Comparison of different exercise tests in assessing outcomes of pulmonary rehabilitation.
BACKGROUND
Common modalities of clinical exercise testing for outcome measurement after pulmonary rehabilitation (PR) include walk tests, progressive cycle ergometry, and cycle endurance testing. We hypothesized that patients' responses to PR, as measured by those 3 tests, are differentially correlated, and we designed a study to investigate the tests' capacity to detect changes after PR.


METHODS
We prospectively tested 37 male patients with stable chronic obstructive pulmonary disease who completed a comprehensive 6-week PR program that included supervised exercise training that emphasized steady-state lower-limb aerobic exercise. Before and after the PR program the patients underwent 6-minute walk test, progressive cycle ergometry, and cycle endurance testing (at 80% of the peak work rate achieved during progressive cycle ergometry). The exercise performance indices of interest were the peak oxygen uptake (VO2max) and maximum work-rate (Wmax) during progressive cycle ergometry, the cycling endurance time, and the 6-minute walk distance (6MWD).


RESULTS
After PR there were statistically significant improvements in 6MWD (16%, p <0.001), VO2max (53%, p=0.004), Wmax (30%, p=0.001), and cycling endurance time (144%, p <0.001). The changes in VO2max and Wmax were significantly correlated (r=0.362, p=0.027), as were the changes in endurance time and Wmax (r=0.406, p=0.013). There was no significant correlation between changes in any other exercise index.


CONCLUSIONS
Among the frequently used exercise tests in PR, the most responsive index is the endurance time. The correlation between the post-PR changes in the various exercise indices is poor.
Ong
Kian-Chung
KC
Department of Respiratory Medicine, Tan Tock Seng Hospital, 11 Jalan Tan Tock Seng, Singapore 308433. kian_chung_ong@ttsh.com.sg
Chong
Wai-Fung
WF
Soh
Cindy
C
Earnest
Arul
A
D000368:Aged; D001642:Bicycling / Q000502:physiology; D016552:Ergometry; D005080:Exercise Test / Q000706:statistics & numerical data; D005081:Exercise Therapy; D006801:Humans; D008297:Male; D008875:Middle Aged; D010807:Physical Endurance; D029424:Pulmonary Disease, Chronic Obstructive / Q000503:physiopathology / Q000534:rehabilitation*; D013147:Spirometry; D013997:Time Factors; D016138:Walking / Q000502:physiology