Treadmill Versus Cycle Ergometry Testing in COPD

Collins EG, Langbein WE, Fehr L, Bammert C, O'Connell S, Tobin M, Laghi F. Treadmill Versus Cycle Ergometry Testing in COPD. Paper presented at: American Thoracic Society Annual International Conference; 2004 May 1; Orlando, FL.

Introduction Choosing the appropriate exercise stress test is important in determining functional status in patients with COPD. The purpose of this investigation was to compare peak performance of patients with COPD on a symptom-limited incremental cycle ergometer (CE) test with a symptom-limited treadmill (TM) test. Methods Sixty-two subjects (96% male, age = 67 8 yr) with COPD (FEV1 = 1.4 0.6 L) were tested on a 10 Watt incremental CE protocol and TM test (1.8 mph with an increase of 0.5% grade every 30 sec; speed increased to 2 mph at 6 min and 0.2 mph every 3 min thereafter). Subjects completed the CE test first and the TM test one week later. Results Oxygen uptake (1.29 0.31 Lmin-1 CE versus 1.51 0.4 Lmin-1 TM, p < 0.001) and peak heart rate (117 19 beatsmin-1 CE versus 121 18 beatsmin-1 TM, p = 0.05) were greater on the TM test when compared to the CE test. Thirty-eight percent of subjects (n = 24) stopped cycling due to leg fatigue and 26% (n = 16) due to breathlessness. Conversely, 38% (n = 24) stopped walking on the TM due to breathlessness and 16% (n = 10) due to leg fatigue. Remaining subjects cited reasons such as breathlessness and leg fatigue or overall fatigue. In the group who stopped cycle testing due to leg fatigue, VE and breathing frequency were lower (p = 0.02 and p = 0.03, respectively) on the CE test than on the TM test. The difference in oxygen uptake between CE and TM testing was greater in those who stopped cycling due to leg fatigue (p = 0.06, Table 1). There were no differences in FEV1 or BMI between the two groups. Conclusion Oxygen uptake is higher in the majority of patients with COPD when testing on the TM versus the CE. Furthermore, the difference in oxygen uptake is even greater between TM and CE testing when patients stop cycle exercise due to leg fatigue.Table 1. Oxygen uptake on CE and TM testing