High-Intensity Interval Training for Knee Osteoarthritis: A Pilot Study
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.
Methodology
- 29 adults with symptomatic knee osteoarthritis, mean age 63 years, 66% women, 66% obese, not meeting physical activity guidelines and medically cleared for participation.
- 29 participants.
- Cycling or treadmill walking.
- Work intervals: 1 minute at 90% VO2peak, or 90% maximum heart rate for treadmill walkers.
- Recovery: 1 minute complete rest.
- Intensity: 90% VO2peak; prescribed vigorous intervals.
- Approximately 23-25 minutes including 3-5 minute warm-up and interval block.
- 2 sessions per week with at least 24 hours between sessions.
- 12 weeks.
- Single-arm feasibility and proof-of-concept intervention study with assessments at baseline, 6 weeks, and 12 weeks.
- WOMAC total and subscale scores, Physical function, Balance, and Isometric knee strength were tracked.
Outcomes
Adherence and completion
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
No adverse events related to the HIIT program were reported, including among participants who discontinued.
Physical function
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
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
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
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
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.
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
- 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.