mHealth to support resistance training using outdoor gyms: the ecofit hybrid type 3 implementation-effectiveness trial.

BACKGROUND: There is a need to scale up effective physical activity interventions among the general population, particularly those incorporating resistance training. Ecofit is a community-based, multicomponent intervention promoting resistance and aerobic physical activity through smartphone technology, the outdoor built environment, and social support. This study aimed to scale up ecofit by comparing Low versus Moderate implementation support on the reach (outdoor gym use) of ecofit within two large regional municipalities. METHODS: A hybrid type 3 implementation-effectiveness trial was conducted across two large municipalities in eastern Australia. Outdoor gyms (n = 18) were randomized to Low (ecofit app only) or Moderate ecofit app, QR (quick response) codes on equipment, face-to-face workout sessions implementation support. The primary outcome of "reach" was defined as the baseline-adjusted difference in the number of outdoor gym users (i.e. adults using outdoor gym equipment for resistance training) between groups. Reach was measured at baseline and 3-month follow-up using a modified System for Observing Play and Recreation in Communities tool, with blinded assessors observing community members perceived to be ≥18 years categorized as Adults (aged 18-59) or Seniors (aged ≥60). Secondary outcomes included app uptake, dose received, implementation fidelity, and acceptability, feasibility, and dose-satisfaction regarding the app and guided sessions. RESULTS: There was no significant difference in people using outdoor gym equipment for resistance training between Low and Moderate support groups at 3-month follow-up incidence rate ratio (IRR) = 1.68, 95% CI: 0.96-2.94. Among adults (aged 18-59), the Moderate support group showed significantly higher outdoor gym use at follow-up (IRR = 1.83, 95% CI: 1.01-3.31) compared to the Low support group. Over 6 months, 1273 users registered for the app, completing 503 workouts, 62% of which occurred indoors. CONCLUSIONS: Ecofit shows promise for promoting resistance training, particularly among adults. Broader marketing and enhanced engagement strategies may be required to increase outdoor gym use and sustain participation over time.