Shannon Hernon ¹ Yashi Singh ¹ Nathan Ward ² Arthur Kramer ³ Thomas G. Travison ⁴ Joe Verghese ^5,6 Roger A. Fielding ⁷ Christopher A. Kowaleski ⁸ Kieran F. Reid ^1*

• ¹ Brigham and Women's Hospital, Harvard Medical School, Boston, Massachusetts, United States
• ² Tufts University, Medford, Massachusetts, United States
• ³ Northeastern University, Boston, Massachusetts, United States
• ⁴ Hinda and Arthur Marcus Institute for Aging Research, Harvard Medical School, Roslindale, Massachusetts, United States
• ⁵ Department of Neurology, Albert Einstein College of Medicine, Bronx, New York, United States
• ⁶ Department of Medicine, Albert Einstein College of Medicine, Bronx, New York, United States
• ⁷ Jean Mayer USDA Human Nutrition Research Center on Aging, Tufts University, Boston, Massachusetts, United States
• ⁸ Somerville Council on Aging, Somerville, MA, United States

The motoric cognitive risk syndrome (MCR) is a syndrome characterized by subjective memory complaints and slow walking speeds that can identify older adults at increased risk for developing Alzheimer's disease or a related dementia (ADRD). To date, the feasibility of community-based physical activity (PA) programs for improving outcomes in MCR have yet to be examined. To address this knowledge gap, we conducted a translational randomized controlled trial (RCT) comparing 24-weeks of PA to a healthy aging education (HE) control intervention delivered within the infrastructure of an urban senior center in Greater Boston (clincaltrials.gov identifier: NCT03750682). An existing senior center employee was trained to administer the multimodal groupbased PA program that included moderate-intensity aerobic walking, strength, flexibility and balance training. Seventy-nine older adults attended for screening, of whom 29 met the MCR criteria and 25 were randomized to PA or HE (age: 74.4±7yrs; BMI: 32.4±7kg/m 2 ; 85% female; 3MSE score: 92.4±7; gait speed: 0.52±0.1 m/sec; SPPB score 4.8±1.9). Participants could successfully adhere to the study interventions (overall attendance rate: PA: 69% vs. HE:70%). Participants successfully completed baseline and follow-up study assessments including a computerized cognitive testing battery and objective tests of physical performance and functional exercise capacity. No study-related adverse events occurred. Notable trends for improved cognitive performance, gait speed and 6-minute walk distance were exhibited in PA. Our study provides important information to aid the design of larger-scale RCTs of PA that may help to preserve the independence of older adults at high risk for ADRD in community-based settings.