PMID 29761054

Research
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Is high-intensity interval cycling feasible and more beneficial than continuous cycling for knee osteoarthritic patients? Results of a randomised control feasibility trial

Keogh JW, Grigg J, Vertullo CJ

Question

Is unsupervised home-based high-intensity interval cycling feasible, safe, and potentially more beneficial than moderate-intensity continuous cycling for middle-aged and older adults with knee osteoarthritis?

Summary

This randomized pilot trial compared 8 weeks of unsupervised home-based HIIT cycling with moderate-intensity continuous cycling in adults with knee osteoarthritis. Among participants who completed the trial, adherence was high in both groups and both groups improved WOMAC scores, while HIIT improved Timed Up and Go more than MICT. Feasibility was qualified by slow recruitment, 37% withdrawal, and adverse events concentrated in one HIIT participant whose Baker's cyst was aggravated.

Methodology

  • Adults aged 40-80 with orthopaedic-surgeon-confirmed knee osteoarthritis, physician clearance, and stationary bicycle access.
  • 27 participants.
  • Stationary cycling.
  • Work intervals: 45 sec.
  • Recovery: 90 sec low-intensity cycling.
  • Intensity: Up to 110 rpm during work bouts with resistance similar or slightly higher than recovery; quite difficult to complete sentences.
  • Approximately 25 min.
  • 4 sessions/week.
  • 8 weeks.
  • Randomized pilot feasibility trial comparing home-based HIIT cycling with home-based MICT cycling.
  • Feasibility, Health-related quality of life, Physical function, and Body composition were tracked.

Outcomes

Feasibility and adherence

Enrolment was 54%, withdrawal was 37%, and completer adherence was high in both groups.

27/50 interested potential participants enrolled; 17/27 completed; adherence HIIT 94%, MICT 88%.

Mixed

Adverse events

Three participants reported adverse events, with most events in one HIIT participant whose Baker's cyst was aggravated.

HIIT: 26 adverse events in 2/9 participants; MICT: 2 adverse events in 1/8 participants; 24 HIIT events were from one participant.

Mixed

WOMAC

Both HIIT and MICT significantly improved WOMAC scores, with no significant between-group difference.

HIIT 36.1 to 21.2, p=0.005, d=0.91; MICT 34.8 to 22.9, p=0.006, d=0.71; between-group p=0.829.

Improved

Timed Up and Go

HIIT improved TUG and improved significantly more than MICT.

HIIT 8.9 s to 7.8 s, p=0.004, d=0.62; MICT 9.1 s to 9.7 s, p=0.401; between-group p=0.043.

Improved

Sit to Stand

HIIT significantly improved Sit to Stand repetitions; MICT did not reach statistical significance, and the between-group difference was not significant.

HIIT 11.1 to 13.1 reps, p=0.012, d=0.73; MICT 9.4 to 10.6 reps, p=0.095; between-group p=0.417.

Improved

Lequesne index, gait speed, and body composition

No significant changes were observed in Lequesne index, gait speed, body mass, BMI, body fat percentage, or muscle mass for either group.

Between-group p-values: Lequesne 0.707, gait speed 0.685, body mass 0.715, BMI 0.784, body fat 0.967, muscle mass 0.861.

No clear change

Insights

  • Low-impact cycling HIIT may be adaptable for knee OA users who are medically cleared and have stationary bike access.
  • Home-based HIIT feasibility should be framed around both high completer adherence and substantial withdrawal.
  • Symptom-guided progression and adverse-event tracking are important for knee OA HIIT programming.
  • This study supports physical-function and WOMAC signals, not body-composition claims.

Limitations

  • Small sample size and pilot design.
  • No specific power analysis.
  • High withdrawal rate.
  • Self-report outcomes and diaries.
  • No objective measure of external workload or internal intensity such as power output or heart rate.
  • Home-based unsupervised protocol may not optimize progression.
  • Participants and assessor were not blinded.
  • Limited generalizability to people without bike access or with contraindications.

Safety

  • Three participants reported adverse events: one MICT and two HIIT.
  • MICT had two adverse events related to bicycle-seat discomfort and pain.
  • HIIT had 26 adverse events, including 24 from one participant whose Baker's cyst was aggravated.
  • The participant with 24 adverse events still completed 25 of 32 requested sessions.
  • Authors suggested caution prescribing cycling, especially HIIT cycling, to people with Baker's cysts.