If you’ve had some cardiac rehab before or if you’ve had some other reason to deal much with an exercise physiologist then you might have heard them toss around the term, METS.
Some of our exercise machines have a METS readout and often our rehab progress notes to patients’ referring physicians will include a comment about METS.
Every so often I’ll have a patient ask me, “What is this METS thing I keep seeing around here?”
First off, because it is capitalized (I don’t know why they write it that way) it looks like it ought to be an acronym for something, but it is not. Some people have even reverse-engineered it into an acronym, claiming it stands for Measure of Exercise Tolerance — but it doesn’t really.
METS is just physiologist shorthand for metabolic rate. METS is a unit that describes how much energy your body is producing to be able to do the amount of work you are currently doing. One METS is said to be enough energy to keep your body alive while you are at rest — also known as basal metabolic rate. Two METS is twice that amount of energy, three METS is three times as much and so on.
Basically, the more energy your body can produce to do work without your having symptoms (extreme breathlessness, chest pain, etc...) the better, so one of our primary goals in cardiac rehab is to increase your METS over time.
It is not uncommon for patients to start rehab with a symptoms-limited capacity of two to three METS and to graduate twelve weeks later with a symptom-free capacity of nearly five to six METS.
This means they have doubled or tripled their ability to do cardiac/aerobic exercise.
Occasionally a patient won’t accept that this magical METS number that we’re always striving for simply means, “metabolic rate.” To them it seems like there must be more to it, and I have had to explain a little of the math behind METS to satisfy them.
For these overachievers, I say that one METS means that your body is metabolizing 3.5 milliliters of oxygen per kilogram per minute. But now you don’t really know any more than you did before I defined it more precisely.
So I guess it’s not really that terrible to call METS a Measure of Exercise Tolerance and leave the math to the physiologist and the doctor.
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Dr. Patrick Parker is the Director of the Cardiopulmonary Rehabilitation program at the Cardiovascular Institute of Mississippi in McComb. Visit RoamingParkers.com to see more of what he does to stay fit, well and healthy.
