Heart Values and the Relationship between them Flashcards
What is cardiac output (Q) ?
The volume of blood ejected from the left ventricle per minute
Measured in - ml/min
How is cardiac output calculated?
Stroke volume x heart rate
What is stroke volume (SV) ?
The volume of blood ejected from the left ventricle per beat
Measured in - ml
What is ejection fraction?
Proportion of blood leaving the left ventricle per beat
Ratio of the volume of blood ejected to the volume of blood in the chamber at the end of relaxation
EF = SV/EDV
What is heart rate (HR) ?
The number of times the heart beats per minute (bpm)
What is a normal resting heart rate for a normal person?
72bpm
Vary between 60-90 (bpm)
How does a trained individuals heart values differ to an untrained person?
Trained Individual:
- Lower resting heart rate (below 60bpm - bradycardia)
- Cardiac hypertrophy causes a greater stroke volume
- Cardiac output is similar but the trained athlete’s heart will work work less (fewer beats) as it has higher stroke volume.
- Heart doesn’t work as hard and therefore doesn’t demand as much oxygen, meaning more oxygen can go to working muscles.
How is cardiac hypertrophy achieved?
Endurance training
What is Starling’s Law?
Starling’s law states that the greater the venous return, the greater the strength of contraction of the heart.
How is maximal heart rate calculated?
220 - age
How does cardiac output increase during exercise for untrained individuals?
The untrained individual needs to increase cardiac output, which can only be achieved by increasing heart rate.
How does cardiac output change during exercise for trained individuals?
The trained individual has a greater blood volume. Venous return is therefore greater during exercise, meaning that there is stronger force of contraction. This results in a greater ejection fraction. Heart rate does not need to increase as much as it does in an untrained individual.
What happens to cardiac output at sub-maximal exercise?
Sub-maximal exercise will see a plateau in cardiac output when a steady state is reached as the cardiovascular system is able to supply the working muscles with adequate oxygen.
What happens to cardiac output at maximal exercise?
Maximal exercise will result in a greater cardiac output than sub-maximal exercise and this will peak and then rapidly decline as maximal exercise cannot be sustained.
