Ainsworth · Medicine and science in sports and exercise 2011 · Reference taxonomy and systematic literature compilation · n=821 activity codes

2011 Compendium of Physical Activities: a second update of codes and MET values.

Cited 6340 times in the scientific literature.

Level 5 - mechanism / opinion, no new human data

Systematic database compilation and reference taxonomy update (by design analogy, not clinical CEBM)

PubMed 21681120 · doi:10.1249/MSS.0b013e31821ece12 · record verified 2026-08-30

What was done

The authors performed a systematic literature database search to update the Compendium of Physical Activities, which provides standardized metabolic equivalent (MET) values for adult activities. Modifications included cataloging published measured MET values with their source citations, adding new activity codes, revising existing code definitions, updating the cross-version tracking guide, and creating an online repository.

What was found

The 2011 Compendium expanded to 821 specific activity codes, adding 217 new codes. Measured MET values were identified for 68% (561/821) of all codes. Of the 604 codes from the previous 2000 version, approximately 52% (317/604) were modified to refine definitions, consolidate overlapping activities, or update MET estimates, with updated MET values accounting for 73% of all modifications made.

Why it matters

This update provides a globally standardized, evidence-linked coding system used in public health surveillance, epidemiological research, and clinical exercise prescription to estimate energy expenditure across human physical activities.

Limits

The abstract does not report individual participant counts or demographic characteristics from the underlying source studies. Approximately 32% of the activity codes still rely on estimated rather than directly measured MET values, and the compendium is specifically designed for adult populations rather than children or clinical sub-populations with altered metabolic efficiency.

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