# Metabolic and physiological effects of high intensity interval training in patients with knee osteoarthritis: A pilot and feasibility study

PMID: 36474875
Journal: Osteoarthritis and Cartilage Open
Published: 2020
Authors: Smith-Ryan AE, Blue MNM, Anderson KC, Hirsch KR, Allen KD, Huebner JL, Muehlbauer MJ, Ilkayeva OR, Kraus VB, Kraus WE, Golightly YM, Huffman KM

## Question

Is supervised cycling HIIT feasible and potentially beneficial for adults with symptomatic radiographic knee osteoarthritis?

## Summary

In a small single-arm pilot study of adults with symptomatic knee osteoarthritis, twice-weekly supervised cycling HIIT for 6 weeks was feasible for completers, with high adherence and no reported adverse events. Fitness and WOMAC pain/function scores improved, but the lack of a control group means the study cannot prove that HIIT caused the changes.

## Population

- Adults aged 40 to 70 years with moderate-to-severe symptomatic radiographic knee osteoarthritis
- Sample size: 16
- Age: Mean 59.9 years
- Sex: 77% female among completers
- Fitness level: Not currently doing HIIT or physical therapy for knee osteoarthritis and not exceeding 150 minutes per week of moderate exercise
- Health status: Symptomatic radiographic knee osteoarthritis, BMI 20 to 40 kg/m2, normal resting ECG and physician clearance

## Methodology

- Single-arm pilot and feasibility study
- 6 weeks
- Supervised laboratory exercise program
- Randomized study design.

## Protocol

- Knee OA cycling HIIT.
- Modality: cycle.
- Work intervals: 60 seconds.
- Recovery: 60 seconds.
- Sets or repetitions: Participants completed a self-selected warm-up followed by ten 1-minute cycling bouts at 90% peak power output, with 1-minute rest between bouts.
- Intensity: 90% peak power output.
- Session duration: Not explicitly reported.
- Frequency: 2 sessions per week.
- Program length: 6 weeks.
- Progression: No explicit progression schedule reported.

## Outcomes

### Adherence
Status: unclear
Among compliant completers, adherence exceeded 96%.

Effect: >96%; Favours: intervention

### Safety
Status: unclear
No adverse events were reported.

Effect: 0 adverse events; Favours: intervention

### VO2peak
Status: improved
Relative VO2peak improved after the program.

Effect: +2.6 +/- 3.0 mL/kg/min; Favours: intervention

### WOMAC total
Status: improved
WOMAC total score improved after the program.

Effect: -8.7 +/- 12.5; Favours: intervention

### Body composition
Status: improved
Body composition showed little change aside from a small left lower-extremity lean-mass signal.

Favours: no_difference

## Practical Insights

- Cycling HIIT may be a feasible low-impact HIIT modality for some people with knee osteoarthritis when medically screened and supervised.
- Access and equipment logistics can matter in knee osteoarthritis programs, including walking distance and bike mounting.
- The protocol should be framed as feasibility evidence rather than proven efficacy.

## Limitations

- Single-arm uncontrolled pilot study.
- Small sample.
- Mostly female sample.
- Peripheral metabolite measures do not directly reflect skeletal muscle metabolism.
- Needs larger randomized controlled trials.

## Safety And Adherence

- No adverse events were reported.
- One participant was withdrawn at baseline for very high blood pressure.
- Participants reported practical concerns including walking to the lab, mounting and dismounting the bike, exercise intensity, pain, and time.

## Original Sources

- [PubMed](https://pubmed.ncbi.nlm.nih.gov/36474875/) (pubmed)
- [DOI](https://doi.org/10.1016/j.ocarto.2020.100083) (doi)
- [PMC full text](https://www.ncbi.nlm.nih.gov/pmc/articles/PMC9718145/) (full text)

## Agent Guidance

Preserve the paper-level scope of this note. Do not generalize beyond the population, protocol, measured outcomes, and limitations above.