Cardiovascular System

• Heart rate (HR)


  The number of times the heart contracts or beats per minute (bpm)
• Resting heart rate (RHR)


  The number of heartbeats per minute while the body is at rest, usually 60-80 bpm with 70 bpm being average
• What happens to the Heart Rate of an individual when they begin to exercise?

  Heart rate increases as a response to the extra oxygen required by the body (meet oxygen demand)
• Purposes of increased heart rate

  • Helps to increase oxygen delivery to the working muscles
  • Aids in the removal of waste products from the muscles and body
• How does Heart Rate increase in relation to increased exercise intensity?

  Heart rate increases directly in proportion (linearly)
• Heart Rate at different exercise intensity levels

  • Light or low-intensity (100-140 bpm)
  • Moderate intensity (140-160 bpm)
  • High-intensity (even higher, up to maximum heart rate)
• Maximum heart rate (MHR)


  The highest heart rate value achieved in an all-out effort to the point of exhaustion
• Explain what is meant by a linear relationship between heart rate and exercise intensity.

  
• Calculation for Max HR = 220 - age
• Trained athletes have lower heart rates at rest and during all exercise intensities compared with untrained individuals.
• Anticipatory Response


  when the Heart Rate rises above resting levels just before the start of exercise due to adrenaline
• Heart rate response to exercise before, during, and after moderate-intensity exercise

  
• Stroke Volume


  the amount of blood ejected from the left ventricle with each beat (contraction) of the heart.
• Stroke volume increases during exercise; however it depends on the exercise intensity, for untrained athletes, somewhere between 40 and 60 per cent of maximal capacity.
• Once the 40-60% of maximum intensity has been reached, it's at this point that stroke volume typically plateaus and remains unchanged despite increases in exercise intensity.
• Trained individuals stroke volume at rest is about 70-90mL per beat
• Why do females tend to have lower Stroke Volume than male counterparts?

  Both at rest and during exercise, as a result of their smaller heart size.
• During exercise, there is an increase in venous blood return to the heart. As a result, the ventricle stretches as it fills more fully with blood, and subsequently contracts more forcefully as a result of the greater elastic recoil.
• There is a decrease in peripheral resistance as a result of vasodilation of the vessels supplying blood to the exercising skeletal muscles. This decrease in resistance facilitates a greater emptying of the blood from the ventricle.
• Stroke volume doesn't increases further at exercise intensities beyond 40-60% of maximal capacity because of the reduced time available for the ventricle to fill. As Heart rate increases with increasing exercise intensities, the filling time is reduced significantly, thereby limiting the amount of blood within the ventricle.
• Cardiac Output


  the amount of blood ejected from the left ventricle of the heart per minute.
• Cardiac Output = Heart Rate x Stroke Volume
• During exercise, cardiac output increases as a result of increases in both heart rate and stroke volume.
• An increase in cardiac output is designed to bring about an increase in oxygen delivery to the working muscles and heart.
• Trained individuals (both male and female) have larger stroke volumes than their untrained counterparts. This is due to an increase in heart size (cardiac hypertrophy) that accompanies training. This is a chronic adaptation to exercise.
• Blood Pressure


  the pressure exerted by the blood against the arterial walls as it is forced through the circulatory system by the action of the heart. 
• Two types of blood pressure?

  Diastolic and Systolic
• Systolic blood pressure is the pressure recorded as blood is ejected during the contraction phase of the heart beat.
• Diastolic blood pressure is the value recorded during relaxation of the heart.
• Blood Pressure = (Systolic / Diastolic) X mmHG
• Normal blood pressure=(120/80) mmHG
• Systolic Blood Pressure during Whole body exercise (e.g. Jogging)

  Blood Pressure Increases as a result of an increase in systolic blood pressure — although there becomes a decrease in resistance against the artery walls due to vasodilation of the blood vessels of the exercising muscles which can offset some of the rise in systolic pressure.
• Diastolic Blood pressure during whole body exercise (e.g. Jogging)


  Diastolic blood pressure changes little during exercise, with increases of more than 10 mmHg considered abnormal. The minimal change in diastolic blood pressure is accounted for by the decrease in peripheral resistance.
• During resistance-type exercise (e.g. lifting weights), large increases in both systolic and diastolic blood pressure are evident
• Redistribution of Blood Flow at rest vs during exercise

  Blood flow to heart remains the same, blood flow to muscles increase, everything else decreases

  
•  Arteriovenous oxygen difference (a-VO2 diff.)


  Is a measure of the difference in the concentration of oxygen in the arterial blood and the concentration of oxygen in the venous blood.
• Diagram of a-vo2 difference at rest vs during exercise

  B

  
• Oxygen extraction from arterial blood at rest is about 25% vs oxygen extraction from arterial blood during exercise is as much as 75% of the available oxygen.
• During exercise, the process of vasoconstriction of the capillaries and arterioles occurs to the organs of the body, and the process of vasodilation occurs to redistribute blood flow to the the working muscles
• Name the acute responses to the cardiovascular system:


  Increased Heart Rate

  Increased Stroke Volume

  Increased Cardiac Output

  Vasoconstriction and Vasodilation (redistribution of blood flow to working muscles)

  Increased a-vo2 diff