Cardiac Output, Stroke Volume & Heart Rate

• Cardiac output definition

  The volume of blood that is pumped by the heart every minute
• Stroke volume = the volume of blood pumped by the heart with each beat
• Cardiac output depend on:

  • Stroke Volume
  • The stroke volume of a fitter individual will be larger than that of a less fit person; this is because their heart muscle is stronger and their heart is larger, so more blood can be pumped with each beat
• Heart rate = the number of beats per minute
• Cardiac output depend on:

  • Heart rate
  • The heart rate of a fitter individual will be lower than that of a less fit individual; this is because of their larger stroke volume, which allows them to achieve the same cardiac output with fewer beats
• cardiac output (Q) = stroke volume (SV) x heart rate (HR)
• Why does the heart rate start to increase before exercise begins?

  This is known as an anticipatory rise and occurs due to adrenaline release before the start of exercise
• • The resting heart rate here is around 65 beats per minute
• • Low intensity exercise (walking) = 115 beats per minute
• • Medium intensity exercise (jogging) = 150 beats per minute
• • High intensity exercise (sprinting) = 185 beats per minute