Effects of the Fit2Thrive technology-supported physical activity promotion intervention components on sedentary behavior and light physical activity in breast cancer survivors

PURPOSE: Less sedentary time (ST) and more light physical activity (LPA) are associated with improved health outcomes among breast cancer survivors. However, less is known about whether interventions designed to increase moderate-to-vigorous physical activity (MVPA) also influence time spent sedentary and in LPA. This study explored the overall and component-specific effects of the Fit2Thrive technology-supported MVPA intervention on ST and LPA in breast cancer survivors. METHODS: = 52.5; SD = 9.9) received a core intervention (Fitbit and Fit2Thrive smartphone app) and were randomized to five components ("on" vs. "off"): Support Calls, Deluxe App, Fitbit Buddy, Online Gym, and Text Messages for 12 weeks. Mixed-effects models examined accelerometer-assessed ST and LPA changes, overall, and by intervention component at 12 and 24 weeks. We also examined relationships between changes in MVPA with ST and LPA, and moderating effects of demographic and disease characteristics on component effects. RESULTS: Compared to baseline, ST significantly decreased at 12 weeks (β = -14.2 min/day; p < 0.01); reductions were maintained at 24 weeks (β = -11.0 min/day; p < 0.01). LPA significantly increased at 24 weeks (β = 7.4 min/day; p = 0.04), but not at 12 weeks. No component effects were significant. Greater increases in MVPA were associated with greater ST decreases and LPA increases. Time since diagnosis moderated effects of the Deluxe App on ST and LPA. CONCLUSIONS: Participation in an mHealth MVPA promotion trial was associated with modest reductions in ST and increases in LPA, while also increasing MVPA. Findings suggest the core intervention may have been sufficient to support favorable changes across movement behaviors. Future research should investigate how to enhance effects while maximizing MVPA and health outcomes. IMPLICATIONS FOR CANCER SURVIVORS: Participation in an mHealth MVPA promotion trial may also result in reduced ST and increased LPA.