A comprehensive study of cardio respiratory system with the use of spirometry, local pulmonary reography, defining diffusion capacity tests, echocardiogrphy and ergospirometry has been carried out among 47 normals and 91 patients with chronic bronchitis in order to work out a method of forecasting a potential level of physical capacity.

It has been established that physical capacity of patients with chronic bronchitis is determined by the functional indicators of airway obstruction, the level of MVV and lung diffusion capacity at rest.

Static parameters of lung function, ventilation-perfusion ratio, parameters of heart pumping function taken at rest come secondary when defining the physical capacity level.

Practical recommendations on defining the physical capacity forecast have been given on the basis of linear regression equation.