Community-based intervention effects on older adults' physical activity and falls: Protocol and rationale for a randomized optimization trial (Ready Steady3.0).

The Ready Steady 3.0 trial is designed to test the main and interactive effects of two behavior change intervention components, within an 8-week physical activity intervention, on older adults' physical activity (PA). Each component is comprised of behavior change strategies that emphasize two different evidence-based ways to motivate older adults to be active: interpersonal and intrapersonal. 308 adults ≥70 years old will be randomized to 1 of 4 conditions in a 2 × 2 full factorial trial in which the two factors represent the receipt (No, Yes) of interpersonal or intrapersonal behavior change strategies. Participants will also receive two core intervention components: the Otago Exercise Program adapted for small groups and a PA monitor. Interventions across conditions will be delivered during 8 weekly, small group, meetings in community settings. The primary outcome of PA, measured objectively, and secondary outcomes of falls and the quality of life will be assessed at baseline and post-intervention: 1 week, 6 months, and 12 months. Findings will enable the identification of behavior change content that contributes to physical activity outcomes within a physical activity intervention for older adults. This study is one of the first to use the MOST framework to guide the development of a community-based physical activity intervention for older adults to reduce the public health problems of low PA and falls. The results will enable the optimization of behavior change content within a PA intervention for older adults and, in turn, other PA interventions for older adults.