Allocation, randomization and concealment Patients are randomized using random permuted blocks (2x2x2) and stratified by gender to ensure an equal number of participants in all groups across the allocation period. The allocation sequence is generated through a standardized computer program by an independent researcher not affiliated to the study and is concealed until the study arms are assigned. Randomization of each patient to one of the three groups in the study is done after the baseline tests have been conducted by the health professionals at the promotion centres. The scientific staff is blinded to the allocation. The health professionals at the promotion centre are not blinded to allocation according to control group (1/3) or intervention groups (1/3: IWT and 1/3: IWTsupport). After the intervention period at the promotion centre, the allocation to either control, IWT or IWTsupport is unsealed to the patients and the health professionals at the promotion centres. The scientific staff is still blinded.