Table 2 Gait parameter definitions used in the ReSPonD trial

Stride

One stride equals two steps and represents one gait cycle.

Stride time

Time taken for one stride

Stride length

Distance traversed by two steps

Step

Defined by consecutive heels strikes of contralateral limbs

Step time

Time taken for one step

Step length

Distance between consecutive heel strikes, mean is calculated by the distance travelled / number of steps taken.

Walking speed

The velocity of walking, calculated as the distance travelled / time taken.

Variability

Variability of the measure of interest, expressed as the standard deviation (SD) and the coefficient of variation (CoV) = SD/mean x 100%.

Double limb support

The period for which both feet are in contact with the floor, calculated by time from heel strike until toe off of the contralateral limb.

Cadence (steps/min),

The number of steps per minute

Stance time (sec)

Duration of stance time (single and double support) in one gait cycle.

Walk ratio

The relationship between the amplitude and frequency of the rhythmic leg movements when walking. Calculated as step length / cadence.

Harmonic ratios (AP and VT)

The ratio of even/odd harmonics of acceleration over one gait cycle. In gait, AP and VT movements repeat each step. Stable gait therefore contains more AP and VT accelerations that repeat twice per stride as measured by even harmonics in the frequency domain.

Harmonic ratios (Matthew Brodie, personal communication, October 24th 2013)

The ratio of even/odd harmonics of acceleration over two gait cycles. In gait, ML movements repeat each stride. Stable gait therefore contains more ML accelerations that repeat twice every two gait cycles as measured by even harmonics in the frequency domain when two strides define the fundamental harmonic.