Promoting Physical Activity Within Breast Cancer Survivors Using Behavior Change Techniques: N-of-1 Randomized Controlled Trials.

Survivors of breast cancer are an important target for health promotion interventions, and physical activity (PA) is recommended with benefits being well established. More and more behavior theory guided interventions are planned and tailored to the individuals, targeting specifics needs and personal characteristics. We aimed to test the effectiveness of two behavior change techniques [coping planning (CP) and self-monitoring (SM)] for promoting PA in survivors of breast cancer, using a single-case design. In a powerful multiple sample N-of-1 RCT, 10 women post-breast cancer (M = 52.8 years) were randomly assigned to four experimental conditions (CP and/or SM, control) for 60 days and their daily step count was observed. The overall effects were analyzed using multilevel time-series with random intercepts. Time-series regression models and supplementary pairwise analyses were conducted for individuals. Multilevel analyses showed significant effects of CP and SM. Single-case analyses showed that six participants walked significantly more on the intervention days, that combined interventions were effective for five participants, but two participants had better results with the other two conditions. Combined self-regulatory techniques were more effective in promoting PA however, individual variability should be considered in future studies with survivors of breast cancer. Retrospectively registered: https://osf.io/eakjy/?view_only=81bf3dc084a0410a8ea28265e0f3c360, 31-01-2023.(raise query).