Scaling Exponent of Human Gait: A Scoping Review

Nonlinear analysis such as detrended fluctuation analysis (DFA) and power spectrum density are often used to describe the gait motor behavior. This is an interdisciplinary effort to understand and evaluate human movement by the complexity field lenses. However, there are conflicting interpretations about the measures. For instance, the same alpha value could be a better adaptation or sign of pathology. Therefore, the purposes of this scope review are: to map scientific production in the application of the scaling exponent for gait and running analysis, identify the scaling methods used in these studies and the results interpretation, and identify knowledge gaps for future studies. Eleven methods and six metrics associated with them were found. Most of the papers use DFA and explain the results through hypotheses about the supraspinal influence and origin of long-range correlations, adaptability and stability during gait and running. Comparing studies and interpretations, we found a broad designation of terms for the same metric. This reflects the lack of agreement and language uniformity in this literature.