Table 1 Intervention chart

PETTLEP approach to MI (Holmes and Collins 2001)

- Study CDs or dropbox link including the audio mix and download to smartphone, laptop, tablet or MP3-player

- 4 sessions on each CD, one for each week

- Headphones or earphones could be used if desired

For example, music titles used in week two were: Unheilig, Der Berg (Intro), 82 bpm; Black, Wonderful Life, 106 bpm; Malcolm Arnold, The River Kwai March, 120 bpm; Uriah Heep, Lady in black, 86 bpm; Abba, Dancing queen, 101 bpm; Toto, Africa, 100 bpm; DJ Bobo, I’m living to love you, 110 bpm; Katy Perry, Firework, 120 bpm.

After completion of the main study, a download of the 3 study CDs will be available upon request from the corresponding author.

- MI introduction, familiarisation and training: in lay language; description of the concept of MI; its application and effects in sports and neurorehabilitation; principles of neuroplasticity; MI perspectives (internal and external) and modes (visual, kinaesthetic).

- Measurement of actual and imagined walking duration over a 6-m distance to monitor the mental process

- Performance feedback for participants and repeated training if desired

- Weekly phone calls for support and adherence reports

- Additional introduction to rhythmic auditory stimulation plus its use in neurorehabilitation

- Rhythmic-cued MI familiarisation

- Practise at any time of the day when alert

- Seated in an upright body position

- Shoulders relaxed

- Avoid tightening the muscles or moving

- Eyes closed

- Normal breathing

- Practice in a quiet place at home

- Imagine walking indoors (long hallway similar to that in the MS Clinic) and walking outdoors (on a straight and familiar path)

- Take long strides

- Take giant strides

- Roll your feet on the ground and feel your body weight on your soles

- Touch the ground with your heels first

- Raise the front of your feet

- Raise your knees

- Pace

- Place/feel your weight on your feet

- Place/feel your weight on your legs

- Stamp your feet while walking

- Walk effortlessly, almost as if you were floating

- Walk forcefully and energetically as if you were an athlete

- March as if you were in the army

- Walk in an extremely upright posture such as when balancing a sachet, filled with rice, on your head

- Feel the swinging of your arms while walking

- Feel the swinging of your legs while walking

- Tempo (cadence) was between 80 and 120 steps/min

- Slow, medium and fast music pieces alternated, with a general progression in the tempo

- The imagined walking tempo was consistent with the music beat at 80–120 bpm.

- See familiarisation

- Additionally, weekly phone call support was provided

MI instructions included motivational and arousal enhancing aspects (e.g. walk forcefully and energetically as if you were an athlete). See instructions under Tasks.

Motivational instrumental music was used with the MI

Kinaesthetic MI from an internal, first-person perspective

The intervention including the preparation of the CDs was provided by the researcher (BS), an experienced physiotherapist with 11 years of musical training.

- MI introduction, familiarisation and training: individually or in small groups (2–3 participants) and depending on the group they were allocated to

- Monitoring of mental process: individually

- Weekly phone calls: individually

- MI introduction, familiarisation, training and monitoring of mental process: at MS Clinic Innsbruck, Department of Physiotherapy

- Cued MI practice: At participants’ homes

17 min, 6 times a week, for 4 weeks

- Intervention adherence was assessed using a participant diary and also during weekly phone calls and at post-intervention

- Recording in excel sheets was performed by the researcher (physiotherapist) who instructed participants

The adherence rate was median 5 (range 4, 6) times per week or 83% (95% confidence interval 0.42, 0.99).