1. Additional methods table.

Binary data	We planned to present the relative risk (or risk ratio) with a 95% confidence interval, and calculate the number needed to treat for an additional beneficial outcome as an absolute measure of treatment effect. We will report the odds ratio (OR) with a 95% confidence interval in future updates of this review, as most studies with a dichotomous outcome report the OR.
Cluster trials	We planned to seek direct estimates of the effect from an analysis that accounted for cluster design. Where the analysis in a cluster trial did not account for the cluster design, we planned to use the approximately correct analysis approach, presented in the Cochrane Handbook for Systematic Reviews of Interventions (Higgins 2011c).
Crossover trials	Where studies presented repeated measurements over time, we planned to only include data from 1 time point from an individual study in any single meta‐analysis. If inadequate data were available to conduct this analysis, we planned to only include data from the first phase of the cross‐over trial, as if it were from a parallel trial design. We planned to combine the results of cross‐over studies with those of parallel studies by imputing the post‐treatment, between‐condition correlation coefficient from an included study that presents individual participant data, and use this to calculate the standard error of the SMD, using the generic inverse‐variance method.
Assessment of reporting biases	Where we identified evidence of publication bias, we planned to consider its likely influence on the observed effect sizes in our interpretation of the results. However, as common tests of publication bias lack sensitivity, we planned to consider the possible influence that a dominance of small trials might have on pooled effect sizes in our interpretation.
Subgroup analysis and identification of heterogeneity	We planned to further explore possible clinical heterogeneity through preplanned subgroup analysis based on important clinical features. We predicted that some trials would include ambulatory participants only (i.e. people who could walk with or without a mobility aid; GMFCS level I, II, and III), and some studies would include participants who could walk without a mobility aid only (i.e. GMFCS level I and II). Where adequate data allowed, we planned to undertake 2 subgroup analyses for studies that included ambulatory people only (i.e. GMFCS level I, II, and III), and for studies that included ambulatory people who walk without a mobility aid only (i.e. GMFCS level I and II).
Sensitivity analysis	We planned to explore the impact of studies at high risk of bias by reanalysis after excluding studies rated at overall high risk of bias. We also planned to explore the impact of excluding studies at high risk of bias for missing data through reanalysis. We planned to explore the influence of using imputed correlation coefficients in our approach to including cross‐over and cluster trials by reanalysing these data with adjusted (higher and lower) coefficient values.

GMFCS: Gross Motor Function Classification System; SMD: standardised mean difference.