A contemporaneous control group of patients was build using propensity score matching (PSM) methodologies taking into account the following matching variables: type of surgery, age, sex, American Society of Anesthesiologists Index (ASA) and adjusted morbidity groups (GMA) grading.

Prospective sample of risk patients who are candidates for major surgery attended in the outpatient offices of the Hospital Clínic de Barcelona.

Inclusion criteria: i) American Society of Anesthesiologists Index (ASA) 3-4; and / or, ii) age ≥ 75 years; and / or iii) major aggressive surgery; and, iv) solid organ transplant candidate.

Exclusion criteria: i) Non-elective surgery; ii) Known metastatic disease before surgery; iii) Unstable respiratory or heart disease; or, iv) Locomotive or cognitive limitations that prevent adherence to the program.

The preoperative standard measures consist of physical activity recommendation and advice on both smoking cessation and alcohol intake reduction. Moreover, in patients presenting with anemia, the anesthesiologists will assess its etiology and treat it accordingly, and nutritional intervention will be performed by a registered dietitian in to those patients at risk of malnutrition (Malnutrition Universal Screening Tool ≥2).

Number of postoperative complications during the initial hospitalization for surgery

Number of days of hospital length of stay during the initial hospitalization for surgery

Severity of postoperative complications during the initial hospitalization for surgery using the Clavien-Dindo classification

Number of postoperative complications during a 30-day period after surgery

Distance covered during the six-minute walk test

Physical activity measured by the Yale Physical Activity Survey (YPAS) (range 0 to 142; the lowest the worst)