100 CHAPTER 5 To calculate a number needed to treat, we used a Fisher’s exact test to compare the proportion of participants in each group who reached the minimal clinically important difference on the SRQ-DLV total score, defined as a difference of ≥ 12 points. 187 The number needed to treat was calculated as the reciprocal of the absolute risk reduction. 191 For our secondary objective, we used paired-samples t-tests to assess the retention of the effects of the MR on all primary and secondary outcomes. To this end, we merged both groups into a single intervention group, comparing the outcome directly after completion of the MR (T1 for MR group, T2 for UC group) with the outcome at 18 weeks follow-up (T2 for MR group, T3 for UC group). All statistical analyses were performed with SPSS (IBM SPSS Statistics for Windows, Version 25.0. Armonk, NY: IBM Corp). Results Inclusion, data acquisition and compliance A total of 105 patients with established NA and scapular dyskinesia were screened for eligibility between March 1st 2018 and March 16th 2020. After applying all inclusion and exclusion criteria, 47 patients were included and randomly assigned to the MR (n = 24) and UC (n = 23) group. Due to the COVID-19 pandemic, we fell slightly short of the intended inclusion of 50 participants. Three out of 47 participants were excluded after the baseline measurement (T0) and randomization: 2 because of late recognition of bilateral involvement (one in each group) and 1 due to late recognition of pre-existing neurological condition (MR group). Ten participants dropped out during the study (all UC group): 5 due to a recurrent NA episode, and 5 on own request. Data from 3 drop-outs could still be used for primary analysis since time of dropout was after T1. Hence, we had 22 participants in the MR and 15 in the UC group for primary analysis. Another 2 participants were lost to follow-up (1 in each group) after T1 (Figure 1). Due to the COVID-19 pandemic, physical measurements (3D-reachable workspace and strength measurements) were not possible for approximately 2 months during the trial and, as a consequence, those outcomes were missing in 5 participants. As for therapy adherence in the MR group, 12 participants received at least 1 MR session online due to COVID-19 pandemic (Supplementary Table 1). In the UC group, there were 2 diaries missing of participants who dropped out. Five participants in the UC group received no treatment at all and the other 7 received mainly a general approach physical therapy that involved either massage, exercises, strength and/or aerobic training (4-29 consultations per participant in total) (Supplementary Table 2). No (serious) adverse effects related to the study and/or intervention were reported. Baseline characteristics Baseline characteristics for both groups are shown in Table 1. There were no group differences for age, sex, education or work status between both groups. A marked group difference, however, was found for the time since onset of NA. Participants in theMR group had a significantly longer period between the onset of NA and their inclusion compared to UC (t = 1.620; p = 0.007). In the MR group, there was 1 outlier with a duration of 204