Introduction
Colorectal cancer (CRC) ranks as the second leading cause of cancer-related deaths. The PREHAB trial revealed that prehabilitation in colorectal surgery leads to a reduction of severe complications and enhanced functional capacity. Nevertheless, risk selection for prehabilitation and the potential benefits for patients without postoperative complications remains unclear. This study aims to assess postoperative functional capacity, also in patients without postoperative complications.

Materials & methods
This study was a secondary analysis of the PREHAB trial. Functional capacity tests, including cardiopulmonary exercise testing (CPET), steep ramp test (SRT), 6-min walking test (6MWT), stair climb test (SCT), 30” sit-to-stand test (STS), timed-up-and-go test (TUG), and muscle strength assessments, were conducted at baseline (T0) and 4 weeks postoperatively (T3). The primary outcome was the relative change in functional capacity from baseline to postoperative (ΔT0-T3) per group (i.e., prehabilitation vs control). Secondary, identical analysis were performed for patients without postoperative complications in each group.

Results
Intention-to-treat analysis included 251 patients. For postoperative functional capacity, prehabilitation patients showed improvements in VO2peak (p = 0.024), VO2AT (p = 0.017), SRT (p = 0.001), 6MWT (p = 0.049), SCT (p = 0.012), and STS (p = 0.001) compared to the control group. Regarding muscle strength, prehabilitation patients showed improvements in estimated 1RM lateral pull down (p = 0.016), 1RM chest press (p = 0.001), 1RM leg press (p = 0.001) and HGS (p = 0.005) compared to controls. Additionally, prehabilitation patients more often reached baseline levels at T3 in VO2AT (p = 0.037), SRT (p = 0.008), 6MWT (p = 0.013), STS (p = 0.012), estimated 1RM lateral pull down (p = 0.002), 1RM chest press (p = 0.001) and 1RM leg press (p = 0.001) compared to controls. Moreover, even patients without postoperative complications in the prehabilitation group showed better postoperative functional capacity and more often reached baseline levels at T3, compared to controls.

Conclusion
Multimodal prehabilitation in CRC surgery is associated with improved postoperative functional capacity, even in patients without postoperative complications.