normal acute responses

normal acute responses - Basic Anatomy - Heart Normal...

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Unformatted text preview: Basic Anatomy - Heart Normal Cardiorespiratory Responses to Exercise KINE 5335 Coronary Arteries Muscle Muscle Myocardium Myocardium Protective Covering Protective Covering Pericardium Pericardium Epicardium Epicardium Endocardium Endocardium Circulatory Circulatory System In one cardiac cycle… from Brubaker, 2002 ACSM Resource Manual, 2001 1 Review - The Fick Equation Basic Principles in Exercise Physiology 1. Fick Principle (Total body oxygen consumption) Q= Total Total Body demand VO VO2 = Cardiac Output (Q) X a-v O2 difference Ou (Q) VO2 a-vO2 difference OR 2. Myocardial oxygen consumption “Heart” “Heart” demand (mVO (mVO2) = heart rate (HR) X systolic BP VO2 (L O2•min -1) = Q (L blood • min -1) X a-vO2 diff (mL O2 • L -1 blood) VO2 (L O2•min -1) = (HR x SV) X a-vO2 diff (mL O2 • L -1 blood) VO2 (L O2•min -1) = (HR x SV) X ( ? X ? ) Rest and Exercise Q (typical) Rest Rest Q = SV x HR SV = 0.07 L•beat -1 X 60 bts•min -1 0.07 L•beat = 4.2 L•min -1 4.2 Exercise Exercise Q = SV x HR SV = 0.16 L•beat -1 X 190 bts•min -1 0.16 L•beat bts•min = 30.4 L•min -1 30.4 Froelicher and Myers, 2000 2 Heart Rate (control of) Autonomic Autonomic nervous system (ANS) Sympathetic Sympathetic (SNS) (“cardioaccelerator nerves”) Adrenergic (general) norepinephrine Adrenergic (general), norepinephrine, epinephrine Parasympathetic(PNS) Parasympathetic(PNS) Acetycholine Acetycholine (muscarinic) Exercise? Exercise? Opie, 1998 HR response to dynamic exercise ANS ANS influence Predominant PNS withdrawal 60 80 100 SNS increases influence 120 140 160 180 200 HR (bts/min) 3 SV response to dynamic exercise Stroke Volume (SV) EDV Stroke Stroke volume = end-diastolic volume end(EDV) - end-systolic volume (ESV) endEjection Ejection fraction (EF)- percentage of EDV (EF)blood blood ejected with each beat = EDV - ESV EDV X 100 EDV = stroke volume X 100 stroke EDV - ESV = SV Rest (ejection fraction = 50%) 70 ml 120 ml ml 50 ml ml Peak Exercise (ejection fraction = 75%) 90 ml 120 ml 30 ml LVEDV (ml) Fox, ‘98 70 60 50 40 30 20 10 SV (ml) LVEDV = left ventricular end-diastolic volume LVESV = left ventricular end-diastolic volume SV = stroke volume 200 180 160 140 120 100 80 LVESV (ml) Fox, ‘98 Athletes Factors Affecting EDV 1. Heart rate (chronotropic) Heart Sedentary Athletes Sedentary 160 140 120 100 80 60 40 Athletes Sedentary Rest 110 130 Heart rate (bts/min) 150 2. Ventricular Compliance - stretch placed on the heart just before contraction (Starlings Law) 3. Filling Pressure (inotropic effect) Filling FrankFrank-Starling mechanism (length-tension (lengthrelationship) relationship) – venous pressure is a result of venous return (amount of blood returning to the heart) Venous Venous return (preload) is affected by Skeletal Skeletal muscle pump Respiratory Respiratory and abdominal pumps Venoconstriction Venoconstriction (body position) 4 Factors affecting ESV SV and Cardiovascular Disease Ventricular Performance 1. Inotropic effect - refers to the contractility of the Inotropic contractility heart (force of contraction of LV) During During exercise the Frank-Starling curve will shift upward and to Frankthe left due to an increase in circulating NE causing contractility to increase SV and Cardiovascular Disease SV Di 2. Afterload – measure of the force resisting the ejection of blood by the heart Example: Example: hypertension Increased Contractility Normal Heart Disease End-diastolic Volume from Brubaker, 2002, pg 43 Factors affecting ESV Plasma epinephrine Activity of parasympathetic Nerves to myocardium stroke volume heart rate = stroke volume 30 T 25 25 20 x heart rate From Vander et al. Human Physiology. 7th ed, 1998 150 UT 100 100 0 0 Rest 15 10 10 5 Rest Max/Pk Exercise Intensity 200 200 UT 15 200 T 150 20 5 Cardiac output Cardiac output 30 Max/Pk Exercise Intensity Heart Rate (bt•min-1) Sympathetic activity of Nerves to myocardium Cardiac Output (l•min-1) REST (start) End-diastolic Ventricular volume Stroke Volume (ml•bt-1) 200 Cardiovascular Responses to Exercise 150 UT T 150 100 100 0 0 Rest Max/Pk Exercise Intensity (Fox, ‘98) 5 Peripheral Factors ArterialArterial-venous oxygen difference (a-vO2 diff) (a diff) Diff. Diff. in oxygen content between arteries (18 to 20 ml O2/ 100 ml blood, rest) and veins (13 to 15 mlO2/100 ml blood) rest = 4 -5 mlO2/100 ml blood Exercise aExercise a-vO2 diff = 16 to 18 ml O2/ 100 ml blood Arterial Arterial O2 content Related Related to partial pressure of O2 Alveolar Alveolar ventilation Hemoglobin Hemoglobin Venous Venous O2 content Ability Ability of muscle to extract O2 from blood (capillary density) Determined Determined by regional blood flow Froelicher and Myers, 2000 Pulmonary System - Ventilation VE = Minute Ventilation (L•min-1) VT = tidal volume (L) x x Ventilatory Responses to Exercise f respiratory frequency (breaths / min) Air Air moving into and out of the lungs is measured in liters per minute (volume x frequency), called minute ventilation, VE ventilation Rest: Rest: VE = 8 to 12 L/min to Peak Peak exercise: VE ~ 150 L/min (highly fit) (highly Determined Determined by: Gas Gas exchange in the lungs Ventilatory Ventilatory requirements for exercise ACSM Resource Manual, 2001 6 Minute Ventilation = VT = tidal volume (L•min-1) VE (L•min-1, STPD) Increase Increase in maximal minute ventilation (VE ) Increase Increase TV and f Increase Increase in ventilatory efficiency through a decrease in ventilatory equivalent for oxygen Increased Increased diffusion capacity during exercise VE Minute Ventilation 180 160 140 120 100 80 60 40 20 5 180 160 140 120 100 80 60 40 20 5 untrained trained REST f respiratory frequency (breaths / min) untrained trained REST MAX VO2 (L•min-1, STPD) How do O2 and CO2 move in and out of the tissues between the air and the blood (extraction)? x x (L) VE (L•min-1, STPD) Respiratory responses to exercise (training) MAX VCO2 (L•min-1, STPD) Blood flow distribution during exercise Diffusion of a gas across tissues is dependent upon the area and thickness of the tissue, diffusability of the gas, and the difference in P between 2 tissues. Cardiac Output = 25 l/min Heavy Exercise 100% 3-5% 2-4% 3-4% 80-85% Rest 100% 20-25% 20% 15% 15-20% Cardiac Output = 5 l/min From Powers and Howley, Exercise Physiology.p 186 7 Hemodynamics Change in BP and TPR during exercise Blood pressure (mmHg) 200 150 15 100 2. Total peripheral resistance TPR = MAP/ Q Diastolic BP 50 0 MAP - mean arterial pressure TPR - total peripheral resistance Rest Pk Ex 10 5 0 Rest Pk Ex Fox. Physiological Basis for Exercise and Sport, 98 Bottom Line: Components of oxygen transport system at rest and during exercise in untrained and in trained = Stroke volume X Heart rate X a-vO2 diff VO2 (mL•min-1) 20 Systolic BP TPResistance (mmHg•L •min-1) 1. Blood pressure MAP = Q x TPR Or MAP = .3(DBP – SBP) + DBP (L•bt-1) UT Rest 300 = 0.075 MaxEx 3100 = 0.112 3100 Endurance Athletes MaxEx 5570 = 0.189 (bt•min-1) X X 82 200 (mlO2•L-1) X X 48.8 138.0 Focus on the cardiovascular system Myocardial Myocardial oxygen consumption (mVO2) Also Also called Rate-Pressure Product (RPP)– Rate(RPP)– Estimated Estimated by the following calculation: RPP = HR (bts•min-1) X SBP (mmHg) (bts• SBP (mmHg) X 190 X 155.0 100 Important when exercise testing those with history of CVD (specifically angina, hypertension) Fox. Physiological Basis for Exercise and Sport, 98 8 Exercise Responses: RPP Those Those who are of a high fitness level will have lower RPP for any given submaximal compared VO2 compared to sedentary Those with cardiovascular disease could Those with cardiovascular disease could have have higher, lower, or the same RPP for any given submax workload compared to healthy counterparts Goal Goal in clinical populations is to push the RPP up as high as possible (safe levels) without inducing signs or symptoms of CVD RPP: Hemodynamic Responses to Exercise Variable Q HR SV TPR SBP DBP MAP LV Work Dynamic Static ++++ + ++ + ++ 0 +++ +++ ++++ 0++++ 0++++ Volume Load Pressure Load ACSM, Resource Manual. P 143, 1998 RPP: Arm Vs. Leg Exercise HR x SBP/100 260 220 arm 180 140 leg 100 0 0 50 150 300 450 Workload (kgm/min) 600 9 ...
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This note was uploaded on 01/16/2012 for the course KINE 430 taught by Professor Dr.jenniferblevins-mcnaughton during the Fall '11 term at Tarleton.

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