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Relationship between; and resting values of: heart rate, stroke
volume and cardiac output.
Heart rate (HR)
The heart rate (HR) represents the number of times the heart ventricles beat in one minute.
The average resting heart rate is 70-72 beats per minute. The maximal heart rate is calculated
using the following equation:
220 Age = Max HR (for example 220 17 =203)
Bradycardia is a resting heart rate below 60 beats per minute. It may indicate a high level of
aerobic fitness. It may also be due to hypertrophy which is an increase in size/ thickness of
the heart muscle walls.
Stroke volume (SV)
The stroke volume is the volume of blood ejected by heart ventricles per beat or the
difference in the volume of blood before and after each ventricle contracts. The average
resting stroke volume is approximately 70ml.
The end diastolic volume (EDV), before contraction, is the volume of blood left in the
ventricles at the end of the relaxation/ filling stage of the cardiac cycle.
The end systolic volume (ESV), after contraction, is the volume of blood left in the
ventricles at the end of the contraction/ emptying stage of the cardiac cycle.
To calculate: SV: EDV ESV = SV
When calculating blood volume, always present figures from 1000 and above in litres (L/min),
especially when referring to cardiac output, e.g. 1000ml = 1 (litre)
Cardiac Output (Q)
This is the volume of blood ejected by heart ventricles in one minute.
Average (rounded): Q = SV X HR
(Litres/min) = (ml/beat) X (bpm)
5 1/min = 70ml X 72
Before during and after exercise HR is continually changing, but it may do any of the
following depending upon exercise undertaken.
Resting Sub-maximal Maximal
SV 60/80 ml 80/100ml 100/120mil
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HR 70/72 bpm Up to 100/130 bpm 220- your age
Q 51/min Up to 10LITRES/min 20-40LITRES/min
Table to show summary: SV, HR and Q values related to exercise intensity.
1. Resting heart rate- the average resting heart rate is 72, but if a question describes
a young, fit aerobic athlete, it may be assumed they will have a resting heart rate
below 60, known as Bradycardia, due to an increase in stroke volume.
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Rapid fall in heart rate as exercise stops due to decrease in stimulation of all the
factors in 2, 3, and 4 above.
7. Slower fall in heart rate towards resting vales. HR elevation above resting values to help
repay oxygen dept (additional oxygen consumed during recovery, above that usually required
when at rest in this time) and to remove the by-products of respiration, for example, lactic