PROJECT SUMMARY Cancer and treatment-related cognitive changes cause distress, hinder resumption of normal routine and roles, and worsen quality of life. Hematopoietic cell transplantation (HCT) is a potentially life-prolonging treatment for patients with hematological malignancies. HCT differs from the delivery of chemotherapy in other cancer settings due to the intensity of chemotherapy and severity of toxicity. Previously reserved for younger patients, in the past decade a growing number of adults 60 years of age and older have received this intense treatment. Our preliminary data shows that post-HCT, 35% of older patients experience significant cognitive impairment compared to 19% pre-HCT. Physical activity improves cognitive function in older adults and survivors of other cancers. While untested in older adults undergoing HCT, we hypothesize that increasing physical activity can also improve cognitive function in this vulnerable population. The objective of this proposal is to adapt and test an evidence-based physical activity intervention, The Community Health Activities Model Program for Seniors II (CHAMPS II), in the HCT setting to improve cognitive function for adults 60 years and older. This program is effective in increasing physical activity for sedentary community-dwelling older adults with multiple chronic health conditions. We will iteratively adapt and implement CHAMPS-II in three waves. During each wave, 2-4 patient/care-partner dyads will participate in a multi-phase, light- to moderate-intensity physical activity program. We will use a Type 1 hybrid effectiveness-implementation design to determine the preliminary effectiveness of the adapted intervention to improve cognitive function compared to an active control condition (N = 34 per group). This novel trial design spans the effectiveness and implementation research to accelerate the translation of physical activity interventions into practice for older adults with cancer. The translation of physical activity interventions into clinical practice remains challenging within cancer survivorship, despite promising evidence of efficacy in improving functional outcomes and quality of life. To become an independent researcher who develops, implements, and disseminates interventions that prevent cognitive decline and improve functional outcomes for older patients with cancer, Dr. Koll requires additional training and experience in: 1) physical activity promotion and principles of exercise training; 2) design and conduct of hybrid effectiveness-implementation clinical trials; and 3) leadership and project management skills needed to execute translational studies requiring collaboration between researchers and clinicians. An outstanding team of mentors and advisors support this proposal with expertise in geriatrics (Fisher), behavioral and implementation science (Estabrooks), clinical exercise trials in older adult and cancer populations (Ehlers), geriatric oncology (Wildes), cognitive ...