Reproducibility of transcranial magnetic stimulation metrics in the study of proximal upper limb muscles

Abstract Objective : Reproducibility of transcranial magnetic stimulation (TMS) metrics is essential in accurately tracking recovery and disease. However, majority of evidence pertains to reproducibility of metrics for distal upper limb muscles. We investigate for the first time, reliability of corticospinal physiology for a large proximal muscle – the biceps brachii and relate how varying statistical analyses can influence interpretations. Methods : 14 young right-handed healthy participants completed two sessions assessing resting motor threshold (RMT), motor evoked potentials (MEPs), motor map and intra-cortical inhibition (ICI) from the left biceps brachii. Analyses included paired t -tests, Pearson’s, intra-class (ICC) and concordance correlation coefficients (CCC) and Bland–Altman plots. Results : Unlike paired t -tests, ICC, CCC and Pearson’s were >0.6 indicating good reliability for RMTs, MEP intensities and locations of map; however values were