Inclusion Criteria:  patients admitted to ICU having a confirmed diagnosis of COVID-19 requiring invasive mechanical ventilation.  Exclusion Criteria:  exclusive palliative care; neuromuscular diseases; patients who evolve with the need for lower limb amputation; previous known diaphragm malformations and dysfunctions; patients transferred from other institutions under invasive mechanical ventilation; clinical conditions that make the respiratory and peripheral muscle assessment through ultrasound unfeasible.