All the subjects will perform a forced spirometry, maximal inspiratory pressure (MIP) and SNIF. If spirometry and MIP are correct the investigators will consider that person has a correct diaphragmatic function and strength. Then the investigators will measure the SNIF test. With all of these SNIF values the investigators will try to achieve the reference values of this test in the different groups of age in Mediterranean population. And the investigators will compare SNIF with MIP.