Neuromotor processes are inherently noisy, which results in variability during movement and fluctu-ations in motor control. Although controversial, low levels of variability are traditionally considered healthy, while increased levels are thought to be pathological. This systematic review and meta-analysisof the literature investigates the thresholds between healthy and pathological task variability.
After examining 13,195 publications, 109 studies were included. Results from over 3000 healthy sub-jects and 2775 patients revealed an overall positive effect size of pathology on variability of 0.59 forwalking and 0.80 for sway. For the coefficient of variation of stride time (ST) and sway area (SA), upperthresholds of 2.6% and 265 mm2discriminated pathological from asymptomatic performance, while 1.1%and 62 mm2identified the lower thresholds for pathological variability. This window of healthy perfor-mance now provides science based evidence for the discrimination of both extremely low and extremelyhigh levels of variability in the identification as well as standardised monitoring of functional status inneurological cases.
N. König, W.R. Taylor, C.R. Baumann, N. Wenderoth, N.B. Singh (2016). Revealing the quality of movement: A meta-analysis review to quantify the thresholds to pathological variability during standing and walking. Neuroscience and Biobehavioral Reviews, 68: 111. https://doi.org/10.1016/j.neubiorev.2016.03.035
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