Protein and Exercise Training in Chronic KIDNEY Disease

1. In order to be eligible to participate in this study, a patient with CKD must meet all of the following criteria: * (e)glomerular filtration rate (GFR) \<45 ml/min/1.73m2 * Age: 18 - 80 y * Able to provide written informed consent 2. In order to be eligible to participate in this study, a healthy subject must meet all of the following criteria: * (e)GFR \>60 ml/min/1.73m2 without albuminuria * Age: 18 - 80 y * Able to provide written informed consent 1\. A potential subject with CKD who meets any of the following criteria will be excluded from participation in this study: * Insulin-dependent diabetes mellitus or two or more oral glucose lowering medications * Active inflammatory disease / malignancies * Uncontrolled hypertension (\>160/100mm Hg), unstable angina pectoris, or arrhythmia * Pulmonary disease restricting exercise performance (e.g. COPD) * A history of neuromuscular problems * Cognitive Impairment * Diagnosed GI tract diseases / dysphagia * Allergies to milk proteins / Lactose intolerance * Pregnancy * Hospitalization \<1 months prior to study period * Participation in any structured exercise program * Any medications known to affect protein metabolism (i.e. corticosteroids or prescription strength acne medications). * Use of DOAC, vitamin-K-antagonist, or multiple anticoagulants. * Dialysis treatment or previous kidney transplantation 2\. A potential healthy subject who meets any of the following criteria will be excluded from participation in this study: * Insulin-dependent diabetes mellitus or two or more oral glucose lowering medications * Active inflammatory disease / malignancies * Uncontrolled hypertension (\>160/100mm Hg), unstable angina pectoris, or arrhythmia * Pulmonary disease restricting exercise performance (e.g. COPD) * A history of neuromuscular problems * Cognitive Impairment * Diagnosed GI tract diseases / dysphagia * Allergies to milk proteins / Lactose intolerance * Pregnancy * Hospitalization \<1 months prior to study period * Participation in any structured exercise program * Any medications known to affect protein metabolism (i.e. corticosteroids or prescription strength acne medications). * Use of DOAC, vitamin-K-antagonist, or multiple anticoagulants.