Effect of Exercise on Cardiovascular System PDF

Effect of Exercise on Cardiovascular System  Students, Learning Objectives: know the basic structure and function of the CVS. List Functions of the CVS during exercise. explain the responses and adaptation of CVS to exercises  Components of the Cardiovascular (C...

Effect of Exercise on Cardiovascular System  Students, Learning Objectives: know the basic structure and function of the CVS. List Functions of the CVS during exercise. explain the responses and adaptation of CVS to exercises  Components of the Cardiovascular (CVS) System: The CVS includes the heart and the vascular system THE HEART : The heart is a muscle that is required to contract continuously throughout the life to deliver oxygen to all organs in the body and breathe out carbon dioxide  Components of the heart Four chambers 2 atria 2 ventricles (left thicker than right) Major veins Superior vena cava Inferior vena cava Pulmonary veins  Major arteries Aorta Pulmonary trunk Valves permit the passage of blood in one direction. Tricuspid Atrioventricular Bicuspid mitral Semilunar Aortic Pulmonary  VASCULAR SYSTEM (BLOOD VESSELS ) Transports blood throughout the body, to and from the heart, via systemic circulation. Transports blood to and from pulmonary circulation. Different names for vessels: Arteries (arterioles) – Carries blood away from heart. Capillaries – gas exchange between tissue and blood. Veins (Venules) – Carries blood toward the heart.  The path of blood from the body to the heart and back out to the body Deoxygenated blood comes from the body to the inferior and superior vena cava. Blood enters right atrium, pressure increases and tricuspid valve opens. Deoxygenated blood enters right ventricle pressure increases and pulmonary valve opens Deoxygenated blood goes to the lungs via pulmonary artery where diffusion occurs in the capillary beds- CO2 and O2 exchange occurs. Oxygenated blood returns via pulmonary veins. Blood enters left atrium pressure increases and bicuspid valve opens. Blood flows into left ventricle pressure increases aortic valve opens. Oxygenated blood flows to the body via aortic arch.  Circulation of Blood: Pulmonary Circulation :deoxygenated blood is pumped from the right side of the heart through the pulmonary arteries to the lungs.Oxygenated blood is returned by the pulmonary veins. Pulmonary Circulation Systemic Circulation: oxygen rich blood is pumped from the left side of the heart through the aorta to the rest of the body.  Functions of The Cardiovascular System during exercise The cardiovascular system serves five important functions during exercise: 1. Delivers oxygen to working muscles 2. oxygenates blood by returning it to the lungs 3- Transports heat from the center to the skin 4. Delivers nutrients and fuel to active tissues 5. Transports hormones  Response and Adaptation of the CVS to Exercise: 1-Heart rate 2-Stroke volume 3-Cardiac output 4-Blood flow 5-Blood pressure 6-Blood  HEART RATE Resting heart rate (HR) averages 60 to 80 beats/min in healthy adults. Short term response :HR increase by the release of noradrenaline (sympathetic) causes increase in the force of contraction of the heart à increased stroke volume à increased ejection fraction.  Long term adaptation :- Heart rate decreases due to decrease in sympathetic tone. In elite endurance athletes heart rates as low as 28 to 40 beats/min. Anticipatory response (increased heart rate before exercise) Caused by the release of epinephrine. Before exercise even begins heart rate increases in anticipation (expectation). This is known as the anticipatory response. It is mediated through the releases of neurotransmitters epinephrine and norepinephrine also known as adrenaline and noradrenaline (adrenal gland).  Stroke volume (SV) Is the amount of blood ejected per beat from left ventricle and measured in ml/beat. Stroke volume increases proportionally with exercise intensity. In untrained individuals stroke volume at rest it averages 50 - 70 ml/beat during intense, physical activity stroke volume increasing up to 110 - 130 ml/beat In elite athletes resting stroke volume averages 90 - 110 ml/beat increasing to as much as 150 - 220ml/beat.  Cardiovascular Drift: an increase in heart rate during steady exercise due to a reduction in stroke volume. Caused by: Exercising in heat Rise in core temp. Decrease in plasma volume.  Ejection fraction: The percentage of blood ejected out of the ventricles during each contraction. – At rest, the ejection fraction is only about 50%. – During exercise, it can increase to 100%. – The ejection fraction at rest is low due to Q (Cardiac output) sufficiently supplying all the cell with oxygen. As the demand for oxygen increases during exercise, the ejection fraction increases to supply the demand of oxygen  Cardiac Output Cardiac output (Q) is the amount of blood pumped by the heart in 1 minute measured in L/min. It is a product of; stroke volume and heart rate (SV x HR). Resting Q: Q = HR x S = 70bpm x 70mL = 4.9 L/min  Cardiac Heart Rate Stroke Output Volume Untrained 5000 70 71 Trained 5000 50 100  Exercise Q Cardiac output provides most significant indicator of circulatory system functional capacity to meet demands for exercise. From rest to steady-rate exercise, Q increases rapidly, followed by gradual increase until its plateau’s. If either heart rate or stroke volume increase, or both, cardiac output increases also. Since Q=HR x SV, cardiac output increases from 4.2 L/min to 25 L/min. Cardiac Output remains relatively unchanged or decreases only slightly following endurance training. During maximal exercise on the other hand, cardiac output increases significantly. This is a result of an increase in maximal stoke volume  Ejection fraction The percentage of blood ejected out of the ventricles during each contraction. At rest, the ejection fraction is only about 50%. During exercise, it can increase to 100%. The ejection fraction at rest is low due to Q sufficiently supplying all the cells with oxygen. As the demand for oxygen increases during exercise, the ejection fraction increases to supply the demand of oxygen.  Blood flow The vascular system can redistribute blood to those tissues with the greatest immediate demand for energy such as muscles (Skeletal muscle receives a greater blood supply) Blood flow from heart increases in direct proportion to exercise intensity At rest 15 - 20% of circulating blood supplies skeletal muscle. During vigorous exercise this increases to 80 - 85% of cardiac output. The body will redirect blood away from the viscera (intestine, pancreas, etc.) and to the working muscles for oxygen delivery, supplying the demand. Body core temperature will also increase, resulting in further vasoconstriction and sphlanchic circulation, increasing blood flow to the skin for loss of heat via radiation  Distribution of Blood at rest and during exercise Distribution of Liver kidneys muscle Brain Heart Skin Blood Rest 1350 ml 1100 ml 1000 ml 700 ml 200 ml 300 Q = 5000 ml m Exercise 500 ml 250 ml 21000 ml 900 ml 1000 ml 600 Q = 25000 ml m  Blood Pressure At rest Atypical systolic blood pressure in a healthy individual ranges from 110 - 140mmHg and 60 - 90 mmHg for diastolic blood pressure. Blood Pressure Acute Response to Exercise: – Blood pressure will increase due to the cardiac output increasing substantially. – During exercise systolic pressure, the pressure during contraction of the heart (known as systole) can increase to over 200mmHg and in highly trained, healthy athletes. Dynamic Exercise: systolic pressure increases with intensity with relatively little change in diastolic pressure. Ex. Walking, jogging, swimming and cycling. – Static Exercise: heavy resistance training increases blood pressure both systolic and diastolic pressure due to muscular contractions compressing peripheral arteries. Ex. Isometric resisted exercise, isometrics. – Dynamic muscular exercise which works specially with arms causes a great increase in the blood pressure above the normal values. Such type of exercise should be avoided with cardiac patients.  Chronic adaptation of blood pressure to exercise Regular endurance training decreases systolic and diastolic pressure.  Blood Blood:transport vehicle for nutrients, hormones, waste products and electrolytes. From exercise point of view, the transportation, temperature regulation and the acid base balance is of prime importance functions of the blood.  55% of total blood volume is plasma, 45% is blood cells and platelets Blood cells include: – Erythrocytes: (RBC’s) Contain hemoglobin that binds to oxygen for transport to tissues. – Leukocytes: (WBC’s) defend the body against disease. – Platelets: (thrombocytes) play a role in the clotting of blood. Plasma: 90% water and 10% solutes – Metabolites and wastes (gases, hormones, vitamins) – Salts (ions) – Plasma proteins  Oxygen Transport in the Blood: Hemoglobin: (Hb) iron containing pigment that binds with oxygen to form oxyhemoglobin. Hb + 4 O2 = Hb4O8 Oxygen carrying capacity of the blood Energy production through Kerbs cycle or mitochondrial respiration depend on continuous supply of oxygen. Enhanced oxygen delivery and utilization during exercise will improve mitochondrial respiration and subsequently the capacity for endurance exercise.. Exercise places an increased demand on the cardiovascular system to pump more oxygen to supply the working muscle to produce energy (aerobic oxidation).. Oxygen demand by the muscles increases, more nutrients are needed and more waste is created.. A reduction in the oxygen carrying capacity in conditions such as anaemia produces fatigue and shortness of breath so affect performance.  A trained subject with greater volume of blood is able to meet the circulatory demands of the active muscles than untrained subjects. Increase in the plasma volume following endurance training increases blood volume, which in turn increase stroke volume and cardiac output with increased availability of oxygen to the active tissue so increasing VO2 max.  On the contrary, when a trained subject stops training (detraining occurs), there is a reduction in the plasma volume which would decrease the VO2max. During strenuous exercise in a hot climate, the sweating rate is from 1 to less than 2 liters per hour. This increased sweating may reduce the total blood volume (haemoconcentration) by 3% or more.  Electrolytes Electrolytes are important because they are what your cells (especially nerve, heart, muscle)use to maintain voltages across their cell membranes and to carry electrical impulses(nerve impulses, muscle contractions) across themselves and to other cells. The kidneys work to keep the electrolyte concentrations in your blood constant despite changes in the body.  When performing exercise heavily or exercise at hot weather, we lose electrolytes in the sweat, particularly sodium and potassium. These electrolytes must be replaced to keep the electrolyte concentrations of your body fluids constant. So,avoid exercising at hot weather and also many sports are encouraged to drink drinks have sodium chloride or potassium chloride added to them.  Summary of Cardiovascular Adaptations to Exercise: Lower resting heart rate. Increased left ventricular volume. Increased stroke vol. and cardiac output. Capillarization: increase in capillary surface area in muscles. Greater arteri-ovenous oxygen diff. (a - vO2)  Benefits of Cardio. Fitness – Improved fat metabolism – Efficient delivery of oxygen – Faster removal of wastes – Decreased levels of stress  Monitoring Exercise Intensity Resting Heart Rate (RHR) Lowest HR, least amount blood required. Between 60 – 100 bpm. Target Heart Rate (THR): HR your are trying to reach for a specific goal. Maximum Heart Rate (MHR): maximum heart rate that you can attain. Based on your genetics, should not train at this rate. MHR =220-age Purpose: used to create target training zones to help improve your cardiovascular capacity and progress the intensity of your workouts  Heart Rate Training Zones: are calculated by taking into consideration your max. heart rate and your resting heart rate.  Training Zones – Warm up zone 50 - 60% of MHR – Fitness zone (fat burning) 60 - 70% of MHR – Aerobic zone 70 - 80 % of MHR – Anaerobic zone 80 - 90% of MHR  Thank You