Globally, about two in three people will need major surgery at some point in their lives.
Author
- Kari Clifford
Senior Research Fellow in Surgical Science, University of Otago
While preparing for a major operation, patients usually focus on the surgery itself. But recovery also places a substantial demand on the body.
Having enough cardiorespiratory reserve – the body’s spare capacity to meet a sudden increase in demand for oxygen, be it from walking up hill or dealing with an infection – is important.
This also helps people cope with the stress of surgery, inflammation and the effort of getting mobile again.
Using the time before surgery to improve a person’s physical fitness and readiness for recovery is called “prehabilitation”. This can include exercise, nutritional support, psychological preparation and making sure other medical conditions are under control.
Exercise is often the central component, but an important question remains: does it matter whether patients exercise under supervision, or can they achieve similar benefits at home on their own?
Our new systematic review of research examined this question. We brought together evidence from 42 studies involving 4,825 adults, including people preparing for colorectal, lung, cardiac, vascular and other major operations.
The answer is encouraging, but not as simple as “supervised is better”.
What the evidence shows
Thirty of the included studies used supervised exercise, while 12 used unsupervised exercise. Supervised exercise took place in a hospital or exercise facility, with healthcare or exercise professionals present.
Unsupervised exercise was usually home-based, supported by instructions, exercise diaries or other forms of monitoring.
None of the studies directly compared supervised and unsupervised exercise in the same trial. Instead, we compared the results of separate groups of studies. That means the findings show associations rather than a causal relationship.
Both types of programmes were associated with improvements in the six-minute walk test, a practical measure of functional capacity. The difference between exercise and usual care (without an exercise programme) was statistically significant, but with no clear evidence that either programme was superior.
This suggests many patients can improve their walking capacity through a structured exercise programme, even when home-based.
However, the size of the improvement in walking distance was small: less than one metre on average in the analyses. This change is unlikely to represent a meaningful improvement in everyday function for most patients.
Post-operative complications
A different pattern emerged for post-operative complications. Aerobic exercise before surgery was associated with lower odds of complications. But this association was only seen in the supervised studies.
Supervised exercise was associated with about 40% lower odds of a post-operative complication. The association was stronger in analyses of high-intensity exercise, where the odds of complications were approximately halved compared with usual care.
The studies included different patient groups and combinations of exercise, nutrition and psychological support. The supervised programmes were more likely to include high-intensity exercise, while unsupervised studies were mostly lower-intensity activity.
Due to these differences, we cannot say with certainty that supervision was the active ingredient. The result could partly reflect differences in exercise intensity, the patients recruited, the operations being undertaken or other components of the programmes.
Why exercise intensity may matter
Cardiorespiratory fitness describes how effectively a person uses oxygen during exercise. One common measure is peak oxygen consumption ( VO₂peak ). In our review, improvements in VO₂peak happened only for people in supervised studies. Most of these programmes included intervals of intense exercise.
Supervision may help in several ways. A clinician or exercise professional can assess whether exercise is safe, monitor symptoms and progressively increase the intensity.
There is also a behavioural component. Attending a supervised session creates structure and accountability. It may be easier to take challenging exercise when someone else is present to encourage.
For patients, the practical message is to ask the surgical or primary-care team whether prehabilitation is available and what type of exercise is appropriate. A programme should ideally include a clear exercise prescription, a way to monitor progress and advice about when to stop exercise.
Our findings suggest supervision may be particularly valuable when the goal is to deliver high-intensity exercise.
But any form of prehabilitation should be safe and accessible. Digital tools such as exercise apps may help, and support from family members or carers may also be useful with appropriate guidance.
What we still need to know
No study directly compared supervised and unsupervised exercise, so we don’t know whether supervision is significantly better than home-based exercise. Future trials should compare clearly defined supervised and unsupervised programmes and focus on reporting outcomes relevant to healthcare.
The most useful outcome is not whether a patient can walk a little further on assessment. It is whether they experience fewer complications, recover more quickly and return to the activities that matter to them.
The evidence suggests exercise before surgery is worth taking seriously. Patients may improve fitness with either supervised or home-based programmes.
But when the aim is to achieve higher exercise intensities that may reduce post-operative complications, professional supervision could be important because it may help patients exercise at a dose that is difficult to achieve safely and consistently alone.
