Clinical safety criteria for contraindication or discontinuation of training protocol The criteria will be to increase the heart rate above 20% of the training target zone, initial systolic blood pressure less than 90 or greater than 160mmHg, blood pressure greater than 170/100 mmHg during exercise, initial oxygen saturation less than 90% or desaturation (greater than 4% during exercise), body temperature greater than 38 °C, severe musculoskeletal pain, chest tightness, major dyspnea or tiredness (greater than 6 on the Borg Scale), dizziness, nausea, vomiting, epistaxis, or any active bleeding, loss or obstruction of the central or peripheral access catheter, loss or obstruction of the bladder catheter / nasogastric/enteral catheter and/or at the patient's request. Moreover, the hemoglobin (less than 7 mg/dl), hematocrit (less than 20%) and platelets (less than 10000 mm3) will be absolute contraindications to perform protocols.