Inclusion Criteria:  Signed and dated informed consent, Age ≥ 18 years, Mini Nutritional Assessment (MNA) and geriatric 8 (G8) health status screening tools for patients ≥ 70 years and oncogeriatric evaluation if G8 ≤ 14, First-line chemotherapy for advanced disease, Histologically confirmed colorectal, pancreatic, esophageal, or gastric cancer (adenocarcinoma or squamous cell carcinoma), Metastatic disease not amenable to surgery, radiation, or combined modality therapy with curative intent (previous resection of primary tumor allowed), Patients able to receive chemotherapy, Eastern Cooperative Oncology Group performance status of 2, Life expectancy ≥ 3 months, Registration in a National Health Care System (Protection Universelle Maladie [PUMa] included).  Exclusion Criteria:  Neuroendocrine histology or primary tumor other than esophageal, gastric, pancreatic, biliary, or colorectal cancer, Any medical (including psychiatric, musculoskeletal, or neurological) condition contra-indicating exercise practice, Ulcerative skin lesions over the quadriceps muscle, Participation to another physical activity program (exercise or NMES), Pacemaker-depended patients, Albuminemia < 25 g/L, Pregnancy or breastfeeding, Protected adults (individuals under guardianship by court order or tutelage). Note: participation to another concomitant clinical trial (except for trials evaluating exercise or NMES programs) is allowed, but the patient must inform about it and get an authorization from the Investigator.