Sample size
The study was conducted with a small effect size of 0.25 and sample size was calculated with G*Power 3.1.9.7 for 4 repeated measures in 2 study groups. For the sample size calculation of within-between interaction ANOVA, power of the study was set at 95% and type I error was taken as 5%. Minimum of 36 subjects would be necessary for the study, however as dropouts are very common in studies, we increased the estimated sample 20%. The needed sample size was 42 (21 in each group).