Development of the strength and powers of endurance increases during their training under the load. The load occurs in exhalation with resistance to exhaled air flow. Exhaling with permanent additional load, besides load on expiratory muscles, we create a pressure boost in bronchial tubes and lungs, which makes respiratory tracts stay open longer, than they are during exhaling without resistance, even when the bronchial wall is weakened or unstable (bronchial collapse). Transportation of phlegm from the bronchial wall improves in comparison with unloaded exhaling.

               Exhaling with changing load causes the following phenomena. Firstly, the exhaled air steam changes from lamellar to turbulent – this happens because of pressure oscillation of exhaled air flow with the frequency, set by the load device. In this case bronchial tubes “works” in the following way: (picture 1)

Picture 1. Scheme of bronchial tubes work during the exhalation with changing load.

                When there is no resistance to exhalation bronchial tubes can stay permanent without dilation (picture 1.1). At the moment when resistance to exhaled air stream is rising, blood pressure increases and bronchial tubes dilates (picture 1.2). Fast decrease of resistance to exhalation causes pressure reduction that leads to constriction of bronchial tubes (picture 1.3). The following fast pressure boost dilates bronchial tubes again (picture 1.4). Fast pressure change of the exhaling air stream and as a consequence fast speed change of it leads to improvement of sputum discharge from bronchial wall and helps to lead it out of lungs (picture 2).

Picture 2. Scheme of phlegm “transportation” out of lungs during the exhalation with changing load.

              Thus, the use of resistance to exhaled air stream with changing low frequency (12-20Hz) helps to achieve next positive phenomena:
1. Development of strength and endurance of expiratory muscles as a result of load increase.
2. Retention of airways in open state for longer period of time in faze of exhalation in order to prevent bronchial collapse.
3. Deepening of inhalation and exhalation
4. Improvement of phlegm transportation in addition to increasing pulmonary ventilation.
5. Inclusion of respiratory tracts areas with insufficient ventilation into the breathing process.
6. Increase of the air stream at the end of exhaling phase (increase of lung capacity).