KIN 292 1st Edition Exam 2 Study Guide Chapter 4 Exercise Metabolism I Rest to exercise transitions a Steady state i Oxygen consumption increases rapidly and reaches a steady state within 1 4 minutes ii Onset of ATP PC system is the first active bioenergetics pathway 1 Then glycolysis 2 Then aerobic energy production oxidative phosphorylation iii Any time steady state is reached oxidative phosphorylation is primary energy system iv Energy needed for exercise is achieved by overlapping of energy system operations b Oxygen deficit i Lag in oxygen uptake at beginning of exercise ii Difference between oxygen uptake in first few minutes of exercise and equal time period after steady state has been obtained iii Figure 4 2 iv Ask The Expert 4 1 II Recovery from Exercise Metabolic Responses a Oxygen debt i Elevated oxygen uptake above resting levels following exercise ii Two portions 1 Rapid a Immediately following exercise b 2 3minutes 2 Slow a Persists for 30 minutes iii Debate on term name 1 Elevated oxygen consumption not entirely due to borrowing oxygen from body s oxygen stores b EPOC i Excess post exercise oxygen consumption ii Part of oxygen consumed immediately following exercise is used to restore PC in muscle and oxygen stores in blood and tissues 1 Occurs within 2 3 minutes post exercise iii Heart rate and breathing remain elevated above resting levels for several minutes following exercise 1 Require additional oxygen above resting levels 2 Every liter of oxygen consumed expends 5 calories iv Elevated body temperature 1 Increased metabolic rate v Specific circulating hormones 1 High levels of epinephrine and norepinephrine increase oxygen consumption vi EPOC greater following high intensity exercise when compared to low to moderate intensity exercise 1 Due to a Differences in amount of body heat obtained b Total PC depleted c Higher lactate levels d Elevated blood levels of epinephrine and norepinephrine III Metabolic Responses to Exercise Influence of Duration and Intensity a Incremental exercise i VO2 Max 1 Maximal oxygen uptake 2 Maximal capacity to transport and utilize oxygen during exercise 3 Most valid measure of cardiovascular fitness ii Physiological factors affecting VO2 Max 1 Maximum ability of cardiorespiratory system to deliver oxygen to contracting muscles a Central component 2 Muscles ability to take up the oxygen and produce ATP aerobically a Central component 3 Genetics a Peripheral component 4 Exercise training a Peripheral component iii Lactate threshold 1 As exercise intensity increases blood levels of lactate begin to rise exponentially 2 Considered lactate threshold a Used to be termed anaerobic threshold 3 Due to a Lack of oxygen hypoxia in working muscle b Increased anaerobic metabolism within contracting muscle because of low levels of oxygen in individual cells 4 Determining pyruvate or lactate formation a Rate of glycolysis i Rapid lactate b Type pf LDH present i Fast fibers forming lactate ii As exercise intensity increases muscle force must be increased by recruiting more fast fibers c Rate of lactate removed from blood during incremental exercise d Can occur due to increase in lactate production or decrease in lactate removal IV Estimation of Fuel Utilization During Exercise a Respiratory exchange ratio i Ratio of carbon dioxide output VCO2 to volume of oxygen consumed VO2 ii VCO2 VO2 R V Factors Governing Fuel Selection a Exercise intensity and fuel selection i Fats are primary fuel source for muscle during low intensity exercise 1 30 VO2 Max ii Carbohydrate is dominant substrate during high intensity exercise 1 70 VO2 Max iii Crossover Point 1 As intensity increases a point is reached where energy derived from carbohydrates exceeds that from fats 2 Progressive shift occurs form fat to carbohydrate metabolism iv Shift occurs because 1 Recruitment of fast fibers a Fast fibers better able to metabolize carbohydrates 2 Increasing blood levels of epinephrine b Exercise Duration and Fuel Selection i During prolonged moderate intensity exercise 40 59 VO2 Max gradual shift from carbohydrate metabolism to increasing reliance on fat as substrate c Interaction of Fat Carbohydrate Metabolism i During prolonged exercise greater than two hours muscle and liver stores of glycogen can reach very low levels 1 Depletion of muscle and blood carbohydrate stores results in muscular fatigue Chapter 9 Circulatory Responses to Exercise I Structure of Heart figure 9 1 a Right Atrium b Right AV tricuspid valve c Right Ventricle d Endocardium e Pulmonary semilunar valve f Pericardium g Epicardium h Myocardium i Left Ventricle j Aortic semilunar valve k Left bicuspid AV valve l Left Atrium II Heart Myocardium and Cardiac Cycle a Myocardium i Heart muscle ii Responsible for contracting and forcing blood out of heart iii Fibers 1 Shorter than skeletal muscle 2 Connected in tight series 3 Typically branched 4 Contraction is involuntary 5 Interconnected via intercalated disks a Permit the transmission of electrical impulses from one fiber to another b Functional syncytium i When one fiber is depolarized to contract all connecting heart fibers become excited and contract as unit 6 Cannot be divided into different fiber types b Cardiac Cycle i Repeating pattern of contraction and relaxation in heart ii Systole 1 Contraction phase 2 Blood ejected form heart iii Diastole 1 Relaxation period 2 Heart fills with blood c Arteriole Blood Pressure i Systolic Blood Pressure 1 Pressure generated as blood is ejected from heart during ventricle systole 2 Higher number in blood pressure reading 3 120 good pressure number 4 Over 140 is hypertension a High blood pressure ii Diastolic Blood Pressure 1 Pressure decrease during ventricle relaxation 2 Lower number on blood pressure reading 3 80 good pressure number 4 Over 90 is hypertension a High blood pressure d Factors That Influence Arterial Blood Pressure i Mean arterial blood pressure cardiac output total vascular resistance ii Determined by two factors 1 Cardiac output CO 2 Total vascular resistance TVR iii Figure 9 8 e Electrical Activity of the Heart i Sinoatrial node SA Node 1 Pacemaker of heart 2 When Sa Node reaches depolarization threshold and fires wave of depolarization spreads over the atria resulting in atrial contraction ii Atrioventricular node AV Node 1 Connects atria with the ventricles by a pair of conductive pathways a Right and left bundle branches iii Electrocardiogram ECG or EKG 1 Recording of the electrical changes