European Respiratory Journal vol:14 issue:6 pages:1314-9
In some patients exercise induces numerous complaints which cannot be attributed to an organic disorder, and which are suggestive of hyperventilation. The study was designed to investigate in this type of patient: 1) exercise capacity and muscle force; 2) breathing pattern and symptoms during maximal exercise and recovery; 3) relationships between symptoms and breathing pattern. Twenty-four patients were compared with 20 healthy subjects. They performed a maximal incremental cycle ergometer test and peripheral and respiratory muscle strength were measured. Patients tended to have a decreased exercise capacity and presented with moderately reduced muscle strength. At comparable minute ventilation, breathing frequency was higher (mean: 24 versus 21 per minute) and tidal volume smaller (mean: 1.42 versus 1.67 L). End-tidal partial pressure of carbon dioxide (PET,CO2) was not significantly different. A significant relation was observed between PET,CO2 and respiratory frequency during recovery in patients, suggesting a reduced flexibility of the ventilatory response to exercise. In patients respiratory complaints and paresthesias were weakly correlated to PET,CO2 at moderate exercise. It is suggested that the physical deconditioning observed in those patients is rather a consequence than a cause of the response to exercise. The link between symptoms and breathing pattern might be explained by a psychological conditioning process.