It is well known that the the training with the IMT device increases the Maximal Inspiratory Pressure. Nonetheless, there are doubts about which muscles are involved during this training. The aim of this study is to determine the diaphragm loading of healthy subjects during the training with a IMT device from a low . Therefore, each subject will be monitored using esophageal and gastric manometry.

This study has a quasi-experimental design. The investigators will recruit ten healthy adult volunteers without anticoagulation or esophageal lesions, after signing a consent form.

After checking the appropriate correct position of each catheter, each subject will use the IMT device throughout different randomized loads (percentages of the maximal inspiratory pressure, counting by tens from 10% to 100%). FluxMed® GrT MBMed respiratory mechanic monitor will be used. Each percentage of resistive load will be maintained for 5 inspirations. Meanwhile, an operator will register the esophageal pressure,the gastric pressure and the transdiaphragmatic pressure. Diaphragm collaboration in each percentage of resistive load will be determine by calculating the relation between the gastric pressure and the transdiaphragmatic pressure (∆Pgas/∆Pdi).

Inclusion Criteria:

• older than 18 years
• healthy subjects

Exclusion Criteria:

• without anticoagulation
• without esophageal lesions
• without airway lesions
• without spirometry alterations

healthy adult volunteers