Physical Activity in Patients With Metastatic Colorectal Cancer Who Receive Palliative First-line Chemotherapy

Inclusion Criteria: * Written informed consent according to ICH/GCP regulations before randomization. * Patient with histologically or cytologically confirmed colorectal carcinoma (CRC) who start palliative first-line systemic therapy for inoperable or metastatic disease. Note: Patients can be included before the start or within the first three weeks of first-line systemic treatment. * Patients with histologically or cytologically confirmed colorectal carcinoma (CRC), who start first-line "conversion"-therapy for borderline resectable metastatic disease and will be reassessed for metastasectomy after 3-4 months of systemic treatment. Note: Patients can be included before the start or within the first three weeks of first-line systemic treatment. Patients who are diagnosed with metastatic disease and were initially treated with surgery and/or radiochemotherapy to the primary tumor are eligible (except if all disease sites/metastases have been removed) Patients who have been curatively treated with histologically or cytologically confirmed nonmetastatic CRC previously and now relapse with metastatic disease are also eligible, irrespective of previous radiochemotherapy and/or adjuvant chemotherapy * Patients must have measurable disease on CT scan or MRI to be performed within 6 weeks before randomization (measurability criteria according to RECIST 1.1, non-nodal lesions ≥10 mm, lymph nodes ≥15mm) OR evaluable disease i.e. patient with nonmeasurable metastases but elevated serum tumor-marker (CEA at least \>2xULN). * Command of written and spoken language allowing for informed consent and for filling in trial questionnaires. * Baseline patient-reported outcomes (PROs) have been completed. * WHO performance status 0-2. * Age ≥18 years Exclusion Criteria: * Pre-existing severe medical conditions precluding participation in a physical activity program as determined by the local investigator. Such conditions include: chronic heart failure (greater than NYHA II), recent myocardial infarction (less than 3 months ago), unstable angina pectoris, clinically significant arrhythmias, uncontrolled hypertension with repeated systolic blood pressure above 160mmHg, and COPD (requiring oxygen supply or GOLD stadium greater than 2). * Inability to ride a cycle ergometer e.g. for musculoskeletal reasons. * Patients in whom all CRC metastases have been removed surgically. It is allowed to include patients for whom metastasectomy might be an option if chemotherapy induces a significant response. * Any serious underlying medical condition (at the judgment of the investigator) which could impair the ability of the patient to participate in the trial (e.g. active autoimmune disease, uncontrolled diabetes). * Concurrent treatment in a trial with experimental drugs or other anti-cancer therapy, which are hypothesized to alter tumor progression. Participation in an observational trial or a translational trial is allowed. Palliative radiotherapy is allowed. * Psychiatric disorder precluding understanding of trial information, giving informed consent, filling out PRO forms, or interfering with compliance. * Any psychological, familial, sociological or geographical condition potentially hampering proper compliance with the trial protocol.