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Why Is Glycogen Converted Back To Glucose When Exercising

Does Glycogen Increase During Exercise?

Does Glycogen Increase During Exercise?

Doug Bennett has been researching and writing nonfiction works for more than 20 years. His books have been distributed worldwide and his articles have been featured in numerous websites, newspapers and regional publications. Bennett's background includes experience in law enforcement, the military, sound reinforcement and vehicle repair/maintenance. Why Are Proteins Used As the Last Source of Energy? Your body requires a constant supply of blood glucose to function properly. To maintain an adequate level of blood sugar, your body stores glucose as glycogen in your liver and skeletal muscles. During strenuous exercise, your body uses these stores to provide critical energy, resulting in a decrease in glycogen during exercise. Glycogen is a polysaccharide and the primary storage form of glucose in your body. Your diet supplies your body with an irregular supply of glucose from carbohydrates. Your body achieves a balance, overcoming the dietary peaks and valleys, by using stores of glycogen. When your glucose levels are high, your body converts glucose to glycogen through glycogenesis and stores it. When your glucose levels are low, your body converts glycogen back to glucose through glycolysis, where it is used as an energy source. During anaerobic exercise, your muscles use glycogen stored within their tissue to produce a small amount of adenosine triphosphate (ATP) and pyruvic acid. However, the buildup of pyruvic acid slows down the production of ATP energy. This is the reason your muscles become exhausted after one to two minutes of high-intensity anaerobic exercise. Furthermore, in the absence of adequate levels of oxygen, the pyruvic acid is converted to lactate acid, which produces the burn you feel during short, high-intensity muscle exercises. During aerobic exe Continue reading >>

Fundamentals Of Human Nutrition/lactic Acids

Fundamentals Of Human Nutrition/lactic Acids

Here are ten things you should know about lactic acid Continue reading >>

Blood Glucose Levels During Exercise

Blood Glucose Levels During Exercise

Exercise has a number of great health benefits. It improves your strength, lowers your blood pressure and improves endurance. For diabetics, exercise is a great way to control high blood glucose levels, according to the American Diabetes Association. Regular exercise can keep blood glucose levels lower for up to a day or more after a workout. Factors Affecting Blood Glucose A variety of factors will affect how much of an effect exercise will have on your blood glucose. It is an individualized effect based on how long the workout lasts, how hard you exercise, what your glucose level was before the workout, what your insulin level was before the workout, your degree of insulin resistance, how well your body is hydrated or dehydrated and your metabolism. When Glucose Increases When you exercise, your body responds to the activity by releasing hormones that cause your body to increase blood glucose levels. This occurs through a process called gluconeogenesis or glycogenesis that happens in the liver. Glucose that has been previously converted and stored in the liver as glycogen is converted back to glucose and sent to the muscles. In the muscles, the glucose is broken down to yield ATP, which is the fuel source for muscles. When Glucose Decreases You body will continue to increase your blood glucose levels as its primary fuel source during your workout. However, once your body uses up its glucose, your blood glucose levels will drop. Instead, your body begins to draw on stored fat to fuel the workout. Aerobic Exercise To get the maximum effect on your blood glucose levels, you should be doing aerobic exercise. Running, jogging, stair steppers, swimming and other aerobic exercises increase your blood flow and the oxygenation of your tissues. These exercises demand more energ Continue reading >>

Glycogen And Glucose

Glycogen And Glucose

Glycogen and Glucose are the two forms of sugar that your body employs to store and use as energy . Glucose is the sugar your body converts into energy. Glycogen is the sugar your body stores in both your liver and muscle cells. Your body can't use glycogen directly as a source of energy, and cannot store glucose. When you eat a well-balanced meal with both carbohydrates and protein, your body converts and absorbs the carbohydrates and part of the protein into glucose. It then attempts to maintain an even blood glucose level. When your blood glucose is too high, your pancreas produces insulin to convert some of that glucose into glycogen and then stores it for later use. When it is running low, it produces glucagon, a hormone secreted by the pancreas which stimulates your liver to convert some glycogen into glucose. Once converted, the glucose can be released into your blood stream. (The glycogen stored in your muscles can't be converted back into sugar, so it can only be used by your muscles.) Your liver can only store 90 to 110 grams of glycogen (the equivalent of about three to four hours of normal activity). When your glycogen reserves are full, and you still have glucose in your blood or glucose being absorbed into your bloodstream from a meal, your liver then starts to convert glucose into fat. That is actually a normal process because with a regular size meal, you will invariably fill up your glycogen reserves. Therefore it is customary to store some fat when you eat. If you don't eat between meals, after around three hours your liver glycogen will be running low and your body will start converting that fat into energy until you eat your next meal. Overall, this is a healthy, natural process of filling up your glycogen supply, storing some fat, and then accessing Continue reading >>

Glycogen Metabolism

Glycogen Metabolism

Glycogen is a readily mobilized storage form of glucose. It is a very large, branched polymer of glucose residues (Figure 21.1) that can be broken down to yield glucose molecules when energy is needed. Most of the glucose residues in glycogen are linked by α-1,4-glycosidic bonds. Branches at about every tenth residue are created by α-1,6-glycosidic bonds. Recall that α-glycosidic linkages form open helical polymers, whereas β linkages produce nearly straight strands that form structural fibrils, as in cellulose (Section 11.2.3). Glycogen is not as reduced as fatty acids are and consequently not as energy rich. Why do animals store any energy as glycogen? Why not convert all excess fuel into fatty acids? Glycogen is an important fuel reserve for several reasons. The controlled breakdown of glycogen and release of glucose increase the amount of glucose that is available between meals. Hence, glycogen serves as a buffer to maintain blood-glucose levels. Glycogen's role in maintaining blood-glucose levels is especially important because glucose is virtually the only fuel used by the brain, except during prolonged starvation. Moreover, the glucose from glycogen is readily mobilized and is therefore a good source of energy for sudden, strenuous activity. Unlike fatty acids, the released glucose can provide energy in the absence of oxygen and can thus supply energy for anaerobic activity. The two major sites of glycogen storage are the liver and skeletal muscle. The concentration of glycogen is higher in the liver than in muscle (10% versus 2% by weight), but more glycogen is stored in skeletal muscle overall because of its much greater mass. Glycogen is present in the cytosol in the form of granules ranging in diameter from 10 to 40 nm (Figure 21.2). In the liver, glycoge Continue reading >>

Energy For Exercise Science Learning Hub

Energy For Exercise Science Learning Hub

Although muscles and engines work in different ways, they both convert chemical energy into energy of motion. A motorbike engine uses the stored energy of petrol and converts it to heat and energy of motion (kinetic energy). Muscles use the stored chemical energy of food we eat and convert that to heat and energy of motion (kinetic energy). Where does the energy for muscle contraction come from? The source of energy that is used to power the movement of contraction in working muscles is adenosine triphosphate (ATP) the bodys biochemical way to store and transport energy. However, ATP is not stored to a great extent in cells. So once muscle contraction starts, the making of more ATP must start quickly. Since ATP is so important, the muscle cells have several different ways to make it. These systems work together in phases. The three biochemical systems for producing ATP are, in order: All muscle cells have a little ATP within them that they can use immediately but only enough to last for about 3 seconds! So all muscle cells contain a high-energy compound called creatine phosphate which is broken down to make more ATP quickly. Creatine phosphate can supply the energy needs of a working muscle at a very high rate, but only for about 810 seconds. Fortunately, muscles also have large stores of a carbohydrate, called glycogen, which can be used to make ATP from glucose. But this takes about 12 chemical reactions so it supplies energy more slowly than from creatine phosphate. Its still pretty rapid, though, and will produce enough energy to last about 90 seconds. Oxygen is not needed this is great, because it takes the heart and lungs some time to get increased oxygen supply to the muscles. A by-product of making ATP without using oxygen is lactic acid. You know when your mus Continue reading >>

Carbohydrates: The Main Energy Food

Carbohydrates: The Main Energy Food

lOrganic compounds that contain carbon, hydrogenand O2 in various combinations l ComplexCHOs (commonly known as starches) l3 or more glucose molecules combined =polysaccharide lMore than 10 glucose molecules combined =glucose polymer (e.g. maltodextrin) lWater soluble dissolved in H2O& metabolized in large intestine (e.g. gums, pectins) lWater insoluble not dissolved or metabolized(e.g. cellulose) lOfficially, theNational Research Council has not established an RDA for CHO lAt least 50-100grams to spare protein catabolism lHealthy,moderately active adults should have at least 200 grams to maintain normalbrain and muscle function lShould be simplesugar limitation of 10% in total lNCI recommends20-35 grams of fiber per day l60-70% of totalcaloric intake in endurance athletes lMajority ofnutrients from CHO breakdown are absorbed in small intestines effect of a particular food upon the rate andamount of increase in blood glucose level lThis may also varyfrom individual to individual lFoods with a highglycemic index will raise blood glucose levels quickly lFoods with a lowglycemic index will lead to a slower insulin response and more stable bloodglucose level lControlled byinsulin (secreted from pancreas) lInsulin activatesGLUT-4 receptors in muscle and fat cells to cause uptake of glucose lMay result fromfoods of high glycemic index lMay be promptedby fast influx of insulin into blood to reduce high glucose level lParticularly forbrain and nervous tissue lConversion toliver or muscle glycogen lLiver glycogencan be converted back to blood glucose lMuscle glycogendoes not convert back to blood glucose lConverted andstored as fat in adipose tissue lExcreted in urinewhen excess amounts exist Can human body make CHO from fat andprotein? lFormation of newglucose from non-glucose Continue reading >>

How To Restore Glycogen

How To Restore Glycogen

Expert Reviewed Three Parts:Restoring Glycogen after ExerciseUnderstanding Glycogen Stores in DiabetesRestoring Glycogen Due to Low Carbohydrate DietsCommunity Q&A Glycogen is the fuel reserve that keeps our body running. Glucose, obtained from carbohydrates in our diet, provides the energy we need throughout the day. Sometimes, the glucose in our body runs low, or even is depleted. When that happens, the body pulls the needed energy from glycogen stores in muscle and liver tissue, converting the glycogen into glucose. Exercise, illness, and some dietary habits, can cause the glycogen stores to be depleted more quickly. Steps to restore the depleted glycogen can vary depending on the underlying reasons for the depletion. Continue reading >>

The Use Of Glucose In Muscle Cells With Exercise

The Use Of Glucose In Muscle Cells With Exercise

Glucose is a common fuel for the body, and all cells use it. Muscle cells and fat cells are relatively efficient at obtaining glucose from the bloodstream, although liver and certain pancreatic cells are even more effective in that regard. Muscles take up glucose because it is one of the best fuels for exercise and is also readily stored. Muscle Cells Skeletal muscle, the type of muscle that moves the body during exercise, contains storage granules of glycogen. Glycogen is the storage form of glucose, and it is made up of individual glucose molecules linked together in branches. As many as 120,000 individual glucose molecules can compose a single glycogen. The storage granules also contain enzymes that can quickly metabolize, or break down, glycogen into the individual glucose molecules that compose it. About 1 percent of the mass of a muscle is glycogen because the muscles have to be ready for exertion at all times. Additional glycogen is stored in the liver for use when your body needs it. Timing of Glucose Use When a muscle cell needs energy, it obtains it from molecules of adenosine triphosphate, or ATP. Although muscle cells have stores of ATP as well as stores of another molecule called creatine-phosphate that can regenerate ATP, these resources last for only 10 seconds at best. Glycogen stores must supply energy once the cell depletes ATP, and the energy from these stores lasts for up to 1.6 minutes. Once the body exhausts these stores, additional energy pathways become involved to supply more glucose and other energy sources to meet continuing demand. Aerobic Energy Release During exercise, your cells obtain energy from glucose primarily through a process known as glycolysis. In a series of energy-releasing reactions, cells break down glucose in several steps to Continue reading >>

Pafmj

Pafmj

Receive 31 July 2008: Accepted 10 Feb 2009 into pyruvic acid during exercise and rapidly produces a small amount of adenosine triphosphate (ATP); the necessary fuel for body cells. However, excessive accumulation of pyruvic acid in muscles can substantially slow down or even stop the process of ATP formation. It has been demonstrated that glycogen is stored in proximity to the site of contraction and sustains high rates of adenosine diphosphate (ADP) phosphorylation. Therefore, glycogen is viewed as the primary fuel for the maintenance of moderate to intense exercise [4]. During high intensity exercise, glycogen becomes the main fuel utilized by the skeletal muscles and there is depletion of muscle glycogen up to 65-85%. Christensen and Hansen established in 1939 that high pre-exercise glycogen levels exert a positive influence on time for exhaustion. The concentration of muscle and liver glycogen prior to the exercise plays an important role in endurance exercise capacity and to ensure optimal exercise performance [5]. The endurance athletes are encouraged to maximise the availability of muscle glycogen through ingestion of a high carbohydrate diet prior to the competition [6]. Muscle fiber type is another important factor implicated in the depletion of glycogen. Due to greater enzymatic capacity of the type II (red) muscle fibers, their glycogen is subjected to rapid depletion during exercise. However, their glycogen replenishment occurs at significantly greater rate than type I (white) muscle fibers [7, 8] In aerobic exercise, glycogen has been associated with the increased work output and duration. Moreover, glycogen is the preferred substrate during endurance exercise because of its efficient energy yield per liter of oxygen consumed. Some of the studies suggest t Continue reading >>

Blood Glucose Regulation

Blood Glucose Regulation

Glucose is needed by cells for respiration. It is important that the concentration of glucose in the blood is maintained at a constant level. Insulin is a hormone produced by the pancreas that regulates glucose levels in the blood. How glucose is regulated Glucose level Effect on pancreas Effect on liver Effect on glucose level too high insulin secreted into the blood liver converts glucose into glycogen goes down too low insulin not secreted into the blood liver does not convert glucose into glycogen goes up Use the animation to make sure you understand how this works. You have an old or no version of flash - you need to upgrade to view this funky content! Go to the WebWise Flash install guide Glucagon – Higher tier The pancreas releases another hormone, glucagon, when the blood sugar levels fall. This causes the cells in the liver to turn glycogen back into glucose which can then be released into the blood. The blood sugar levels will then rise. Now try a Test Bite- Higher tier. Diabetes is a disorder in which the blood glucose levels remain too high. It can be treated by injecting insulin. The extra insulin allows the glucose to be taken up by the liver and other tissues, so cells get the glucose they need and blood-sugar levels stay normal. There are two types of diabetes. Type 1 diabetes Type 1 diabetes is caused by a lack of insulin. It can be controlled by: monitoring the diet injecting insulin People with type 1 diabetes have to monitor their blood sugar levels throughout the day as the level of physical activity and diet affect the amount of insulin required. Type 2 diabetes Type 2 diabetes is caused by a person becoming resistant to insulin. It can be controlled by diet and exercise. There is a link between rising levels of obesity (chronic overweight) and i Continue reading >>

How Insulin And Glucagon Work

How Insulin And Glucagon Work

Insulin and glucagon are hormones that help regulate the levels of blood glucose, or sugar, in your body. Glucose, which comes from the food you eat, moves through your bloodstream to help fuel your body. Insulin and glucagon work together to balance your blood sugar levels, keeping them in the narrow range that your body requires. These hormones are like the yin and yang of blood glucose maintenance. Read on to learn more about how they function and what can happen when they don’t work well. Insulin and glucagon work in what’s called a negative feedback loop. During this process, one event triggers another, which triggers another, and so on, to keep your blood sugar levels balanced. How insulin works During digestion, foods that contain carbohydrates are converted into glucose. Most of this glucose is sent into your bloodstream, causing a rise in blood glucose levels. This increase in blood glucose signals your pancreas to produce insulin. The insulin tells cells throughout your body to take in glucose from your bloodstream. As the glucose moves into your cells, your blood glucose levels go down. Some cells use the glucose as energy. Other cells, such as in your liver and muscles, store any excess glucose as a substance called glycogen. Your body uses glycogen for fuel between meals. Read more: Simple vs. complex carbs » How glucagon works Glucagon works to counterbalance the actions of insulin. About four to six hours after you eat, the glucose levels in your blood decrease, triggering your pancreas to produce glucagon. This hormone signals your liver and muscle cells to change the stored glycogen back into glucose. These cells then release the glucose into your bloodstream so your other cells can use it for energy. This whole feedback loop with insulin and gluca Continue reading >>

The Role Of Skeletal Muscle Glycogen Breakdown For Regulation Of Insulin Sensitivity By Exercise

The Role Of Skeletal Muscle Glycogen Breakdown For Regulation Of Insulin Sensitivity By Exercise

The Role of Skeletal Muscle Glycogen Breakdown for Regulation of Insulin Sensitivity by Exercise 1Department of Physical Performance, Norwegian School of Sport Sciences, Oslo, Norway 2Third Faculty of Medicine, Department of Medicine, Charles University, Prague, Czech Republic 3Protein Phosphorylation Research Group, de Duve Institute, Universit Catholique de Louvain, Brussels, Belgium Edited by: Heikki Veli Huikuri, Univeristy of Oulu, Finland Reviewed by: Francesco Giorgino, Universit degli Studi di Bari Aldo Moro, Italy; Niels Jessen, Aarhus University Hospital, Denmark *Correspondence: Jrgen Jensen, Department of Physical Performance, Norwegian School of Sport Sciences, P.O. Box 4014, Ullevl Stadion, 0806 Oslo, Norway. e-mail: on.hin@nesnej.negroj Received 2011 Jul 26; Accepted 2011 Dec 9. Copyright 2011 Jensen, Rustad, Kolnes and Lai. This is an open-access article distributed under the terms of the Creative Commons Attribution Non Commercial License , which permits non-commercial use, distribution, and reproduction in other forums, provided the original authors and source are credited. This article has been cited by other articles in PMC. Glycogen is the storage form of carbohydrates in mammals. In humans the majority of glycogen is stored in skeletal muscles (500 g) and the liver (100 g). Food is supplied in larger meals, but the blood glucose concentration has to be kept within narrow limits to survive and stay healthy. Therefore, the body has to cope with periods of excess carbohydrates and periods without supplementation. Healthy persons remove blood glucose rapidly when glucose is in excess, but insulin-stimulated glucose disposal is reduced in insulin resistant and type 2 diabetic subjects. During a hyperinsulinemic euglycemic clamp, 7090% of glucose dispos Continue reading >>

How Is Glycogen Used During Exercise?

How Is Glycogen Used During Exercise?

Piper Li, a professional freelance writer, began writing in 1989. Her articles appear online at Biz Mojo, Walden University and various other websites. She is the co-editor for "Kansas Women: Focus on Health." With a bachelor's degree in journalism from Mesa State, Li enjoys writing about health, horticulture and business management. Physical activity, including formal exercise, requires fuel for energy. Your body stores energy in the form of glycogen, a readily available fuel. The amount of glycogen in your body plays a major role in determining your level of endurance. Without adequate glycogen, prolonged exercise can lead to fatigue and loss of stamina. Carbohydrates provide the major source of fuel for physical activities. Your body naturally separates glucose from consumed carbohydrates, depositing this form of sugar into your bloodstream, while storing the excess amount of glucose in the form of glycogen. Your liver and your muscle cells are the main storage tissues for glycogen. To store glycogen, your body produces an enzyme known as glycogenin. This enzyme enables the attachment of glucose molecules to muscle and liver cells, where they remain until your body requires them for fuel. Exercise can cause a slight drop in blood sugar, the amount of glucose circulating in your bloodstream. Your body responds to this slight decrease by producing two hormones: glucagon and epinephrine. The liver and muscles react to the hormonal changes by converting the stored glycogen into glucose and releasing this substance into the blood stream for immediate use. Related: What Happens When Your Body Runs Out of Glycogen During a Long Workout? Your muscles and liver only store enough glycogen to fuel your body for approximately 90 minutes. Intense exercise that lasts beyond 90 mi Continue reading >>

Muscle Metabolism Flashcards | Quizlet

Muscle Metabolism Flashcards | Quizlet

- (without oxygen) make ATP (glycolysis; fermentation) -if oxygen supply to the exercising muscle cells doesn't match the rate at which glycolysis makes pyruvate for the aerobic pathway, then some of the pyruvate is converted to lactic acid. O2 supply is only one of several factors that cause an increase un muscle and blood lactate levels during exercise. some lactic acid can be produced in resting cells. -lactic acid is a byproduct of anaerobic cellular respiration -makes ATP for activities lasting longer than a minute -the aerobic pathways of cellular respiration occur in the mitochondrion and make far more ATP then glycolysis -store ATP that they make by cellular respiration creatine + ATP --> creatine phosphate + ADP -convert glucose that comes into the cell into glycogen (glycogenesis) -muscle cells depend on the breakdown of glycogen during exercise to supply glucose to make ATP by cellular respiration Glucose + 6O2 --> 6CO2 + 6H2O + 30-32 ATP -anaerobic process that occurs in the cytoplasm -results in a net gain of 2 ATP and forms 2 NADH (reduced coenzymes which carry e's to the ETC's in the mitochondria to make ATP) -if there is enough O2 in the cell, then all of the pyruvate goes into the mitochondria -all of the mitochondrial stages of cellular respiration require O2 -If O2 is available, the pyruvate enters the mitochondrion and is broken down to CO2 and H2O as about 20 ATP form 1) most of the ATP gained by cellular respiration is formed in the mitochondria 2) the CO2 that forms is a gaseous waste product of cellular respiration 3) CO2 diffuses out of the cell, then into the blood. the blood takes it to the lung where it is exhaled. -if O2 is unavailable, then all of the mitochondrial stages of cellular respiration shut down -CO2 is generated in the mitochond Continue reading >>

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