To prevent the development of ICUAW, both early mobilization and neuromuscular electrical stimulation (NMES) have been shown to prevent muscle atrophy in critically ill patients by preserving muscle mass. Furthermore, it is of great value that muscle assessment using kinesiological ultrasound becomes routine to monitor this patient's profile with regard to strength, muscle quality and muscle mass. Our objective is to evaluate the muscular changes promoted by NMES in patients under mechanical ventilation. This is a randomized clinical trial study, which will perform NMES sessions for at least 10 days in mechanically ventilated patients. They will also undergo ultrasound assessments of the quadriceps. Patients will be divided into a control group and an NMES group. In addition, general information recorded in the medical record will be collected, such as basic characteristics, laboratory tests and general assessments.