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Table 2 Summary of the extracted measures

From: ISway: a sensitive, valid and reliable measure of postural control

Measure abbreviation Description
JERK Sway jerkiness, time derivative of acceleration[m2/s5] J E R K = 1 2 0 t d A C C L AP d t 2 + d A C C L ML d t 2
Time-domainmeasures  
DIST Mean distance from center of COP (ACC) trajectory[mm] ([m/s2])
RMS Root mean square of COP (ACC) time series [mm]([m/s2])
PATH Sway path, total length of COP (ACC) trajectory[mm] ([m/s2])
RANGE Range of COP displacement (acceleration) [mm]([m/s2])
MV Mean velocity COP: PATH/trial duration [m/s];ACC: A C C L AP 2 + A C C L ML 2 [mm/s]
MF Mean frequency, the number, per second, of loopsthat have to be run by the COP (ACC), to cover atotal trajectory equal to PATH (MF = PATH/(2*π*DIST*trial duration) (Hz)
AREA Sway area, computed as the area spanned fromthe COP (ACC) per unit of time [mm2/s] ([m2/s5])
Frequency-domainmeasures  
PWR Total power [mm2] ([m2/s4])
F50 Median frequency, frequency below which the50% of PWR is present (Hz)
F95 95% power frequency, frequency below which the95% of PWR is present (Hz)
CF Centroidal frequency (Hz)
FD Frequency dispersion (−)