Fig. 2

The feasibility (A–D) and reliability (E, F) of the perturbation protocol. p-values are indicated for the different variables if significant differences were found. Bar graphs indicate mean and standard deviation values. A Subjective rating of how relaxed and disturbed children with cerebral palsy (CP) and typically developing children (TD) felt before and after the perturbation trials. B Stride-cycle normalized ankle angle for both typically developing and cerebral palsy group during Pre and Post trials and unperturbed (unp)strides during perturbed trial. Color coding corresponds with that as indicated in the next sub-figure. C Comparison of parameters calculated for the Pre, Post and unperturbed strides for both participant groups. D Comparison between the unperturbed and perturbed strides and the five recovery strides for both groups using t-tests (group indicated at the specific p-value). E Evaluation of the GM and SO muscle response to the highest intensity perturbation over time (i.e., repetitions) for both groups in bold as well as the individual values in lighter colors. EMG is normalized to the average maximum of each participant during push-off of the unperturbed strides. Note that the perturbations were applied during two different trials with a short break in between, which did not visibly affect the results. F Coefficient of variation (COV) between the 1000 bootstrap repetitions per subset of n (2–8) random selection of strides from the available perturbed strides per participant and the average over participants in bold