CHO 1_2 Slides PDF

5/6/20 The pictures used in this lecture are only intended to be used as pictures and NOT the associated website or information attached to them School of Physiotherapy and Exercise Science FACULTY OF HEALTH SCIENCES Substrate Utilisation: Carbohydrates Presented by Dr Carly Brade Materials provi...

5/6/20 The pictures used in this lecture are only intended to be used as pictures and NOT the associated website or information attached to them School of Physiotherapy and Exercise Science FACULTY OF HEALTH SCIENCES Substrate Utilisation: Carbohydrates Presented by Dr Carly Brade Materials provided by Dr Carly Brade & Dr Kagan Ducker HUMB2006 Exercise Physiology Semester 1 2019 1 5/6/20 Readings § McArdle, W.D., Katch, F.I., & Katch, V.L. (2014). Exercise Physiology: Nutrition, Energy and Human Performance 8th Edition . Baltimore, USA: Lippincott, Williams & Wilkins § Ch 1. Part 1. Carbohydrates pp 7-18 § Ch 6. Energy Transfer in the Body pp 133-150 Additional Sources § Kenney, W.L., Wilmore, J., Costill, D. (2012). Fuel for Exercise: Bioenergetics and Muscle Metabolism. In Physiology of Sport and Exercise with Web Study Guide 5th Edition (pp 56 – 60). Champaign, USA: Human Kinetics. § Powers, S.K. & Howley, E.T. (2012). Bioenergetics. In Exercise Physiology: Theory and Application to Fitness and Performance 8th Edition (pp 51 – 67). New York, USA: McGraw Hill. Sour ces used t o develop t his lect ur e § McArdle, W.D., Katch, F.I., & Katch, V.L. (2014). Exercise Physiology: Nutrition, Energy and Human Performance 8th Edition. Baltimore, USA: Lippincott, Williams & Wilkins § Kenney, W.L., Wilmore, J., Costill, D. (2012). Physiology of Sport and Exercise with Web Study Guide 5th Edition. Champaign, USA: Human Kinetics. 2 5/6/20 Learning Outcomes On completion of this topic the student will be able to: § Describe the role, function and recommended intake of carbohydrates within the body § Describe and classify carbohydrates according to chemical structure § Describe the role of carbohydrate in exercise performance, including feeding during endurance events and factors influencing gastric emptying § Define the glycaemic index (GI) and relevance to carbohydrate § Describe in detail the process of glycolysis including by not limited to the use and resynthesis of ATP, enzymatic contributions, the process of lactic acid production, the citric acid cycle and electron transport chain § Describe the role of lactate in the body and relevance to exercise intensity § Differentiate between aerobic and anaerobic glycolysis § Describe the process of oxidative phosphorylation § Describe the mechanism of the bicarbonate buffering system § Describe specific types of muscle fibres including but not limited to slow-twitch oxidative, fast-twitch oxidative glycolytic fibres and glycolytic fibres § Describe the predominance of muscle fibre phenotype in specific athlete cohorts Energy § The body requires energy to function and is supplied by the breakdown of a molecule called Adenosine TriPhosphate (ATP) § Limited stores of ATP in the body and they need constant replenishment HOW? § Food contains macronutrients, when they undergo catabolism = release energy § Catabolism = set of metabolic pathways that break down molecules to release energy 3 5/6/20 Substrates for Energy Macronutrients LIPIDS (FAT) PROTEIN (PRO) http://www.nobullsupplements.com.au/wpcontent/uploads/protein-for-health1.jpg http://www.newhealthadvisor.com/images/1HT01073/PART1.jpg CARBOHYDRATES (CHO) http://exercisesforabiggerbutt.com/wpcontent/uploads/2016/03/Good-Fats-Bad-Fats.jpg Basic principles § Fuel is essential for physical activity § Adequate nutrition is important to initiating, maintaining and recovering from bouts of activity § Understanding energy production is important to optimising physical performance in any setting https://s-media-cacheak0.pinimg.com/originals/3e/f0/20/3ef0209d695733af8762b7eacbb4cc0c.jpg http://static1.squarespace.com/static/563b167be4b0bdb19f1dd4e9/563b27ebe4b02b3bc1e3b2ac/57 761e0003596e9e20e78bb3/1468132104537/Champs-Elysees_3350416b.jpg?format=1000w https://www.eatforhealth.gov.au/sites/default/files/imag es/the_guidelines/n55_agthe_large.jpg 4 5/6/20 Carbohydrates Polysaccharide (10+) e.g fibre, starch Oligosaccharide (3-9) e.g. soy beans https://www.precisionnutrition.com/wp-content/uploads/2009/02/1feb23.gif Disaccharide e.g. Surcose, Lactose, Maltose Monosaccharide e.g. Fructose, Glucose https://img.aws.livestrongcdn.com/ls-article-image-673/ds-photo/getty/article/94/180/149162559.jpg http://www.bbc.co.uk/staticarchive/fae340ba1aaf2f4a42b716a3fd4796312d173e97.gif Carbohydrate Storage § After absorption, CHO can stay in the blood to maintain blood glucose levels or be stored § Blood glucose levels are highly regulated § = 3.9 - 6.7 mmol/L § Fasted glucose level § = < 5.5 mmol/L McArdle et al., 8th Ed Figure 1.4, p 14 5 5/6/20 How do we store Glucose? § Excess blood glucose is converted to glycogen for storage in either the muscle or liver by the process of: GLYCOGENESIS GLUCOSE à GLYGOGEN § 1 gram CHO = 4.15 Kcals (e.g. 500 g x 4.15 = 2000 kcal) § Therefore, 4 kcal x 4.184 J = 16.736 kJ/gram CHO § So the average person stores ~8400 kJ (500 g x 17 kJ) § If CHO stores are full the excess is converted to FAT How do we use Glycogen? § Glycogen needs to be converted to glucose for eventual potential use as energy § Process of converting glycogen to glucose= GLYCOGENOLYSIS Glycogen Glucose § This glucose is then transferred to the muscles via the blood https://www.google.com.au/search?q=glycogenesis&biw=1378&bih=822&source=lnms&tbm=isch&sa=X&ved=0ahU KEwiTgKTW8cjKAhULF5QKHVsOAocQ_AUIBigB#imgrc=U9bZe6rBNeUUiM%3A 6 5/6/20 CHO RO LES 1 - ENERG Y SO URCE § CHO is a predominant source of energy for the human body § Main fuel for high intensity, short duration exercise § Start of exercise and high intensity exercise – muscle glycogen can provide energy without oxygen and thus contributes greatly § Glucose from the blood starts moving into the muscle § Liver glycogen then supplies glucose to maintain blood glucose levels § Liver glycogen stores after one hour will be depleted by 55%, by two hours almost fully depleted, via glycogenolysis § For moderate and prolonged exercise § Energy is supplied for the transition from rest to moderate intensity § 40-50% energy contribution next 20 min McArdle et al., 8th Ed Figure 1.5, p 15 CHO is important for performance McArdle et al., 8th Ed Figure 1.7, p 17 7 5/6/20 CHO Stores § Finite store needs daily replenishment § Increased CHO is converted to fat § Glycogen stores limited (2,500 kcal), must rely on dietary carbohydrate to replenish § How far will the body’s CHO stores get you? McArdle et al., 8th Ed Figure 1.4, p 14 “HITTING THE WALL” § § § § Linked to depletion of glycogen stores Commonly reported by marathon runners after about 35km When glycogen stores are exhausted, performance is affected Signs and Symptoms § Tingling and numbness in the legs and arms, thinking becomes confused, pace slows considerably http://thebrainofjordan.com/wp-content/uploads/2013/11/konacrawl1.jpg https://i.ytimg.com/vi/g_utqeQALVE/hqdefault.jpg http://2.bp.blogspot.com/_8J91GJLYeL4/Sp1f6PKKwWI/AA AAAAAAAS4/PcGZ_HjlL8Y/s320/PNFCollapsebyCruse.jpg 8 5/6/20 Kona Hawaii Ironman § § § § § § § § Swim = 3.9 km Cycle = 180.2 km Run = 42.2 km Course records § Male = 8 hr 3 min § Female = 8 hr 54 min 15 hours for some people, race is stopped after 17 hours Average Temps = 21-28 ˚C, can exceed 37˚C Consider the radiant heat from asphalt Humidity 40% in afternoon Video https://www.youtube.com/watch?v=cWPT9a9frbE https://www.youtube.com/watch?v=LKf1eTzmK14 9 5/6/20 CHO RO LES 2 - PRO T EI N SPARI NG § Protein is essential for tissue maintenance, repair and growth § Depletion of glycogen levels due to: § strenuous exercise § reduced CHO intake § starvation § Can result in gluconeogenic pathways GLUCONEOGENESIS Protein Glucose § In the extreme this reduces lean muscle mass and increases kidney load § Adequate CHO spares the use of protein McArdle et al., 8th Ed Figure 1.24, p 37 CHO RO LES 3 - M ETABO LI C PRI M ER § By-products of CHO breakdown are essential for fat breakdown/oxidation § Makes those by-products primer substrates § Therefore, there must be adequate CHO supply for FAT breakdown to occur § Lack of CHO due to diet, or exercise = Incomplete fat breakdown = ­­ ketones (¯ pH) = ¯¯ max/effort McArdle et al., 8th Ed Figure 1.6 B, p 16 10 5/6/20 CHO ROLES 4 - FUEL FOR CNS § CNS almost exclusively uses glucose as its fuel § Therefore, glucose is essential for its functioning § ¯¯ CHO due to prolonged exercise, CHO depleted diet or poorly regulated diabetes = low blood glucose levels (<2.7 mmol.L) = Hypoglycaemia = weakness, hunger and dizziness § If this is prolonged it can potentially result in loss of consciousness, coma or irreversible brain damage CHO Intake § Typical daily intake = 40-50% of total calorie intake § For athletes - amount depends on frequency, duration and intensity of the exercise and consumption should alter with changing demands § Training athletes = 60% § Intense training = 70% 11 5/6/20 CHO intake around an event § Pre competition § Aim = To ensure adequate CHO to maximise liver and muscle glycogen stores and hydration § Carbohydrate Loading = maximising muscle glycogen stores whilst tapering § During competition § Aim = reduce the rate of muscle and liver glycogen depletion § Consuming 30 - 60g of CHO per hour during exercise benefits high intensity, long duration (>1hr) aerobic exercise and repetitive short bouts of near maximal effort § Post competition § Aim = to replenish used muscle and liver glycogen stores Carbohydrate Absorption § Glycaemic index describes the absorption rate of CHO § How quickly blood glucose levels are raised B. High GI A. Low GI McArdle et al., 8th Ed Figure 3.11, p 97 12 5/6/20 Factors Affecting Gastric Emptying McArdle et al., 8th Ed Figure 3.14, p 101 CHO drinks § 5 to 8% solution of glucose is optimal § Doesn’t impair gastric emptying § Contributes to thermoregulation and fluid balance like H2O § High CHO solutions (i.e. 20 – 25%) may impede rehydration, especially in hot weather, and are more suited to recovery § Consider the different drinks, pre, during and post Beverage % CHO Gatorade 6 PowerAde 7 Vitamin water 5.5 Coke 11 Orange Juice 11 Red Bull 11 https://i.ytimg.com/vi/XSHlHcz72rg/hqdefault.jpg 13 5/6/20 ATP Synthesis – Energy Systems Three ATP synthesis pathways: 1. ATP-PCr system (anaerobic) § Phosphagen System § The immediate energy system 2. Glycolytic system (anaerobic) § Predominantly CHO § Short-term energy system 3. Oxidative system (aerobic) § Predominantly CHO and Lipids § Long-term energy system Stage 3 Stage 2 Chemiosmotic phosphorylation Kreb’s Cycle McArdle et al., 8th Ed Figure 11.2, p 229 Stage 1 Mitochondria l membranes McArdle et al., 8th Ed Figure 6.8, p 142 14 5/6/20 Carbohydrate as Fuel § Complete oxidation of CHO occurs over 3 Stages: 1.Glycolysis § Anaerobic 2.The Krebs/citric acid cycle § Aerobic 3. The Electron Transport Chain (ETC) § Aerobic § CHO only macronutrient that can be utilised to supply ATP anaerobically Glycolytic System: Fuels Glucose C6H12O6 http://www.easynotecards.com/uploads/511/25/_6da06025_13a2d7978ef__8000_00000079.png http://www.bbc.co.uk/staticarchive/fae340ba1aaf2f4a42b716a3fd4796312d173e97.gif 15 5/6/20 Glycolytic System: Fuels Glycogen C24H42O21 http://study.com/cimages/multimages/16/754px-glykogen.svg.png GLUT 2 Transporters § Allows for bidirectional flow of glucose for: • Liver, Pancreas, Renal tubules • Why? • Liver – to allow for excess glucose to be stored as glycogen • Pancreas – to detect concentration of glucose in blood http://www.austincc.edu/apreview/Em phasisItems/Glucose_regulation.html 16 5/6/20 GLUT 4 Transporters • Transport into skeletal muscle and adipose tissue • Why do these tissues want glucose? • In skeletal muscle, glucose can b/d to produce ATP needed for muscular contraction, or be stored as glycogen • In adipose tissue, extra glucose can be converted to triglycerdies http://www.austincc.edu/apreview/Em phasisItems/Glucose_regulation.html Glycolysis Stage 1 of CHO breakdown 17 5/6/20 Glycolysis = Anaerobic metabolic pathway converting GLUCOSE (glycogen) to PYRUVATE Literal meaning = “to split sugar” Rate of Glycolysis impacts the fate of PYRUVATE McArdle et al., 8th Ed Figure 6.10, p 145 Glycolysis: Overview § Glucose à two pyruvate molecules (10 Reactions) § 4 ATP produced § 2 ATP sacrificed § Net gain: 2 ATP § Glycogen à two pyruvate molecules (9 reactions) § 4 ATP produced § 1 ATP sacrificed § Net gain: 3 ATP 18 5/6/20 http://www.bbc.co.uk/staticarchive/fae340ba1aaf2f4a42b716a3fd4796312d173e97.gif STEP 1 Glucose Phosphorylation of glucose prevents transport out of cell McArdle et al., 5th Ed Figure 6.11, p 142 http://oregonstate.edu/dept/biochem/hhmi/hhmiclasses/bb450/winter2002/GH/GLU6P.GIF http://www.bbc.co.uk/staticarchive/fae340ba1aaf2f4a42b716a3fd4796312d173e97.gif STEP 1 (just after) Glucose Glycogen McArdle et al., 5th Ed Figure 6.11, p 142 http://oregonstate.edu/dept/biochem/hhmi/hhmiclasses/bb450/winter2002/GH/GLU6P.GI F 19 5/6/20 http://oregonstate.edu/dept/biochem/hhmi/hhmiclasses/bb450/winter2002/GH/GLU6P.GIF STEP 2 McArdle et al., 5th Ed Figure 6.11, p 142 http://oregonstate.edu/dept/biochem/hhmi/hhmiclasses/bb450/winter2002/EF/F6 P.GIF http://oregonstate.edu/dept/biochem/hhmi/hhmiclasses/bb450/winter2002/EF/F6 P.GIF STEP 3 Phosphofructokinase McArdle et al., 5th Ed Figure 6.11, p 142 https://s3.amazonaws.com/classconnection/325/flashcards/10834325/gif/f16dpf15333C6EAE94890D2AA.gif 20 5/6/20 Modulators of Phosphofructokinase Stimulators Inhibitors ADP ATP PFK PCr Pi Low pH PFK believed to control the rate of glycolysis PFK highly responsive to energy requirements Summary: Step 1 - 3 § ATP used to phosphorylate glucose: GLUCOSE à GLUCOSE 6-PHOSPHATE Why = to keep glucose in the cell and FRUCTOSE 6-PHOSPHATE à FRUCTOSE 1, 6BIPHOSPHATE Why = Primes the process of glycolysis § Breaking the bond of molecules with Pi can be used to release energy 21 5/6/20 https://s3.amazonaws.com/classconnection/325/flashcards/10834325/gif/f16dpf15333C6EAE94890D2AA.gif STEP 4 and STEP 5 One 6-C molecule splits into two 3-C molecules Dihydroxyacetone phosphate (DHAP) 3-Phosphoglyceraldehyde 3-Phosphoglyceraldehyde McArdle et al., 5th Ed Figure 6.11, p 142 McArdle et al., 5th Ed Figure 6.11, p 142 STEP 6 3-Phosphoglyceraldehyde Glyceraldehyde 3-phosphate dehydrogenase 1, 3-Biphosphoglycerate ETC ETC 3-Phosphoglyceraldehyde 1, 3-Biphosphoglycerate https://upload.wikimedia.org/wikipedia/commons/c/cd/1%2C3-bisphosphoglycerate.png 22 5/6/20 STEP 7 2, 3 DPG 1, 3-Biphosphoglycerate 1, 3-Biphosphoglycerate 3-Phosphoglycerate 3-Phosphoglycerate McArdle et al., 5th Ed Figure 6.11, p 142 STEP 8 & STEP 9 3-Phosphoglycerate 2-Phosphoglycerate Phosphoenolpyruvate McArdle et al., 5th Ed Figure 6.11, p 142 3-Phosphoglycerate 2-Phosphoglycerate Phosphoenolpyruvate 23 5/6/20 STEP 10 Phosphoenolpyruvate Phosphoenolpyruvate Pyruvate Pyruvate The End-ish McArdle et al., 8th Ed Figure 6.10, p 145 McArdle et al., 5th Ed Figure 6.11, p 142 24 5/6/20 McArdle et al., 8th Ed Figure 6.10, p 145 GLUCOSE -1 ATP GLUCOSE/GLYCOGEN -1 ATP +1 NADH + H+ +1 NADH + H+ +1 ATP +1 ATP +1 ATP +1 ATP Balance Sheet § GLUCOSE Energy investment -2 ATP Energy harvest +4 ATP NET production +2 ATP § GLYCOGEN Energy investment -1 ATP Energy harvest +4 ATP NET production +3 ATP Both substrates also yield 2 x NADH + H+ which go to the ETC 25 5/6/20 http://images.clipartpanda.com/walk-clipartnTEjqRGTA.png Fate of Pyruvate https://encrypted-tbn3.gstatic.com/images?q=tbn:ANd9GcRY9aLoq01ZP5Pb567Hkzw13B8tlPmQeiPk_D2-2SUAk5ZUv1nO Low-Moderate Energy Demand § PYRUVATE continues to Stage 2 § Krebs Cycle § Requires O2 § Oxidative Phosphorylation § Aerobic glycolysis? High Energy Demand § PFK ‘senses’ increased energy demand § Glycolysis rate increases § O2 not required – not rapid enough § Glycolytic Energy System Glycolytic Energy System 26 5/6/20 McArdle et al., 5th Ed Figure 6.11, p 142 Remember STEP 6 3-Phosphoglyceraldehyde Glyceraldehyde 3-phosphate dehydrogenase 1, 3-Biphosphoglycerate ETC ETC 3-Phosphoglyceraldehyde 1, 3-Biphosphoglycerate https://upload.wikimedia.org/wikipedia/commons/c/cd/1%2C3-bisphosphoglycerate.png Electron Carriers § Dehydrogenase enzymes catalyse Hydrogen release from substrate § Coenzymes (which assist enzymes) § NAD+ = Nicotinamide Adenine Dinucleotide § FAD = Flavin Adenine Dinucleotide = electron carriers § Carries the electrons to the electron transport chain § These electrons are high energy electrons 27 5/6/20 OIL RIG Oxidation is Loss Reduction is Gain NAD + McArdle et al., 5th Ed Figure 6.11, p 142 § NAD+ to NADH + H+ § 1 electron goes to NAD+ to make NAD (NAD+ is being reduced) § 1 whole hydrogen atom (proton and electron) attaches to NAD = NADH = neutral charge § 1 x hydrogen proton H+ then follows (doesn’t attach but follows) http://www.sciencekids.co.nz/images/pictures/chemistry/hydrogenatom.jpg § NAD+ = cation (has lost an electron thus the + sign) § NAD+ takes pairs of hydrogen atoms (2 x Hydrogen atoms) 28 5/6/20 The Problem § NAD+ collects the Hydrogen electrons the in cytoplasm and transports them to the mitochondria § specifically the Electron Transport Chain § If energy demand is HIGH: § Glycolysis Rate > ETC Rate The Solution H+ Lactate LACTIC ACID is a relatively unstable compound Rapidly disassociates to LACTATE and H+ http://oregonstate.edu/instruct/bb450/450material/stryer7/16/unnumbered_16_p468.jpg https://image.slidesharecdn.com/metabolism-24178/95/metabolism-6-728.jpg?cb=1170399173 29 5/6/20 McArdle et al., 8th Ed Figure 6.11, p 146 High Energy Demand NAD: NADH ratio 2 Lactic Acid Simplified version H+ H http://oregonstate.edu/instruct/bb450/450material/stryer7/16/unnumbered_16_p468.jpg 30 5/6/20 Lactate Accumulation What if energy demand remains HIGH? https://encrypted-tbn3.gstatic.com/images?q=tbn:ANd9GcRY9aLoq01ZP5Pb567Hkzw13B8tlPmQeiPk_D2-2SUAk5ZUv1nO Rate of lactate production > Rate of lactate removal Accumulation of LACTATE and H+ The Fate of Lactate and H + § LACTATE + H+ leave the cell § Facilitated Diffusion via lactate transport proteins § Monocarboxylate transporters (MCTs) How do we deal with Lactate and H+ once in the blood? 1. Buffering H+ buffered to control pH changes 2. The Cori Cycle Gluconeogenic pathway - Gluconeogenesis 31 5/6/20 1. Buffering H + § Increased H+ in the blood = decreased blood pH § Homeostasis needs to be maintained § BUFFERING SYSTEMS can help § Maintain pH within tolerable limits, neutralise acidic/alkaline conditions § Chemical Buffers § Restore pH within a fraction of a second § Bicarbonate buffering system § Physical Buffers § Assist chemical buffers and provide long-term control § § Ventilatory Renal (Long term control) Bicarbonate Buffering System H+ + HCO3Bicarbonate H2CO3 CO2 + H2O Carbonic Acid Ventilatory Breakpoint Indicator of anaerobic metabolism Increased ventilation 32 5/6/20 2. The Cori Cycle https://static.wixstatic.com/media/0681e2_7c51f243cdcb4eabb6587780dff0b3e9.png/v1/fill/w_479,h_469,al_c,usm_0.66_1.00_0.01/0681e2_7c51f243cdcb4eabb6587780 dff0b3e9.png Another option: Reconversion http://oregonstate.edu/instruct/bb450/450material/stryer7/16/unnumbered_16_p468.jpg 33 5/6/20 LACTATE + H+ (Lactic Acid) Good or Bad? Advantage or Disadvantage? 34 5/6/20 Good or Bad? If pH decreases and causes fatigue L PYRUVATE and LACTATE act as a store for H+ Glycolysis can continue at rapid rate J Blood Lactate Measurement § Blood Lactate at Rest § 1-2 mmol·L-1 § Represents RBC metabolism § Exercise will always produce some lactate § Low intensity not enough to overwhelm clearance § Maximal blood lactate § ~ 20 – 22 mmol·L-1 http://www.axonlab.com/var/em_plain_site/storage/images/media/bilder/axonlabschweiz/privathomepages/laktat/lactatepro-lt-1730/55085-1-ger-CH/LactateProLT-1730_lightbox.jpg 35