The purpose of this study is to test the effect of walking intensity on both frailty category (i.e., frail, pre-frail, and nonfrail) and frailty score as a continuous outcome on the SHARE-FI (frailty instrument). As well as test the effect of walking intensity on mobility, physical function, balance, and total Physical Activity.

Frailty impacts up to 60% of older adults and is a leading cause of dependency among older adults. Frail older adults experience physical problems such as balance difficulties, weakness, decreased endurance, and reduced walking speed that increase risk for falls, hospitalizations, institutionalization, and death. Physical activity has multi-system health benefits and is the most recommended frailty management intervention, but guidelines regarding the specific intensity of physical activity remain unclear. High intensity physical activity is an established and safe therapeutic approach in other populations, but it is unclear as to the extent to which high intensity activity can reduce or reverse frailty. This cluster-randomized study will compare a high intensity walking (HIW) intervention to a self-selected, casual speed walking (CSW) intervention implemented within retirement communities for pre-frail and frail older adults. Investigators will randomize 10 retirement communities with 20 participants at each site (200 total participants) to either a 4-month HIW or CSW intervention. All participants will receive 48, individually supervised overground walking sessions occurring within their retirement community. At the beginning and end of the study, investigators will measure participants' frailty, mobility, physical functioning, balance, and total physical activity measured via an ActivPal accelerometer worn for a 1-week observation period to compare which treatment strategy, HIW or CSW, worked better to reduce frailty (aim #1). Investigators will use the SHARE-Frailty Instrument to evaluate frailty as both a categorical (e.g. non-frail, pre-frail, or frail) and a continuous outcome. This approach will allow investigators to determine how participants move between frailty categories as well as within frailty categories in response to intervention. In aim #2, investigators will determine the effect of walking intensity on mobility, physical functioning, balance, and total physical activity. Investigators hypothesize that HIW participants will show decreased frailty and improved mobility, physical functioning, balance, and physical activity at 4 months. Currently, the optimal physical activity guidelines for older adults with frailty are uncertain. Results from this study will provide important knowledge to inform activity guidelines for older adults with frailty and information on a transformative approach to reducing frailty, improving function, and increasing physical activity among a growing segment of the older adults population.

Inclusion Criteria:

• • > 60 years of age with pre-frailty or frailty as determined on the SHARE-FI.

  • Able to ambulate at least 10 feet with moderate assistance (<50% physical assistance) or less. Participants will be able to use their assistive device (e.g. cane or walker) during sessions.
  • Resident of one of the 10 enrolled retirement community locations. Individuals must be > 60 years of age to move into the retirement communities by virtue of the individual community policies.
  • Provision of informed consent and clearance for participation as determined by the Exercise and Screening for You (EASY).

Exclusion Criteria:

• • Uncontrolled cardiovascular, metabolic, renal, or respiratory disease that limits exercise participation (e.g., previous heart attack within 3 months of enrollment or uncontrolled diabetes)

  • Resting blood pressure > 180/110 mmHg.