Lung transplantation is now accepted as an appropriate treatment for selected patients with end-stage pulmonary disease. Over the last two decades, there has been growing evidence that several aspects of respiratory and exercise physiology present unique changes after lung transplantation. Many of these changes do not affect the clinical status of the patients, but some do; a typical example is the prominent limb muscle dysfunction that impairs the exercise capacity and does not allow the patients to fully benefit from the improvements in pulmonary function and gas exchange. This chapter presents an overview of a large number of studies on posttransplant respiratory and exercise physiology. It deals primarily with human studies because in most areas, physiological changes seen in experimental conditions differ from those occurring after human transplantation; in addition, it focuses on studies done in patients with well-functioning grafts and does not address alterations in physiology associated with specific complications [e.g., broncheolitis obliterans (BO)]. It should be emphasized that most of the studies discussed in this chapter require careful interpretation due to one or more of the following methodological limitations. The studies were frequently retrospective in design, involving a small number of patients with different types of transplants and a variety of pretransplant diseases. The rationale behind the selection of the control group (e.g., healthy subjects vs.

heart transplant recipients) was not always appropriately discussed. Most studies were primarily descriptive. Finally, very few studies provided longitudinal data obtained pre-and posttransplant, which made it difficult to interpret posttransplant abnormalities.