Long-term effect of smartphone-delivered Interval Walking Training on physical activity in patients with type 2 diabetes: protocol for a parallel group single-blinded randomised controlled trial

Introduction: Physical activity is a cornerstone in type 2 diabetes (T2D) rehabilitation. Effective long-term and low-cost strategies to keep these patients' physically active are needed. However, maintaining physical activity behaviour is difficult once formalised interventions end. Structured exercise training supported by mobile technology and remote feedback is potentially an effective strategy. The objective of the trial is to investigate whether mobile health support using the InterWalk application for smartphones is effective in increasing physical activity levels in persons with T2D over time compared with standard care. We investigate whether Interval Walking Training using the InterWalk application is superior to Danish municipality-based rehabilitation in increasing moderate-and-vigorous physical activity levels in patients with T2D across 52 weeks. Secondary, we hypothesise that a motivational programme added from end of intervention to 52 weeks further increases level of physical activity in everyday life in patients with T2D. Methods and analysis: The trial is a parallel-group, open-labelled, randomised controlled trial with long-term follow-up at 52 week including patients with T2D. The primary outcome is change in moderate-and-vigorous physical activity. The key secondary outcome includes motivation for physical activity behaviour change. Other secondary outcomes are VO2-peak, strength in the lower extremities. Exclusion criterion is medical contraindication to exercise. We include up to 246 patients and randomly allocate them into a control (standard group) or an experimental group (8-12 weeks of IWT supported by the smartphone-based InterWalk application) in a 1: 2 fashion. After intervention, the experimental group is randomly allocated into two follow-up conditions with unsupervised IWT with or without motivational support until 52-week follow-up. The intention-totreat principle is applied. Ethics and dissemination: The local regional Research Ethics Committee in Denmark (H-1-2014074) and the Danish Data Protection Agency (j.nr.2014-54-0897) have approved the trial. Positive, negative or inconclusive results will be disseminated in scientific journals and conferences.