While emphysema and chronic bronchitis are primarily lung di seases, one of their major consequences is to deeply affect the function of the respiratory muscles. Lung hyperinflation shortens the inspiratory muscles due to increased airways resistance, more of their effort is demanded and changes in nutritional status wea ken them further. Their malfunction can lead to severe dyspnea and to failure of the ventilatory pump. Over the last 10 years we have witnessed an explosion of information of how respiratory muscles function in health and disease, new techniques for their evaluation have been...