Understanding METs and MET Testing
Posted on Thu, Jun 17, 2010 @ 11:58 AM
The following post was written by blog team member, Dr. Leonard N. Matheson, PhD. Leonard is a psychologist, author and inventor who was a pioneer in the field of occupational rehabilitation. He is the Research Scientist and Founding Director of EpicRehab. To see Dr. Matheson's full biography, please visit our Matheson Blog Team page.
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The METs column on the PDC chart (shown below) can be quite useful. It presents the range of typical energy expenditure that corresponds to one of the five physical demand characteristics levels.
I first recognized the need for a crosswalk from the United States Department of Labor's Physical Demand Characteristics system to METs when I was working in the cardiac rehab program at Rancho Los Amigos hospital in Downey California in 1973. I was responsible for the work rehabilitation segment of the program, helping people to return to work after a myocardial infarction. I used the newly published Handbook for Analyzing Jobs to do job analysis, but found that the method that was normally used to evaluate the work capacity of the person after a heart attack did not relate to the Department of Labor's system. I sought direction from two cardiologists, Harry Rice and Ron Selvester, as well as George Watson, a vocational evaluator at Rancho. The most scientific method to determine work capacity after a heart attack involved a treadmill cardiac stress test that was used to estimate the maximum safe work capacity, from which an estimate of workday work capacity could be developed.
The cardiologists were able to interpret the results of the stress test in terms of METs, a unit of energy expenditure that is based on oxygen consumption. MET means "metabolic equivalent of task", or is sometimes simply called "metabolic equivalent". One MET is the oxygen consumed by the individual at rest. Numerous studies have been undertaken to estimate MET levels of various job tasks, taken as a multiple of the amount of oxygen consumed by the individual at rest. We used these studies to identify tasks that could be placed in one of the five PDC levels.
Initially, we found that we could range the tasks across eight levels and developed hyphenated levels such as Light-Medium. While we found these to be useful in the cardiac rehab program, as Work Capacity Evaluation, Functional Capacity Evaluation, and Work Hardening were exported to other sites, the hyphenated levels created confusion. By the early 1980s, we had abandoned the hyphenated levels. Over the intervening years, as new studies of energy expenditure have been published, we made minor corrections to the MET range that corresponds to each PDC level. The most recent revision is presented below:
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Note from Roy Matheson:
MET Testing is an essential part of a Functional Capacity Evaluation.
We have noticed recently that there is a fair amount of confusion and uncertainty about how to properly perform a MET test. Please watch an archived version of our free webinar to review the concept and correct procedure for MET testing.
Click Here To Watch the Matheson MET Testing Webinar!
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