ABOTT, TOMALHARBI, FAHAD OBAID2025-10-262025lancet citationhttps://hdl.handle.net/20.500.14154/76734تجدون بالمرفقات الشهاده والدزرتيشن ملفين 2Abstract Background: Exercise-based prehabilitation is increasingly becoming a critical pathway to improving postoperative outcomes in high-risk adult patients undergoing elective colorectal surgery. In line with the dissertation objectives: to identify and evaluate the existing evidence, to synthesize the definitions and measurement of complications, and compare prehabilitation with standard care, this systematic review assesses the effectiveness of exercise-based prehabilitation on the elective colorectal surgery clinical outcomes. Methodology: A systematic review of 23 randomized controlled trials (RCTs) was done, which focused on high-risk adults undergoing elective colorectal surgery. Searches were conducted in PubMed, Embase, CINAHL, Web of Science, and Cochrane CENTRAL databases. The selection of studies was done according to predetermined eligibility criteria such as those only involving exercise-based prehabilitation interventions. RoB 2 tool was used to determine methodological quality. The data extracted involved the characteristics of the intervention, the definition of postoperative complications, and clinical outcomes in terms of complication rates and hospital length of stay (LOS). Results: Exercise-based prehabilitation programmes varied in terms of duration (2-12 weeks), intensity (moderate to high), and setting (home-based vs. supervised). Most of the studies showed a significant decrease in the total and severe complications (Clavien-Dindo III or more) with exercise-based prehabilitation, improved functional capacity (improved preoperative fitness and VO2 peak and postoperative recovery), reduced length of stay (LOS) (a mean reduction in LOS of 1.5 days (95% CI: -2.3 to -0.7) compared to standard care. Conclusion: Exercise-based prehabilitation has significant beneficial clinical effects on complications and recovery outcomes in high-risk adult colorectal surgery patients. Nevertheless, disparities in reporting outcomes indicate that standardised definitions and larger, high-quality trials are needed. These results suggest the inclusion of exercise-based prehabilitation in high-risk colorectal cancer recovery pathways with enhanced recovery pathways, but individualised interventions may be required depending on the risk of the patient and the surgical setting. Keywords: Exercise-based, Prehabilitation, elective colorectal surgery, postoperative surgery outcomes, high-risk adult patients, systematic review.104enKeywords: Exercise-basedPrehabilitationelective colorectal surgerypostoperative surgery outcomeshigh-risk adult patientssystematic review.Thesis