Table 1 Sensor-based outcome measures

Step/stride time

Time-interval between two consecutive/alternate acceleration peaks

 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]

Unbiased auto-correlation coefficients of gait signal, representing left-right step coordination

[11, 40]

Sample entropy, representing the predictability of walking cycles

[41,42,43]

 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)