Mechanisms to dyspnoea and dynamic hyperinflation related exercise intolerance in COPD.

Expiratory flow limitation can develop in parallel with the progression of COPD, and as a consequence, dynamic hyperinflation and lung mechanical abnormalities can develop. Dynamic hyperinflation can cause increased breathlessness and reduction in exercise tolerance. Achievement of critical inspiratory reserve volume is one of the main factors in exercise intolerance. Obesity has specific lung mechanical effects. There is also a difference concerning gender and dyspnoea. Increased nerve activity is characteristic in hyperinflation. Bronchodilator therapy, lung volume reduction surgery, endurance training at submaximal intensity, and heliox or oxygen breathing can decrease the degree of dynamic hyperinflation.