# Acute effects of high-intensity interval training on retinal microvascular circulation in cancer patients and healthy controls: insight from the optical coherence tomography angiography

PMID: 41343070
Journal: European journal of applied physiology
Published: 2026 Apr
Authors: Wefelnberg MM, Hubert J, Baumann FT, Zubac D

## Question

How does an acute cycling HIIT session affect retinal microvascular circulation in cancer patients compared with healthy controls?

## Summary

This small prospective study tested an acute cycling HIIT session in young cancer patients receiving treatment and healthy controls. The protocol was medically screened and monitored, produced different acute retinal microvascular responses between groups, and the authors reported no adverse events during recruitment or data collection.

## Population

- Twelve young cancer patients and eleven healthy controls completed acute HIIT
- Sample size: 23
- Age: Cancer 32.8 +/- 4.6 years; controls 30.4 +/- 4.1 years
- Sex: Cancer 66% women; controls originally 50% women
- Fitness level: Cancer patients had lower VO2peak and PPO than controls
- Health status: Solid tumors under acute treatment versus healthy controls

## Methodology

- Prospective acute interventional comparison study
- Two visits within 48-72 hours
- University Hospital Cologne exercise and ophthalmic testing setting
- Controlled study design.

## Protocol

- Acute PPO-anchored cycling HIIT.
- Modality: Stationary cycling.
- Work intervals: 1 minute.
- Recovery: 2 minutes at 30% PPO.
- Sets or repetitions: 7 intervals.
- Intensity: 90% PPO.
- Session duration: About 19 minutes for intervals and recoveries.
- Frequency: Single acute session.
- Program length: Acute study.
- Progression: None.
- Healthy-control same HIIT protocol.
- Modality: Stationary cycling.
- Work intervals: 1 minute.
- Recovery: 2 minutes at 30% PPO.
- Sets or repetitions: 7 intervals.
- Intensity: 90% PPO.
- Session duration: About 19 minutes.
- Frequency: Single acute session.
- Program length: Acute study.
- Progression: None.

## Outcomes

### Retina
Status: mixed
Deep and superficial retinal OCTA measures showed group-by-time effects.

eta2 0.165-0.473; p<0.01.

### Optic disc
Status: no clear change
Optic-disc measures did not show the same group-by-time response.

No significant group-by-time effect reported.

### Fitness
Status: worse/safety concern
Cancer patients had lower baseline exercise capacity than controls.

PPO 2.40 +/- 0.59 vs 3.48 +/- 0.34 W/kg; VO2peak 29.4 +/- 6.9 vs 40.3 +/- 3.4 ml/kg/min.

### Safety
Status: no clear change
No adverse events occurred during recruitment or data collection.

## Practical Insights

- Relative-intensity cycling HIIT can be completed by carefully screened young cancer patients in a monitored setting.
- Clinical safety screening matters more than the interval structure for consumer translation.
- Mechanistic retinal outcomes should not be presented as direct fitness benefits.

## Limitations

- Small sample.
- Heterogeneous cancer therapies.
- Acute-only study.
- OCTA image-quality issues reduced usable data.
- Limited generalizability beyond young ECOG 0-1 cancer patients.

## Safety And Adherence

- The authors explicitly reported no adverse events during recruitment or data collection.
- Medical clearance was required, with stress ECG or ultrasound recommended when needed.
- One healthy participant withdrew before HIIT; five cancer candidates failed inclusion before the final sample.

## Original Sources

- [PubMed](https://pubmed.ncbi.nlm.nih.gov/41343070/) (pubmed)
- [DOI](https://doi.org/10.1007/s00421-025-06072-x) (doi)
- [PMC full text](https://www.ncbi.nlm.nih.gov/pmc/articles/PMC13171977/) (full text)

## Agent Guidance

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