Shoulder impingement is the main cause of shoulder pain. Manual therapy is one of the proposed therapeutic strategies. In this context, the Mulligan maneuver implies anterior axial rotation of the clavicle, emulating the action of the subclavius muscle, which hypothetically would increase the subacromial space. However, there are no antecedents that provide experimental support for this hypothesis. The objective of the present study was to explore whether the axial rotation of the clavicle, produced by the Mulligan maneuver, has an effect on the pressure registered in the subacromial space, with the purpose of having methodological antecedents that can contribute to the design of future studies that address the problem exposed and consider a larger sample size. Through an ex-vivo exploratory study, two anatomical preparations comprising the scapula, clavicle, and proximal two-thirds of the humerus, both with glenohumeral and acromioclavicular joint sparing, were evaluated. In these, the pressure in the subacromial space and the axial rotation of the clavicle were recorded, all during the performance of an anterior clavicular axial rotation maneuver. Pressure differences between a basal condition and during the maneuver were analyzed, as well as the maximum axial rotation of the clavicle. These variables were recorded using a pressure sensor and a movement analysis system. The pressure in the subacromial space during the maneuver decreased in all repetitions in a range between 21-51% of the basal pressure. The maximum axial rotation recorded was between 3.9-10 degrees. The results of this exploratory study give rise to the hypothesis that the anterior axial rotation maneuver of the clavicle produces a decrease in subacromial pressure, in the area immediately below the acromion.