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EXERCISE PHYSIOLOGY Hazzaa M. AlAl-Hazzaa, Ph D, FACSM Professor & Director Exercise Physiology Laboratory King Saud University Tel (office): 4678411 (Lab): 4678406 http://faculty.ksu.edu.sa/hazzaa 504 RHS – Spring 2011 KSU What is Exercise Physiology? The study of the physiological responses and adaptation to exercise and training and detraining at various environmental conditions. From systemic to sub-cellular level. During both acute (short term) exercise and chronic (long term) training. Involving people of all ages (children to elderly) and abilities (diseased, healthy and athlete). Exercise Bioenergetics It is the study of the metabolic processes that can lead to the production and utilization of energy in forms such as ATP molecules. KSU Energy Energy is the capacity to do work. It is either potential energy (stored energy) or kinetic energy (energy of motion). Forms of Energy: v Light (sun) v Mechanical v Electric v Nuclear v Heat (solar) v Chemical (fuel, oil) Energy First Law of Thermodynamics l Conservation of Energy – Energy can not be “Created” or “Destroyed” l Our body simply transforms energy (Chemical) into muscle contraction (mechanical) and heat. AdenosineTri Phosphate (ATP) Ø ATP is the energy currency used for all processes in the living cells: l ATP – Chemical as Potential Energy l Phosphate bonds: High Energy l Food energy: re-synthesizes more ATP Immediate Energy for muscle contraction (ATP) أدﯾﻨﻮﺳﯿﻦ ﺛﻼﺛﻲ اﻟﻔﻮﺳﻔﺎت Adenosine P P Adenosine P P (ADP) P + أدﯾﻨﻮﺳﯿﻦ ﺛﻨﺎﺋﻲ اﻟﻔﻮﺳﻔﺎت Pi + Energy Phosphorylation ATP ←→ ADP + P + ENERGY CP ←→ C + P + ENERGY Energy for muscle Contraction Phosphocreatine Creatine ADP Creatine + Energy P Pi P ATP Energy for muscle Contraction أدﯾﻨﻮﺳﯿﻦ ﺛﻼﺛﻲ (ATP) اﻟﻔﻮﺳﻔﺎت Breakdown Synthesis أدﯾﻨﻮﺳﯿﻦ ﺛﻨﺎﺋﻲ (ADP) اﻟﻔﻮﺳﻔﺎت ATP – CP Energy System Small amount of ATP is stored l l 85 g in whole body (about 2 seconds of muscle contraction) Must be re-synthesized CP: quick energy for ATP re-synthesis l CP stored in larger quantities (enough for 5-6 seconds of muscle contraction) All out Exercise – 6 to 8 seconds ATP – CP Energy System Assuming 20 kg of muscle is used in exercise, then the Phosphagen energy system can supply energy for the working muscle for: v Walking for one minute v Jogging for 20-30 sec, or v Running at maximum speed for 6-8 sec Bergstrom, et al., In: Muscle metabolism During Exercise, 1971, 422: 539 Hultman, Scand J Clin lab Invest (Suppl), 1967 Anaerobic Energy Energy for Muscle Contraction C + Pi CP CHO Glycogen breakdown Anaerobic Glycolysis Energy Cytoplasm Pyruvic Acid ATP Energy ADP + Pi For muscle CAC CO22 CO eETS Fatty Acids Mitochondrion Aerobic Oxidation + H2O Anaerobic Glucose Energy ATP H+ Pyruvic Acid (2) Lactic Acid (2) Inter Cellular Fluid Fatty Acids Amino Acids CO2 CO2 & H+ Mitochondria Aerobic Acetyl Co-A (2) Krebs Cycle Energy H+ ATP To ETC Aerobic Glycolysis Krebs Cycle l H+ → Electron Transport Chain ETC l 2H+ + Oxygen → H2O + Energy Glycolysis KSU Aerobic Oxidation Energy Krebs Cycle ATP CO2 H+ 2H+ + -- O = H2O Electron Transport Chain ATP Anaerobic vs Aerobic Energy Systems Anaerobic l l ATP-CP : ≤ 10 sec. Anaerobic Glycolysis: < 2 minutes Aerobic l l l Krebs cycle (Aerobic glycolysis) Electron Transport Chain ß-Oxidation 2 minutes + How do we relate the energy systems into duration and intensity of exercise? Maximal Power & Capacity of the Energy Systems Energy System Maximal Power Maximal Capacity Immediate (ATP ATP--PC PC)) Short term (Anaerobic Glycolysis) Long term (Aerobic) (mole/min) (Total ATP) Very High Very Limited Somewhat Somewhat limited High Low Almost Unlimited Available Energy for Muscles (based on energy system) Energy System Immediate (ATP ATP--PC PC)) Short term (Anaerobic Glycolysis Glycolysis)) Maximal power (w/kg) Time to depletion 800 20 sec 325 60 sec 150 60 min > 6 hours Long term (Aerobic) • Aerobic Glycolysis • FFA Oxidation Knuttgen, PSM, 2003, 31(3): 35 75 Energy System Contribution (%) during all out Exercise for 30 sec 50 25 Phosphocreatine 25 Anaerobic Glycolysis Aerobic Glycolysis Greenhaff, & Timmons,ESSR,1998, 1-30; Serresse, et al., IJSM, 1988, 9: 456-460 Bicycle Ergometer Relationship of metabolic power and mechanical power, based on the energy systems Knuttgen, PSM, 2003, 31(3): 35 Energy Systems for Exercise Energy Systems Immediate: Phosphagen (Phosphocreatine and ATP) Short Term: Glycolysis (Glycogen-Lactic Acid) Long Term: Aerobic Mole of ATP/min Time to Fatigue 4 5 to 10 sec 2.5 1.0 to 1.6 min 1 Unlimited time Energy Transfer Systems and Exercise % Capacity of Energy System 100% Anaerobic Glycolysis Aerobic Energy System ATP - CP 10 sec 30 sec 2 min 5 min + Energy Systems What happens when we heavily use anaerobic glycolysis glycolysis? ? Lactic Acids concentration in the working muscles rises Then we can see its concentration rises in the blood. But, so What? The acidity can negatively effect muscle contraction in 2 ways: 1- Interferes with ca++ attachment to Troponin , and 2- Inhibits some of the key enzymes in Glycolysis Glycolysis.. Lactate is not a Waste Product Lactate can be used as a Fuel during Exercise v It can be utilized by slow twitch muscle fibers (Type I), through the “lactate shuttle” Lactate to Pyruvate to Acetyle Co-A ------ Krebs Cycle v Used by the heart muscle v Converted back to glucose in the liver via the Cori cycle (Gluconeogenesis) Cori Cycle What determines which path does lactate go through? Lactic acid (mMol/L) Active vs Passive Recovery and Lactate removal اﺳﺘﺮداد ﻏﯿﺮ ﻧﺸﻂ اﺳﺘﺮداد ﻧﺸﻂ Time (min) Costill, et al, JAP, 1977, 43: 695-699 Control of Bioenergetics ATP-PC System PC + ADP Glycogen C + ATP 1 Glucose Rate Limiting Enzymes 1. Creatine kinase 2. Phosphofructokinase 3. Isocitrate dehydrogenase 4. Cytochrome oxidase Glucose 6-phosphate 2 Glycerol Triglycerides Phosphoglyceraldehyde Glycolysis Pyruvic Acid Lactic Acid β-ox Acetyl CoA Fatty acids Ketone bodies C4 Krebs Cycle 3 Amino Acids C6 Urea NADH FADH C5 Proteins ETC 4 Why does our body resort to anaerobic energy system when it can get more ATP from aerobic energy system? system ? Rest-to-Exercise: Aerobic v Assume sitting on the bike requires 15 ATP and 0.3 liters/min of oxygen v Assume pedaling at a power of 100 watts requires 80 ATP and 1.5 liter/min of oxygen v A person can go from sitting to full pedaling at 100 watts in a mater of seconds. v But, it takes 3-4 minutes for the oxygen requirement to go from 0.3 to 1.5 liters/min v Where does the ATP needed to pedal at 100 watts come from until adequate oxygen can be supplied? Rest-to-Exercise: The Oxygen Deficit Aerobic