People with chronic obstructive pulmonary disease (COPD) experience a gradual decline in functional status that is associated with dyspnea on exertion and physical deconditioning. One of the earliest specific problems they report is dyspnea with activities that involve the upper extremities. The intense dyspnea experienced during the use of upper extremities is related to multiple factors, including hyperinflation of the chest and alterations of ventilatory muscle recruitment.1 It is ultimately accompanied by an increased use of the accessory muscles of respiration in the chest wall and shoulders. The muscles of the chest wall and shoulders function to simultaneously support ventilation and stabilize the chest during upper-extremity work, and in a sense, both activities compete against each other. This is associated with intense dyspnea during simple daily activities such as carrying groceries, sweeping the floor, combing hair, and others. To minimize dyspnea, people limit the use of their arms and become more sedentary. Dyspnea with upper-extremity activities is a major problem for people with moderate to severe COPD; however, in pulmonary rehabilitation, most of the emphasis is on lower-extremity training.

The physical deconditioning of COPD is well documented in terms of its effects on lower-extremity functioning, and less is known about its effects on the upper extremities, especially on endurance of the upper extremities. There is substantial evidence demonstrating a loss of strength in both the lower and upper extremities.2 A decline in general aerobic capacity is well documented, but it is measured with incremental exercise tests that engage the larger muscles of the lower extremities through the use of treadmills and cycle ergometry. These tests reflect endurance of the lower extremities and are probably not sensitive to changes in the smaller muscles of the upper extremities. Little is known about endurance of the upper extremities, possibly because of a lack of standardized measures that can be used in the clinical setting.

Strength and endurance of the skeletal muscles are readily modifiable through exercise training, although relatively little attention has been given to training of the upper extremities in COPD. There is a small body of research describing the isolated effects of upper-extremity training. Existing evidence supports the use of strength training to improve upper-extremity strength.3-5 The evidence for endurance training is promising. Endurance training of the upper extremities produced improved endurance, as demonstrated by arm ergometer tests,6 tests that require the lifting of weighted dowels,7,8 and a peg board ring test.9 The differences in endurance measures and inadequate characterization of endurance measures make it difficult to synthesize this body of research and draw conclusions about the appropriate exercise prescription.

Despite the limitation in research, it is recommended that upper-extremity strength and endurance training be included as a part of pulmonary rehabilitation.10 Many pulmonary rehabilitation programs include upper-extremity strength and endurance training, but in most programs, the upper-extremity training component is not comprehensive and not designed to produce maximal gains in strength and/or endurance. It may include 10 to 15 minutes of arm cranking on a cycle ergometer and the lifting of a few light hand weights. This is surprising considering the extent of limitations that COPD patients experience during arm work.

Part of the problem in this field is a lack of reliable and valid measures to document progress with upper-extremity training. There are well-established methods for measuring upper-extremity strength, most notably the one-repetition maximum test or a variation of it. There are no well-established methods for measuring upper-extremity endurance. Consequently, Zhan and colleagues11 have advanced the field with their characterization of the peg board and ring test (PBRT). This test can easily be performed in the clinical setting. It requires a minimal amount of equipment and no special expertise to conduct the test.

This research provides solid evidence for the reliability of the PBRT as a measure of upper-extremity endurance, but further research is needed to facilitate the interpretation of results in the clinical setting. Zhan and colleagues11 demonstrated that short-term test-retest reliability was excellent when the test was conducted twice in the same day. The mean absolute difference between tests was less than 10% and the mean difference was approximately 2%. The interval between repeated tests can influence test-retest reliability, and in the clinical setting, repeated tests are likely to be conducted at weekly or monthly intervals. With longer intervals between tests, the test-retest reliability may not be as high. In addition, most tests of physical performance require that subjects overcome a learning curve, especially if the test involves a novel activity. The data presented by Zhan and colleagues do not suggest the presence of a substantial learning effect, but further testing is required to adequately address this issue. To adequately interpret results in the clinical setting, it will be important to know more about the magnitude and duration of the learning effect and the day-to-day variation in performance after subjects have learned to perform the test.

The results of this research provide support for the validity of the PBRT, that it measures endurance of the upper extremities, although validity is always difficult to establish without a gold standard for comparison. In this case, Zhan and colleagues have demonstrated that the results of the PBRT are consistent with theoretical expectation. The moderate correlations among the PBRT, the FEV1 percent predicted, and the FVC percent predicted are precisely what one would expect to see, that is, deterioration in function associated with worsening of the disease. Furthermore, the weaker relationship between the PBRT and the pulmonary Functional Status Dyspnea Questionnaire is totally consistent with expectations, given the potential for measurement error associated with self-report instruments and the diversity of activities included in this questionnaire. The healthy subjects performed approximately 30% better than the COPD subjects (P < .001). It was somewhat surprising that the difference between COPD and healthy subjects was not greater, given the extent of airflow obstruction in the COPD group. Nevertheless, the much higher scores for the cooks in the healthy sample provide evidence that the PBRT is responsive to differences in habitual use of the upper-extremities.

In summary, upper-extremity training has the potential to improve functioning and reduce a major source of distress for people with COPD. The field has been hampered by a lack of standardized measures, and this work by Zhan and colleagues advances the field in this regard. The PBRT is promising, although further research is needed to fully characterize this and other tests of upper-extremity endurance. Advancements in measurement often serve as a catalyst to advance the science in a given field, and this could occur with upper-extremity training in COPD.

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