ERAS and early mobilisation: a 2022 review
2022 review of early mobilisation in ERAS pathways: complications, walking again, hospital stay. A summary, not a new study.
Blog · Steps and oxygenation
Exercise intensity and VO₂max: a meta-analysis of 14 trials
Meta-analysis of 14 randomised trials in abdominal and cardiothoracic surgery: effect of exercise on VO₂max 0.44, of HIIT 0.51. An average figure.
A network meta-analysis in the Journal of Clinical Medicine (2025/2026) pooled fourteen randomised trials in people awaiting major abdominal or cardiothoracic surgery. It compared the components of prehabilitation (exercise, nutrition, psychological support and their combinations) for their effect on VO₂max, and split exercise by intensity, HIIT (high-intensity interval training) included.
The meta-analysis results
Exercise versus control showed an effect size of 0.44 on VO₂max. With exercise grouped by intensity, the largest effect was for HIIT versus control (ES: 0.51).
The authors note that a low VO₂max before surgery is associated with worse outcomes afterwards.
Look at which group of people the study followed.
Which exercise, and for whom
HIIT requires a good functional baseline.
The meta-analysis does not say which exercise suits a single person: the choice between intense training and more moderate activity, such as walking, is for the care team.
How much intensity before surgery
The meta-analysis measures the effect of exercise on VO₂max, not how much to train in the days before the operation. Progressive reduction of intensity in the final weeks (tapering) is decided case by case.
VO₂max estimated by a watch
Many sports watches give an estimate of VO₂max: it is an estimate, not the result of a laboratory exercise test.
Your doctor knows your history. The study does not.
The Digital Twin and this research
The Digital Twin lines up the data your devices write to your phone, such as steps, heart rate and sleep, and shows you how they change over time. It does not set the programme and it does not diagnose: this research describes groups of people, not you. Preparation for surgery is decided and followed by the care team.
The source is at the bottom. Open it.
The source
This summary starts from research by others. It is not medical advice for you: talk it over with your doctor.
Their study. Your data.
Related reading
Exercise and lung surgery: a meta-analysis of seven studies
Meta-analysis of seven studies, 404 people having lung cancer surgery: those who exercised first had fewer complications. The 5,000 steps come from one.
Exercise before major surgery: a 2014 review
2014 review: high-quality evidence for exercise before cardiovascular surgery; for other surgery, only circumstantial.
More studies, same rule: read the source.