Table 1.

Sensor-based outcome measures

Parameter	Description	Reference
Step/stride time	Time-interval between two consecutive/alternate acceleration peaks
Gait Variability
Step/stride time variability	Coefficient of variation (%), standard deviation of step/stride time over mean step/stride time	[17]
PSD max	Maximum height of the PSD distribution curve representing the amount of walking that occurs at the dominant frequency	[38, 39]
PSD width	The width of the PSD curve at half of the maximum height representing the range of walking frequencies	[38, 39]
PSD slope	The slope of the PSD curve from the peak to the width representing the variability of walking.	[38, 39]
Dominant frequency	The frequency at which the PSD curve attains its peak, representing the frequency at which most of the walking cycles occur	[38, 39]
Gait Asymmetry
	Unbiased auto-correlation coefficients of gait signal, representing left-right step coordination	[11, 40]
Gait Irregularity
	Sample entropy, representing the predictability of walking cycles	[41–43]
Continuous Walking Quantitative Measures
No. of continuous walks	Total number of continuous walks in the 48 h duration
Total continuous walking duration	Total duration of continuous walks in the 48 h duration
Max walking bout	Maximum duration of continuous walking in 48 h
Max no. of continuous steps	Maximum number of continuous steps in the longest duration continuous walking bout in 48 h
Walking bout variability	Coefficient of variation (%), standard deviation of walking bouts over mean walking bout
Duration of non-continuous walks (% of total walking duration)	Duration of walks which were not continuous for 60s or longer (total duration of 60s walking minus continuous walking with no pause)

PSD Power Spectral Density