Multiple intervention strategies have been found effective for increasing physical activity among breast cancer survivors, yet most breast cancer survivors fail to meet physical activity recommendations. Optimization of interventions can facilitate real word implementation to ensure effective and efficient intervention delivery. Using a full-factorial design based on the Multiphase Optimization Strategy, 337 breast cancer survivors were randomized to receive a combination of four intervention components: (1) supervised exercise sessions, (2) facility membership, (3) Active Living Every Day (ALED), and (4) Fitbit. Moderate-to vigorous (MVPA) and light-intensity physical activity (LPA) were measured at baseline, 3 months, and 6 months with a hip-worn Actigraph GT3X+. Normal linear mixed models with separate intercepts for each subject were fit in the SAS 9.4 Mixed procedure. Participants who received supervised exercise sessions engaged in more MVPA, 153.58 min/week vs. 133.0 min/week (F = 3.97, p = 0.048) and LPA, 170.26 min/day versus 160.98 light PA minutes/day (F = 4.67, p = 0.032), compared to participants who did not receive supervised exercise. The effects of the three other intervention components on MVPA were not significant; however, those that received ALED engaged in less LPA (F = 6.6, p = 0.011). Supervised exercise sessions resulted in significant increases in MVPA and LPA in a sample of breast cancer survivors. Of note, these sessions were provided only during the first 6 weeks of the intervention and effects remained significant at 6 months. Results of this trial could inform future implementation efforts to ensure effective and efficient delivery of physical activity programs for breast cancer survivors.
