CVS and aerobic exercise Flashcards
How do cardiac output, HR, and systolic blood pressure (SBP) change with work rate during exercise?
Linear Increase: Cardiac output, HR, and SBP increase linearly with work rate.
Mechanism: This is due to the decreased parasympathetic (PNS) activity and increased sympathetic (SNS) activity, allowing the heart to pump more effectively and efficiently as exercise intensity rises.
SNS releases norepinephrine and blood vessel consticts
What happens to cardiac output at maximal aerobic exercise (VO2MAX)?
Maximal Cardiac Output: At VO2MAX, cardiac output is maximized due to both HR and stroke volume reaching their peak levels.
Significance: This ensures maximum delivery of oxygen and nutrients to the working muscles, facilitating sustained aerobic performance.
How does total peripheral resistance (TPR) change with work rate during exercise?:
Linear Decrease: TPR decreases linearly with work rate.
Reason: Peripheral vasodilation occurs in the vascular beds of working muscles
Peripheral vasodilation is the widening of blood vessels, specifically in the skeletal muscles that are actively working. This increases blood flow to those muscles, ensuring they receive enough oxygen and nutrients.
Although blood pressure increases during exercise due to an increase in cardiac output (heart rate and stroke volume), the overall TPR decreases because the vasodilation in the active muscles is greater than the vasoconstriction in non-essential areas.
==> there is vasoconstriction in less active areas (like the gut and kidneys) to help maintain blood pressure and direct more blood to the muscles that need it.
How is VO2 affected by increased work rates?
Increased VO2: Oxygen consumption increases with higher work rates due to greater oxygen extraction by working muscles.
Supportive Changes: This is supported by increased minute volume (more breaths per minute and higher tidal volume), decreased TPR, and increased HR and cardiac output, delivering more oxygen per minute.
What causes local vasodilation in working muscles during exercise?
The exact mechanisms remain unknown, though several candidates exist, including local metabolite release (e.g., lactate, adenosine) and shear stress.
Effect: These factors contribute to increased blood flow to active muscles, optimizing oxygen delivery and nutrient exchange.
How does altitude affect oxygen pressure and aerobic performance?
Reduced Oxygen Pressure: At altitude, oxygen pressure—not concentration—is altered, leading to reduced inhaled oxygen and blood oxygen levels.
Physiological Responses: This results in hyperventilation and decreased blood CO2, increased hematocrit (Hct), increased HR and cardiac output, and reduced VO2MAX/peak performance due to lower oxygen availability.
