MET's - Full Compendium and a calculator

[Colinm39]

Here is a full compendium of MET's activities in pdf format. With that, and the Calculator you can perform comparative calculations to get the "feel" of the number of MET's for an activity.  This will help you understand the concept of MET and the effort required.

I will use snow shovelling as an example "Shovelling Snow - Moderate effort" has a MET value of 5.3

 Using the calculator, I would have to walk on a non-gradient with Gross energy at 4.2mph to generate 5.3 MET's. The MET's is constant because that is the effort, but the longer I walk, I get more calories.That speed of walk I would also generate close to 100% VAM if I kept the speed constant
 

Link to the MET's PDF Compendium  http://tinyurl.com/kpexgop

Link to the Calculator  http://www.exrx.net/Calculators/WalkRunMETs.html

[Colinm39]

Here is a full compendium of MET's activities in pdf format. With that, and the Calculator you can perform comparative calculations to get the "feel" of the number of MET's for an activity.  This will help you understand the concept of MET and the effort required.

[Colinm39]

I will use snow shovelling as an example "Shovelling Snow - Moderate effort" has a MET value of 5.3

[Colinm39]

 Using the calculator, I would have to walk on a non-gradient with Gross energy at 4.2mph to generate 5.3 MET's. The MET's is constant because that is the effort, but the longer I walk, I get more calories.That speed of walk I would also generate close to 100% VAM if I kept the speed constant
 

Link to the MET's PDF Compendium  http://tinyurl.com/kpexgop

Link to the Calculator  http://www.exrx.net/Calculators/WalkRunMETs.html

[Mary]

Thanks, Colin.  I like those! 

I wonder if this link would help some people understand the concept, too.

http://en.wikipedia.org/wiki/Metabolic_equivalent

Based on that it sounds like the MET value is a multiplier and your calorie estimate is your MET value X your BMR for the period.  I assume Fitbit uses your per minute BMR.  To get that you can look at a period of inactivity on your graph and hover over a bar.  Mine gives me 14 calories for each 15 minute segment.  So my BMR is 14/15= .93 calories/minute.  So walking at 3.5mph which has a MET value around 3.7 should give me around (3.7 X .93) calories per minute, or 3.4 calories per minute.  I actually get around 5, so maybe it thinks I'm moving faster.  Though if I manually log a 3 mile walk over 1 hour it gives me 3.6 calories per minute from the database, which is much closer to 3.4.  So the Fitbit seems a bit generous.  Anyone else find that?   

[WendyB]

Thanks Colin!

[Colinm39]

@MaryI did a similar manual activity but for walking at 4mph and 4.5mph and the Compendium goes from 5 MET to 7 MET on that difference.

The calories calculated on the 4mph are 166 and the BMR MET calculation is 165, spot on, but as soon as I go to 4.5mph I get 209 calories,100% VAM, but the BMR MET calculation is 231 calories.

There are variables now with more testing and we can see how complex it must be for Fitbit to encapsulate the variations. This link is to the 2011 Compendium and a section on corrected MET's which shows the variations that can be expected in gender and weight.

2011 Corrected MET's

[ExOnc]

Fitbit is only using the "standard" [MET] of 3.5 mL/kg/min (standard by convention only), which is not very accurate for individual assessments. "Standard" METs are meant to harmonize data for population research. The Compendium of Physical Activity has updated METs that are much better than the "standard" MET (from 1990) that Fitbit is using, particularly for adults 60 years old or older. Additionally, there are corrected METs that can be used for adults between age 18 and age 60. Since Fitbit has age, weight, gender, and other body measurements they can easily correct METs for individual users. Why isn't Fitbit correcting METs or using older adult METs? From the Compendium of Physical Activity's website:

https://pacompendium.com/older-adult-compendium/
https://pacompendium.com/corrected-mets/

"[MET]" is also the standardized UCUM unit - for machine readability (https://ucum.org/) and a ONC HIT standard (https://www.healthit.gov/isp/representing-units-measure-use-numerical-references-and-values)

[LZeeW]

Hello @ExOnc and welcome to the Community.  Please note that this thread is from 2014.  The state of the art Fitbits were the One and the Charge.  Neither one has a heart rate monitor.  There was no exercise app and every exercise was added manually.  Fitbit used that full compendium of activities.  If I logged a bike ride, I chose my average speed.

All Fitbits have heart rate monitors and use heart rate based algorithms to estimate calorie burn.

[ExOnc]

Lee, sure it's from 2014, but after spending too much time trying to get through to support (unsuccessful) and fitabase (limited info) this thread covers METs, so now there's an updated post that should apply to all fitbit devices using METs (whether users are aware of METS or not).  Checking the current 1 MET value used by fitbit (standard MET value of 3.5 mL/kg/min) - not the Compendium of Physical Activities for an activity's MET that you used to manually input - fitbit still does not use corrected METs or older adult METs, both of which would give better estimates for individual users than the standard MET value.  METs can be converted to calories too.

[YachatsMike]

I use a formula in a spreadsheet to track mets

Mets = calories/min * 200 / weight(kg) / 3.5

I can't remember where I got this formula but I've seen it in a couple of different sources.  I trust it more than interpolating the Compendium.

I trust the machine I'm using for calorie values because only it knows the internal power you are consuming and the efficiency of the machine in converting your calories into their watts.

ACSM has well researched formulas for treadmills and running.  They are based on weight, time, speed, and grade.  I noticed that I get the same result from my calculation as the tracker on my treadmill reports.

[ExOnc]

The "3.5" in the formula you show is the value, in mL oxygen per kilogram per minute, for a standard MET.  I'm willing to bet that most fitness machines are still using that same value when calculating METs for display, summary, categorizing fitness and intensity, or converting to calories.  The old ACSM treadmill and running formulas use the standard MET value (3.5) too.

The 'Older Adult Compendium" (60 and older) MET value is "2.7" mL/kg/min, which is 22% less than the standard 3.5 MET.  There are also MET "corrections" that use a person's demographic information, which fitbit and fitness machines collect, e.g., age, gender, height and weight (European Journal of Clinical Nutrition (2000) 54, Suppl 3, S77-S91; and, https://pacompendium.com/corrected-mets/)

If not getting one's Resting Metabolic Rate (RMR) measured, few health clubs offer that, the non-standard METs are a better estimation of RMR than using the 3.5 value.

[YachatsMike]

I use Mets to answer two questions.

1.  Am I exercising hard enough.

2.  How does my exercise intensity stack up against my age-group peers

For both of these questions I compare against online statistics and standards that were probably based on a resting VO2 rate of 3.5 ml/kg/min.  I'll continue to use that number in my spreadsheet for continuity even if there might be a slightly more accurate number for absolute Mets.

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