In several diseases in which muscle weakness is a determining factor for morbidity and mortality, inspiratory muscle training has been shown to be useful in improving the function of ventilatory muscles, delaying or minimizing the development of complications due to the reduction of inspiratory muscle strength.

The breath-stacking technique emerges as an easily applicable alternative, and it can be used in poorly collaborative patients. The technique described in the literature aims to increase pulmonary volumes.

This gain occurs with the coupling of a silicone mask on the patient's face, a unidirectional valve and with the expiratory branch occluded. Thus, inspirations occur sequentially in this medium, generating pulmonary hyperinflation and increasing the contractility power of the expiratory muscles, which are fundamental for coughing. This hyperinflation also improves the peripheral air distribution in the lungs by increasing intrathoracic pressure.

The objective of this study is to evaluate the effect of the breath-stacking (BS) technique on the ventilatory muscle strength of young and healthy individuals.

Initially, participants will be submitted to a learning session on the evaluation of ventilatory muscle strength and the breath-stacking technique. Between 24-72 hours after the learning, the evaluation of the muscular muscular strength will be performed through the maximal inspiratory pressure (MIP) and the maximum expiratory pressure (MEP). PI max will be measured from a maximum expiration; While PE max will be measured from a maximum inspiration, using a digital manovacuometer (MVD 300®)

Inclusion Criteria:

• No signs and symptoms of pulmonary diseases, normal ventilatory muscle strength and agreement to participate and sign the informed consent form.

Exclusion Criteria:

• Presenting neuromuscular diseases, claustrophobia, ruptured eardrum, history of spontaneous pneumothorax and playing wind instruments or being a singer. Sample loss will be considered as non-attendance at all training sessions.