many athletes have some pattern of glycogen depletion.

This situation may lead to muscle damage and chronic overtraining. In fact, muscle damage limits the capacity of the muscles to store glycogen, so even while consuming a high-carbohydrate diet, an athlete can have difficulty maintaining adequate glycogen stores if the muscles are damaged.

Research indicates a correlation between training and competing with high muscle glycogen content and improved exertion capacity and overall performance. Results suggest that muscle glycogen availability can affect performance during both short-term and more prolonged high-intensity intermittent exercise 1.

Additionally, MuscleSound delivers immediate data with post-performance scans that can identify the warning signs of muscle fatigue, muscle damage and overtraining.

This post-performance insight allows for the concentrated muscle recovery necessary to optimize consistent future performance and prevent long-term muscle injury. MuscleSound allows users to not only optimize, but also capitalize on, the reliable and regular measurement of muscle glycogen content with their patented scientific methodology, practical technology and cloud-based software.

The non- invasive, real-time and proactive muscle-specific benefits make MuscleSound superior to existing methods of glycogen testing, performance preparation and recovery technologies.

Bol Assoc Med P R. Carbohydrate nutrition before, during and after exercise. Fed Proc. Gonzalez JT, Fuchs CJ, Betts JA, van Loon LJC. Glucose plus fructose ingestion for post-exercise recovery — greater than the sum of its parts?

Harty PS, Cottet ML, Malloy JK, Kerksick CM. Nutritional and supplementation strategies Sports Med Open. Hashiwaki J. Effects of post-race nutritional intervention on delayed-onset muscle soreness and return to activity in Ironman triathletes. Hoppel F, Calabria E, Pesta D, Kantner-Rumplmair W, Gnaiger E, Burtscher M.

Physiological and pathophysiological responses to ultramarathon running in on-elite runners. Front Physiol. Howatson G, van Someren KA. The prevention and treatment of exercise-induced muscle damage. Sports Med. Ivy JL, Kuo CH. Regulation of GLUT4 protein and glycogen synthase during muscle glycogen synthesis after exercise.

Acta Physiol Scand. Ivy J, Portman R. The right macronutrients, Ch 10 in Nutrient Timing. The Future of Sports Nutrition , Basic Health Publications, Inc. Jentjens R, Jeukendrup A. Determinants of post-exercise glycogen synthesis during short-term recovery.

Kerksick CM, Arent S, Schoenfeld BJ, Stout JR, Campbell B, Wilborn CD, Taylor L, Kalman D, Smith-Ryan AE, Kreider RB, Willoughby D, Arciero PJ, VanDusseldorp TA, Ormsbee MJ, Wildman R, Greenwood M, Ziegenfuss TN, Aragon AA, Antonio J.

International Society of Sports Nutrition position stand: nutrient timing. J Intl Soc Sports Nutr. Kerksick CM, Harvey T, Stout JR, Campbell B, Wilborn CD, Kreider RB, Kalman D, Ziegenfuss TN, Lopez H, Landis J, Ivy JL, Antonio J.

Millard-Stafford M, Childers WL, Conger SA, Kampfer AJ, Rahnert JA. Recovery nutrition: timing and composition after endurance exercise. Curr Sports Med Rep. Nieman DC, Mitmesser SH. Potential impact of nutrition on immune system recovery from heavy exertion: a metabolomics perspective.

Orru S, Imperlini E, Nigro E, Alfieri A, Cevenini A, Polito R, Daniele A, Buono P, Mancini A. Role of functional beverages in sports performance and recovery.

Passaglia DG, Emed LGM, Barberato SH, Guerios ST, Moser AI, Silva MMF, Ishie E, Guarita-Souza LC, Costantini CRF, Faria-Neto JR.

Acute effects of prolonged physical exercise: evaluation after a twenty-four-hour ultramarathon. Arq Bras Cardiol.

Peters EM. Nutritional aspects in ultra-endurance exercise. Curr Opin Clin Nutr Metab Care. Rodriguez NR, Di Marco NM, Langley S. American College of Sports Medicine position stand.

Nutrition and athletic performance. Position of the American Dietetic Association, Dietitians of Canada, and the American College of Sports Medicine: Nutrition and athletic performance. J Am Diet Assoc. ten Haaf DSM, Flipsen MA, Horstman AMH, Timmerman H, Steegers MAH, de Groot LCPGM, Eijsvogels TMH, Hopman MTE.

The effect of protein supplementation versus carbohydrate supplementation on muscle damage markers and soreness following a km road race: a double-blind randomized controlled trial. International Society of sports Nutrition Position Stand: nutritional considerations for single-stage ultra-marathon training and racing.

J Int Soc Sports Nutr. Vilella RC, Vilella CC. What is effective, may be effective, and is not effective for improvement of biochemical markers on muscle damage and inflammation, and muscle recovery? Open J Pharmacol Pharmacother.

Warhol MJ, Siegel AJ, Evans WJ, Silverman LM. Skeletal muscle injury and repair in marathon runners after competition. Am J Pathol. Wilkinson JG, Liebman M. Carbohydrate metabolism in sport and exercise, Ch 3 in Nutrition in Exercise and Sport , 3 rd Ed.

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.

Recommended carbohydrate intake. Glycogen is how the body stores carbohydrates for energy at the muscular level. Importance of High Muscle Glycogen High muscle glycogen content allows athletes in both endurance sports and intermittent sprint sports i.

In endurance athletes, high muscle glycogen content can increase the time to fatigue during exertion. In addition, multiple studies have indicated that endurance athletes completing time trials can perform better with high muscle glycogen content than with lower glycogen levels. In studies on intermittent sprint exercise simulating the demands of team sports, athletes can spend more time at higher intensity levels and improve their performance when they have high muscle glycogen content.

Higher muscle glycogen content allows soccer players to spend more time in moderate- to high-speed running and allows hockey players to skate longer and faster during each shift.

But more recent research has added some subtleties that are worth considering. Here are some of the highlights. First, some background. So the first important question is: How do you refill those stores as quickly and fully as possible?

If you need to be as recovered as possible within eight hours, then starting the refueling process immediately after the first workout is important. For that purpose, foods with medium and high glycemic index may have an advantage.

Adding some protein 0. Whether the glycogen boost from protein is really significant is debatable, but protein is a good idea anyway to help stimulate muscle repair.

The typical advice is to aim for about 50 grams of carbohydrate every two hours post-workout; but doubling that to 50 grams every hour for the first four hours seems to boost glycogen storage rates by 30 to 50 percent.

For reference, a PowerBar energy bar has 43 grams of carbs.

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.

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. 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. If you do post-exercise glycogen repletion right, you can restore muscle glycogen levels to normal in 24 hours. 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. 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.

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 minutes after exercise for a duration of minutes Jentjens , and represents the first stage of rapidly replenishing your muscle glycogen. 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.

By translocating glucose receptors, depleted muscles become glucose sponges, taking up as much as they can without needing insulin. This is the second step of replenishing your muscle glycogen, and — like the first — it requires, simply, carbs. But how much?

Much research has clearly shown that the highest muscle glycogen synthesis rates are achieved by CHO intakes of 0. 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. 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.

Fortunately, hydration is also satisfied if you use liquid drinks like Ultragen. 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.

After long-duration, strenuous, exhausting exercise, starting recovery immediately — immediately! Maximizing glucose intake after exercise with consistent and continued intakes of carbohydrates can replete muscle glycogen to normal in 24 hours.

Furthermore, results for recovery and overall health are also better with starting recovery quickly. 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.

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PreRace Liquid Shot EFS Drink Mix EFS-PRO High Carb. Athletes Articles Films. Replenishing muscle glycogen for maximal, faster recovery.

By Dr. 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. 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.

ANYTHING ELSE TO HELP CARBS GET INTO POST-EXERCISE STARVED MUSCLES? SUMMARY After long-duration, strenuous, exhausting exercise, starting recovery immediately — immediately! References for Glycogen Window for Recovery Blom PC, Hostmark AT, Vaage O, Kardel KR, Maehlum S.

Effect of different post-exercise sugar diets on the rate of muscle glycogen synthesis. Med Sci Sports Exerc. Bongiovanni T, Genovesi F, Nemmer M, Carling C, Aberti G, Howatson G. Nutritional interventions for reducing the signs and symptoms of exercise-induced muscle damage and accelerate recovery in athletes: current knowledge, practical application and future perspectives.

Eur J Appl Physiol. Bonilla DA, Perez-Idarraga A, Odriozola-Martinez A, Kreider RB. Int J Environ Res Public Health. Bosch A, Smit KM. Nutrition for endurance and ultra-endurance training, Ch 13 in Sport and Exercise Nutrition , Lanham-New SA, Stear SJ, Shirrefs SM, Collins SL, Eds.

Bucci LR. Nutritional ergogenic aids — macronutrients, Ch 2 in Nutrients as Ergogenic Aids for Sports and Exercise , CRC Press, Boca Raton, FL, , pp.

Buonocore D, Negro M, Arcelli E, Marzatico F. Anti-inflammatory dietary interventions and supplements to improve performance during athletic training. J Am Coll Nutr. Burke LM, Kiens B, Ivy JL.

Carbohydrates and fat for training and recovery, Ch 2 in Food, Nutrition and Sports Performance II. The International Olympic Committee Consensus on Sports Nutrition , Maughan RJ, Burke LM, Coyle EF, Eds. Burke LM. Fueling strategies to optimize performance: training high or training low?

Scand J Med Sci Sports. Nutrition for post-exercise recovery. Aust J Sci Med Sport. Costa RJS, Knechtle B, Tarnopolsky M, Hoffman MD. Nutrition for ultramarathon running: trial, track, and road. Int J Sport Nutr Exerc Metab. Costill DL. Carbohydrate for athletic training and performance.

Bol Assoc Med P R. Higher muscle glycogen content allows soccer players to spend more time in moderate- to high-speed running and allows hockey players to skate longer and faster during each shift. Risks of Low Muscle Glycogen Content Athletes with low muscle glycogen content will experience a decrease in exertion capacity as well as an increased risk for overtraining and muscle damage.

Due to the high demand for glycogen as energy for exertion, many athletes have some pattern of glycogen depletion. This situation may lead to muscle damage and chronic overtraining. In fact, muscle damage limits the capacity of the muscles to store glycogen, so even while consuming a high-carbohydrate diet, an athlete can have difficulty maintaining adequate glycogen stores if the muscles are damaged.

Research indicates a correlation between training and competing with high muscle glycogen content and improved exertion capacity and overall performance. Results suggest that muscle glycogen availability can affect performance during both short-term and more prolonged high-intensity intermittent exercise 1.

Additionally, MuscleSound delivers immediate data with post-performance scans that can identify the warning signs of muscle fatigue, muscle damage and overtraining. This post-performance insight allows for the concentrated muscle recovery necessary to optimize consistent future performance and prevent long-term muscle injury.

MuscleSound allows users to not only optimize, but also capitalize on, the reliable and regular measurement of muscle glycogen content with their patented scientific methodology, practical technology and cloud-based software.

Scrutiny of the evidence for the optimal dosage of carbohydrates to be ingested in the early hours of post-exercise recovery reveals that there is only one study available comparing 1.

While it is difficult to compare results between different studies given that different methodological approaches have been used, it appears that there is a good relationship between the dosage and the amount of muscle glycogen resynthesis spanning at least from 0 to 1. Thus, given that there is also a relationship between training status and the capacity to store muscle glycogen [ 28 ], it could be hypothesized that, absorption permitting, higher ingestion rates would be favorable to elite athletes whose relative proportion of muscle mass is higher.

More research is required to elucidate if this is the case. In addition to this, an emerging topic within the post-exercise recovery period, with an aim to improve functional capabilities of athletes, is the type of carbohydrates ingested in recovery.

Namely, advances have been made on the type of carbohydrates i. While there appears to be no benefit of ingesting multiple types of carbohydrates i.

Advancing these data are studies showing that recovery of cycling exercise capacity is greater after ingestion of a combination of glucose-based carbohydrates and fructose as compared to glucose-based carbohydrates only [ , ], likely because of higher carbohydrate availability within both liver and muscle glycogen pools.

It has been hypothesized but not established that combining glucose with both galactose and fructose would result in more rapid replenishment of both glycogen pools [ ]. Interestingly, this strategy did not translate into improved cycling performance [ ].

The results of the latter study are thus surprising. However, a close examination of the results offers a potential explanation and opens new research questions.

Namely, two studies [ , ] quantified utilization of in-recovery ingested carbohydrates in the subsequent exercise bout and found an increase in its use, indicating an increased carbohydrate availability. However, the increase of carbohydrate oxidation rates in the study assessing subsequent cycling performance was such that by the time the cycling time trial was initiated, glycogen stores within the body were likely the same in both conditions.

Thus, more work is required to define the precise scenarios when a functional benefit can be expected; however, there appears to be a uniform observation that in terms of metabolism, ingestion of composite carbohydrates is beneficial.

A summary of current knowledge on the effectiveness of different monosaccharide types on repletion of different glycogen depots i. Based on the current evidence, it could be recommended that athletes seeking to recover glycogen stores as quickly as possible consider ingesting carbohydrates from a combination of glucose-based carbohydrates and fructose to optimally stimulate both liver and muscle glycogen resynthesis.

The same recommendation cannot currently yet be given for galactose as whilst combined galactose-glucose favorably affects liver glycogen synthesis it is currently unknown how effective it is in the replenishment of muscle glycogen stores.

Short-term recovery of muscle and liver glycogen stores after exhaustive exercise using different combinations of monosaccharides. Fructose-glucose carbohydrate mixtures have been demonstrated to be very effective in replenishment of both muscle and liver glycogen stores.

On the other hand, while glucose-based carbohydrates cause robust rates of muscle glycogen replenishment, liver glycogen synthesis rates are inferior as compared to a combination of fructose-glucose- and galactose-glucose-based carbohydrates.

No data are currently available for muscle glycogen synthesis rates after ingesting a galactose-glucose mixture. It is hypothesized but not established that combining fructose-galactose-glucose-based carbohydrates would be optimal for post-exercise repletion of both glycogen pools.

CHO carbohydrate. Training can be described as undertaking structured workouts with an aim to improve or maintain performance over time by manipulating the structure, intensity, duration and frequency of training sessions [ , , ].

As total energy requirements and, consequently, carbohydrate demands are high in endurance-based sports, it is fair to assume that optimization of carbohydrate intake in these sport disciplines plays an important role. Early sports nutrition guidelines [ ] advised athletes to both train and compete with high carbohydrate availability, and this approach dominated until , when Hansen and colleagues observed that a reduction in carbohydrate availability before certain training sessions in untrained individuals could potentially enhance training adaptations [ ].

In this study, leg kicking exercise training was performed in a week-long training study. Each leg was subjected to a different treatment. Muscle biopsy analysis also showed more positive metabolic adaptations hydroxy acyl-CoA dehydrogenase [HAD] and citrate synthase [CS] activity in the leg training with reduced muscle glycogen stores.

While very attractive, the strategy was found to be effective in untrained individuals, and more work was required to see if similar findings could be observed in already trained individuals. As a result, this study was a landmark study paving the way for further investigations into whether different approaches to nutrient availability in trained athletes are beneficial based on different goals: training adaptation or competition performance.

In addition to carbohydrate availability manipulations to influence training adaptations, the concept of training the gut also needs to be considered to become a part of the training process to potentially improve tolerance to high carbohydrate ingestion rates during exercise especially [ , ], as the prevalence of gastrointestinal issues during exercise is large [ , ].

While the concept of training with high carbohydrate intakes to improve tolerance to ingested carbohydrates seems warranted, it remains to be established whether such practice leads to improved absorption of ingested carbohydrates and by what mechanisms or leads to just improved tolerance.

Recent evidence from rats indicates that a combination of a high carbohydrate diet and exercise does not result in an increased number of glucose transporters in the intestines [ ], and it could be thus speculated that improved tolerance can occur independently of improved absorption capacity.

Building from the study by Hansen and colleagues, research started to focus on ways to optimize training adaptations and not necessarily optimize performance within these training sessions in trained individuals. Indeed, studies investigating molecular signaling responses after acute bouts of training with low muscle and liver glycogen stores in trained individuals provided promising results [ 10 , ].

The concept is well described elsewhere [ , ]. Using this approach, some studies demonstrated metabolic benefits, such as reduced reliance on carbohydrates during moderate-intensity exercise [ , ].

However, a recent meta-analysis of nine studies investigating long-term benefits of carbohydrate periodization on performance outcomes suggests that this approach does not always enhance performance in the long term over training with high carbohydrate availability [ ].

Perhaps important to understand when interpreting these data is that large training volumes are accompanied by substantial energy turnover.

Even if a training session is initiated with adequate muscle glycogen stores, they will be markedly reduced by the end of it [ 28 ], creating a suitable environment for activation of crucial molecular signaling pathways thought to be responsible for positive adaptations [ ]. One of the fundamental principles of endurance training is achieving sufficient training volume [ , ].

For instance, elite cyclists are reported to cover more than 30, km on the bike in a single year [ ]. Large training volumes are reported in other endurance sports as well [ ]. This provides support for the notion that accumulation of sufficient training volume is of paramount importance among elite endurance athletes.

Training with high carbohydrate availability i. Thus, training with low carbohydrate availability should likely be at best viewed as a more time efficient way to train [ , ] rather than the optimal way. Thus, manipulating carbohydrate availability before and during training sessions could affect molecular responses after exercise bouts.

However, focusing solely on activation of pathways such as AMPK could be too reductionist, as it does not account for the recovery that is required after such a session, as, for instance, it is well known that protein breakdown is increased during such sessions [ , ].

In addition to this, recent evidence indicates that the time between two exercise sessions rather than carbohydrate availability is the important modulator of the training responses after the second exercise bout [ , ].

To circumvent this, attempts have been made to rescue the reduction in training capacity by utilization of ingestion of ergogenic aids. In line with this, carbohydrate and caffeine mouth rinsing have been shown to improve high-intensity exercise performance when conducted under a carbohydrate-restricted state [ ].

Whether training adaptation can be enhanced with this approach has not been studied. More recently, building on previous work [ ], the effects of delayed carbohydrate feeding in a glycogen depleted state i. While performance outcomes were unclear, delayed carbohydrate feeding enabled maintenance of stable blood glucose concentrations without suppressing fat oxidation rates and thus created a favorable metabolic response.

Again, whether such an approach leads to longer-term enhancement in training adaptation remains to be seen. More broadly there is a need to further explore the potential benefits of commencing exercise with low carbohydrate availability to maximize both the metabolic and mechanical i.

Another popular reason for undertaking training with low carbohydrate availability is the notion that such an approach would lead to increases in fat oxidation rates during competition and spare endogenous carbohydrate stores with a limited storage capacity and by doing so improve performance [ 18 , ].

A recent study indicated that the capacity to utilize fat during exercise in an overnight fasted state is best correlated with CS activity [ ], a marker of mitochondrial content [ ] that is itself well correlated with training volume [ ]. More research is required to better understand if training and diet can be structured so that substrate oxidation rates would be altered in favor of fat oxidation without being part of general improvements seen with training per se, and whether this could lead to improvements in endurance performance.

Unfortunately, the prevalence of relative energy deficiency in sport RED-S remains high [ ]. Building on the previous evidence that sufficient carbohydrate intake can ameliorate symptoms of overtraining [ , ], it has recently been proposed that there might be a link between relative RED-S and overtraining and that a common confounding factor is carbohydrate [ 11 ].

Recent data support an important role for dietary carbohydrate, as low carbohydrate, but not low energy availability, affects bone health markers [ ], and deliberately inducing low carbohydrate availability to promote training adaptations and remaining in energy balance by increasing fat intake does not offer any benefits over a combination of energy and carbohydrate deficit—even more, it can impair glycemic regulation [ ].

Whether carbohydrate availability is the crucial part in the development of RED-S remains to be properly elucidated. Collectively, periodizing carbohydrate intake based on the demands of training and especially an upcoming training session currently appears to be the most sensible approach as it 1 allows the execution of the prescribed training program, 2 minimizes the risk of high carbohydrate availability impeding training adaptations and 3 helps minimize the risk for occurrence of RED-S.

A framework for carbohydrate periodization using this concept is depicted in Fig. Framework for carbohydrate periodization based on the demands of the upcoming exercise session. Exercise intensity domain selection refers to the highest intensity attained during the exercise session.

The exact carbohydrate requirements are to be personalized based on the expected energy demands of each exercise session. CHO carbohydrates, CP critical power, LT1 lactate threshold 1, LT2 lactate threshold 2, MLSS maximal lactate steady state. While provision of exact recommendations for carbohydrate intake before and during exercise forms part of sports nutrition recommendations provided elsewhere [ 1 , 2 ], we believe that interindividual differences in energy and thus carbohydrate requirements are such that optimization of carbohydrate intake should be personalized based on the demands and the goals of the exercise session one is preparing feeding for.

For instance, aggressive provision of carbohydrate intake during exercise deemed beneficial among one population [ 73 ] in another population could lead to unwanted increase in muscle glycogen utilization [ 81 ].

In addition to this, even within sports commonly characterized as featuring extreme energy turnover rates, day-to-day differences are such that provision of exact carbohydrate guidelines would be too inaccurate [ 22 , ].

Thus, personalization of carbohydrate intake during exercise is warranted, as described in the next section.

A certain level of personalization of energy and carbohydrate intake has been a standard part of nutritional guidelines for athletes for years [ 1 , 2 , ].

Practitioners and athletes have a wide array of tools available that can help them personalize energy and carbohydrate intake.

For instance, energy turnover for past training sessions and even energy requirements of the upcoming training sessions can relatively easily be predicted in sports where wearables exist to accurately quantify external work performed i.

Assuming fixed exercise efficiency one can then relatively accurately determine energy turnover during exercise. Knowing the relative exercise intensity of a given training session can further advance the understanding of the carbohydrate demands during exercise, as depicted in Fig.

As described in Sect. Thus, it is possible for athletes to predict energy turnover rates during exercise and adjust the carbohydrate intake accordingly.

In addition to this, the literature describing the physiological demands of a given sporting discipline can also be very insightful. For instance, energy turnover using gold-standard techniques has been assessed in many sporting contexts, including football [ ], cycling [ 22 ] and tennis [ ].

By knowing the energy demands, structure and goals of an upcoming training session, one can devise a suitable carbohydrate feeding strategy.

Besides making predictions on total energy turnover during exercise, it is useful to establish the rate of glycogen breakdown, as very high-intensity efforts can substantially reduce muscle glycogen content without very high energy turnover rates [ 34 , ], especially as low glycogen availability can negatively affect performance [ 30 ].

Attempts have been made to find ways to non-invasively and cost-effectively measure muscle glycogen concentrations e. These data can be useful for practitioners to determine the relative i.

However, whilst knowledge of exercise demands can help with tailoring, an implicit assumption is that all athletes will respond in a similar manner to an intervention, which may not be the case. In this respect, despite the present limitations in the practical assessment of muscle glycogen in field settings, gaining more readily accessible information on individual athlete physiological responses could still be of value to achieve higher degrees of personalization than those that current guidelines allow.

Recently, use of continuous glucose monitoring CGM devices has been popularized among endurance athletes, with an aim of personalizing carbohydrate intake around exercise for optimal performance. Certainly, knowledge of blood glucose profiles has the advantage that specific physiological data are generated from the individual athlete.

These devices have a rich history in the field of diabetes treatment, and their utility has clearly been demonstrated [ ]. For a device to be deemed of use and its use recommended to a wider audience, both of the following criteria must be met: 1 the parameter that the device is measuring should have contextual relevance i.

While there is no doubt that CGM devices are useful in non-exercise contexts, their utility during exercise per se remains to be clearly established. Indeed, CGM devices appear to have limited validity during exercise [ , ], and this may be due to the complex nature of blood glucose regulation during varying types and intensities of exercise.

Blood glucose concentrations are a result of glucose uptake by the tissue and glucose appearance i. While it has been known for a long time that hypoglycemia can associate with task failure [ ], its occurrence does not always precede it [ ].

Therefore, further investigative work is required to establish whether differential blood glucose profiles using validated technology during exercise can be identified and be used to individualize carbohydrate intake during exercise.

In addition to tracking glycaemia during exercise, tracking it throughout the day could also be proven useful. A recent study utilizing CGM devices compared daily blood glucose profiles in elite trained athletes with those in a sedentary population and discovered large discrepancies in blood glucose concentrations throughout the day between both groups [ ].

Elite athletes spent more time in hyper- and hypoglycemia as compared to sedentary controls, giving an appearance that glycemic control might be impaired.

While periods of hyperglycemia are expected due to post-exercise high carbohydrate intakes, observations of hypoglycemia occurring especially at night during sleep were somewhat surprising. This knowledge can then be used to potentially individualize strategies to counter these episodes of impaired glycemic control in real time.

While utilization of CGM devices during exercise to guide carbohydrate intake during exercise cannot be presently advised, athletes could individualize carbohydrate ingestion rates during exercise by establishing their highest exogenous carbohydrate oxidation rates [ 25 ].

To do this, one requires the ability to know carbon isotope enrichments of the ingested carbohydrates and in expired carbon dioxide. For example, advances have been made in methodology to easier quantify stable carbon isotope abundance in expired air [ ], a methodology currently used for quantification of exogenous carbohydrate oxidation rates [ 25 ].

Thus, this approach could be spun off from research and be used in practice as well to identify carbohydrate intake rate and carbohydrate compositions that optimize exogenous carbohydrate oxidation in individual athletes.

Finally, most research to date has investigated carbohydrate intake in a healthy male population, and thus current carbohydrate guidelines are founded on this evidence.

Despite decades of intense carbohydrate research within the field of sports nutrition, new knowledge continues to be generated with the potential to inform practice. In this article, we have highlighted recent observations that provide a more contemporary understanding of the role of carbohydrate nutrition for athletes.

For example, our article suggests a stronger emphasis be placed on scaling carbohydrate intake before competition to the demands of that subsequent activity, with particular attention paid to the effects of concomitant exercise during the preparatory period.

At high ingestion rates during exercise i. Furthermore, short-term recovery may be optimized by combining glucose-fructose to target both liver and muscle glycogen synthesis simultaneously. Finally, there has been substantial investigation into the role of commencing selected exercise sessions with reduced carbohydrate availability to provide a beneficial stimulus for training adaptation.

The abovementioned suggestions are designed to build on the wealth of knowledge and recommendations already established for athletes. Nonetheless, what this review has also revealed is that gaps in our current understanding of carbohydrate nutrition and metabolism in relation to exercise performance remain.

Some remaining research questions arising from the present article are presented in Table 1. Answering these research questions could allow continued advancement and refinement of carbohydrate intake guidelines and, by doing that, further increase the possibility of positively impacting athletic performance.

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Every time your body is low on glucose it taps into stored glycogen and breaks it down for energy. This means the more active you are, the more glycogen you need. You need to maximize glycogen stores to have the energy you need.

But too much glycogen can lead to an excess - and that surplus is stored as fat. Adenosine triphosphate ATP is a complex molecule used by all cells in your body for energy. It drives all our chemical processes and is vital for life. During exercise, the rate of ATP utilization increases proportional to the intensity.

In other words, the harder your workout - the more energy you use. At rest or at low intensities ATP is produced within a special organelle called the mitochondria - using both fatty acids and glucose. The journey that fat and glycogen take to generate ATP is long and complex.

And when your body only requires a trickle of ATP at a constant rate, that long-winded process is worth it.

During anaerobic glycolysis, your cells use glycogen to generate the energy bond called ATP. If it switches from aerobic glycolysis which uses fat and glucose for energy and chooses anaerobic glycolysis instead, it can generate ATP faster.

By skipping the use of fatty acids and bypassing the mitochondria. Because the mitochondria provide much more ATP. Anaerobic glycolysis can only use glycogen for fuel. How much ATP you can produce is down to many variables - one of those is the glycogen content in the muscle. In other words, glycogen is hugely important during high-intensity workouts.

Your body gets glucose for energy, either from the food you eat or by tapping into stored glycogen. When you eat a carb-rich meal your cells take what they need and dump the rest into glycogen reserves ready for a rainy day. According to a study published in the Journal of Physiology 4 the ability of muscle to exercise is seriously compromised when the glycogen store is reduced to low levels.

Even when there is an abundance of other fuel sources. Research has shown on several occasions that when athletes perform with low glycogen levels, both strength and endurance suffers. For example, a study of healthy participants experienced a loss in grip strength 5 after strenuous exercise.

Another study showed a reduction in endurance. The link between low glycogen and fatigue is due to several factors. One of the most important is the reduced calcium release from the sarcoplasmic reticulum that negatively impacts the ability to produce force.

Bonking is a phenomenon known all too well by marathon runners and other endurance athletes. It will make you feel weak, shaky and dizzy. And because your brain is using glycogen for fuel it leaves you feeling lightheaded, confused and drunk-like.

Endurance training uses up a lot of glycogen due to the intensity and duration of exercise. Overtraining is a condition where your athletic performance is significantly reduced, even when training has stopped. It can last weeks, sometimes months and is characterized by fatigue, low mood, reduced performance and poor sleep.

As a multifactorial syndrome, overtraining has many underpinning causes.