Fig. 1

Outline of the course of testing and intervention. Single asterisk indicates the following: all testing consisted of baseline questionnaires (G8 and fried frailty), nutritional screening (PG-SGA) and anthropometric measurement, blood work, cardiopulmonary exercise test (CPET), handgrip strength, leg extension strength test, 6-min walk test, sit to stand test (30 s), and stair climb test (30 s), in that exact chronological order. Double asterisk indicates the following: the intervention consisted of individual training three times a week with a minimum of 10 sessions. Nutritional counseling within the first week of inclusion (1.5 h), 0.4 g/kg bodyweight protein supplement two times a day, and medical optimization. Medical optimization was performed on the same day of baseline testing. Triple asterisk indicates the following: discharge managed through standardized discharge criteria. Adherence to Enhanced Recovery After Surgery (ERAS) was recorded each day during admission