part 7 Cardiorespiratory responses

part 7 Cardiorespiratory responses - Lecture 7:...

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Lecture 7: Cardiorespiratory Responses to Exercise How are the following factors affected by exercise? Heart rate (HR) Stroke volume (SV) Cardiac output (Q) Blood pressure (BP) Blood flow Blood /plasma volume What happens to stroke volume and heart rate during cardiovascular drift? Why is a fraction of the cardiac output directed toward the skin? How does temperature affect cardiovascular drift? (continued) Lecture 7: Cardiorespiratory Responses to Exercise What are the cardiovascular adjustments to acute exercise? How does the cardiovascular system respond to increased demands during exercise? How does the respiratory system function during exercise and how can it limit physical performance? How does the respiratory system maintain acid–base balance? Why is the acid–base balance important during exercise? (continued) Cardiovascular Response to Acute Exercise The components of the cardiovascular system must meet the increased demands for blood flow to the exercising muscle Heart rate (HR) Stroke volume (SV) Cardiac output (Q) Blood pressure (BP) Blood flow Blood .
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Resting Heart Rate Averages 60 to 80 beats per minute (bpm) Highly trained athletes: 28-40 bpm (increased vagal tone) RHR is affected by environmental factors (extreme temperatures and altitude) Preexercise heart rate is usually higher than RHR because of an anticipatory increase in sympathetic activity Heart Rate During Exercise HR increases in direct proportion to the increase in exercise intensity HR will plateau at a maximum even as workload continues to increase (HR max ) HR max remains constant day to day and declines ~1 beat per year HR max can be estimated: HR max = 220 – age in years HR max = 208 – (0.7 x age in years) Heart Rate vs. Relative Workload HR increases in direct proportion to the increase in exercise intensity HR will plateau at a maximum even as workload continues to increase (HR max )
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SV is the major determinant of cardiorespiratory endurance capacity Four factors that determine SV: 1. The volume of venous blood returned to the heart (preload) 2. Ventricular distensibility 3. Ventricular contractility 4. Aortic or pulmonary artery pressure (afterload) Stroke Volume Increases With Exercise SV increases with increases in work rate SV usually plateaus at ~40-60% of VO 2max SV is influenced by body position due to postural differences in venous return to the heart . Stroke Volume (SV) vs. Relative Workload
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part 7 Cardiorespiratory responses - Lecture 7:...

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