Even 20-50% of patients under sedation and mechanical ventilation develops myopathy and / or neuropathy which difficulties both the process of extubation and the functional recovery. The objective of this project is to analyze the effect of muscle electrostimulation (ESM) on muscle weakness acquired in Intensive Care Unit (ICU) and its consequences. Study design: a single center, prospective, randomized trial to be held in the ICU of " Universitarian hospital La Fe" in collaboration with the service of Neurophysiology of the hospital. All patients undergoing sedation and mechanical ventilation (with an expected duration longer than 48h) and without any of the exclusion criteria detailed in the Methodology section will be included in the study. The intervention will consist of a muscular electrostimulation with the Super Pro Excel 70,UltratoneTM. The stimulation will be performed in 10 muscle groups (5 per side) following established protocols, at least 5 days a week. We will evaluate muscle strength by Medical Research Council scale, functional capacity by Barthel scale and Neurophaty Disability Scale, all clinical events will be collected and electrophysiologic, echographic and histologic parameters will be measured. The process of extubation will be performed following an established protocol, the duration will be collected as the same manner as ICU.

Inclusion Criteria:

• Patients older than 18 years.
• Sedated and mechanically ventilated critically ill patients, more than 48 hours.

Exclusion Criteria:

• Body mass index > 45 or < 20 kg/m2.
• Pregnant.
• Epilepsia.
• Use muscular blocks.