CATEGORY: EXERCISE & MOVEMENT
In the weeks before a major operation, patients assigned by chance to an exercise program had about half the odds of a complication afterward and left the hospital nearly a day sooner, according to an analysis in The BMJ that pooled 186 randomized trials of prehabilitation involving 15,684 surgical patients.1 Nutrition support before surgery lowered the odds of complications by 38%, while the elaborate multi-part programs many hospitals favor did no better than exercise on its own.
Getting in Shape for an Operation, Tested 186 Times
Prehabilitation—a structured program of preparation in the weeks before surgery—rests on a simple idea: an operation is a physical ordeal, and the body that arrives fitter weathers it better, much as a hiker who trains before a mountain handles the climb better than one who starts cold. Researchers gathered every randomized trial that tested at least seven days of preparation before an operation—programs built from exercise, nutrition support, psychological preparation, thinking exercises, or combinations of these—and used the pooled data to compare each approach against usual care and against the others. Because every trial assigned its patients to a program by chance rather than letting them choose, the groups started out alike, and differences in how they fared can be credited to the preparation itself. Nearly half the operations studied were cancer surgeries, about a quarter were orthopedic procedures such as joint replacements, and the rest included heart, blood vessel and other major operations.
Half the Odds of Trouble, and Almost a Day Less in the Hospital
Patients assigned to exercise-only programs had 50% lower odds of a complication after surgery—problems such as infections, breathing trouble or poor wound healing—than patients given usual care, and their hospital stays were 0.93 days shorter on average. Nutrition-only programs, typically protein supplements or dietary counseling, went with 38% lower odds of complications and stays about a day shorter. Programs that combined exercise with psychological support showed the largest reduction in time in the hospital, at 2.44 fewer days. The gains did not come from exotic training: most exercise programs were ordinary aerobic conditioning, such as walking or cycling, often paired with basic strength work, done at home or in a clinic in the last few weeks before the operation.
The Teamwork the Researchers Expected, and Did Not Find
The study team, which included patients and caregivers as partners, went in expecting combinations to win: the partners, the authors wrote, had “expressed a strong belief in the likely underlying clinically meaningful interaction of different prehabilitation components.” The data said otherwise. The three-part combination of exercise, nutrition and psychological support lowered the odds of complications by 36%—a real benefit, but no better than exercise alone—and no multi-part program beat the single ingredients it was built from.
Why the Authors Still Grade the Evidence Cautiously
Most of the 186 trials were small, and many had design weaknesses, so the authors rate the certainty of the evidence as low to very low overall—meaning the true sizes of these effects could shift as larger trials report. The core findings were not fragile, though: when the analysis was restricted to the trials at lowest risk of bias, the benefits of exercise and of nutrition support held up.
A Separate Analysis of Abdominal Surgery Lands the Same Way
An independent research group reached a matching conclusion after pooling 25 randomized trials of 2,674 patients preparing for major abdominal operations: aerobic exercise beforehand lowered the odds of complications by 39%, and pairing it with inspiratory muscle training—breathing exercises against resistance that strengthen the muscles used to fill the lungs—went with far fewer pneumonias after surgery, about 138 fewer cases for every 1,000 patients.2
Key Takeaways
- Across 186 randomized trials of 15,684 patients, exercise programs in the weeks before major surgery halved the odds of complications afterward and shortened hospital stays by nearly a day.
- Nutrition support before surgery lowered complication odds by 38%; combination programs helped, but no more than exercise alone—the opposite of what the researchers expected.
- The evidence is rated low-certainty overall because many trials were small, but the exercise and nutrition results held when only the most rigorous trials were counted.
- An independent pooled analysis of abdominal surgery trials found the same pattern, with breathing-muscle training linked to markedly fewer pneumonias.
References
- McIsaac DI, Kidd G, Gillis C, et al. Relative efficacy of prehabilitation interventions and their components: systematic review with network and component network meta-analyses of randomised controlled trials. BMJ. 2025;388:e081164. link
- Ricci C, Alberici L, Serbassi F, et al. Physical Prehabilitation in Patients who Underwent Major Abdominal Surgery: A Comprehensive Systematic Review and Component Network Meta-Analysis Using GRADE and CINeMA Approach. Annals of Surgical Oncology. 2024;31(3):1725–1738. link