T Nation

Re: Activity Factors- from the pound-Jason Nocross and others

“Where did the Activity Factors ORIGINALLY come from?”

I'm not sure exactly what you mean by your question but I think you are refering to METs which are metabolic equivalents. I think that they were derived from relative oxygen consumption durring different activities. For example they would make bed rest 1 just to make things standard and then make everything relative to that. I have heard that 1 MET is equivalent to 3.5 ml of oxygen per kilogram body weight per minute. Im not sure if the 2 mets would be 6 mls of oxygen per kg per min or not.. Im not sure if it is linear or exponential or what....

Ohh yeah and to Eric and the others that replied saying they were high...They are just averages...I would imagine that they may be high if your are efficient at exercise. For your own exact number of METs you would need a Metabolic exercise test which would measure your oxygen consumption at exercise. That would be very impractical considering that it would be 1 value for 1 exercise at that intensity.

By the way how do you know that they are high? Why couldnt it be the formula that Berardi uses to derive RMR that is too high? Everything else might be spot on but due to the initial value being too high the results of the rest of the equations are subsequently also too high.

As for where they came from...deep in Africa...

By the way if you were really rich and could afford to buy a device that measured METs it would be one of the best ways to monitor training status. Eg you would know if you were overtraining if your MET value was unusually high durring any activity...

Chris-Jason DEFINITELY knows what a MET is (as do I).


A few things:

  1. 2 METs=7 ml O2. It is linear.
  2. It could be derived from the METs from all the activities during the day, but it would be VERY difficult to do, as there is a lot of variability. How much is one sleeping? Does one tap their feet while sitting? The list goes on and on.
  3. I strongly urge you to check out a previous thread called “El Mac Stupid Question of the Week.” Jason and I were both actively involved in it, and it proved to be an educational thread for many contributors to the forum. It should answers your questions to the METs, etc. questions.


    I just spoke with Jason; he’ll be posting to clarify. Thanks for posting! Hope this helps.

Actually, we’re not talking about METs, but rather the activity factor multipliers, which are not really related to the MET value of exercise.

Also, you are right in that it could be the forumula for RMR. But I've also seen the research to support why he chose that equation, so it is more likely to be a problem with the activity factors.

Okay… so a MET value tells you how much oxygen you are using relative to the resting state. If you know how much oxygen you are using could you from that work out how much extra energy you are using relative to resting and wouldnt that give you an activity factor. It doesnt seem that difficult… just say that at a MET value of 2 most people are burning calories at 127.83737838939283839378% of the normal rate. Then you would make 1.27 the activity factor. I realize that you said

"It could be derived from the METs from all the activities during the day, but it would be VERY difficult to do, as there is a lot of variability. How much is one sleeping? Does one tap their feet while sitting? The list goes on and on."

But isnt that kinda the point. Its just a rough estimate, anytime that you try to come up with a set of figures that are applicable to the 6 billion people you will strugle. You yourself said that you did not think that they were particurlarly accurate. Also wouldnt METs face all the same problems ie tapping ones feet while sitting would also make the MET value inaccurate... Like the BMI is a shocking test but is still used by most medical practitioners and many insurance agencies as their standard. In fact most data is achieved through equally dodgy means.

Actually dont worry about it, i am not mentally constipated as of now…

Chris Aus

It’s still very good thinking on your part. As Jason said, it’s possible, but I still can’t see it being the most effective way to retermine RMR. I can only surmise that it is some sort of weighted average of a study involving a large sample size with a variety of self-determined activity levels. Again, great thinking!

Sorry, that last post should have been directed to Chris AUS. I’m getting my Aussies mixed up:(