How to Measure Cardiac Efficiency
Measuring cardiac efficiency is a tool that many athletic trainers, doctors, nurses and athletes use in order to figure out how efficient their heart is at pumping blood when in motion or at rest. Defined as the ratio between the work produced (blood pumped) and input of energy in order to make the heart work, it is a matter of some simple equations. It can also be expressed as the ratio of stroke work to oxygen consumption. No matter what you call it, the process to calculate the cardiac efficiency is the same.
Things You'll Need
- Calculator
- Stopwatch
- Blood pressure cuff
- Stethoscope
- Paper
- Pencil or pen
Instructions
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1
Calculate your baseline pulse by placing two fingers (not your thumb) onto the veins on the underside of your wrist at a spot in line with the base of your thumb. Wait until you feel a pulse. Count how many times it beats in 15 seconds. Then multiply that number by four. This is how many beats per minute your heart produces. Write this down on paper.
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2
Calculate your stroke volume by taking the amount of liters of blood pumped per minute multiplied by how many beats per minute your heart makes. The average human heart pumps about 80mL (milliliters) per beat, and 4 - 5L per minute. An average heart beats 72 beats per minute.
Using the pulse you recorded and calculator, multiply it by 80mL. This will give you how many milliliters you have pumped per minute. Convert it to liters per minute by taking the milliliters per minute and dividing it by 1000. This will give you your stroke volume. Write this down on paper.
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3
Place the blood pressure cuff onto your upper arm, above the elbow. Make sure it is secure and snug around the arm, only allowing a space for two fingers to be able to slip in between the cuff and your arm before the cuff is inflated. Place the stethoscope between the cuff and your arm on the brachial pulse (towards the bottom of the cuff closest to the elbow) and put the ear pieces inside your ears.
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Start pumping the squeeze ball until the cuff is inflated tightly around the arm, approximately 10 squeezes (until the meter gauge reaches 160mmHg).
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Slowly turn the knob located by the squeeze ball until it begins very slowly releasing air from the cuff.
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Record the number you noticed on the dial at the instant when you heard your heart beat again through the stethoscope. This is the systolic blood pressure.
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Keep listening as the cuff deflates. Record the number on the dial at the instant the sound of your heartbeat stops in the stethoscope. This is the diastolic blood pressure.
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Calculate the Mean Arterial Pressure (MAP) by doubling the diastolic pressure (bottom number = D) and add the systolic pressure (top number = S) and then divide by three.
MAP = [(2 x D) + S] / 3
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Determine the ratio of stroke volume and mean arterial pressure (MAP). This is your total cardiac efficiency. It can be written as a fraction, mathematical sentence, or percentage.
In a normal, healthy young person, the systolic, diastolic and heart rate should increase by 10 or 15 points. According to www.smm.org, this is considered a baseline for good cardiac efficiency.
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Tips & Warnings
It is much easier for a partner to take your blood pressure using a cuff, but it can be done solo.
If pain occurs when using the blood pressure cuff, release the air immediately. You have it too tight. It should be tight but not causing pain.
