# Is high-intensity interval cycling feasible and more beneficial than continuous cycling for knee osteoarthritic patients? Results of a randomised control feasibility trial PMID: 29761054 Journal: PeerJ Published: 2018-05-09 Authors: 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. ## Population - Adults aged 40-80 with orthopaedic-surgeon-confirmed knee osteoarthritis, physician clearance, and stationary bicycle access. - Sample size: 27 - Age: Eligibility 40-80 years; completers mean 62.4 years - Sex: Completers: 4 male, 13 female - Health status: Knee osteoarthritis; comorbidities allowed if not contraindicating unsupervised home exercise. ## Methodology - Randomized pilot feasibility trial comparing home-based HIIT cycling with home-based MICT cycling. - 8 weeks - Home-based or gymnasium stationary cycling with baseline and post-test assessments at a university clinic. - Randomized and controlled study design. ## Protocol - Home-based HIIT cycling. - Modality: Stationary cycling. - Work intervals: 45 sec. - Recovery: 90 sec low-intensity cycling. - Sets or repetitions: 5 high-intensity bouts. - Intensity: Up to 110 rpm during work bouts with resistance similar or slightly higher than recovery; quite difficult to complete sentences. - Session duration: Approximately 25 min. - Frequency: 4 sessions/week. - Program length: 8 weeks. - Progression: Conservative initial sessions with cadence/workload reductions, then progressive increase if no cardiovascular or joint pain. - Home-based MICT cycling. - Modality: Stationary cycling. - Work intervals: 20 min continuous moderate-intensity cycling. - Sets or repetitions: 1 continuous bout. - Intensity: 60-80 rpm at an intensity allowing complete sentences. - Session duration: Approximately 25 min. - Frequency: 4 sessions/week. - Program length: 8 weeks. ## Outcomes ### Feasibility and adherence Status: mixed 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%. ### Adverse events Status: mixed 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. ### WOMAC Status: improved 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. ### Timed Up and Go Status: improved 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. ### Sit to Stand Status: improved 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. ### Lequesne index, gait speed, and body composition Status: no clear change 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. ## Practical 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 And Adherence - 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. ## Original Sources - [PubMed](https://pubmed.ncbi.nlm.nih.gov/29761054/) (pubmed) - [DOI](https://doi.org/10.7717/peerj.4738) (doi) - [PMC full text](https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5949056/) (full text) ## Agent Guidance Preserve the paper-level scope of this note. Do not generalize beyond the population, protocol, measured outcomes, and limitations above.