Relationship and responsiveness of three upper-limb tests in patients with chronic obstructive pulmonary disease

To determine (1) the relationship among three common upper-limb tests for patients with chronic obstructive pulmonary disease (COPD): unsupported upper limb exercise test (UULEX), 6-minute pegboard and ring test (6PBRT), and a muscle-strength test using a hand-held dynamometer; and (2) the responsiveness of these three tests to changes after pulmonary rehabilitation that included a resistance arm-training programme.

The study was a secondary analysis of a randomized controlled trial (RCT). The UULEX and the 6PBRT were used to measure peak arm exercise capacity and arm function, respectively. A handheld dynamometer was used to measure elbow and shoulder flexion force. We analyzed baseline data for all participants in the RCT, as well as baseline and post-PR data for those who completed 6-week follow-up testing.

36 patients with COPD (mean forced expiratory volume in 1 second [FEV1]=35% [SD 15%] predicted; age 66 [9] y) participated, of whom 13 completed an arm-training programme. The correlations among the test results ranged from 0.41 to 0.81 (p<0.0001). Standardized response means were 1.0 for muscle force of elbow flexion, 1.2 for shoulder flexion, and 1.8 for the 6PBRT and UULEX.

Although the three tests (UULEX, 6PBRT, and muscle-strength test using a hand-held dynamometer) are intended to measure different constructs, they were moderately to highly correlated with one another. The 6PBRT, UULEX, and muscle-strength test were demonstrated to be responsive to the resistance arm-training programme.