To prepare this future study, the investigators set out to test the feasibility of such a study with a feasibility study using an open label randomized cross-over trial including 32 persons aged 40 years or more. The primary aim is to evaluate whether the instructions are clear, the intervention and the study procedures are acceptable and to assess the proportion of participants withdraw from the study (drop outs). Secondary aims are the assessment of between group differences in the changes of the gait stability.