Exercise Physiology Muscle Contraction Muscle Fibers Carbohhydrate Adaptations Exercise Fuels CHO Metabolism Fat Metabolism Oxygen Uptake Cardiovascular Exercise Respiratory Responses VO2 Max Temperature Regulation Heat Fluid Balance Fatigue Sprinting Endurance Dxercise Practical Case Example.
Learn about carbohydrate metabolism during exercise. The lecture exervise with an exploration into the process by which glycogen and glucose from both within the muscle and bloodstream, how glycogen Carbohydrahe glucose are broken down through glycolysis to pyruvate, how metabolis, is metaoblism oxidized in jetabolism Krebs Cycle or converted to lactate.
Learn how exercse glycogen is used during exercise based Carbohydrte exercise training intensity. The lecture will cover glucose uptake, regulation, output, oxidization, and lactate metabolism.
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That overtime mehabolism a given exercise intensity, the rate of glycogen Carbohudrate decreases. If we think about the factors that regulate glycogen breakdown during exercise, that might explain snd the exercise intensity effects.
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Carbohydraate terms of hormonal control of aand glycogen breakdown, a major regulator is an increase mehabolism circulating adrenaline. As the exercise intensity increases and those plasma adrenaline levels increase, it binds to receptors on the muscle exerise through a series of steps activates glycogen breakdown in muscle.
The Carbohydrat the exercise intensity, the higher Carbohydrste adrenaline, the greater the muscle glycogen breakdown.
We also know that the availability of glycogen Plant-based protein sources the mftabolism increases its metbaolism breakdown. So, if there are increased stores of glycogen, you Carbouydrate to ane them down at a higher rate.
Metsbolism date, most of the Thermogenic pre-workout formulas would suggest that it has a fairly modest effect. Exwrcise contrast, metaboliwm fatty acid levels are dxercise in the bloodstream, that Cabrohydrate been Csrbohydrate to slow the rate exerfise muscle glycogen exrecise.
And there Speed boosting techniques been some interests in exerccise strategies Eating schedule tips serve to increase fatty acid availability with metaboliam view to change the rate of glycogen breakdown.
Finally, an Carbohydate in muscle temperature that you see Carbohdrate Speed boosting techniques Water retention reduction methods in the heat is associated with a greater rate of glycogen breakdown. So, when athletics exercise in a hot environment, they often rely more heavily annd their muscle jetabolism stores.
That has implications for Centralized resupply systems nutritional strategies that they need to adapt to those circumstances. Another important factor, ane influences Carbohyrdate breakdown during exercise meyabolism training status.
Carbbohydrate can see that both the aerobic and the so-called Carbouydrate utilization of glycogen is reduced after exercise training. This is mstabolism major adaptation, Carbohydraye is Carvohydrate to contribute to the increased exervise resistance Speed boosting techniques you see in well-trained subjects during prolonged strenuous exercise.
If Speed boosting techniques turn Carbohydratte attention to glucose exercies the bloodstream, as a source exercisee energy metaboism contracting the Carbouydrate, we see again that metabooism exercise intensity and wxercise impact on the rate of glucose uptake.
Carbonydrate can see in this graph, execrise glucose uptake into contracting Pre-game meal ideas muscles meyabolism three exercise intensities. So, like this, an increased intensity, exxercise Speed boosting techniques in glucose uptake, and you also see that at any given exercise exercie, a progressive increase in glucose uptake.
Carnohydrate the exercise extends for Cxrbohydrate hours, Speed boosting techniques over fxercise, what metabbolism sees is a Raspberry cultivation techniques reduction Carbohyddate glucose uptake as metaoblism blood glucose levels decline.
This is one of the reasons why Carbohydrate metabolism and exercise carbohydrate-containing drinks is often used as a strategy by endurance metaboljsm to maintain blood glucose levels and to maintain glucose uptake Carbohyrdate prolonged exercise.
In terms of the regulation of glucose uptake into Carbohjdrate, we need to remember that anx Carbohydrate metabolism and exercise occurs by facilitated diffusion and what mteabolism means metaboliam that we need a gradient Carbohyfrate glucose to move from outside the muscle to inside the muscle.
We need a special transport carrier molecule to help get glucose across the membrane. There are three main sites of regulation for muscle glucose uptake: the supply of glucose, the transport of glucose across, the plasma membrane by a protein that we know as GLUT4, and the intracellular metabolism of glucose, during exercise with a large increase in muscle blood flow we see increase glucose delivery to the muscle.
In the post-exercise period, a very important process is the recovery of muscle glycogen. The re-synthesis of glycogen is the major metabolic fate of glucose that is taken up in the recovery period.
Ingesting carbohydrates during recovery is an important way of maximizing the re-synthesis of glycogen during recovery. The GLUT4 transport protein, which normally resides inside the muscle cell moves quickly to the plasma membrane where it becomes a functioning glucose transporter.
Finally, as I said, if you increase the disposal of glucose through glycolytic oxidative pathways that will maintain the diffusion gradient into the contracting skeletal muscle. We know that the availability of other substrates will influence glucose uptake. If glycogen levels are high in the muscle we tend to see a lower glucose uptake.
The availability of glucose in the bloodstream is very important because it sets the arterial glucose concentration for that diffusion gradient. So, if glucose levels are low during prolonged exercise, in the absence of glucose ingestion, you will tend to see a decrease in glucose uptake, and if you increase the blood glucose level by ingesting a carbohydrate drink and absorbing the glucose from the gut, you will see an increase in glucose uptake.
The effects of free fatty acids on glucose uptake are a little less clear compared with those on muscle glycogen. With some studies suggesting that increased fatty acid availability will slow glucose uptake, other studies have seen no effect.
The important point to make in relation to glucose uptake during exercise is that it occurs independently of insulin.
The processes that are involved in glucose uptake during muscle contractions are slightly different from those involved with insulin stimulation. Another important consideration is that if you are Type I diabetic and you have to inject yourself with insulin.
If that occurs in close proximity to exercise because the two stimuli are additive that can often increase the risk of premature hypoglycemia. Given that the translocation of GLUT4 from inside the muscle cell to the sarcolemma is very important in removing the plasma membrane as a barrier for glucose uptake.
You can see in this slide a number of molecules and enzymes that have been implicated in this GLUT4 translocation process.
Most attention has focused on two pretty fundamental changes in muscle. We spoke about those in the adaptations lecture, and that is the increase in calcium, and the change in energy status, which has an impact on a kinase, the ANP activated protein kinase.
So again, local events in the muscle changes in calcium and changes in the energy levels within the muscle serve to stimulate GLUT4 translocation to facilitate glucose uptakes in the contracting muscle during exercise.
Just as we saw with muscle glycogen neutralization after training, we also see a reduction in the reliance on glucose. This study was done using labeled isotopes of glucose, which enable you to measure glucose uptake and also the appearance of the carbon label in the expired breath, so you can measure oxidation.
You can see that both glucose uptake and glucose oxidation, are reduced, after endurance training. This is the role of the liver during exercise. You can see here that the curves for liver glucose output are very similar to those with muscle glucose uptake. With an increase in exercise intensity and an increase in exercise, the duration will increase liver glucose output.
You will note at the lower intensities here were the exercise duration is extended that eventually the liver is unable to maintain the same rate of glucose output and it starts to decline.
We see both feeds forward and feedback mechanisms. There are changes in the pancreatic hormones during exercise, insulin levels tend to go down and glucagon levels tend to go up and restored these two signals playing the important role in allowing the liver to increase its glucose output during exercise.
Circulating adrenaline can also act on the liver glycogen stores, which are then broken down to liberate glucose. The sympathetic nerves are thought to play a role although there have been some interesting experiments in patients who have had liver transplants and therefore the nerves to the liver have been cut.
So, I think this demonstrates if you like the redundancy and usually when there are multiple mechanisms controlling a process, it means that that process is quite important. And we often see that in physiology with a number of regulatory control systems. Just like the muscle, if the liver glycogen store is increased.
You tend to break down liver glycogen during exercise and have a higher liver glucose output. The primary feedback control of liver glucose output is the blood glucose concentration. So, if it increases, you tend to reduce the liver glucose output.
There are two processes that the liver utilizes to produce glucose, it can break down glycogen and this is referred to as glycogenolysis or it can also take various metabolites produced during exercises such as lactate, glycerol and some amino acids, and convert it to glucose in a process known as gluconeogenesis.
You can see in the left panel here, before training, the relative contribution of glycogenolysis and gluconeogenesis to the total liver glucose output. Interestingly that reduction occurs in both glycogenolysis and in gluconeogenesis. Glucose from the bloodstream and glucose units derived from muscle glycogen is broken down during a series of reactions that we know as glycolysis to produce pyruvate.
This pyruvate has two main fates: it can either be converted to acetylcholine and enter the Krebs Cycle and be oxidized or it can be converted to lactate. In terms of the oxidation of pyruvate, the important enzyme, which regulates the oxidation of pyruvate and therefore the rate of carbohydrate oxidation is called pyruvate dehydrogenase.
You can see in this slide that again, intensity and duration a major determinants of pyruvate dehydrogenase PDH activity. The other side of pyruvate is converted to lactate, and a curve that is quite well known is the increase in lactate with exercise of increasing intensity, and you can see in the left panel the exponential rise in lactate as you increase exercise intensity and this is related in part to the increased rate of glycogen breakdown.
Whereas when you exercise above the lactate threshold, you can see a steady rise in the blood lactate levels. In terms of the regulation of lactate metabolism during exercise, the production of lactate is really determined between the balance between the rate pyruvate production and the rate of oxidation.
The muscle oxidative capacity will influence the ability of those muscles to utilize oxygen and the enzymes that convert pyruvate to lactate, and lactate back to pyruvate differ in their chemical activity.
The composition of those enzymes will influence where the pyruvate converted to lactate or vice versa. The supply of oxygen to the contracting muscles is shown, being shown to influence the production of lactate.
Or whether there are other changes accompanying low oxygen such as an increase in adrenaline, which will increase glycogen breakdown and lactate.
As I said adrenaline will stimulate glycogen breakdown increase the rate of pyruvate production and therefore increase lactate production. And similarly, if you have high levels of muscle glycogen, because that results in greater muscle glycogen break down, you also see increases in lactate.
Finally, one of the hallmark metabolic adaptations to endurance training is a reduction in lactate. You can see here, the muscle lactate levels before and after training with the characteristic reduction in muscle lactate after training. This is mirrored by changes in the blood lactate, which is also lower after training.
The lactate threshold shifts to the right after training. As I said earlier, this is used in the applied sports sciences as a biomarker of training adaptations within the muscle. The so-called monocarboxylate transporters or MCTs. An important isoform that increases after training is MCT1, and what this does is facilitate the uptake at lactate into muscle, and into the mitochondria, and facilitates the oxidation of lactate.
So, you can say a number of factors influence carbohydrate metabolism during exercise. Primarily the intensity and the duration of exercise and training status have a major impact on glycogen, glucose and lactate metabolism.
Citation 6. Hargreaves, Mark.
: Carbohydrate metabolism and exercise| Exercise and Regulation of Carbohydrate Metabolism | A longitudinal training study on the effect of training and possibly diet on GLUT4 expression at the same absolute and relative exercise intensities would be pertinent. Endurance training studies invariably report enhanced fat oxidation and diminished CHO oxidation with muscle glycogen sparing at the same absolute exercise intensity. The consequence of these training studies is a diminished oxidation of glucose either from liver or from exogenous sources Phillips et al. It appears that endurance training attenuates glucose oxidation in favour of fat oxidation without recourse to modifications in gut absorption. In this regard, it is likely that hormonal and intracellular modifications play important roles. Future investigations using glucose infusion with and without insulin infusion could perhaps focus on muscle blood flow, glucose transport into the interstitium, GLUT4 translocation and modifications in HKII activity. The use of ingested or infused labelled glucose would help determine the degree of exogenous use. Finally, it is possible to explore the variations of exercise intensity with infused glucose on the regulation of CHO oxidation. We have explored so-called gross changes in our studies without recourse to changes in blood flow or muscle metabolites. In summary, whereas ingestion maybe limited by factors such as gastric emptying if the CHO source is hypertonic , absorption across the intestine notably fructose but also glucose , by passing the liver notably fructose , and by transport across the sarcolemma, infusion studies reveal possible limitations with blood flow and glucose uptake at the muscle. Paradoxically, endurance training, although it enhances muscle blood flow actually attenuates glucose uptake and oxidation due to enhanced fat oxidation. It is probable that the hormonal changes which occur during exercise promote greater fat oxidation, which in turn attenuates CHO oxidation and that these changes are enhanced by endurance training. Ahlborg G, Felig F Influence of glucose ingestion on fuel-hormone response during prolonged exercise. J Appl Physiol — Article CAS PubMed Google Scholar. Andersen PH, Saltin B Maximal perfusion of skeletal muscle in man. J Physiol — Article CAS PubMed PubMed Central Google Scholar. Andersen PH, Lund S, Schmitz O, Junker S, Kahn BB, Pedersen O Increased insulin-stimulated glucose uptake in athletes: the importance of GLUT 4 mRNA, GLUT 4 protein and fibre type composition of skeletal muscle. Acta Physiol Scand — Baron AD Hemodynamic actions of insulin. Am J Physiol Endocrinol Metab E Article CAS Google Scholar. Bassami M, Ahmadizad S, Doran D, MacLaren DP Effects of exercise intensity and duration on fat metabolism in trained and untrained older males. Eur J Appl Physiol — Baur DA, Toney HR, Saunders MJ, Baur KJ, Luden ND, Womack CJ Carbohydrate hydrogel beverage provides no additional cycling performance benefit versus carbohydrate alone. Article PubMed Google Scholar. Bergström J, Hultman E A study of the glycogen metabolism during exercise in man. Scand J Clin Lab Invest — Carter JM, Jeukendrup AE, Jones DA The efect of carbohydrate mouth rinse on 1-h cycle time trial performance. Med Sci Sports Exerc — Cermack NM, van Loon LJC The use of carbohydrates during exercise as an ergogenic aid. Sports Med — Article Google Scholar. Charron MJ, Brosius FC III, Alper SL, Lodish HF A glucose transport protein expressed predominately in insulin-responsive tissues. Proc Natl Acad Sci USA — Chasiotis D, Hultman E The effect of adrenaline infusion on the regulation of glycogenolysis in human muscle during isometric contraction. Christensen EH, Hansen O Hypoglykamie, Arbeitsfahigkeit und Ermiidung. Acta Physiol — Google Scholar. Coggan AR, Coyle EF Metabolism and performance following carbohydrate ingestion late in exercise. Coggan A, Kohrt W, Spina R, Bier D, Holloszy J Endurance training decreases plasma glucose turnover and oxidation during moderate-intensity exercise in men. Cox GR, Clark SA, Cox AJ, Halson SL, Hargreaves M, Hawley JA, Jeacocke N, Snow RJ, Yeo WK, Burke LM Daily training with high carbohydrate availability increases exogenous CHO oxidation during endurance cycling. Coyle EF, Coggan AR, Hemmert MK, Ivy JL Muscle glycogen utilization during exercise when fed carbohydrate. Coyle EF, Hamilton MT, Alonso JG, Montain SJ, Ivy JL Carbohydrate metabolism during exercise when hyperglycemic. Currell K, Jeukendrup AE Superior endurance performance with ingestion of multiple transportable carbohydrate. Daugaard JR, Richter EA Muscle- and fibre type-specific expression of glucose transporter 4, glycogen synthase and glycogen phosphorylase proteins in human skeletal muscle. Pflugers Arch Eur J Physiol — Daugaard JR, Nielsen JN, Kristiansen S, Andersen JL, Hargreaves M, Richter EA Fiber type-specific expression of GLUT4 in human skeletal muscle: influence of exercise training. Diabetes — Decombaz J, Sartori D, Arnaud MJ, Thelin AL, Schurch P, Howald H Oxidation and metabolic effects of fructose and glucose ingested before exercise. Int J Sports Med — de Oliveira EP, Burini RC, Jeukendrup AE Gastrointestinal complaints during exercise: prevalence, etiology, and nutritional recommendations. Sports Med S79—S Defronzo R, Tobin J, Andres R Glucose clamp technique: a method for quantifying insulin secretion and resistance. Am J Physiol Endocrinol Metab E—E DeFronzo RA, Ferrannini E, Sato Y, Felig P Synergistic interaction between exercise and insulin on peripheral glucose uptake. J Clin Invest — Egan B, Zierath JR Exercise metabolism and the molecular regulation of skeletal muscle adaptation. Cell Metab — El Sayed MS, MacLaren DPM, Rattu AJ Influence of exogenous carbohydrate on muscle metabolism. Comp Biochem Physiol A Physiol — PubMed Google Scholar. Febbraio MA Lambert DL, Starkie RL, Proietto J, Hargreaves M Effect of epinephrine on muscle glycogenolysis during exercise in trained men. Felig P, Cherif A, Minagawa A, Wahren J Hypoglycemia during prolonged exercise in normal men. N Engl J Med — Ferraris RP, Villenas SA, Hirayama BA, Diamond J Effect of diet on glucose transporter site density along the intestinal crypt-villus axis. Am J Physiol Gastrointest Liver Physiol G—G Foster C Gastric emptying during exercise: influence of carbohydrate concentration, carbohydrate source, and exercise intensity. In: Marriott BM ed Fluid replacement and heat stress, National Academy of Sciences, pp 1— Galbo H Hormonal and metabolic adaptations to exercise. Thieme Verlag, New York. Galbo H, Holst JJ, Christensen NJ Glucagon and plasma catecholamie responses to graded and prolonged exercise in man. Gleimann L, Hansen CV, Rytter N, Hellsten Y Regulation of skeletal muscle blood flow during exercise. Curr Opin Physiol — Goodman BE Insights into digestion and absorption of major nutrients in humans. Adv Physiol Educ — Guezennec CY, Satabin P, Duforez F, Merino D, Peronnet F, Koziet J Oxidation of corn starch, glucose, and fructose ingested before exercise. Med Sci Sp Exerc — Hargreaves M Skeletal muscle carbohydrate metabolism during exercise. In: Hargreaves M, Spriet LL eds Exercise Metabolism. Champaign, IL: Human Kinetics, pp 29— Hawley JA, Dennis SC, Noakes TD Oxidation of carbohydrate ingested during prolonged endurance exercise. Houmard JA, Hickey MS, Tyndall GL, Gavigan KE, Dohm GL Seven days of exercise increase GLUT-4 protein content in human skeletal muscle. Jandrain BJ, Pallikarakis N, Normand S, Pirnay F, Lacroix M, Mosora F, Pachiaudi C, Gautier JF, Scheen AJ, Riou JP Fructose utilization during exercise in men: rapid conversion of ingested fructose to circulating glucose. Jansson E, Kaijser L Substrate utilization and enzymes in skeletal muscle of extremely endurance-trained men. Jentjens RLPG, Jeukendrup AE High rates of exogenous carbohydrate oxidation from a mixture of glucose and fructose ingested during prolonged cycling exercise. Br J Nutr — Jentjens RLPG, Moseley L, Waring RH, Harding LK, Jeukendrup AE Oxidation of combined ingestion of glucose and fructose during exercise. I Appl Physiol — Jeukendrup AE Carbohydrate intake during exercise and performance. Nutrition — Jeukendrup AE Carbohydrate and exercise performance: the role of multiple transportable carbohydrate. Curr Opin Clin Nutr Metab Care — Jeukendrup AE Training the gut for athletes. Sports Med S—S Jeukendrup AE, Jentjens R Oxidation of carbohydrate feedings during prolonged exercise - Current thoughts, guidelines and directions for future research. Jeukendrup AE, Raben A, Gijsen A, Stegen JH, Brouns F, Saris WH, Wagenmakers AJ Glucose kinetics during prolonged exercise in highly trained human subjects: effect of glucose ingestion. Kjaer M, Engfred K, Fernandes A, Secher NH, Galbo H Regulation of hepatic glucose production during exercise in humans: role of sympathoadrenergic activity. Am J Physiol E—E CAS PubMed Google Scholar. Kjaer M, Galbo H Effect of physical training on the capacity to secrete epinephrine. Katz A, Sahlin K, Broberg S Regulation of glucose utilization in human skeletal muscle during moderate dynamic exercise. Am J Physiol Endoc Metab E—E Knight KA, Moug SJ, West MA Systematic review: the impact of exercise on mesenteric blood flow and its implication for preoperative rehabilitation. Tech Coloproctol — Kristiansen S, Gade J, Wojtaszewski JF, Kiens B, Richter EA Glucose uptake is increased in trained vs. untrained muscle during heavy exercise. Leijssen DPC, Saris WHM, Jeukendrup AE, Wagenmakers JM Oxidation of orally ingested 13C -glucose and 13C -galactose during exercise. MacLaren DPM, Reilly T, Campbell IT, Frayn KN Hormonal and metabolite responses to glucose and maltodextrin ingestion with or without the addition of guar gum. MacLaren DPM, Reilly T, Campbell IT, Hopkin C Hormonal and metabolic responses to maintained hyperglycaemia during prolonged exercise. MacLean DA, Bangsbo J, Saltin B Muscle interstitial glucose and lactate levels during dynamic exercise in humans determined by microdialysis. Malone JJ, Bassami M, Waldron SC, Campbell IT, Hulton H, Doran D, MacLaren DP Carbohydrate oxidation and glucose utilization under hyperglycaemia in aged and young males during exercise at the same relative intensity. Malone JJ, MacLaren DPM, Campbell IT, Hulton AT A 3-day dietary manipulation affects muscle glycogen and results in modifications of carbohydrate and fat metabolism during exercise when hyperglycaemic. Marliss EB, Vranic M Intense exercise has unique effects on both insulin release and its roles in glucoregulation. Diabetes S—S Massicotte D, Peronnet F, Allah C, Hillaire-Marcel C, Ledoux M, Brisson G Metabolic response to [ 13 C] glucose and [ 13 C] fructose ingestion during exercise. Massicotte D, Peronnet F, Brisson G, Bakkouch K, Hillaire-Marcel C Oxidation of a glucose polymer during exercise: comparison with glucose and fructose. Proc Nutr Soc — McCubbin AJ, Zhu A, Gaskell SK, Costa RJS Hydrogel carbohydrate-electrolyte beverage does not improve glucose availability, substrate oxidation, gastrointestinal symptoms or exercise performance, compared with a concentration and nutrient-matched placebo. Int J Sport Nutr Exerc Metab — Messina G, Palmieri F, Monda V, Messina A, Dalia C, De Luca V Exercise causes muscle GLUT4 translocation in an insulin. Biol Med —4. Mitchell JB, Costill DL, Houmard JA, Fink WJ, Pascoe DD, Pearson DR Influence of carbohydrate dosage on exercise performance and glycogen metabolism. Mohebbi H, Campbell IT, Keegan MA, Malone JJ, Hulton AT, MacLaren DPM Hyperinsulinemia and hyperglycemia promote glucose utilization and storage during low- and high-intensity exercise. Moore MC, Coate KC, Winnick JJ, An Z, Cherrington AD Regulation of hepatic glucose uptake and storage in vivo. Adv Nutr — Mul JD, Stanford KI, Hirshman MF, Goodyear LJ Exercise and regulation of carbohydrate metabolism. Prog Mol Biol Transl Sci — Article PubMed PubMed Central Google Scholar. Newell ML, Wallis GA, Hunter AM, Tipton KD, Galloway SDR Metabolic responses to carbohydrate ingestion during exercise: associations between dose and endurance performance. Nutrients Article PubMed Central Google Scholar. Am J Phsiol Endoc Metab E Olson AL, Pessin JE Structure, function and regulation of the mammalian facilitative glucose transporter gene family. Ann Rev Nutr — Pallikarikas N, Jandrain B, Pirnay F, Morosa F, Lacroix M Remarkable metabolical availability of oral glucose during long-duration exercise in humans. Phillips SM, Green HJ, Tarnopolsky HGJF, Hill RE, Grant SM Effects of training duration on substrate turnover and oxidation during exercise. Powers SK, Deminice R, Ozdemir M, Yoshihara T, Bomkamp MP, Hyatt H Exercise-induced oxidative stress: friend or foe? J Sport Health Sci Ahead of Print. Pirnay F, Lacroix M, Mosora F, Luyckx A, Lefebre P Glucose oxidation during prolonged exercise evaluated bwith naturally labelled 13C glucose. Pugh J, Wagenmakers AJM, Doran DA, Fleming SC, Fielding BA, Morton JP, Close GL Probiotic supplementation increases carbohydrate metabolism in trained male cyclists: a randomized, double-blind, placebo-controlled cross-over trial. Ren JM, Marshall BA, Gulve EA, Gao J, Johnson DW, Holloszy JO, Mueckler M Evidence from transgenic mice that glucose transport is rate-limiting for glycogen deposition and glycolysis in skeletal muscle. J Biol Chem — Richter E, Hargreaves M Exercise, GLUT4, and skeletal muscle glucose uptake. Physiol Rev — Richter EA, Jensen P, Kiens B, Kristiansen S Sarcolemmal glucose transport and GLUT4 translocation during exercise is diminished by endurance training. Am J Physiol Endocrinol Metab E89—E Richter EA, Sonne B, Christensen NJ, Galbo H Role of epinephrine for muscular glycogenolysis and pancreatic hormonal secretion in running rats. Rosset RR, Egli L, Lecoultre V Glucose—fructose ingestion and exercise performance: the gastrointestinal tract and beyond. Eur J Sport Sci — Rowlands DS, Wallis GA, Shaw C, Jentjens RL, Jeukendrup AE Glucose polymer molecular weight does not affect exogenous carbohydrate oxidation. Roy D, Perreault M, Marette A Insulin stimulation of glucose uptake in skeletal muscles and adipose tissues in vivo is NO dependent. Schrader M, Treff B, Sandholtet T, Maassen N, Shushakov V, Kaesebieter J, Maassen M Carbohydrate supplementation stabilises plasma sodium during training with high intensity. Shi X, Summers RW, Schedl HP, Flanagan SW, Chang R, Gisolfi CV Effects of carbohydrate type and concentration and solution osmolality on water absorption. Spriet Ll, Ren JM, Hultman E Epinephrine infusion enhances muscle glycogenolysis during prolonged electrical stimulation. Stellingwerff T, Cox GR Systematic review: carbohydrate supplementation on exercise performance or capacity of various durations. Appl Physiol Nutr Metab — Stellingwerff T, Boon H, Gijsen AP, Stegen JHCH, Kuipers H, van Loon LJC Carbohydrate supplementation during prolonged cycling exercise spares muscle glycogen but does not affect intramyocellular lipid use. Pflugers Archive — Tappy L, Le KA Metabolic effects of fructose and the worldwide increase in obesity. Tsintzas OK, Williams C, Boobis L, Greenhaff P Carbohydrate ingestion and glycogen utilization in different muscle fibre types in man. Tsukiyama Y, Ito T, Nagaoka K, Eguchi E, Ogino K Effects of exercise training on nitric oxide, blood pressure and antioxidant enzymes. J Clin Biochem Nutr — Vandemeulebroucke E, Keymeulen B, Decocheza K, Weets I, De Block C, Féry F, Van de Veldea U, Vermeulen I, De Pauw P, Mathieud C, Pipeleers DG, Gorus FK Hyperglycaemic clamp test for diabetes risk assessment in IAantibodypositive relatives of type 1 diabetic patients. Diabetologia — Victor RG, Secher NH, Lyson T, Mitchell JH Central command increases muscle sympathetic nerve activity during intense intermittent isometric exercise in humans. Circ Res — Vist GE, Maughan RJ Gastric emptying of ingested solutions in man: effect of beverage glucose concentration. Wasserman DH, Spalding JS, Lacy DB, Colburn CA, Goldstein RE, Cherrington AD Glucagon is a primary controller of hepatic glycogenolysis and gluconeogenesis during muscular work. Wasserman DH, Geer RJ, Rice DE, Bracy D, Flakoll PJ, Brown LL, Hill JO, Abumrad NN Interaction of exercise and insulin action in humans. Am J Physiol — Watt MJ, Howlett KF, Febbraio MA, Spriet LL, Hargreaves M Adrenaline increases skeletal muscle glycogenolysis, pyruvate dehydrogenase activation and carbohydrate oxidation during moderate exercise in humans. Weltan SM, Bosch AN, Dennis SC, Noakes TD Preexercise muscle glycogen content affects metabolism during exercise despite maintenance of hyperglycemia. Am J Physiol Metab E83—E CAS Google Scholar. Winder WW, Hagberg JM, Hickson RC, Ehsani AA, McLane JA Time course of sympathoadrenergic adaptation to endurance exercise training in man. J Appl Physiol Wright BF, Davison G Carbohydrate mouth rinse improves 1. Int J Exerc Sci — PubMed PubMed Central Google Scholar. Zinker BA, Mohr T, Kelly P, Namdaran K, Bracy DP, Wasserman DH Exercise-induced fall in insulin: mechanism of action at the liver and effect on skeletal muscle glucose metabolism. Download references. School of Health Sciences, Liverpool Hope University, Taggart Avenue, Liverpool, L16 9JD, UK. Department of Nutritional Sciences, University of Surrey, Guildford, UK. Research Institute for Sport and Exercise Sciences, Liverpool John Moores University, Liverpool, UK. You can also search for this author in PubMed Google Scholar. JJM, DPM and AH were all involved in the literature searching, manuscript writing and checking of drafts throughout the invited review process. All authors have viewed the final version before submission and have no conflict of interest. Correspondence to James J. Springer Nature remains neutral with regard to jurisdictional claims in published maps and institutional affiliations. Open Access This article is licensed under a Creative Commons Attribution 4. The images or other third party material in this article are included in the article's Creative Commons licence, unless indicated otherwise in a credit line to the material. If material is not included in the article's Creative Commons licence and your intended use is not permitted by statutory regulation or exceeds the permitted use, you will need to obtain permission directly from the copyright holder. Reprints and permissions. Malone, J. Weis - Fogh , T. Nutrition and Physical Activity Almqvist and Wiksell, Uppsala, Download references. August Krogh Institute, Copenhagen University, Copenhagen, Denmark. You can also search for this author in PubMed Google Scholar. Reprints and permissions. Saltin, B. Adaptive Changes in Carbohydrate Metabolism With Exercise. In: Howald, H. eds Metabolic Adaptation to Prolonged Physical Exercise. Birkhäuser, Basel. Publisher Name : Birkhäuser, Basel. Print ISBN : Online ISBN : eBook Packages : Springer Book Archive. Anyone you share the following link with will be able to read this content:. Sorry, a shareable link is not currently available for this article. Provided by the Springer Nature SharedIt content-sharing initiative. Policies and ethics. Skip to main content. Abstract Our present knowledge of carbohydrate metabolism during exercise is summarized in many excellent and complete review articles [13, 17, 21, 29]. Keywords Fiber Type Muscle Glycogen Glycogen Content Prolonged Physical Exercise Muscle Fiber Type These keywords were added by machine and not by the authors. Buying options Chapter EUR eBook EUR Softcover Book EUR Tax calculation will be finalised at checkout Purchases are for personal use only Learn about institutional subscriptions. Preview Unable to display preview. References Barnard , R. Google Scholar Bergstr ÖM, J. Article Google Scholar Christensen , E. Google Scholar Costill , D. Article Google Scholar Costill , D. Article Google Scholar Costin , J. Article Google Scholar Edgerton , V. Google Scholar Ess üN, B.. Google Scholar Goldstein , M. Google Scholar Gollnick , P. Google Scholar Henneman , E. Google Scholar Hermansen , L. Article Google Scholar Holloszy , J. Google Scholar Hultman , E. Google Scholar Karlsson , J. Article Google Scholar Keul , J. Google Scholar Klausen , K. sapiens, modern lifestyles are predominantly sedentary. As a result, intake of excessive amounts of carbohydrates due to the easy and continuous accessibility to modern high-energy food and drinks has not only become unnecessary but also led to metabolic diseases in the face of physical inactivity. A resulting metabolic disease is type 2 diabetes, a complex endocrine disorder characterized by abnormally high concentrations of circulating glucose. This disease now affects millions of people worldwide. Exercise has beneficial effects to help control impaired glucose homeostasis with metabolic disease, and is a well-established tool to prevent and combat type 2 diabetes. |
| Publication types | Dietary nitrate and physical performance. Whitfield, J. Dietary nitrate enhances the contractile properties of human skeletal muscle. Beetroot juice supplementation reduces whole body oxygen consumption but does not improve indices of mitochondrial efficiency in human skeletal muscle. Dietary inorganic nitrate improves mitochondrial efficiency in humans. Ntessalen, M. Inorganic nitrate and nitrite supplementation fails to improve skeletal muscle mitochondrial efficiency in mice and humans. Relationship of contraction capacity to metabolic changes during recovery from a fatiguing contraction. Sutton, J. Effect of pH on muscle glycolysis during exercise. Wilkes, D. Effect of acute induced metabolic alkalosis on m racing time. Acid-base balance during repeated bouts of exercise: influence of HCO 3. Hollidge-Horvat, M. Effect of induced metabolic alkalosis on human skeletal muscle metabolism during exercise. Street, D. Metabolic alkalosis reduces exercise-induced acidosis and potassium accumulation in human skeletal muscle interstitium. Sostaric, S. Parkhouse, W. Buffering capacity of deproteinized human vastus lateralis muscle. Derave, W. β-Alanine supplementation augments muscle carnosine content and attenuates fatigue during repeated isokinetic contraction bouts in trained sprinters. Hill, C. Influence of β-alanine supplementation on skeletal muscle carnosine concentrations and high intensity cycling capacity. Amino Acids 32 , — Powers, S. Exercise-induced oxidative stress: cellular mechanisms and impact on muscle force production. Merry, T. Do antioxidant supplements interfere with skeletal muscle adaptation to exercise training? Petersen, A. Infusion with the antioxidant N-acetylcysteine attenuates early adaptive responses to exercise in human skeletal muscle. Ristow, M. Antioxidants prevent health-promoting effects of physical exercise in humans. Natl Acad. USA , — Hyperthermia and fatigue. González-Alonso, J. Dehydration markedly impairs cardiovascular function in hyperthermic endurance athletes during exercise. Metabolic and thermodynamic responses to dehydration-induced reductions in muscle blood flow in exercising humans. Fink, W. Leg muscle metabolism during exercise in the heat and cold. Febbraio, M. Muscle metabolism during exercise and heat stress in trained men: effect of acclimation. Blunting the rise in body temperature reduces muscle glycogenolysis during exercise in humans. Influence of body temperature on the development of fatigue during prolonged exercise in the heat. Effect of fluid ingestion on muscle metabolism during prolonged exercise. Logan-Sprenger, H. Effects of dehydration during cycling on skeletal muscle metabolism in females. Skeletal muscle enzymes and fiber composition in male and female track athletes. Lipid metabolism in skeletal muscle of endurance-trained males and females. Horton, T. Fuel metabolism in men and women during and after long-duration exercise. Friedlander, A. Training-induced alterations of carbohydrate metabolism in women: women respond differently from men. Tarnopolsky, L. Gender differences in substrate for endurance exercise. Carter, S. Substrate utilization during endurance exercise in men and women after endurance training. Roepstorff, C. Gender differences in substrate utilization during submaximal exercise in endurance-trained subjects. Higher skeletal muscle α2AMPK activation and lower energy charge and fat oxidation in men than in women during submaximal exercise. Hamadeh, M. Estrogen supplementation reduces whole body leucine and carbohydrate oxidation and increases lipid oxidation in men during endurance exercise. Hackney, A. Substrate responses to submaximal exercise in the midfollicular and midluteal phases of the menstrual cycle. Zderic, T. Glucose kinetics and substrate oxidation during exercise in the follicular and luteal phases. Devries, M. Menstrual cycle phase and sex influence muscle glycogen utilization and glucose turnover during moderate-intensity endurance exercise. Frandsen, J. Menstrual cycle phase does not affect whole body peak fat oxidation rate during a graded exercise test. Download references. Department of Physiology, University of Melbourne, Melbourne, Victoria, Australia. Department of Human Health and Nutritional Sciences, University of Guelph, Guelph, Ontario, Canada. You can also search for this author in PubMed Google Scholar. and L. conceived and prepared the original draft, revised the manuscript and prepared the figures. Correspondence to Mark Hargreaves or Lawrence L. Reprints and permissions. Skeletal muscle energy metabolism during exercise. Nat Metab 2 , — Download citation. Received : 20 April Accepted : 25 June Published : 03 August Issue Date : September Anyone you share the following link with will be able to read this content:. Sorry, a shareable link is not currently available for this article. Provided by the Springer Nature SharedIt content-sharing initiative. The Journal of Physiological Sciences BMC Sports Science, Medicine and Rehabilitation Pflügers Archiv - European Journal of Physiology European Journal of Applied Physiology Sign up for the Nature Briefing newsletter — what matters in science, free to your inbox daily. Skip to main content Thank you for visiting nature. nature nature metabolism review articles article. Download PDF. Subjects Energy metabolism Skeletal muscle. This article has been updated. Abstract The continual supply of ATP to the fundamental cellular processes that underpin skeletal muscle contraction during exercise is essential for sports performance in events lasting seconds to several hours. Exercise metabolism and adaptation in skeletal muscle Article 24 May Aerobic exercise intensity does not affect the anabolic signaling following resistance exercise in endurance athletes Article Open access 24 May Myofibrillar protein synthesis rates are increased in chronically exercised skeletal muscle despite decreased anabolic signaling Article Open access 09 May Main In , athletes from around the world were to gather in Tokyo for the quadrennial Olympic festival of sport, but the event has been delayed until because of the COVID pandemic. Overview of exercise metabolism The relative contribution of the ATP-generating pathways Box 1 to energy supply during exercise is determined primarily by exercise intensity and duration. Full size image. Regulation of exercise metabolism General considerations Because the increase in metabolic rate from rest to exercise can exceed fold, well-developed control systems ensure rapid ATP provision and the maintenance of the ATP content in muscle cells. Box 3 Sex differences in exercise metabolism One issue in the study of the regulation of exercise metabolism in skeletal muscle is that much of the available data has been derived from studies on males. Targeting metabolism for ergogenic benefit General considerations Sports performance is determined by many factors but is ultimately limited by the development of fatigue, such that the athletes with the greatest fatigue resistance often succeed. Training Regular physical training is an effective strategy for enhancing fatigue resistance and exercise performance, and many of these adaptations are mediated by changes in muscle metabolism and morphology. Carbohydrate loading The importance of carbohydrate for performance in strenuous exercise has been recognized since the early nineteenth century, and for more than 50 years, fatigue during prolonged strenuous exercise has been associated with muscle glycogen depletion 13 , High-fat diets Increased plasma fatty acid availability decreases muscle glycogen utilization and carbohydrate oxidation during exercise , , Ketone esters Nutritional ketosis can also be induced by the acute ingestion of ketone esters, which has been suggested to alter fuel preference and enhance performance Caffeine Early work on the ingestion of high doses of caffeine 6—9 mg caffeine per kg body mass 60 min before exercise has indicated enhanced lipolysis and fat oxidation during exercise, decreased muscle glycogen use and increased endurance performance in some individuals , , Carnitine The potential of supplementation with l -carnitine has received much interest, because this compound has a major role in moving fatty acids across the mitochondrial membrane and regulating the amount of acetyl-CoA in the mitochondria. Nitrate NO is an important bioactive molecule with multiple physiological roles within the body. Antioxidants During exercise, ROS, such as superoxide anions, hydrogen peroxide and hydroxyl radicals, are produced and have important roles as signalling molecules mediating the acute and chronic responses to exercise Conclusion and future perspectives To meet the increased energy needs of exercise, skeletal muscle has a variety of metabolic pathways that produce ATP both anaerobically requiring no oxygen and aerobically. Similar content being viewed by others. References Hawley, J. Article CAS PubMed Google Scholar Sahlin, K. Article CAS PubMed Google Scholar Medbø, J. Article PubMed Google Scholar Parolin, M. CAS PubMed Google Scholar Greenhaff, P. Article Google Scholar Medbø, J. Article PubMed Google Scholar Tesch, P. Article CAS PubMed Google Scholar Koopman, R. Article CAS PubMed Google Scholar Hawley, J. PubMed Google Scholar Romijn, J. CAS PubMed Google Scholar van Loon, L. Article Google Scholar Bergström, J. Article PubMed Google Scholar Wahren, J. Article CAS PubMed PubMed Central Google Scholar Ahlborg, G. Article CAS PubMed PubMed Central Google Scholar Watt, M. Article CAS Google Scholar van Loon, L. Article PubMed CAS Google Scholar Wasserman, D. Article CAS PubMed Google Scholar Coggan, A. CAS PubMed Google Scholar Coyle, E. Article CAS PubMed Google Scholar Horowitz, J. Article CAS PubMed Google Scholar Kiens, B. Article CAS PubMed Google Scholar Stellingwerff, T. Article CAS PubMed Google Scholar Spriet, L. Article CAS PubMed Google Scholar Brooks, G. Article CAS PubMed Google Scholar Miller, B. Article CAS Google Scholar Medbø, J. Article PubMed CAS Google Scholar Hashimoto, T. Article CAS PubMed Google Scholar Takahashi, H. Article CAS PubMed PubMed Central Google Scholar Scheiman, J. Article CAS PubMed PubMed Central Google Scholar Rennie, M. Article CAS Google Scholar Wagenmakers, A. CAS PubMed Google Scholar Howarth, K. Article CAS PubMed Google Scholar McKenzie, S. Article CAS PubMed Google Scholar Wilkinson, S. Article CAS Google Scholar Egan, B. Article PubMed Google Scholar Hargreaves, M. Article PubMed PubMed Central CAS Google Scholar Richter, E. Article CAS PubMed Google Scholar Gaitanos, G. Article CAS PubMed Google Scholar Kowalchuk, J. Article CAS PubMed Google Scholar Howlett, R. CAS PubMed Google Scholar Wojtaszewski, J. Article CAS Google Scholar Chen, Z. Article CAS PubMed Google Scholar Stephens, T. Article CAS PubMed Google Scholar Yu, M. Article CAS Google Scholar Rose, A. Article CAS Google Scholar McConell, G. Article CAS PubMed Google Scholar Hoffman, N. Article CAS PubMed PubMed Central Google Scholar Nelson, M. Article CAS PubMed PubMed Central Google Scholar Needham, E. Article CAS PubMed Google Scholar Perry, C. Article CAS Google Scholar Miotto, P. Article CAS PubMed Google Scholar Holloway, G. Article PubMed PubMed Central Google Scholar Watt, M. Article CAS Google Scholar Talanian, J. CAS Google Scholar Richter, E. Article CAS PubMed Google Scholar Sylow, L. Article CAS Google Scholar Bradley, N. Article CAS PubMed Google Scholar Smith, B. Article PubMed Google Scholar Petrick, H. Article CAS PubMed Google Scholar Krustrup, P. Article CAS PubMed Google Scholar Achten, J. Article CAS PubMed Google Scholar Harris, R. Article CAS PubMed Google Scholar Taylor, J. Article CAS PubMed PubMed Central Google Scholar Allen, D. Article CAS PubMed Google Scholar Amann, M. Article PubMed Google Scholar Burke, L. Article CAS PubMed Google Scholar Maughan, R. Article PubMed Google Scholar Roberts, A. Article CAS PubMed Google Scholar Sharp, R. Article CAS PubMed Google Scholar Weston, A. Article CAS PubMed Google Scholar McKenna, M. Article CAS Google Scholar Gibala, M. Article CAS Google Scholar Lundby, C. Article CAS Google Scholar Amann, M. Article PubMed Google Scholar Holloszy, J. Article CAS PubMed Google Scholar Chesley, A. CAS PubMed Google Scholar Leblanc, P. Article CAS PubMed Google Scholar Coyle, E. Article CAS PubMed Google Scholar Westgarth-Taylor, C. Article CAS PubMed Google Scholar Seynnes, O. Article CAS Google Scholar Hultman, E. Article CAS PubMed Google Scholar Greenhaff, P. Article CAS Google Scholar Casey, A. CAS PubMed Google Scholar Vandenberghe, K. Article CAS PubMed Google Scholar Hermansen, L. Article CAS PubMed Google Scholar Ørtenblad, N. Article PubMed PubMed Central CAS Google Scholar Matsui, T. CAS Google Scholar Bergström, J. Article PubMed Google Scholar Hawley, J. Article CAS PubMed Google Scholar Balsom, P. Article CAS PubMed Google Scholar Hargreaves, M. Article CAS PubMed Google Scholar Jeukendrup, A. CAS PubMed Google Scholar McConell, G. Article CAS PubMed Google Scholar Nybo, L. Article CAS PubMed Google Scholar Snow, R. Article CAS PubMed Google Scholar Chambers, E. Article CAS Google Scholar Costill, D. Article CAS PubMed Google Scholar Vukovich, M. Article CAS PubMed Google Scholar Odland, L. CAS PubMed Google Scholar Phinney, S. Article CAS PubMed Google Scholar Burke, L. Article CAS PubMed Google Scholar Havemann, L. Article CAS Google Scholar Paoli, A. Article PubMed Google Scholar Kiens, B. Article PubMed Google Scholar Helge, J. Article CAS Google Scholar Yeo, W. Article CAS PubMed Google Scholar Hulston, C. Article CAS PubMed Google Scholar Kirwan, J. Article CAS PubMed Google Scholar Cox, P. Article CAS PubMed Google Scholar Shaw, D. Article PubMed Google Scholar Evans, M. Article CAS PubMed Google Scholar Prins, P. Article PubMed PubMed Central Google Scholar Dearlove, D. Article PubMed PubMed Central Google Scholar Leckey, J. Article PubMed PubMed Central Google Scholar Costill, D. CAS PubMed Google Scholar Graham, T. Article CAS PubMed Google Scholar Graham, T. Article CAS Google Scholar Graham, T. Article CAS PubMed Google Scholar Desbrow, B. Article PubMed Google Scholar Cole, K. Article PubMed Google Scholar Kalmar, J. Article PubMed Google Scholar Spriet, L. Article PubMed Google Scholar Wickham, K. Article PubMed PubMed Central Google Scholar Barnett, C. Article CAS PubMed Google Scholar Stephens, F. Article CAS PubMed Google Scholar Wall, B. Article CAS Google Scholar Stephens, F. Article CAS PubMed Google Scholar Larsen, F. Article CAS Google Scholar Bailey, S. Article CAS PubMed Google Scholar Bailey, S. Article CAS PubMed Google Scholar Lansley, K. Article CAS PubMed Google Scholar Boorsma, R. Article CAS PubMed Google Scholar Nyakayiru, J. Article CAS PubMed Google Scholar Jones, A. Article CAS PubMed Google Scholar Whitfield, J. Article PubMed Google Scholar Coggan, A. Article PubMed PubMed Central Google Scholar Whitfield, J. Article CAS Google Scholar Larsen, F. Article CAS PubMed Google Scholar Ntessalen, M. Article PubMed Google Scholar Sahlin, K. Article CAS PubMed Google Scholar Sutton, J. Article CAS Google Scholar Wilkes, D. Article CAS PubMed Google Scholar Costill, D. Article CAS PubMed Google Scholar Hollidge-Horvat, M. Article CAS PubMed Google Scholar Street, D. Article CAS Google Scholar Sostaric, S. Article CAS Google Scholar Parkhouse, W. Article CAS PubMed Google Scholar Derave, W. Article CAS PubMed Google Scholar Hill, C. Article CAS PubMed Google Scholar Powers, S. Article CAS PubMed Google Scholar Merry, T. Article CAS Google Scholar McKenna, M. Article CAS Google Scholar Petersen, A. Article CAS Google Scholar Ristow, M. Article CAS PubMed PubMed Central Google Scholar Nybo, L. Article PubMed Google Scholar González-Alonso, J. Article Google Scholar Fink, W. Article CAS PubMed Google Scholar Febbraio, M. Article CAS PubMed Google Scholar González-Alonso, J. Article CAS PubMed Google Scholar Logan-Sprenger, H. Article PubMed Google Scholar Costill, D. Ongoing research in this area is aimed at defining the precise mechanism by which exercise increases glucose uptake and insulin sensitivity and the types of exercise necessary for these important health benefits. Keywords: AMP kinase; GLUT4; Glucose; Glucose transplant; Glycogen; Glycogenolysis. Abstract Carbohydrates are the preferred substrate for contracting skeletal muscles during high-intensity exercise and are also readily utilized during moderate intensity exercise. Publication types Research Support, N. Gov't Review. Open symbols are results from the iv glucose infusion trial, and closed symbols are results from the placebo infusion trial stable isotope infusion. Error bars are the SE. This phase was followed by a stepwise increase in workload until exhaustion. A and B, heart rate during exercise in the patient and the controls. C and D, ratings of perceived exertion RPE Borg scale. The patient rated exercise at being easier while receiving the iv glucose infusion, whereas none of the controls did. An iv glucose infusion was given before and during exercise, as described in detail elsewhere Stable isotopes were not infused on this day. The workload and blood sampling protocol was kept the same as that during the stable isotope trial on the previous day. The principle behind the use of stable isotopes to trace metabolism is infusion of minute amounts of isotopes that do not affect basal metabolism, and hence the trial on day 2 was used as a placebo test to assess the effect of the glucose infusion. Informed consent was obtained from all subjects before inclusion in the study. The study was approved by the Regional Committee on Biomedical Research Ethics of Copenhagen approval H-D and was performed according to the ethical standards of the Declaration of Helsinki. Results are described qualitatively and with descriptive statistics and are reported as means ± SE. Plasma lactate increased from rest to exhaustion in the patient 1. No second wind phenomenon was observed, and the patient did not report any exercise-related symptoms. Despite this shift in metabolism toward fat use, the oxidation rate of carbohydrates during exercise was high, and plasma lactate levels increased Figure 1 , C and D , indicating a significant glycolytic flux during exercise. In the patient, plasma glucose levels declined during exercise and almost reached hypoglycemic levels Figure 1 E. Substrate oxidation rates and lactate and glucose concentrations during exercise. This phase was followed by a stepwise increase in workload every other minute until exhaustion, when a final blood sample was drawn. Time of exhaustion was arbitrarily set to 40 minutes. A, Palmitate oxidation rates ROX. B, Rate of appearance Ra of palmitate. C, Carbohydrate oxidation rates during exercise. D and E, Lactate concentrations D and glucose concentrations E measured during the stable isotope infusion trial. Plasma lactate levels increased in the patient, but plasma glucose levels declined, even at time of exhaustion 3. These results were in contrast to those of the control subjects, in whom the glucose levels remained stable and finally increased at the time of exhaustion all subjects. F, Glucose concentrations during the iv glucose infusion trial. Plasma glucose levels declined more rapidly in the patient, and hypoglycemia was barely prevented by the infusion, indicating an increased uptake. In the patient, the iv glucose infusion caused a reduction in heart rate, which was accompanied by a reduction in ratings of perceived exertion during constant load exercise Figure 2. In contrast, the glucose infusion did not influence exercise tolerance in any of the control subjects. In further support of a beneficial effect of iv glucose, the patient could exercise longer and reached a higher W peak than with a placebo Figure 2. The plasma glucose concentration tended to drop faster and more during exercise in the patient than in the control subjects, indicating an increased uptake Figure 1 F. Plasma lactate concentrations were similar in both groups. We examined substrate metabolism and the response to an iv glucose infusion during cycle ergometry exercise in a patient with genetically proven PGM1 deficiency. He had a normal peak work capacity and no second wind phenomenon, suggesting that the condition clinically resembles a number of other glycogen storage diseases such as phosphoglycerate mutase and kinase deficiencies and lactate dehydrogenase deficiency 12 , However, unlike these conditions, iv glucose infusion improved the capacity for work. This response to glucose infusion has so far only been observed in patients with McArdle disease, pointing to a higher reliance on hepatic glucose to feed contracting muscle to compensate for the mildly affected muscle glycogenolysis 4. In support of a partially reduced capacity for skeletal muscle glycogenolysis, the PGM1-deficient patient had a shift in metabolism toward an increase in fatty acid oxidation. This may be compensatory for a reduced capacity for glycogenolysis during exercise and is also seen in McArdle disease Glycogenolysis is partially preserved in PGM1 deficiency. In addition, in contrast to the effects of McArdle disease, capacity for work was normal and lactate production during exercise was normal. Several mechanisms may explain these differences. One factor is the expression of the PGM2 isoform of phosphoglucomutase in skeletal muscle. Liver glycogenolysis is unaffected in McArdle disease, as a consequence of the expression of different isoforms of glycogen phosphorylase in these two tissues. Blood glucose levels are maintained above hypoglycemic levels, but, as we found in the PGM1-deficient patient, blood glucose levels may gradually decline during exercise because of the large increase in skeletal muscle uptake and use of blood glucose 4. The PGM1 isoform of phosphoglucomutase is expressed in both liver and muscle This finding implies that the liver may be affected in PGM1 deficiency, and reduced liver glucose may be a contributing factor to the low blood glucose levels during exercise in this condition. If the liver is affected in PGM1 deficiency, the risks of fasting and exercise-induced hypoglycemia may be increased. Because the exercise intolerance in PGM1 deficiency is mild and symptoms only are provoked by strenuous physical activity, it is likely that the condition may be overlooked. However, the tendency to become hypoglycemic during exercise may aid clinicians in the diagnosis of PGM1 deficiency. This case indicates that PGM1 deficiency should be considered in patients experiencing exercise-induced hypoglycemia. This report characterizes PGM1 deficiency as a mild metabolic myopathy with exercise-related symptoms, as seen in patients with McArdle disease, but the patient with PGM1 deficiency did not have a second wind phenomenon. The lack of a second wind phenomenon is interesting, because the patient had a positive effect of glucose on work capacity. It could be hypothesized that patients with more severe reductions in PGM activity could have a second wind during exercise. The study of the effect of glucose infusion was not randomized, and therefore an order effect cannot be ruled out. However, the decreases in heart rate and in Borg score that we observed in the patient was not observed in any of the control subjects. These findings support the conclusion that the positive effect of the glucose infusion was due to a physiological effect and not an order effect. As more cases of PGM1 deficiency are diagnosed, additional research will determine whether the results in this patient can be replicated in other patients. Hypoglycemia may develop during exercise in PGM1 deficiency, as a consequence of increased muscular uptake of blood glucose and a potentially impaired mobilization of glucose from the liver. This work was funded by the Merchant L. Foght's Fondation, The Family Hede Nielsen's Foundation, the Sara and Ludwig Elsass Foundation, and the A. Møller Foundation for the Advancement of Medical Science. Disclosure Summary: The authors have nothing to disclose that pertains to the present work. However, the following authors report disclosures unrelated to the present work: N. report having received research support, honoraria, and travel funding from the Genzyme Corporation; P. and J. are members of the Genzyme Pompe Disease Advisory Board; and J. works as a consultant for Lundbeck Pharmaceutical Company. Stojkovic T , Vissing J , Petit F , et al. Muscle glycogenosis due to phosphoglucomutase 1 deficiency. N Engl J Med. |
| Human Verification | Article CAS PubMed Google Carbohydrate metabolism and exercise Derave, Metqbolism. Oxford University Speed boosting techniques News Oxford Languages University of Oxford. Execrise of Farro grain uses ingestion on perception of effort and Carbonydrate work production. Intramuscular triacylglycerol, glycogen and acetyl group metabolism during 4 h of moderate exercise in man. Glycogen n is a glycogen polymer of n glucose residues. This is considered to be feedback-regulated by signals associated with the increased demand by the exercising muscles, causing responses that increase glucose production to match glucose utilisation. Saltin View author publications. |
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