PPA	Peak positive acceleration measured during the stance phase at heel strike
VILR	Vertical instantaneous loading rate in the slope from 20% to 80% of impact phase
VALR	Vertical average loading rate in the slope from 20% to 80% of impact phase
SF	Stride frequency or cadence. Number of steps taken per minute
COP	Center of pressure at the foot
COM	Center of mass of the body
CGT	Contact ground time. Time that the foot is on the ground during the stance phase