The Effect of Muscle Stimulation and Amino Acid Intake on Protein Metabolism During Critical Illness

The goal of this clinical trial is to study how whole-body electrical stimulation combined with amino acid intake affects muscle health in ventilated ICU patients. The main questions to answer are: * Does electrostimulation improve the balance of muscle protein in ICU patients? * Does combining electrostimulation with amino acid help build muscle and prevent muscle loss? Researchers will compare three groups of patients: 1. Sham electrostimulation (no current applied) + the standard nutrition 2. Electrostimulation + the standard nutrition 3. Electrostimulation + a 20g amino acid bolus Participants will: * Receive either real or sham electrostimulation * Get their standard nutrition or a 20g amino acid bolus * Have marked amino acids given through an IV * Have blood samples taken to measure the amino acids and glucose in the blood * Undergo ultrasound of the upper arm to measure the blood flow