Gait analysis is one of the most commonly used approaches for quantifying mobility in people with neuromuscular movement disorders. Walking is relatively easy to assess, can be performed in a clinical setting, and provides an objective measure of functional ability. The analysis can be as simple as using a stopwatch to quantify gait speed or it can be quantified using instrumentation, such as the Zeno Walkway System, providing a multitude of outcome measures. Gait speed is probably the most widely used gait measurement. It is a good measure of mobility and has been shown to be a good indicator of overall health and motor function. However, the problem with concentrating only on gait speed is it can be influenced by balance, fatigue, muscle weakness, cardiorespiratory fitness, neuromuscular function and motivation. While gait speed tells us how fast someone walks, instrumented gait analysis may help us understand why and how they walk the way they do.
Study
A recent study published in Scientific Reports set out to examine whether gait speed is the best way to measure motor function among people with Multiple Sclerosis. Bilek et al. designed a study to determine which gait metrics are most effective at predicting corticospinal tract (CST) function in patients with MS.
The CST’s primary function is regulation of voluntary human movements. Many neuromuscular disorders, such as MS, disrupt CST function, leading to mobility impairments. Literature has shown that Transcranial Magnetic Stimulation (TMS) is a method to measure real-time CST function.
78 subjects completed TMS testing and gait analysis using the Zeno Walkway System. These subjects generally had limited or no MS-related gait impairments as evidenced by their average 178 cm/s gait speed and median EDSS score of 2.0. In addition to Gait Speed, other gait outcome measures were carefully chosen and categorized as Spatial (Stride Length, Step Length, Absolute Step Length, and Stride Width), Temporal (Double Support %, Stride Time, Single Support %, Cadence, and Swing Time), or Stability (SS COP Distance, DS COP Distance, and Stride Length coefficient of variation).
Next, the researchers used a 3-step process, consisting of a simple linear regression and two hierarchical regressions, to determine which gait variables correlated best with CST function.
Although gait speed showed a relationship with one measure of CST function, it did not add independent predictive value. Narrower stride width, longer step length, shorter double support %, shorter stride time, and longer center of pressure trajectory during single support all correlated with CST function, in varying degrees. Single Support Center of Pressure Distance was found to have the strongest association to higher corticospinal excitability.
The study suggests that subtle changes in postural control may be detectable by using instrumented gait analysis to measure outcomes such as COP excursion, double-support time, stride width, and stride-time characteristics, even when an individual continues to walk at a normal speed. This distinction could be particularly important in early MS and clinically stable MS, where detecting subtle changes before obvious functional decline could have implications for patient rehabilitation.
What is SS COP Dist?
Single Support Center of Pressure Distance (SS COP Dist) proved to be one of the most predictive gait metrics in this recently published study. It would not be surprising if a researcher or clinician who is well-versed in gait analysis outcomes was unfamiliar with this measure. Single support time and percentage are commonly used metrics to define the amount of time a person spends with just one foot on the ground during the gait cycle. While the amount of time spent in single support has shown utility, the SS COP Dist can further our understanding of what is taking place during single support. The distance the COP travels during single support is a measure of how well forward momentum is maintained during single support. It is a measure of the effectiveness of gait’s second rocker. The ability to progress your body weight forward with a single point of contact with the ground proved to be very important in describing gait stability within people with MS.
The Broader Implications
A main focus within movement disorders research is to find sensitive, repeatable ways of identifying minor changes in motor function. Early identification of abnormal gait symptoms is important as it allows for early intervention and the best opportunity for clinicians to change the trajectory of a person’s health and mobility. The evidence presented by Bilek et al. supports continued exploration of advanced gait analysis using technologies such as the Zeno Walkway System. By examining COP movement, gait variability, and lesser used temporal spatial metrics alongside traditional gait metrics, researchers may be able to identify subtle changes in neurological function earlier and better understand how neuromuscular disorders such as MS affect mobility. Gait speed tells us how fast someone walks. Advanced gait analysis may help us understand why they walk the way they do and what that movement can tell us about the body.
Bilek, F., Chaves, A.R., Fesenko, O. et al. Gait instability is a more specific predictor of corticospinal tract function than gait speed in clinically stable multiple sclerosis. Sci Rep 15, 26822 (2025). https://doi.org/10.1038/s41598-025-10830-4