In Patients With Obstructive Airway Disease, Investigate the Effects of Different Breathing Strategies and Pedaling Rates on the Physiological Response to Bicycle Exercise

The definition of obstructive airway disease is a ratio of the forced expiratory volume in one second (FEV1) to the forced vital capacity (FVC) of less than 0.7, which includes conditions such as chronic obstructive pulmonary disease, asthma, lymphangioleiomyomatosis, and bronchiolitis obliterans syndrome. For example, lung obstruction adversely affects many aspects of a patient's health, such as lung function and exercise capacity. Pulmonary rehabilitation is widely used in patients with obstructive airway disease, and the prescription of pulmonary rehabilitation depends on exercise capacity parameters such as peak oxygen uptake (peak VO2), peak workload, and anaerobic threshold. However, patients often have difficulty achieving training goals due to severe dyspnea during exercise. Dynamic hyperinflation is a common cause of dyspnea during exercise in patients with obstructive airway disease. Investigators aim to alleviate breathlessness by reducing dynamic hyperinflation, making it easier to achieve training goals. Methods to reduce dynamic hyperinflation include pursed lip breathing, reducing breathing rate to prolong expiratory time, using bronchodilators, and undergoing lung volume reduction surgery. Among these methods, reducing breathing rate to prolong expiratory time may be the most feasible, and investigators aim to change the rhythm and pace of breathing by adjusting the pedal rate of cycling exercise. The pedaling rate is typically set at 60 revolutions per minute. The European Respiratory Society recommended a pedal rate range of 40-70 revolutions per minute in 2019. There is still no consensus on the relationship between pedal rate and respiratory rate. This prospective observational study, using a crossover design, aims to investigate the effects of pedal rate during exercise testing on dynamic hyperinflation and exercise capacity in patients with obstructive airway disease.