1. Measuring The Health of Your Heart

2.  Your heart pumps blood through your body to provide it with oxygen and nutrients.  Oxygen and nurients react to release energy that our bodies use for things like moving and thinking  While most of your cells have enough nutrients to last a while, they need a constant supply of oxygen  The more blood your heart can pump, the more oxygen it can give your cells and the more energy you can use

3.  You use the most energy when you exercise. That is why your heart has to pump more oxygen to your muscles. Also, when you exercise, your blood vessels change their diameters to redirect blood flow to your muscles

4.  Still, some people have stronger heart than others. Their heart can pump more blood and allow them to do more work  The amount of blood that your heart pumps in a minute is called Cardiac Output (Q)

5.  How is it measured?  The total amount of blood your heart pumps in a given time is equal to the number of beats (heart rate) times the amount of blood the heart pumps in each beat (stroke volume). Cardiac Output = Heart Rate x Stroke Volume

6.  Cardiac output is usually measured in Litres per minute  When someone is resting, their cardiac output is usually 5-6 L/min  Question:  If someone has a resting heart rate of 70 beats/min and a resting cardiac output of 5.5 L, what is their stroke volume??

7. Answer (Using Grass Method): Given - cardiac output (Q)= 5.5 L heart rate (HR) = 70 beats/min Required – Stroke Volume (SV) Analysis - Q = HR x SV so SV = Q/HR substitute SV = 5.5/70 Solve:.079 L or 79 ml Statement: His stroke volume is 79 ml

8.  Aerobic, or cardiovascular exercise (e.g. distance running, swimming or bike riding) makes the heart stronger.  This will cause the heart to increase its stroke volume which will allow it to beat slower

9. NORMAL HEARTSTRONG HEART  Cardiac output at rest is 5-6 L/min  Resting Heart Rate is ``60-85 beats/min  SV at rest is usually 70-80 ml  Maximum Q = ~20 L/min  Cardiac output at rest is 5-6 L/min  Resting Heart Rate is ~40-60 beats/min  SV at rest could be as over 120 ml  Maximum Q = ~40 L/min

10.  So the lower your resting heart rate, the stronger your heart. But it also depends on your age

11. 1. If the cardiac output is 6.3 L/min and the pulse rate is 80 beats/min, what is the stroke volume? 2. If the stroke volume is 65 mL/beat and the cardiac output is 5.7 L/min, what is the heart rate? TRY THEM!!