In a group of 30 men aged 44-60 years with chronic bronchitis the effect of physical effort was assessed on the value of airways resistance and expired air flow. Physical effort was noted to increase the air flow and decreases airways resistance in most cases of chronic bronchitis. A significant negative correlation was demonstrated between the TGV value and the flow-volume value, and changes of air flow after effort in chronic bronchitis patients depended on the resting TGV value.