The Sedentary to Active Rising to Thrive (START) Trial

The goal of this behavioral clinical trial is to compare two different ways of becoming less sedentary and more active in 60 older adults at elevated risk of becoming frail. The main question this project aims to answer are whether participants in each intervention are able to gradually replace 30 minutes of sedentary (sitting-like) behavior with very light walking over 60 days. There are other questions this project aims to answer that include: 1. whether it is easier to replace sedentary behavior with one 30-minute walking bout or three 10-minute walking bouts 2. whether becoming less sedentary and more active leads to feeling better, have less stress, pain, and fatigue and have more confidence in becoming more regularly active 3. whether becoming less sedentary and more active leads to better regulation of inflammation and metabolism Participants will be randomized into one of two sedentary reduction behavior programs; one program that gradually replaces sedentary time with one 30-minute walking bout and the other program that gradually replaces sedentary time with three 10-minute walking bouts in the morning, afternoon, and evening. Researchers will compare both programs to see which one is easier to achieve and maintain over 60 days.

Inclusion Criteria: * Adults aged ≥65 years * Pre-frail defined as having 1-2 of the following criteria: * Self-reported unintentional weight loss * Self-reported fatigue * Self-reported low activity * Slowness measured during a 4-m walking test * Weakness measured with grip strength * Self-reported regular physical activity \2 times in the past month * Participation in another clinical trial * Plan to move out of the area within 6 months * Inability to provide self-transportation to study assessment visits * Inability to complete a usual-paced 400m walking test within 15 minutes without sitting or the help of another * Uncontrolled resting hypertension (\>160/90 mmHg) * Cognitive impairment determined using the Montreal Cognitive Assessment Test