To assess the feasibility and changes in outcomes of a 12-week high-intensity interval training (HIIT) program in individuals with symptomatic knee osteoarthritis (OA).
The single-arm trial included 29 participants (mean ± SD age 63 ± 7 years; 66% women; 66% obese). Measures of participant flow, adherence, and tolerability were collected. Pain, function, and balance were assessed at baseline, 6 weeks, and 12 weeks using the Western Ontario and McMaster Universities Osteoarthritis Index, 20-m fast-paced walk test, 30-second chair-stand test, stair-climb test, timed up and go test, and single leg stance. Cardiorespiratory fitness, strength, and body composition were evaluated using peak oxygen consumption (VO peak), isometric knee extensor/flexor strength, and dual-energy x-ray absorptiometry, respectively. HIIT was completed two times/week (cycling or treadmill) and consisted of 10 repetitions of 1-minute bouts at 90% VO peak, with 1-minute rest periods. Separate multivariable-adjusted linear mixed models were fit for each outcome with fixed effects of time, age, sex, body mass index, and random effects of baseline values to estimate mean changes and 95% confidence intervals (CIs) between baseline and 12-week assessments.
Recruitment aligned with the anticipated enrollment rate, adherence was 70%, and no adverse events were reported. At 12 weeks, improvements were observed for most outcomes, with notable mean changes for the 20-m fast-paced walk (-1.13 [95% CI -1.61 to -0.64] seconds), 30-second chair-stand (2.6 [1.8-3.4] stands), and VO peak (0.14 [0.03-0.24] liters/minute).
In this 12-week pilot study, HIIT improved multiple aspects of health in individuals with knee OA; larger studies are needed.

© 2021 The Authors. ACR Open Rheumatology published by Wiley Periodicals LLC on behalf of American College of Rheumatology.