A high intensity vs. casual speed walking intervention to reverse frailty among older adults: a cluster randomized controlled trial.

Interventions to reduce frailty and promote healthy aging are critical to improving quality of life and reducing disability in older adults. Walking is the most common form of exercise among older adults; however, the optimal walking intensity for prefrail and frail adults remains unclear. We conducted a cluster-randomized, assessor- and participant-blinded trial to determine whether high-intensity walking (HIW) improves frailty more than casual-speed walking (CSW). Fourteen retirement communities were randomized to either HIW or CSW using a modified minimal sufficient balance randomization scheme. We recruited 165 prefrail and frail adults aged ≥60 years, of whom 105 were included in the analytic cohort. Participants were able to ambulate at least 10 feet with moderate assistance or less. The HIW group targeted 70% of heart rate maximum (HRmax), while the CSW group walked at self-selected speeds below 60% HRmax. Supervised walking sessions were 45 minutes, three times per week, for 16 weeks. The primary outcome was improvement by at least one frailty category on the SHARE-FI (Survey of Health Among Retired Europeans - Frailty Index). Secondary outcomes included the Timed Up and Go, Short Physical Performance Battery, Berg Balance Scale, and 6-Minute Walk Test (6MWT), measured at baseline and 16 weeks. Participants had a mean (SD) age of 79.2 (8.0) years; 79% were female, and 75% were non-Hispanic White. Improvement in frailty category occurred in 32 of 46 (69.6%) HIW participants versus 26 of 56 (46.4%) CSW participants (OR = 2.91, 95% CI 1.19-7.13, p = 0.02). HIW participants showed greater gains in gait speed (mean difference = 0.08 m/s, 95% CI 0.03-0.13, p = 0.036) and 6MWT distance (mean difference = 48.99 m, 95% CI 21.1-76.9, p = 0.0088). Mean HRmax was 71% in HIW vs. 59% in CSW (p < 0.001). Median completed sessions were similar (HIW = 35; CSW = 36; p = 0.07). This cluster-randomized trial demonstrates that high-intensity walking can reverse frailty more effectively than casual-speed walking due to increased physiologic stimuli during more intensive activity. This study is registered at ClinicalTrials.gov ID NCT03654807 (https://clinicaltrials.gov/study/NCT03709251) Registered 10/12/2018.