skdh.gait_old.RegularityIndexV

class skdh.gait_old.RegularityIndexV

The combination of both step and stride regularity into one endpoint. The goal is to provide an assessment of the regularity for consecutive steps and strides, for the vertical axis acceleration. Values closer to 1 indicate high levels of symmetry between left and right steps.

Methods

predict(fs, leg_length, gait, gait_aux)

Predict the bout level gait endpoint

Notes

The vertical axis regularity index \(R_V\) is simply defined per

\[R_V = 1 - |R_{(stride, V)} - R_{(step, V)}|\frac{2}{R_{(stride, V)} + R_{(step, V)}}\]

where \(R_{(stride, V)}\) is the stride regularity for the vertical axis (same notation for step regularity).

The Regularity Index term came from [1], where it was defined without the subtraction from 1. However, the definition from [2] (under the term “symmetry”) keeps the values in the same range as others (including step/stride regularity), aiding in ease of interpretation. “Regularity Index” however serves to eliminate confusion given other endpoints already labeled with “symmetry” in the name.

References

[1]

L. Angelini et al., “Is a Wearable Sensor-Based Characterisation of Gait Robust Enough to Overcome Differences Between Measurement Protocols? A Multi-Centric Pragmatic Study in Patients with Multiple Sclerosis,” Sensors, vol. 20, no. 1, Art. no. 1, Jan. 2020, doi: 10.3390/s20010079.

[2]

L. Angelini et al., “Wearable sensors can reliably quantify gait alterations associated with disability in people with progressive multiple sclerosis in a clinical setting,” J Neurol, vol. 267, no. 10, pp. 2897–2909, Oct. 2020, doi: 10.1007/s00415-020-09928-8.