A unified framework for the measurement of mobility in older persons.

"Declaration of Conflicts of Interest M.B. holds a Tier 2 Canada Research Chair in Mobility, Aging, and Chronic Disease. P.R. holds the Raymond and Margaret Labarge Chair in Research and Knowledge, is the Director of the McMaster Institute for Research on Aging and the Labarge Centre for Mobility in Aging, and holds a Tier 1 Canada Research Chair in Geroscience. Declaration of Sources of Funding Funding for activities was provided by the McMaster Institute for Research on Aging (MIRA). This special supplement is funded by European Commission through AAL Programme Budget."

"Declaration of Sources of Funding Funding for activities was provided by the McMaster Institute for Research on Aging (MIRA). This special supplement is funded by European Commission through AAL Programme Budget."