1.21 The Short-Term Effects Of Exercise On The Cardiac System

Question 1

What is the cardiac equation?

Answer 1

Stroke volume (SV) * heart rate (HR) =
cardiac output (Q)

Question 2

What is stroke volume? (SV)

Answer 2

The amount of blood pumped out of the heart per beat.

Average testing stoke volume is around 70ml per heart beat (ml/beat)

Question 3

What is heart rate? (HR)

Answer 3

The number of beats per minute that the heart generates.

The average resting heart rate is 75 bpm per minute (bpm)

Question 4

What is cardiac output? (Q)

Answer 4

The volume of blood pumped out the heart per minute.

The average resting cardiac output is around 5 litres per minute (l/min)

Question 5

What happens to values in the cardiac equation when you exercise?

Answer 5

They increase because the working muscles need more oxygen and so your blood needs to circulate around your body more quickly.

Your heart, therefore, increased the amount of blood being pumped out per minute, which increases speed at which blood circulates.

As a result, oxygen is delivered to your muscles more quickly to meet their demands and allow them to work aerobically, while extra carbon dioxide is carried away more quickly

Question 6

What is the short effect of exercise on stroke volume?

Answer 6

Stroke volume increases as exercise intensity rises. The heart contracts with more force, and squeezes out more blood per contraction.

Heart can only contract so hard, once it reaches max. As exercise intensity intensity continues to rise, stroke volume reduces slightly. This is because the heart rate is now so high that there is not enough time for the heart to fill up fully with blood between beats.

Question 7

What is the short effect of exercise on heat rate?

Answer 7

Heart rate starts to rise slightly before exercise commences as you anticipate the activity. This is called anticipatory rise.

Once exercise begins, heart rate will increase as exercise intensity rises.

Heart rate reached a plateau either at the point where exercise intensity allows it. Or when it reaches maximum heart rate.

After, heart rate reduces slowly to allow recovery to take place.

Question 8

What is the short effect of exercise on cardiac output?

Answer 8

Cardiac output is directly influenced by heart rate. It starts to rise slightly before the exercise commences (anticipatory rise)

Once exercise begins, cardiac output is directly influenced by stroke volume and heart rate and therefore increases as exercise intensity increases

Cardiac output reaches a plateau either at the point where exercise intensity allows or when it reaches the max. (Maximal line on a graph)

Following exercise, cardiac output remains elevated and reduces slowly to allow recovery to take place