Exercise Physiology Week 5 Notes
Exercise Physiology Week 5 Notes PE 3070
Popular in Exercise Physiology
Popular in Physical Education
This 5 page Class Notes was uploaded by Aurora Moberly on Saturday September 24, 2016. The Class Notes belongs to PE 3070 at Southern Utah University taught by Dr. Julie Taylor in Fall 2016. Since its upload, it has received 7 views. For similar materials see Exercise Physiology in Physical Education at Southern Utah University.
Reviews for Exercise Physiology Week 5 Notes
Report this Material
What is Karma?
Karma is the currency of StudySoup.
You can buy or earn more Karma at anytime and redeem it for class notes, study guides, flashcards, and more!
Date Created: 09/24/16
Test: 10/5 PE 3070 Chapter 2: Bioenergetics and Muscle Metabolism Substrates: Fuel sources from which we make energy molecules (ATP): CHO, fat, protein Bioenergetics: Process of converting substrates into energy; Performed at a cellular level Metabolism: Chemical reactions in the body Catabolism: Breaks things down Anabolism: Building things ATP Only 40% of total energy consumed is used to generate ATP, 60% is released as heat ATP is a highenergy compound, the primary energy molecule for the human body, derived from food sources and local phosphorylation When the ATP molecule combines with water and ATPase the last phosphate group splits away releasing large amounts of free energy reducing ATP to ADP and P i Phosphorylation: A phosphate group is added to the lowenergy compound, ADP, to form ATP Local Phosphorylation: ATP production that occurs within the muscle cell Substrate Level Phosphorylation: ATP generated independent of oxygen Oxidative Phosphorylation: ATP generation that requires oxygen Energy 1 kilocalorie is the amount of heat energy needed to raise 1L of water 1°C CHO and Protein 4kcal/g; Fat 9kcal/g CHO CHO is the preferred substrate because it is an easier molecule to metabolize and is used in 2 out of 3 energy pathways CHO is found in the body as blood glucose, liver glycogen, muscle glycogen Fat Fat is less readily available because it has to be reduced from triglycerides to glycerol and free fatty acids Free fatty acids (FFA) are used to form ATP Protein Only used for energy during very long bouts of exercise or starvation Gluconeogenesis: The process by which protein is converted into glucose Lipogenesis: The process of converting protein into FFA Only the amino acids of protein can be used for energy Rate of Energy Production Rate is determined by: 1. Availability of the primary substrate 2. Enzyme activity 3. Availability of cofactors Mass Action Effect: Increased substrate availability increases the rate of the metabolism Enzymes: Proteins that speed up reactions by lowering the activation energy required to begin a reaction Many enzymes require cofactors to function so their availability can effect enzyme activity as well RateLimiting Enzyme: One enzyme that controls the rate of the reaction The three energy systems are (Fast to Slow): 1. Phosphagen System (Anaerobic metabolism) 2. Glycolysis (Anaerobic metabolism) 3. Oxidative Phosphorylation (Aerobic metabolism) All three systems are always active Phosphagen System: ATPPCr System and Myokinase System Initiates every muscular movement; Substrate level metabolism; CHO only Phosphocreatine (PCr): Highenergy molecule stored in cells This system can sustain the muscle’s energy needs for 315sec during high intensity exercise ATPPCr System: ATPPCr is used more than myokinase system PCr + ADP + Creatine kinase ATP + Creatine The energy released from the break of PCr is used to regenerate ATP Creatine Kinase: Enzyme that breaks P from PCr i Activity is increased when concentrations of ADP or P are inireased Activity is inhibited when concentrations of ATP are increased Myokinase System: Not the preferred pathway because we don't have a lot of myokinase 2ADP + Myokinase ATP + AMP Glycolytic System 1. Glycolysis begins with a 6carbon glucose molecule (glucose6phosphate) Blood glucose is converted to glucose6phosphate by the enzyme hexokinase, this process costs one ATP Muscle glycogen is converted to glucose6phosphate by the enzyme phosphorylase, this doesn't cost any ATP 2. Phosphofructokinase (PFK): Rate limiting enzyme for glycolysis; Early in the glycolysis process; Uses 1 ATP If ATP concentrations are high the activity of PFK decreases If ADP and P cincentrations are high the activity of PFK increases 3. Fast Glycolysis: Glycolysis done in the absence of oxygen Produces 2 H that are transported to the electron transport chain (ETC) by coenzyme NAD 4. Aerobic Glycolysis: Glycolysis done in the presence of oxygen Produces 2 H that are transported to the ETC by coenzyme NAD 5. Pyruvate: End product of glycolysis + Fast glycolysis produces pyruvate converts it to lactic acid that dissociates into lactate and H Aerobic glycolysis produces pyruvate converts it to acetyl CoA using oxygen that then travels to the mitochondria to begin oxidative phosphorylation 6. Products of Glycolysis: Blood glucose glycolysis results in a net production of 2 ATP Muscle glycogen glycolysis results in a net production of 3 ATP + Glycolysis results in 4 H ions (2 from fast glycolysis and 2 from aerobic glycolysis) Glycolysis results in 2 pyruvate molecules that can be converted to lactic acid or acetyl CoA + Fatigue from glycolysis occurs because of the buildup of H causing acidification of muscle fibers which impairs glycolytic enzyme function Acidification also decreases muscle fibers calciumbinding capacity impeding muscle contraction Glycolysis operates within the cell cytoplasm; Substrate CHO Glycolysis used during the first 2 minutes of exercise Cori Cycle: How the body processes lactic acid/lactate Lactate in the muscle diffuses into the blood stream then travels to the liver Lactate in the liver goes through a series of enzymatic (cori cycle) steps and is converted to glucose that can reenter the blood stream or it is converted to glycogen and stored in the liver Oxidative System: Overview Occurs in the mitochondria; Substrates can be CHO or fats Three main processes: Glycolysis, Krebs cycle, Electron transport chain 1. 2 Pyruvic acids from glycolysis are converted to 2 acetyl CoA 2. Each acetyl CoA enters the Krebs cycle and produces ATP, carbon dioxide and hydrogen 3. Hydrogen in the cell combine with two coenzymes NAD and FAD that carry it to the ETC 5. ETC Hydrogen gradient produces ATP 7. ETC recombines hydrogen atoms with oxygen to produce water and prevent acidification of the muscle 8. ATP production results in 32/33 from glucose/glycogen or 100+ from FFA 9. ETC Products: ATP, CO , Wa2er Oxidative System: Krebs Cycle 2 Krebs cycles occur due to the 2 acetyl CoA produced Products (2 Krebs cycle):4 (3NAD 1FAD), 12 CO , 2 ATP 2 Oxidative System: Electron Transport Chain H are transported to the ETC via NAD and FAD + Every H that NAD drops off to the ETC results in 3 ATP but nets 2.5 ATP because it costs energy to transport H + + Every H that FAD drops off results in a net of 1.5 ATP At the end of the ELC H combines with oxygen to form water preventing acidification of the cell Net energy production is 33/34 ATP per molecule of glucose/glycogen Oxidative System: Fat Fat is stored as triglyceride and broken down into one molecule of glycerol and three molecules of FFA this process is known as lipolysis Lipases: Enzymes that break down triglycerides; Occurs in the fat cell Fat is stored within muscle fibers and in adipose tissue cells called adipocytes βoxidation: Process in which FFAs are converted into acetyl CoA; Requires 2 ATP for activation Every two carbons of the FFA are broken off to form acetyl CoA (16carbon FFA would form 8 acetyl CoA) + + Every bond broken in FFA releases 2 H (1NAD 1FAD) (16carbon FFA would release 14 H ) FFA requires more oxygen because FFA contains more carbon molecules than a glucose molecule Fats are heterogeneous, (every FFA molecule is different) the amount of ATP produced depends on the FFA oxidized Oxidative System: Protein Gluconeogenesis: Process of glucose being converted amino acids When amino acids are catabolized they release nitrogen which cannot be oxidized by the body Nitrogen can be used to form new amino acids or is converted to urea and excreted out of the body through urine This conversion requires the use of ATP Oxidative Capacity of Muscle Oxidative Capacity of Muscle: The maximal capacity of muscle to use oxygen Oxidative Capacity depends on: 1. Oxidative enzyme concentrations and activity 2. Fiber type composition 3. Oxygen availability Enzyme activity can be measured to determine the oxidative capacity of a muscle The most commonly measured enzymes are succinate dehydrogenase and citrate synthase The more oxidative enzyme activity a muscle has the greater its oxidative capacity Type I fibers have a greater capacity for aerobic activity because they have more mitochondria at greater concentrations than type II fibers The more type I fibers a muscle has the greater its oxidative capacity Type II fibers can be trained to have a greater oxidative capacity In response to exercise the body increases respiration, heart rate, force of heart beat, dilates arterioles, ect. this is all done to increase oxygen levels in the body The availability of oxygen is the number one determinate of the oxidative capacity of a muscle The human body stores little oxygen so the oxygen entering the blood is directly proportional to the amount of oxygen used by tissues for oxidative metabolism Enzymes Overview Myosin ATPase: Releases energy from ATP on the myosin head Creatine Kinase: Breaks apart PCr to form ATP in the phosphagen system Myokinase: Breaks apart one ADP to form ATP from another ADP in the phosphagen system Hexokinase: Breaks apart one ATP to form glucose6phosphate from blood glucose to begin glycolysis Phosphorylase: Converts muscle glycogen to glucose6phosphate to begin glycolysis Phosphofructokinase (PFK): Rate limiting enzyme of glycolysis; Uses one ATP to convert molecules early in the glycolysis process Succinate Dehydrogenase: Complex II in the ETC and the only enzyme that participates in the Krebs cycle and the ETC Citrate Synthase: Catalyzes the first reaction in the citric acid cycle; The condensation of acetylCoA and oxaloacetate to form citrate Chapter 5: Energy Expenditure and Fatigue Measuring Oxidative Capacity Direct Calorimetry: Measures the body’s heat production to calculate energy expenditure Indirect Calorimetry: Calculates energy expenditure from the respiratory exchange ratio (RER) of CO and O2 2 RER RER equation: VCO /VO 2 2 RER value at rest is 0.80 and the range is from 0.701.0 The closer your RER is to 0.70 the more your body is relying on fats for fuel; Closer to 1.0 means your body is relying on CHO for fuel CHO RER: C H O 6> 12 A6 + 6CO + 6H O 2 2 CHO Requires 9 O to fully catabolize the glucose molecule, we already have 3 O from the glucose molecule 2 2 therefore we need 6 O fr2m the environment We get 1.0 for CHO RER because we produce 6 CO2 and consume 6 O therefore 6 CO 26 O = 1.0 2 2 Fat RER: C H 16 32 120ATP + 16CO + 16H O 2 2 Requires 24 O t2 fully catabolize this FFA, we already have 1 O from th2 FFA molecule therefore we need 23 O 2 form the environment We get 0.70 for Fat RER because we produce 16 CO2 and consume 1 O therefore 16 C2 /23 O = 0.70 2 2 Protein is not considered because of its minimal influence Isotopes Isotopes: Radioactive molecules that can be tracked for long term measurements of daily metabolism Carbon 13 can be infused in the body and is selectively traced to determine its movement and distribution 2 Doubly Labeled Water: H (deuterium) is infused with water and ingested; The rate at which the substrate leaves the body is monitored and used to calculate how much energy is expended Measuring Energy Expenditure Metabolic Rate: Rate at which the body expends energy at rest and during exercise measured as wholebody oxygen consumption and its caloric equivalent (Means that it’s measured in kcals) Basal Metabolic Rate: Minimum energy required for essential physiological function; Measured in very controlled conditions Resting Metabolic Rate: Very similar to BMR except for the measurement conditions are not strictly controlled (Usually results in a higher measured expenditure than BMR) Total Daily Energy Expenditure: The energy required for normal daily activity Factors that affect BMR: 1. Increased fatfree mass (muscle) increased BMR 2. Increased body surface area increased BMR 3. Increase in age gradually decreases BMR 4. Increased body temperature increased BMR 5. Increased stress increased BMR 6. Increased levels of thyroxine and epinephrine (stress hormones) increased BMR Metabolic Rate During Submaximal Exercise Metabolism increases as exercise intensity increases Increase in power output increases VO 2 VO sresponse as high rates of work don’t follow the pattern of a steadystate of work Slow Component of Oxygen Uptake Kinetics: Power outputs above lactate threshold cause the oxygen consumption to increase beyond the typical 12 min needed to reach a steadystate value The mechanisms for this slow component is due to the alteration in muscle fiber recruitment for more type II muscle fibers which are less efficient with oxygen consumption VO 2Drift: Slow increase in VO du2ing prolonged submaximal constant power output exercise; Observed at power outputs below lactate threshold Maximal Capacity for Aerobic Exercise Maximal Oxygen Uptake (VO 2max: Maximal capacity for the oxygen consumption by the body during maximal exertion Best single measure of cardiorespiratory endurance VO 2max increases with 812 weeks of training and then plateaus even with continued training but athletes can develop the ability to perform at a higher percentage of their VO 2max VO 2max is expressed relative to body weight because energy requirements vary with body size As intensity increases some subjects can reach volitional fatigue (muscle fatigue) before plateau occurs in VO response 2 Peak Oxygen Uptake (VO 2peak: Highest oxygen uptake achieved during exercise when volitional fatigue is reached before the plateau of VO 2esponse Factors that Affect VO 2max 1. Age: 2530 years VO 2maxdecreases about 1% each year 2. Gender: Women have lower VO 2maxdue to higher body fat and lower blood hemoglobin content Anaerobic Effort and Exercise Capacity (Figure 5.5 pg129) Oxygen consumption is required for several minutes to reach fully functional aerobic processes and as a result the body experiences an oxygen deficit Oxygen Deficit: Occurs due to the difference in oxygen needs and supply during the transition from rest to exercise Excess Post Exercise Oxygen Consumption (EPOC): Volume of oxygen consumed during the minutes immediately after exercise ends that is above normal consumption at rest Factors causing EPOC to occur: 1. During the initial phase of exercise some oxygen is barrowed from oxygen stores and that must be replaced 2. Respiration post exercise remains temporarily elevated in an effort to clear CO tha2 has accumulated in body tissue 3. Body temperature elevating metabolic and respiratory rates which require more oxygen 4. Elevated concentrations of norepinephrine and epinephrine that require more oxygen 5. Replenishing ATP and PCr concentrations 6. Clearing lactate produced by anaerobic metabolism Lactate Threshold: The point at which blood lactate begins to substantially accumulate above resting concentrations during exercise of increasing intensity; Point during exercise when rate of lactate production exceeds the rate of lactate clearance Expressed as the percentage of maximal oxygen uptake %VO 2max Untrained adults have lactate threshold between 5060% VO 2max Elite endurance athletes have lactate threshold between 7080% VO 2max High VO and a high % VO are two major determinants of a successful endurance athlete 2max 2max The lactate threshold determines the fastest pace that can be tolerated during a longterm endurance event
Are you sure you want to buy this material for
You're already Subscribed!
Looks like you've already subscribed to StudySoup, you won't need to purchase another subscription to get this material. To access this material simply click 'View Full Document'