Randomization and blinding
DIAfit was a cluster randomized controlled single-blind trial 1:1. At the start of the clinical program, two different exercise frequency variants were introduced and tested. Patient groups were allocated per cluster (i.e., treatment centre) to randomly start one program variant first and then the other using concealed opaque envelopes. Each centre thus provided both variants. Selection and randomization took place 2 weeks before the start of each program and were performed by a central coordinator (OG) who was not involved in the study. Patients signed informed consent before knowing their group allocation. Health care providers and investigators were blinded to group allocation before the start of the first program. The primary outcome assessors were always blinded to the respective variant. Patients and the clinical staff such as the physical therapists could not be blinded since they knew how many sessions per week were attended. Both program variants were matched by number of sessions (Details of the standard and alternative interventions.HR, heart rate; RM, repetition maximum.