Am Fam Physician. 2000;61(12):3708-3710
Studies have shown that patients with chronic obstructive pulmonary disease (COPD) can improve their ability to perform certain tasks by becoming involved in lower-extremity exercise programs. According to some studies, high-intensity exercise programs lead to significantly greater improvements in endurance in these patients compared with low-intensity exercise programs. In these studies, however, the level of intensity was defined by the symptom limitations of the patients and not by physiologic testing. Gimenez and colleagues looked at the outcomes of a maximally tolerated 45-minute aerobic training program in patients with COPD compared with those of a commonly prescribed moderate exercise program.
The authors conducted a prospective randomized trial of patients with established COPD whose condition had been clinically stable for one month. Patients who qualified for the trial were randomly assigned to high-or moderate-intensity exercise groups. Patients in the high-intensity group were evaluated with a bilevel exercise ergometer to establish their maximum exercise intensity level. These patients exercised at their determined level for 45 minutes per day, five days a week, for six weeks. Patients in the moderate-exercise group followed the same time schedule but exercised at a moderate-intensity level.
Patients in the high-intensity exercise group significantly reduced dyspnea symptoms at rest and increased peak oxygen consumption (V̊ O2) and total physical work capacity. They also significantly increased their grip and forearm strength and endurance. These improvements were significantly better in the high-intensity group when compared with the moderate-intensity group. The high-intensity group also increased maximum voluntary ventilation while decreasing ventilatory equivalent during exercise. No adverse events occurred in either group during the training program.
The authors conclude that a maximally intense endurance program can be safely implemented in most patients with COPD. This program can significantly improve respiratory and skeletal muscle strength. It can also decrease symptoms and improve endurance in these patients.