Five RCTs were included (n=91). Quality scores ranged from 5 to 8 out of 10. All studies scored points for random allocation, baseline comparability, between-group analyses and reporting of point estimates and variability. Concealed allocation and blinding of therapists were each adequate in single studies. Assessors and participants were blinded in two studies. Intention-to-treat analysis was performed in two studies. Follow-up was adequate in three studies.
Four of the five RCTs reported improvements of the electrical stimulation in outcomes related to muscle function. There was a significant improvement in peak torque (mean difference 9.64 Newton metre, 95% CI 1.23 to 18.05; three RCTs) and walking distance (mean difference 47.6m, 95% CI 9.1 to 86.0m; three RCTs). There was no evidence of heterogeneity for either meta-analyses (I2=0%). Other outcomes were assessed in one or two studies.
None of the studies reported any adverse effects specific to electrical stimulation.