The heart's response to exercise
Heart rate, stroke volume, cardiac output, estimated maximal heart rate and cardiac drift.
- 15 cards
- 5 topics
- Free
The outline, topic by topic
Each topic is weighted the way the exam weighs it.
- Concepts
- The numbers
- Predict, then see
- Scenarios
- Understand
A few cards from the deck
Cardiac output: what is it?
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Blood pumped per minute: heart rate × stroke volume.
About 5 L/min at rest, 20 to 25 at maximal effort.
In a hot marathon at a steady pace, heart rate climbs 15 beats. Why?
- Dehydration and heat lower stroke volume
- Heat raises the blood volume the heart must pump
- Stroke volume rises and drives the heart faster
- VO2max rises with temperature
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Dehydration and heat lower stroke volume
That is cardiac drift: the heart beats faster to keep the same output.
Stroke volume: what is it?
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The volume ejected by a ventricle each beat.
It plateaus at around 40 to 60 % of VO2max in untrained people.
Why does endurance training raise maximal cardiac output?
- Maximal heart rate rises markedly with training
- Stroke volume rises while maximal heart rate stays stable
- The heart beats faster at rest and keeps a reserve
- The arteries tighten and push the blood harder
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Stroke volume rises while maximal heart rate stays stable
It is the volume per beat that improves.