Other Authors on Glycogen, Body Weight, and Performance
1. Optimum Performance With Proper Hydration
2. Understanding Bodyweight and Glycogen Depletion
3. Glycogen Replenishment after exhaustive Exercise
4. Glycogen Supercompensation
Article 1 : OPTIMUM PERFORMANCE WITH PROPER HYDRATION
Director of Sports Performance Nutrition
Texas Tech University
Whenever your body
is short of water, performance bombs. Why you ask ? Exercise increases body
temperature in direct proportion to the exercise load. Your body tries to
maintain its resting temperature of 98.6 F, by moving the extra heat to the
skin via the blood. There it dissipates into the air, mainly by evaporation
of sweat. But your blood must also carry oxygen and nutrients to the muscles
and remove the wastes of muscle metabolism. Available blood is shared between
all these tasks. The higher your core temperature rises, the more blood is
used for cooling and less is available for muscles. So, the cooler you stay
during exercise, short of being cold, the better your muscles will function.
Understanding Bodyweight and Glycogen Depletion
January 2, 2009 in articles with 45 Comments
Quick take — If you diet or are planning to start a diet, understanding the relationship between bodyweight and glycogen (Glycogen is carbohydrates as stored by your body) depletion is paramount.
Your body stores energy as fat and glycogen. Whereas fat stores can vary dramatically from person to person, your body can only store so much energy as glycogen.
Glycogen requires water to be stored. In the initial stages of diet/caloric restriction and exercise, your body depletes these glycogen stores, reducing your bodyweight from the elimination of both the weight of the stored glycogen and the weight of the water. Note that nowhere in this process is the much-desired loss of fat!
Thus, even as it will feel good to shed 5 – 10 lbs. simply from a few days of exercise mixed with a caloric-restricted diet, the weight loss will be primarily from a reduction in glycogen stores and water. In other words, what you’ll have lost in the beginning is really little more than water weight.
Take heart in understanding the relationship between glycogen stores and bodyweight as an improved understanding will help you set realistic expectations on whatever diet or exercise regiment you are undertaking in 2009.
A deeper dive:
I first learned about the relationship between stored carbohydrates and water retention from Gary Taubes’ Good Calories, Bad Calories. The gist is that for every gram of stored carbohydrate (Stored as glycogen) in your body, there is a set amount of additional water storage that is required.
Taubes had pinned the carb/water storage ratio at two grams of water per one gram of carbohydrate. A random Googled source (Vitanet) pins it at 2.7 gram water per gram of glycogen. I found a research paper titled, Glycogen storage: illusions of easy weight loss, excessive weight regain, and distortions in estimates of body composition, which offers the following data on the ratio:
Glycogen is stored in the liver, muscles, and fat cells in hydrated form (three to four parts water) associated with potassium (0.45 mmol K/g glycogen). . . .
Glycogen losses or gains are reported to be associated with an additional three to four parts water, so that as much as 5 kg weight change might not be associated with any fat loss.
Lyle McDonald of Body Recomposition has also weighed in on this subject:
Carbohydrate (stored in your muscles and liver as glycogen) is accompanied by a good bit of water. For every gram of glycogen stored, you store anywhere from 3-4 grams of water with it.
How does this relationship affect bodyweight? In short, diet and exercise will deplete glycogen stores. If your diet is working, the depletion will occur early and have a significant impact on your bodyweight without impacting a permanent change in your body composition.
Let’s take me as an example. I estimate that I have around 155 – 160 pounds of lean tissue. Tack on another 12 – 17 pounds of fat. After a week or two of being on a low-carbohydrate diet that involves intermittent fasting and plenty of exercise (see here), my liver and muscle glycogen stores will be completely depleted. I’ll weigh about 172.
If I go on to eat a bunch of carbohydrates — cookies, pretzels, breads, fruits and other starchy foods (by eating a bunch, I mean consuming something on the order of 1000 grams of carbohydrates over the course of 24 hours, which is about 4000 calories), I will fully replenish my glycogen stores. In the process of replenishment, the 1000 grams of carbohydrates will require anywhere from 3000 to 4000 grams of water for storage! Converting from grams to pounds, the impact on my bodyweight should be an increase of 9 to 11 pounds, taking my weight up to 183*! Of course, the same change would happen in reverse: re-depleting glycogen stores would drop my weigh back to the low 170s.
Mike over at the IF life alluded to this fact in three bullets back on his Trainer Tells All post:
Muscle size is mostly glycogen and water . . . I can go up and down 10lbs in a week easily depending on glycogen and water balance . . . The first big amount of lbs you lose in the first week dieting is mostly water
Mike’s anecdotal experience is explained by the storage ratio between glycogen and water. What it means is that in the early stages of a diet, the magical drop in bodyweight will be mostly water weight.
Another implication of the water/glycogen relationship on bodyweight is that whereas the first 4000 calorie deficit you create will reduce your weight some ten pounds, the next 4000 calorie deficit is likely only going to reduce your bodyweight a paltry two pounds! This is because a pound of fat stores 3500 calories and requires about a pound of water for storage. Thus, the initial weight-loss will seem easy compared to the drudging continued weight-loss when you’re actually burning stored fat.
Failing to understand what is going on with glycogen stores and water retention will set yourself up for a shock when you inevitably “fall off the wagon” — even if the “fall” is only for a day or two of heavy-carb or more “normal” eating.
Understanding the impact of glycogen depletion/repletion on bodyweight is just one more reason why merely weighing yourself on a scale provides a poor indication of your body composition. You’re better served by taking some physical measurements (waist size, for example). Or even better, take some periodic camera phone self-portraits — over time, you should be able to compare them and get a great feel for your progress (or lack thereof).
* I’ve witnessed this fluctuation on numerous occasions over the past year, but I didn’t quite fully understand it until today. You see, I was fully glycogen depleted going into New Year’s Eve. I proceeded to go on a pre-planned “refeed” (that just happpened to coincide with NYE, of course!). The refeed involved eating plenty of pretzels, chips, breads, fruits, cookies, cereal, donuts, etc. Some incredibly unhealthy, albeit tasty, foods. I also drank a good bit of Pinot Noir NYE, which is the opposite of what you should do if you are re-feeding in that your body will be needing water and alcohol will dehydrate you past certain levels of intake. Anyway, after a 24 hour refeed, my bodyweight went from 172 to 184. Hard to believe unless you understand what is going on. And this kind of fluctuation would be entirely disheartening to the ignorant dieter who might feel they just blew their diet in one day! As it is, I expect I’ll be back in the low 170s within five days after I do a fast and get two or three workouts in.
Article 3: Understanding Bodyweight and Glycogen Depletion
February 11, 2008
Submitted by: Gregory Tardie, Ph.D.
Original link: http://thesportjournal.org/article/glycogen-replenishment-after-exhaustive-exercise/
Throughout the centuries, dietary intake has been a source of concern to athletes in search of an ergogenic edge over opponents.
It wasn’t until 1866 that it was demonstrated that there was insignificant, if any use of protein as a fuel during exercise. Since that time, innumerable studies have refuted the notion that a high protein intake will enhance athletic performance.
Since the conclusion of the Kraus-Weber Tests in the 1950s, there has been ever- increasing awareness and concern for cardiopulmonary fitness and health in Americans. Endurance type activities such as Nordic skiing, cycling, running, triathalons, and swimming have become in vogue, and as a result, more intense attention has been devoted to dietary manipulations which may provide an ergogenic effect, thus prolonging time to exhaustion, or delaying the onset of blood lactate accumulation (OBLA) in an attempt to compete at a higher intensity, longer.
The classic study by Christensen and Hansen in 1939 established the effect of a high carbohydrate diet upon endurance time, and that pre-exercise glycogen levels exerted an influence in time to exhaustion. Subsequently, it was discovered that if an athlete, after depleting glycogen reserves, consumed a high carbohydrate diet for two to three days prior to an athletic event, there would in fact be higher glycogen levels than prior to exercise. This “supercompensation” effect became the basis for carbohydrate loading undertaken by endurance athletes.
Therefore, the concentration of muscle and liver glycogen prior to exercise plays an important role in endurance exercise capacity. In exhaustive exercise many studies have observed significant depletion of both liver and muscle glycogen. It is interesting to recognize that the point of exhaustion seems to occur upon the depletion of liver glycogen. Conversely, muscle glycogen reserves, though significantly lower are only 65-85% depleted, versus the 85-95% depletion exhibited for liver glycogen. This should make it readily apparent that liver glycogen is an integral determining factor in an athlete’s time to exhaustion. It follows that endurance athletes who maintain a daily regimen of endurance training without glycogen repletion may severely deplete their glycogen reserves.
Glycogen, the major reservoir of carbohydrate in the body, is comprised of long chain polymers of glucose molecules. The body stores approximately 450-550 grams of glycogen within the muscle and liver for use during exercise. At higher exercise intensities, glycogen becomes the main fuel utilized. Depletion of liver glycogen has the consequence of diminishing liver glucose output, and blood glucose concentrations accordingly. Because glucose is the fundamental energy source for the nervous system, a substantial decline in blood glucose results in volitional exhaustion, due to glucose deficiency to the brain. It appears that the evidence presented in the literature universally supports the concept that the greater the depletion of skeletal muscle glycogen, then the stronger the stimulus to replenish stores upon the cessation of exercise, provided adequate carbohydrate is supplied.
Though most of the evidence presented on glycogen is related to prolonged aerobic exercise, there is evidence that exercise mode may play a role in glycogen replenishment, with eccentric exercise exhibiting significantly longer recovery periods, up to four days post-exercise. Muscle fiber type is another factor implicated in the replenishment of glycogen in athletes, due to the enzymatic capacity of the muscle fiber, with red fiber appearing to be subjected to a greater depletion, but also undergoing repletion at a significantly grater rate.
Though early literature appeared to indicate that the time course of glycogen replenishment after exercise-induced depletion was 48 hours or more, more recent data have controverted this thought. One study reported that a carbohydrate intake totaling up to 550-625 grams per day was found to restore muscle glycogen stores to pre-exercise levels within the 22 hours between exercise sessions. The findings of this study were supported by second study in which a carbohydrate intake of 3100 kcal resulted in complete resynthesis of glycogen within 24 hours.
There also appears to be a two-hour optimal window immediately after the cessation of exercise for the administration of carbohydrates. Simple carbohydrates appear to be the preferred replacement during this replenishment period.
Normally, 2% of glycogen is resynthesized per hour after the initial 2 hours immediately after exercise. With administration of 50 grams of carbohydrate every 2 hours, the rate rose to 5% per hour, but did not rise when additional carbohydrate was administered. Administration of .7grams per kg body weight every two hours is another strategy that appears to maximize the rate of glycogen resynthesis. There is also some evidence that even smaller loads (28 grams every 15 minutes) may induce even greater repletion rates.
Therefore, at least 20 hours are required to recover muscle glycogen stores, even when the diet is optimal. So, athletes working out two times per day should complete one workout at a diminished workload to relieve the reliance on glycogen reserves.
The principle of glycogen resynthesis and supercompensation has great practical implications, not only in athletics, but also within industry for workers who consistently undergo depletion of glycogen stores due to prolonged bouts of exertion, or extended lifting tasks which would be glycolytic in nature; due to the duration, and also the myofibrillar ischemia induced by static contractions.
Article 4: Glycogen Supercompensation
By Ian Matthews Mar 17, 2003
In my last Bodybuilding.com article I detailed my bulking diet and how I followed up a carbohydrate depletion period with a day where I consumed only fruit juice to create a glycogen supercompensation effect.
Original link: http://www.bodybuilding.com/fun/ian4.htm
So What Is Glycogen Supercompensation?
Glycogen supercompensation is when your muscles are able to hold a greater amount of glycogen than they normally would be able to. They will not only appear fuller and more pumped, but they will also have plenty of fuel to work hard.
Muscles need energy to contract. The muscles use ATP for energy, but ATP stores are quickly depleted. At first the body will create ATP by having creatine phosphate donate a phosphate molecule to ADP, but creatine phosphate is also depleted quickly. For the muscles to continue to work over longer periods of time, ATP must be created from muscle glycogen through glycolysis. Therefore, the more glycogen the muscles can hold, the more ATP can be produced for anaerobic muscle contraction.
So now that we see how glycogen supercompensation can positively affect appearance and workout intensity, how do we cause our muscles to hold more glycogen than they normally would? By depleting the muscle glycogen stores our bodies will adjust by more readily creating and storing glycogen for perceived future shortages. Simple, deplete the muscles of glycogen, and they will more readily store glycogen.
Since carbohydrates are the body's main source for creating glycogen, glycogen depletion is best achieved by cutting carbohydrates out of the diet. The body can also create glycogen from protein and fat, but it is not as efficient at doing so. Glycogen is further depleted through working out since it is the body's preferred source of energy.
"The more quickly the consumed carbohydrates can be broken down into glucose, the quicker glycogen stores will be replaced."
Once the muscles are depleted of glycogen, glycogen supercompensation can be achieved by simply consuming carbohydrates. Since the muscles will now readily hold glycogen, they will immediately create glycogen once the carbohydrates are broken down into glucose. The more quickly the consumed carbohydrates can be broken down into glucose, the quicker glycogen stores will be replaced. Therefore, simple sugars such as dextrose and glucose would fill glycogen stores the quickest. Carbohydrates that are lower on the glycemic index will still fill glycogen stores, it will just take longer and the glycogen supercompensation effect will be more gradual.
Why Does It Work?
Glycogen normally draws water into the muscle, so if carbohydrates are consumed without excess water, water from underneath the skin will be pulled into the muscle. This is why bodybuilders who use glycogen supercompensation for a full, dry appearance at a competition normally choose dry carbohydrate sources.
During the all-juice day of my bulking diet we are trying to refill glycogen stores as quickly and as fully as possible, therefore simple sugars with no added fiber, protein, or fat will get the job done more efficiently. Muscle building is also more efficient when the body has plenty of water to work with and is not dehydrated, that is why fruit juice is the optimal source of carbohydrates in this situation. Drinking water mixed with dextrose would also be a viable option, but I feel using fruit juice is healthier and more bearable.
So there you have it, a complete breakdown on glycogen supercompensation. How or whether you use it is up to you.
Jeff Bayer, Original url link: http://www.askmen.com/sports/bodybuilding_150/180_fitness_tip.html
After the release of the 2007 movie 300, many men made gaining lean muscle tissue their primary goal at the gym. Unfortunately, the addition of lean muscle mass does not always come easily, especially if you aren't new to weightlifting. Because of this, sometimes you need to resort to using more advanced training protocols in order to kick-start your body again and start seeing new gains. The depletion workout type of training that the cast of 300 used will do just that. If that body type is your goal, you will definitely want to give these techniques some thought.
Depletion workouts are weightlifting sessions that are geared toward exhausting the body's muscle glycogen supply. Muscle glycogen is the storage form of carbohydrates in the body, and this is what powers you throughout your workouts. When it becomes depleted, you will not physically be able to continue, as the body will be exhausted.
Depletion of muscle glycogen is a good thing for those looking to gain lean muscle mass; however, it's important to note that if you take correct measures as far as your diet is concerned, the muscles will overcompensate with their ability to uptake the nutrients, leaving you with fuller muscles that are able to store more glycogen.
Along with this, a very large intake of food immediately after the workout will send your body into an anabolic state, which is required in order to gain lean muscle tissue. As long as your food intake is planned properly, you should not see much in the way of fat gains, and most of the calories you take in will be directed toward repairing and growing your muscles.
To do a depletion workout, you want to adopt a circuit-style training protocol. Basically, you will be moving from one exercise to the next with little or no rest in between. You are also going to aim to perform 15-20 reps per set, so take note that the weight you are lifting should be on the lighter side.
Generally, the less carbohydrates you have in your diet, the less work you will need to do in order to deplete the muscles of their glycogen (since less will be replaced on a continual basis from dietary carbohydrates). Therefore, if you are already eating a low-carb diet, you may only perform one to two rounds of the circuit, whereas if you regularly consume a larger portion of carbohydrates, you will need more reps to burn through the carbs.
Most individuals will want to perform the complete workout circuit 4-5 times. If you find you get to the third one and are feeling extremely fatigued, however, then you should stop there, as pushing yourself too far will inhibit certain enzymes in the muscle that aid in glycogen supercompensation, thereby defeating the whole purpose for doing the depletion work in the first place.