Data extraction
We extracted following data by a standardized electronic form (Microsoft Office, Excel sheets): first author’s name, publication year and country, design of study, gender and age of subjects, sample size, intervention duration and creatine dose. Also, we extracted mean and SD of plasma CK and LDH at baseline and after the intervention. Any recorded standard errors of mean (SEM), were converted to SDs through this formula: (SD = SEM × √n (n = number of individuals in intervention or placebo groups). At last, in papers that reported information in figures, extraction was carried out using GetData Graph Digitizer 2.24 (26).