Table 1 Data collection schedule on feasibility aspects and related uncertainties

 Eligibility screening process (PC1)^a and inclusion rate (PC2)^a

X

  Retention rate (PC3)^a

X

X

X

X

 Information and communication accuracy

X

 Inclusion and exclusion assessment

X

 Assessment on demography and clinical characteristics

X

 Acceptability of time required for assessment procedures

X

X

 Blood-sampling procedures

X

 Attitude towards long-term follow-up assessments

X

 Training session time of day and weekly frequency

X

 Duration of training session

X

 Individual adjustment of:

  Exercises related to intervention progression

X

X

X

  Level of challenge across the progression blocks

X

X

X

  Exercises related to disability level and variation in daily capacity

X

X

X

 Monitoring of level of challenge

X

X

X

 Group training despite divergence in level of overall MS disability

X

 Individual balance exercises

X

 Safety in training

X

 Home exercise program as substitute for group training session

X

 Individual effort required for participation

X

 Motivation in training

X

 Attendance at training sessions (PC4)^a

X

 Perceived intervention effect on balance control

X

 Willingness to recommend the training (PC5)^a

X

 Primary outcome:

  Primary outcome suitability of the Mini-BESTest^c (PC6)^a

X

X

 Secondary outcomes:

  10-Meter Walk Test^c

X

X

  2-Minute Walk Test^c

X

X

  APDM^b Gait analysis (spatial and temporal gait parameters)

X

X

  APDM^b Sway test

X

X

  Six Spot Step Test^c

X

X

  Multiple Sclerosis Walking Scale^c

X

X

  Falls Efficacy Scale International^c

X

X

  Frenchay Activities Index

X

X

  Multiple Sclerosis Impact Scale-29^c

X

X

  Modified Fatigue Impact Scale^c

X

X

  Hospital Anxiety and Depression Scale

X

X

  EuroQol-5D (Index and Visual Analog Scale^c)

X

X

  Life Satisfaction Scale

X

X

  Acceptance of Chronic Health Condition Scale

X

X

  Trail Making Test^c

X

X

  Ray Auditory Verbal Learning Test^c

X

X

  Symbol Digit Modalities Test^c

X

X

  Immunological markers in blood

X

X