# High-Intensity Interval Training for Knee Osteoarthritis: A Pilot Study PMID: 34363745 Journal: ACR open rheumatology Published: 2021-10-01 Authors: Golightly YM, Smith-Ryan AE, Blue MNM, Alvarez C, Allen KD, Nelson AE ## Question Among adults with symptomatic knee osteoarthritis, is a two-session-per-week, 12-week supervised HIIT program feasible and tolerable, and what short-term changes occur in symptomatic, functional, fitness, strength, balance, and body composition outcomes? ## Summary This single-arm pilot study tested whether adults with symptomatic knee osteoarthritis could complete a 12-week, twice-weekly supervised HIIT program using cycling or treadmill walking. The protocol used 10 one-minute hard bouts at about 90% VO2peak with one-minute complete rests. Adherence was 70% through 12 weeks, enjoyment was high for about two-thirds of completed sessions, and no HIIT-related adverse events were reported. Most physical function, WOMAC symptom, knee extensor strength, balance, and VO2peak outcomes improved, while body composition did not change significantly. ## Population - 29 adults with symptomatic knee osteoarthritis, mean age 63 years, 66% women, 66% obese, not meeting physical activity guidelines and medically cleared for participation. - Sample size: 29 - Age: Mean 63 +/- 7 years; eligibility 40-75 years. - Sex: 66% women; 34.5% male at baseline. - Fitness level: Insufficiently active by physical activity guideline criteria; baseline VO2peak 2.1 +/- 0.7 L/minute. - Health status: Symptomatic knee osteoarthritis with WOMAC pain score at least 6 of 20; BMI 18.5-50 kg/m2; many participants overweight or obese. ## Methodology - Single-arm feasibility and proof-of-concept intervention study with assessments at baseline, 6 weeks, and 12 weeks. - 12 weeks - University clinical/research setting with one-on-one supervised HIIT sessions led by trained research personnel. ## Protocol - Supervised knee OA HIIT. - Modality: Cycling or treadmill walking. - Work intervals: 1 minute at 90% VO2peak, or 90% maximum heart rate for treadmill walkers. - Recovery: 1 minute complete rest. - Sets or repetitions: 10 repetitions. - Intensity: 90% VO2peak; prescribed vigorous intervals. - Session duration: Approximately 23-25 minutes including 3-5 minute warm-up and interval block. - Frequency: 2 sessions per week with at least 24 hours between sessions. - Program length: 12 weeks. - Progression: Tailored to participant capabilities and mode preference; no formal workload progression rule reported. ## Outcomes ### Adherence and completion Status: improved 25 of 29 participants completed 6 weeks and 21 of 29 completed the full 12-week program; adherence was reported as 70% at 12 weeks. ### Adverse events Status: no clear change No adverse events related to the HIIT program were reported, including among participants who discontinued. ### Physical function Status: improved All performance-based physical function measures improved significantly from baseline to 12 weeks. 20-m fast-paced walk -1.13 seconds (95% CI -1.61 to -0.64); 30-second chair stand +2.6 stands (1.8 to 3.4); stair climb -1.42 seconds (-2.13 to -0.71); timed up and go -0.58 seconds (-0.95 to -0.22). ### WOMAC symptoms Status: improved WOMAC total score and pain, stiffness, and function subscales improved significantly from baseline to 12 weeks. WOMAC total -9.2 (95% CI -13.6 to -4.9); pain -1.7 (-2.8 to -0.6); stiffness -1.2 (-1.7 to -0.7); function -6.3 (-9.6 to -3.1). ### Cardiorespiratory fitness Status: improved VO2peak and time to exhaustion improved significantly from baseline to 12 weeks. VO2peak +0.14 L/minute (95% CI 0.03 to 0.24); time to exhaustion +1.07 minutes (0.63 to 1.50). ### Knee extensor strength Status: improved Right and left knee extensor maximum strength improved significantly from baseline to 12 weeks. Right knee extensor +9.99 Nm (95% CI 1.80 to 18.18); left knee extensor +9.86 Nm (0.40 to 19.33). ### Body composition Status: no clear change Lean mass, fat mass, visceral fat, leg lean mass, and fat percentage did not show statistically important changes. Baseline-to-12-week CIs for body composition outcomes crossed zero. ## Practical Insights - A twice-weekly 10 x 1-minute HIIT protocol can be feasible for medically screened adults with symptomatic knee OA when supervised and delivered with low-impact modalities. - Complete rests and cycling/walking modality options are important translation details for joint-sensitive users. - This study supports cautious programming around function and fitness, not body composition change. - Initial supervision or highly guided onboarding should be considered before expecting symptomatic knee OA users to perform independent HIIT. ## Limitations - Single-arm design with no control group. - Small pilot sample. - Not powered for hypothesis testing. - No outcome assessments before 6 weeks. - Diet and caloric intake were not monitored. - No long-term follow-up after the 12-week intervention. - Supervised cycling/treadmill protocol may not generalize to unsupervised or high-impact HIIT. ## Safety And Adherence - No adverse events related to HIIT were reported. - Participants completed ECG and physician clearance before participation. - Sessions were supervised one-on-one and heart rate was monitored. - Mode modifications were used for stiffness and range-of-motion limitations. ## Original Sources - [PubMed](https://pubmed.ncbi.nlm.nih.gov/34363745/) (pubmed) - [DOI](https://doi.org/10.1002/acr2.11318) (doi) - [PMC full text](https://www.ncbi.nlm.nih.gov/pmc/articles/PMC8516105/) (full text) ## Agent Guidance Preserve the paper-level scope of this note. Do not generalize beyond the population, protocol, measured outcomes, and limitations above.