Once the indication for the surgical intervention is given patients may be included into the study. Patients of the experimental group will be provided with a tailored training program aiming at maximally improving physical fitness in order to withstand the surgical stress. Depending on the urgency of the operation this training program will last between two and six weeks. Three weekly trainings are foreseen of which two will be performed in a setting supervised by a physiotherapist and one at the patient's home.