The study aims to find out if complications after surgery for large bowel (colon) cancer can be reduced or avoided in the most frail and elderly by letting them go through an exercise- and diet regime prior to the surgical procedure.

All patients with colon cancer who are intended for curative surgery without neoadjuvant chemotherapy who are >=60 years old will be screened with an ergospirometry. The ones that have a ventilate anaerobic threshold (VAT) of less than 11 mg/ml/kg will be included in the study as they are considered extra frail and have a previously proven high risk for complications. These patients will be randomized to standard care or an intervention of prehabilitation consisting of immunonutrition (protein supplement, multivitamin supplement, Selene etc) and an exercise regimen with 4x1 hours per week of cycling on an ergometer. The exercise regimen will be performed in a group of patients and will be led by a physical therapist to ensure compliance. The resistance of the ergometer will be standardized according to the patient's VAT.

The primary outcome measures will be number of and severity of postoperative complications. Secondary outcome measures include quality of life during prehabilitation with repeated measurements during 5 years after surgery, disease-free survival and overall survival.

Inclusion Criteria:

• 60 years of older
• Colon cancer diagnosis (macroscopic, microscopic or x-ray diagnosed)
• Ventilatory Anaerobic Threshold <11mg/ml/kg
• Planned open or laparoscopic colectomy due to colon cancer

Exclusion Criteria:

• Lower extremity amputee
• Disease requiring radio- and/or chemotherapy prior to surgery/palliative disease
• Distal metastases (Locoregional lymph nodes are OK)