As described in:
2011 Compendium of Physical Activities: A Second Update of Codes and MET Values
AINSWORTH, BARBARA E.1,2; HASKELL, WILLIAM L.3; HERRMANN, STEPHEN D.1,2; MECKES, NATHANAEL1,2; BASSETT, DAVID R. JR.4; TUDOR-LOCKE, CATRINE5; GREER, JENNIFER L.1,2; VEZINA, JESSE1,2; WHITT-GLOVER, MELICIA C.6; LEON, ARTHUR S.7
Medicine & Science in Sports & Exercise: August 2011 - Volume 43 - Issue 8 - p 1575-1581