Statistical analysis
NRS
The sample size was determined prior to the start of the experiment based on a pilot study with a difference in PPV between ML I to ML II of 20 cm/s and sigma of 20, with the significance level set at The data were analyzed using SPSS version 27 (IBM Corp. Released 2016. IBM SPSS Statistics for Windows, Armonk, NY: IBM Corp.) in cooperation with a statistician. The four tested plateau times, 0.5, 1.5, 3 and 5. seconds, did not demonstrate any statistically significant difference regarding PVV or NRS, regardless of the electrode setup or measurement level. For this reason, the outcome values for PVV and NRS used in the final statistical analysis were based on all values, for all participants, obtained during the four different plateau times. Based on the relatively small number of participants and the Shapiro–Wilk indicating non normal distribution, the non-parametric Wilcoxon signed rank test was chosen to determine if there were any statistically significant differences between medians regarding current intensity (mA), PVV or NRS, for the two electrode setups. The data included some outliers, which were handled both using a rank-based statistics test and by adjusting the values of the outliers to the lowest/highest value within 1.5 times the interquartile range from the first respectively third quartile for the inferential statistics (Altman 