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Exercise Physiology

Exercise Physiology

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Exercise Physiology

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  1. Exercise Physiology J.M. Cairo, Ph.D. LSU Health Sciences Center New Orleans, Louisiana jcairo@lsuhsc.edu

  2. Somatic Factors Sex and Age Body Dimension Health Training Adaptation Psychic Factors Attitude Motivation • Bioenergetics • Storage Fuels • Fuel Intake • Oxygen Uptake • Cardiac Output • Heart Rate • Stroke Volume • (A-V)O2 Difference • Pulmonary Ventilation Environment Temperature Altitude Inhaled Gases Nature of Work Intensity Duration Rhythm Technique Position Energy Yielding Processes From Astrand and Rodahl, Textbook of Work Physiology, New York McGraw-Hill, 1972 Physical Performance Capacity

  3. From Richardson, DR, Randall, DC, Speck, DF: Cardiopulmonary System. Madison, CT, Fence Creek, 1998

  4. From Wasserman, K., Hansen, J.E., Sue, D.Y., Casaburi, R, and Whipp, B.J.: Principles of Exercise Testing and Interpretation, 3rd Edition. Philadelphia, Lippincott Williams and Wilkins, 1999.

  5. The Fick Principle VO2 = Q x (CaO2 - CvO2)

  6. RESTING CONDITIONS FOR A TYPICAL HEALTHY ADULT VO2 = 250 ml/min Q = 5 L/min CaO2 = 200 ml/L of whole blood CvO2 = 150 ml/L of whole blood CaO2-CvO2 = 50 ml/L of whole blood

  7. MAXIMUM EXERCISE RESPONSE FOR A WORLD CLASS ATHLETE VO2 = 5000 ml/min Q = 25 L/min CaO2 = 200 ml/L of whole blood CvO2 = 20 ml/L of whole blood CaO2-CvO2 = 180 ml/L of whole blood

  8. Cardiac Output + + Heart Rate Stroke Volume + + Preload Contractility - Afterload

  9. HRMAX = 220 - age (yrs)

  10. PRELOAD Volume of blood in the ventricle at the end of diastole LVEDV Venous Return

  11. Frank-Starling Mechanism Stroke Volume LVEDV

  12. PRELOAD Volume of blood in the ventricle at the end of diastole LVEDV Venous Return Skeletal Muscle Pump Venous Tone Thoraco-abdominal Pump

  13. Contractility Stroke Volume LVEDV

  14. Factors influencing the Pulmonary Response to Exercise • Ventilation • Diffusion of Oxygen and Carbon Dioxide Across the Alveolar-Capillary Membrane • Perfusion • Ventilation/Perfusion • O2 and CO2 Transport • O2 uptake by the tissues

  15. Control of Breathing During Exercise • Immediate Response • Neural Component • Central Command • Learned Response • Direct Connection from Motor Cortex • Coordination in Hypothalamus • Proprioceptors or Mechanoreceptors From Levitzky, MG: Pulmonary Physiology, 5th Edition. New York, McGraw-Hill, 1999

  16. Response to Moderate Exercise Arterial Chemoreceptors Metaboreceptors Nociceptors Cardiac Receptors Venous Chemoreceptors Temperature Receptors Response to Severe Exercise Arterial Chemoreceptors Central Chemoreceptors Control of Breathing During Exercise

  17. Factors Influencing the Maintenance of the Arterial Oxygen Content (CaO2) • Increase in Alveolar Ventilation • Decrease in VD/VT • Increased Perfusion of the Lungs • Decrease in Pulmonary Vascular Resistance • Recruitment and Distension of Pulmonary Capillaries • Improvement in VA/QC • Increased Diffusion of O2 and CO2 across the Alveolar-Capillary Membrane

  18. Effective Ventilation – VD/VT 0.40 VD/VT 0.25 Rest Max

  19. Factors Influencing Unloading/Uptake of Oxygen at the Tissues (CvO2) • Shifting of the Oxyhemoglobin Dissociation Curve to the Right • Increase in Core Temperature • Increase in CO2 Production • Increase in H+

  20. MAXIMUM EXERCISE RESPONSE FOR A WORLD CLASS ATHLETE VO2 = 5000 ml/min Q = 25 L/min CaO2 = 200 ml/L of whole blood CvO2 = 20 ml/L of whole blood CaO2-CvO2 = 180 ml/L of whole blood

  21. MAXIMUM EXERCISE RESULTS FOR A TYPICAL HEALTHY ADULT VO2 = 2500 ml/min Q = 15 L/min CaO2 = 200 ml/L of whole blood CvO2 = 33 ml/L of whole blood CaO2-CvO2 = 167 ml/L whole blood

  22. Principles of Physical Training • Overload • Specificity • Reversibility

  23. Training for Improved Aerobic Endurance • Type of Exercise • Intensity • Duration • Frequency

  24. Anaerobic Threshold • The anaerobic threshold is defined as the level of exercise VO2 above which aerobic energy is supplemented by anaerobic mechanisms and is reflected by an increase in lactate and lactate/pyruvate ratio in skeletal muscle and arterial blood. • See Wasserman, K., Hansen, J.E., Sue, D.Y., Casaburi, R, and Whipp, B.J.: Principles of ExerciseTesting and Interpretation, 3rd Edition. Philadelphia, Lippincott Williams and Wilkins, 1999.

  25. Karvonen Formula for Prescribing Exercise Heart Rate HREx = HRRest + 0.60 (HRMax – HRRest)

  26. Detraining and VO2MAX • Decreased maximum attainable cardiac output and arteriovenous O2 difference • Initial (12-14 days) • Decrease due to decreased stroke volume • Decreased plasma volume • Prolonged (3 weeks – 12 weeks) • Attenuation of arteriovenous O2 difference changes • Decreased muscle mitochondrial density

  27. Effects of Endurance Training on Skeletal Muscle Morphology • Capillary Density • Myoglobin • Mitochondria

  28. Effects of Endurance Training on Skeletal Muscle Metabolism • Mobilization of FFA • Transport of FFA from Cytoplasm to the Mitochondria • Mitochondrial Oxidation of FFA • Beta-oxidation • Lactate Removal