Exercise and CVD


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Exercise and CVD

  1. 1. Protective Effects of Exercise <ul><li>Being physically fit reduces the risk of cardiovascular disease, with people who do not exercise being TWICE as likely to develop heart disease </li></ul><ul><li>Exercise is thought to decrease the many of the risk factors for CHD by: </li></ul><ul><ul><ul><li>strengthens the heart muscle (myocardium) so that it can pump more blood with each beat therefore improving efficiency of the heart </li></ul></ul></ul><ul><ul><ul><li>lowering resting heart rate </li></ul></ul></ul><ul><ul><ul><li>improves blood lipid profile by decreasing LDL and increasing HDL levels </li></ul></ul></ul><ul><ul><ul><li>lowers blood pressure by maintaining the elasticity of the arteries </li></ul></ul></ul><ul><ul><ul><li>helps weight loss by decreasing % body fat </li></ul></ul></ul><ul><ul><ul><li>decreasing development of atheroma </li></ul></ul></ul><ul><ul><ul><li>controlling stress </li></ul></ul></ul><ul><li>Even a small amount of moderate exercise, such as walking, can improve the quality of life and increase life expectancy </li></ul>
  2. 2. How does the CVS respond to exercise? <ul><li>During exercise the CVS must INCREASE delivery of O 2 and nutrients to the exercising muscle and remove waste effectively </li></ul><ul><li>This is done by: </li></ul><ul><ul><li>INCREASING Cardiac Output </li></ul></ul><ul><ul><li>REDISTRIBUTING Blood Circulation </li></ul></ul>
  3. 3. Increasing Cardiac Output <ul><li>During exercise SYSTOLIC BP can increase from 120 to 200 mm Hg, showing that the walls of the ventricles are working much harder; diastolic pressure remains fairly constant </li></ul><ul><li>As a result the volume of blood pushed out of the heart with every beat ( STROKE VOLUME ) INCREASES </li></ul><ul><li>Since HEART RATE and STROKE VOLUME both increase during exercise, it follows that cardiac output is also greatly increased </li></ul><ul><li>CO = HR x SV </li></ul>
  4. 4. Redistribution of Blood <ul><li>During exercise muscles need more blood to receive more O 2 and glucose </li></ul><ul><li>There is only a finite volume of blood in the body, so if some tissues receive an increased blood supply it follows that others must receive a decreased blood supply during exercise </li></ul><ul><li>This change in distribution of blood is brought about by the widening of arterioles ( VASODILATION ) increasing the blood supply to the active tissues and the narrowing of arterioles ( VASOCONSTRICTION ) decreasing the supply to those tissues which are not actively involved in exercise </li></ul>
  5. 5. The brain requires a constant supply of glucose and oxygen. It could not survive for long with a smaller blood supply. Therefore during exercise its blood supply must be maintained The abdominal organs can survive with a smaller blood supply during exercise As muscles work harder during exercise heat is produced. Increasing blood flow to the skin means that this heat can be lost to the air thus cooling the body down
  6. 6. The ‘Athletic Heart’ <ul><li>Athletes are people who are fitter than most people because they undergo a regime of training - involves exercising at more extreme levels and for greater periods of time than most people can maintain </li></ul><ul><li>Athletic heart syndrome refers to the normal changes that the heart undergoes in very well conditioned athletes: </li></ul><ul><ul><ul><li>heart is LARGER and its VENTRICLE WALLS THICKER than in nonathletes [CARDIAC HYPERTROPHY] </li></ul></ul></ul><ul><ul><ul><li>The chambers inside the heart enlarge </li></ul></ul></ul><ul><li>This is due to an increase in protein synthesis in the muscle fibres of the heart and thus allows the heart increase its stroke volume without much increase in heart rate </li></ul><ul><li>When an athlete stops training, the athletic heart syndrome slowly disappears — that is, heart size and heart rate tend to return gradually to that of the nonathlete </li></ul>
  7. 7. Principles of Exercise Testing <ul><li>There are many reasons why it may be necessary to assess the physiological fitness of a person </li></ul><ul><ul><li>Monitor effectiveness of exercise program </li></ul></ul><ul><ul><li>Rehabilitation of cardiac patients </li></ul></ul><ul><li>Testing can be MAXIMAL or SUB-MAXIMAL </li></ul>Measures the MAXIMUM RATE at which the body is able to take up and use OXYGEN [V O2 max] The greater the V O2 max the fitter the individual A less extreme form of testing to predict V O2 max Relies on two assumptions: 1) that there is a linear correlation between V O2 max, heart rate and intensity of exercise, and 2) individual's maximum heart rate = 220 - age Individual's pulse rate and oxygen uptake are measured at various levels of activity. These results are used to construct a graph of pulse rate against oxygen uptake. A straight line is drawn through the points on the graph and extrapolated to the maximum heart rate to predict V O2 max
  8. 8. Disadvantages of Testing
  9. 9. <ul><li>A STRESS TEST (or exercise ECG test) records an individual's ECG traces before, during and after exercise e.g. walking on treadmill, pedalling on stationary bike </li></ul><ul><li>The exercise is gradually increased in intensity until the individual is too tired to go on or until symptoms such as chest pain or breathlessness are felt </li></ul><ul><li>The results are used to establish exercise limits and to develop a fitness programme for the rehabilitation of cardiac patients [no longer bed rest!] </li></ul><ul><li>The stress test is repeated periodically to monitor the individual's progress </li></ul><ul><li>A programme of medically supervised exercise leads to better recovery and survival rates </li></ul>Exercise Stress Testing
  10. 10. Summary of a few of the many benefits of Exercise …! <ul><li>makes the heart stronger and the lungs fitter, increasing STROKE VOLUME and VO 2 MAX </li></ul><ul><li>lowers BLOOD PRESSURE </li></ul><ul><li>reduces the levels of total LDL CHOLESTEROL which in turn reduces the risk of HEART ATTACK, STROKE , and CORONARY ARTERY DISEASE . Other conditions that are less likely to occur with regular exercise include COLON CANCER and some forms of DIABETES </li></ul><ul><li>makes muscles STRONGER , allowing people to perform tasks that they otherwise might not be able to do. Most everyday tasks require muscle strength and good range of motion in joints, and regular exercise can improve both </li></ul><ul><li>STRETCHES MUSCLES and JOINTS , which in turn can increase FLEXIBILITY and help PREVENT INJURIES </li></ul><ul><li>Weight-bearing exercise STRENGTHENS BONES and helps PREVENT OSTEOPOROSIS . </li></ul><ul><li>can IMPROVE FUNCTION and REDUCE PAIN in people with OSTEOARTHRITIS </li></ul><ul><li>increases the body's level of ENDORPHINS therefore helps improve mood and energy levels and may even help alleviate depression. </li></ul><ul><li>helps BOOST SELF - ESTEEM by improving a person's overall HEALTH and APPEARANCE </li></ul><ul><li>helps older people remain INDEPENDENT by improving functional ability and by PREVENTING FALLS AND FRACTURES </li></ul><ul><li>Increases APPETITE , reduces CONSTIPATION , and promotes SLEEP … </li></ul>… SO GET MOVING !
  11. 11. WARNING !!! <ul><li>The benefits of exercise diminish within months after a person stops exercising </li></ul><ul><li>Heart strength, muscle strength, and the level of high-density lipoprotein (HDL) cholesterol (the good cholesterol) decrease , whereas blood pressure and body fat increase </li></ul><ul><li>Even former athletes who stop exercising do not retain measurable long-term benefits. They have no greater capacity to perform physical activities and no fewer risk factors for heart attacks those who have never exercised, nor do they regain fitness any faster! </li></ul>