# Prehab before major surgery: where five evidence sources agree, conflict and fall short

> A network meta-analysis, an umbrella review, an ASCO guideline, a lung resection trial and a knee arthroplasty review mostly favour prehabilitation, but most certainty ratings are low to very low.

AthleticsMD Clinical Desk · 2026-10-15 · https://blog.athleticsmd.org/prehab-before-major-surgery-where-five-evidence-sources-agree-conflict-and-fall

Prehabilitation refers to interventions delivered to adults preparing for surgery. It is built from exercise, nutritional, cognitive or psychosocial components, used alone or in combination, and has been studied for its effect on postoperative complications, length of stay, health-related quality of life and physical recovery [2]. Five sources address it from different angles: a 2022 American Society of Clinical Oncology (ASCO) guideline, a 2022 umbrella review, a 2025 network meta-analysis in the BMJ, a 2025 multicentre randomised trial in lung resection, and a 2025 systematic review of swelling after total knee arthroplasty [1, 2, 3, 4, 5]. Read together, they point in a broadly consistent direction, but the certainty attached to most pooled estimates is low to very low [2, 3].

## The sources and how strong their designs are

The designs differ in kind, and that shapes how far each finding can be taken [1, 2, 3, 4, 5].

- The ASCO guideline is a practice guideline built on a systematic search of PubMed and the Cochrane Library from January 2000 to May 2021. It drew on 52 systematic reviews (42 for exercise, nine for diet and one for weight management) plus 23 additional randomised controlled trials in adults during active cancer treatment [1].
- The umbrella review, meaning a systematic review of systematic reviews, screened 1412 titles and included 55 systematic reviews of elective adult surgery searched to October 20, 2020. It rated certainty with GRADE (Grading of Recommendations Assessment, Development and Evaluation) and stratified its primary syntheses by surgery type [3].
- The BMJ review is a systematic review with network meta-analysis, used here to estimate the relative efficacy of individual and combined prehabilitation interventions compared with usual care. It added a component network meta-analysis that compared individual components such as exercise and nutrition, pooled 186 randomised controlled trials with 15 684 participants, and rated certainty with CINeMA (Confidence in Network Meta-Analysis) [2].
- The lung resection study is a prospective multicentre randomised controlled trial in which 122 patients completed the study [5].
- The knee arthroplasty review is a systematic review of 140 clinical studies (7 meta-analyses, 125 randomised controlled trials and 8 cohort studies) on interventions to reduce postoperative swelling, of which prehabilitation is only one [4].

## Where the sources agree

On direction of effect, the two large syntheses largely concur that prehabilitation is associated with fewer complications and shorter hospital stays, with the caveat that most estimates carry low or very low certainty [2, 3]. The umbrella review found low to very low certainty evidence that any prehabilitation reduces complications in mixed, cardiovascular and cancer surgery, reduces non-home discharge after orthopaedic surgery, and shortens length of stay in mixed, cardiovascular and cancer surgery [3]. It found the same low to very low certainty for exercise prehabilitation reducing complications, non-home discharge and length of stay, and for nutritional prehabilitation reducing complications, mortality and length of stay [3].

The strongest single finding in the umbrella review concerned patients with cancer: moderate certainty evidence supported improved functional recovery with any prehabilitation before cancer surgery [3]. The ASCO guideline, which addressed exercise during cancer treatment more broadly rather than prehabilitation alone, reported that exercise during cancer treatment improved cardiorespiratory fitness, strength, fatigue and other patient-reported outcomes [1].

The network meta-analysis pointed the same way as the umbrella review on complications. Compared with usual care, isolated exercise prehabilitation had an odds ratio for complications of 0.50 (95% CI 0.39 to 0.64), isolated nutritional prehabilitation 0.62 (0.50 to 0.77), and combined exercise, nutrition and psychosocial prehabilitation 0.64 (0.45 to 0.92), all at very low certainty [2]. An odds ratio below 1 here indicates lower odds of complications than with usual care [2]. The component analysis identified exercise and nutrition as the individual components most likely to improve all critical outcomes [2].

## Which components, and what they shift

In the network meta-analysis, the most favourable intervention differed by outcome [2]. For length of stay, the abstract reports four estimates: combined exercise and psychosocial prehabilitation (-2.44 days, 95% CI -3.85 to -1.04; very low certainty), combined exercise and nutrition (-1.22 days, -2.54 to 0.10; moderate certainty), isolated nutritional prehabilitation (-0.99 days, -1.49 to -0.48; very low certainty) and isolated exercise prehabilitation (-0.93 days, -1.27 to -0.58; very low certainty) [2].

For health-related quality of life and physical recovery, the multicomponent package of exercise, nutrition and psychosocial support was the intervention most likely to improve outcomes [2]. Its estimated mean differences were 3.48 points on the Short Form-36 physical component scale (95% CI 0.82 to 6.14) and 43.43 metres on the six-minute walk test, a measure of distance walked in six minutes (5.96 to 80.91), both rated very low certainty [2]. The authors reported that certainty across comparisons was generally low to very low because of trial-level risk of bias and imprecision, but that results for exercise and nutritional prehabilitation held when trials at high risk of bias were excluded [2].

## Lung surgery: a guideline and a trial side by side

The ASCO guideline and the 2025 trial both address lung surgery, though from different starting points: the guideline concerns patients with lung cancer, while the trial abstract describes patients undergoing elective lung resection without specifying the indication [1, 5]. The ASCO panel reported that preoperative exercise in patients with lung cancer reduced postoperative length of stay and complications, and stated that oncology providers may recommend preoperative exercise for patients undergoing surgery for lung cancer [1].

The 2025 trial tested a narrower and more selective model [5]. Investigators enrolled only patients judged high risk for postoperative pulmonary complications, defined as a VE/VCO2 slope of 33 or higher on cardiopulmonary exercise testing; the VE/VCO2 slope is a measure of ventilatory efficiency that the authors describe as a strong predictor of postoperative pulmonary complications [5]. Participants were randomised to usual care or a 14-day programme combining high-intensity respiratory muscle training, smoking cessation, nutritional support and psychological support [5]. The 122 patients who completed the study were 46% female and aged 64 to 75 years [5].

Postoperative pulmonary complications occurred in 34% of patients randomised to prehabilitation and 55% of patients receiving usual care, reported as an odds ratio of 2.29 (95% CI 1.10 to 4.77; P=0.029) [5]. Hospital stay was 7 [6 to 9] days after prehabilitation compared with 9 [7 to 11] days with usual care (P=0.038) [5]. Mean VE/VCO2 slope fell from 39 (SD 8) to 36 (SD 9) after prehabilitation (P=0.01), and patient-reported quality of life also improved [5]. Within its selected high-risk population, this randomised design supports a direct statement that the programme reduced pulmonary complications and length of stay [5].

## Knee arthroplasty: prehabilitation as one lever among many

In total knee arthroplasty, the swelling review places prehabilitation below its best-supported measures [4]. The review concluded that the strongest evidence supported tranexamic acid, minimising tourniquet use, maintaining postoperative knee flexion of 30° to 90° for 6 to 72 hours, and cryotherapy during the first 2 weeks [4]. Prehabilitation was grouped with aspirin cessation, cold intra-articular irrigation, mechanical compression and adjunctive therapies such as diosmin, acupuncture and kinesiotaping as "other promising strategies" [4].

## Where the sources diverge

The first tension concerns single versus combined interventions [2, 5]. In the network meta-analysis, isolated exercise had the most favourable point estimate for complications among the three interventions reported, while the three-part multicomponent package had a less favourable point estimate and a wider interval; the multicomponent package was instead the one most likely to improve quality of life and walking distance, at very low certainty [2]. The lung trial showed a complication benefit from a four-part programme in a high-risk group, so its result cannot be attributed to any single component [5].

The second tension concerns certainty and precision [2, 3]. Combined exercise and nutrition for length of stay was rated moderate certainty, yet its confidence interval of -2.54 to 0.10 days includes no difference, whereas several very low certainty estimates had intervals excluding no difference [2]. The umbrella review rated most outcomes low to very low and reported moderate certainty for functional recovery after cancer surgery [3].

The third difference is scope [1, 2, 3]. The ASCO guideline found evidence for dietary and weight loss interventions during cancer treatment very limited, and it recommended against neutropenic diets because they did not decrease infection risk [1]. The network meta-analysis and umbrella review both reported favourable but low or very low certainty signals for nutritional prehabilitation before surgery [2, 3]. The populations and questions differ, so these findings are better read as complementary than contradictory [1, 2, 3].

## What remains unknown

The sources name their own gaps explicitly [1, 2, 3, 4].

- The umbrella review states that optimal patient selection, intervention design and intervention duration must still be determined, and calls for low risk of bias randomised trials synthesised to recommended standards [3].
- The network meta-analysis calls for multicentre trials appropriately powered for high-priority outcomes and at low risk of bias [2].
- The ASCO panel highlights a critical need for more research, particularly on diet and weight loss interventions during cancer treatment, and separately discusses special considerations such as exercise in advanced cancer [1].
- The knee arthroplasty review asks for standardised outcome reporting and for study of the synergistic effects of combined interventions [4].

The lung trial bears on the selection question only partly: it enrolled only patients with a VE/VCO2 slope of 33 or higher, so its abstract offers no estimate for lower-risk patients [5].

## Limitations

This review draws on abstracts rather than full texts, so details such as risk-of-bias judgements, the reference group for the lung trial's odds ratio and the handling of participants who did not complete the study are not available here [2, 5]. The syntheses searched overlapping periods and databases, and the abstracts do not report how many trials they share, so their agreement should not be counted as independent confirmation [1, 2, 3]. The umbrella review's search ended in October 2020 and the ASCO search in May 2021, before the network meta-analysis update of October 2023 [1, 2, 3]. The lung trial is a single study with 122 completers in a selected high-risk population aged 64 to 75 years, which limits generalisation [5]. The knee arthroplasty review addressed swelling only, so its placement of prehabilitation says nothing about other outcomes after knee replacement [4].

## References

1. Ligibel JA, Bohlke K, May AM, et al. Exercise, Diet, and Weight Management During Cancer Treatment: ASCO Guideline. J Clin Oncol. 2022;40(22):2491-2507. doi:10.1200/JCO.22.00687. PMID: 35576506. https://pubmed.ncbi.nlm.nih.gov/35576506/
2. 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. doi:10.1136/bmj-2024-081164. PMID: 39843215. https://pubmed.ncbi.nlm.nih.gov/39843215/
3. McIsaac DI, Gill M, Boland L, et al. Prehabilitation in adult patients undergoing surgery: an umbrella review of systematic reviews. Br J Anaesth. 2022;128(2):244-257. doi:10.1016/j.bja.2021.11.014. PMID: 34922735. https://pubmed.ncbi.nlm.nih.gov/34922735/
4. McGarry L, Kearney J, Rotaru J, Gunaratne R. Swelling Management in Total Knee Arthroplasty: A Systematic Review. JBJS Rev. 2025;13(9). doi:10.2106/JBJS.RVW.25.00109. PMID: 40920881. https://pubmed.ncbi.nlm.nih.gov/40920881/
5. Brat K, Sova M, Homolka P, et al. Multimodal prehabilitation before lung resection surgery: a multicentre randomised controlled trial. Br J Anaesth. 2025;135(1):188-196. doi:10.1016/j.bja.2025.03.018. PMID: 40374400. https://pubmed.ncbi.nlm.nih.gov/40374400/