How should we train the upper limbs?

The article by McKeough and colleagues in this issue of Chronic Respiratory Disease is the first study to compare different modes of upper extremity training in individuals with chronic obstructive pulmonary disease (COPD). Limitations during exercise and daily activity in individuals with COPD are not limited to lower extremity activities such as walking or stair climbing; most of the patients experience difficulty during activities that involve their arms due to the sensation of dyspnea and/or arm fatigue. ¹ Upper extremity training for patients with COPD is an important component of pulmonary rehabilitation (PR), resulting in improvements in arm exercise capacity, arm function and muscle strength. ^2,3 However, there is limited evidence on what type of training should be performed. The study by McKeough and colleagues adds to the growing body of evidence in the area of upper extremity training in COPD and provides support for the inclusion of arm endurance and strength training as a part of PR.

The study is a randomized controlled trial (RCT) that aimed to compare the effects of arm endurance training; arm strength training, a combination of arm endurance and strength training; and no arm training (control group) on endurance arm exercise capacity, functional arm exercise capacity and health-related quality of life (HRQL) in individuals with mild-to-very severe COPD. The authors found a significant improvement in arm endurance time (arm endurance capacity) between the endurance group and control group. There were nonsignificant trends in arm endurance time favoring the strength training and combined groups compared with the control group. In terms of symptoms, the authors demonstrated that the combined group had a significantly greater reduction in dyspnea and rate of perceived exertion at the end of the functional arm exercise test compared with the control and with each of the intervention groups. When the combined group was compared with the other two intervention groups, the improvement in HRQL (measured using the St George’s Respiratory Questionnaire) exceeded the minimum clinically important difference of 4 units, although it did not reach statistical significance.

Until the beginning of the century, several RCTs ^{4 –8} had been conducted to examine the effects of upper extremity training in individuals with COPD. However, there were considerable variations in the exercise protocols rendering it impossible to determine the optimal training regimen for these patients. Moreover, the impact of upper extremity training on other clinical outcomes besides arm exercise capacity was unclear as shown consistently by four systematic reviews. ^{9 –12} More recently, four RCTs examining the effects of arm exercise training in individuals with COPD have been published. ^2,3,6,13 Holland and colleagues ⁶ compared the effects of unsupported upper limb endurance training with lower extremity training alone. The authors found that unsupported upper limb endurance training improved upper limb exercise capacity but had no additional effects on the symptoms or HRQL compared with lower extremity training alone. Costi and colleagues ² examined the effects of upper extremity resistance training in patients with COPD compared with standard PR. The authors demonstrated improvement in arm functional exercise capacity (measured using the 6-minute pegboard and ring test) and in performance during activities of daily living (ADL) measured by an ADL field test. In addition, the authors found a decrease in arm fatigue at the end of the ADL test in the intervention group. Our research group also examined the effects of arm resistance training in patients with COPD. ³ We demonstrated that resistance arm training is effective in improving arm exercise capacity, arm function and muscle strength. Moreover, we demonstrated that patients in the intervention group achieved better performance during tests of arm exercise capacity without any increase in the symptoms of dyspnea or arm fatigue after training, which reflects a positive effect on the patient’s functional status. The study by Subin and colleagues ¹³ included three groups: unsupported upper limb exercise training alone that consisted of functional exercises such as throwing ball, passing bean bag and moving rings across a wire; unsupported upper limb exercise training combined with lower extremity and lower extremity training alone. They demonstrated that the combined upper limb and lower limb training group had a significant improvement in arm exercise capacity and HRQL. This study by McKeough and colleagues extends the observations made during the previous RCTs by demonstrating that the favorable mode of training to increase endurance arm exercise capacity is arm endurance training and that combined arm endurance and strength training may alleviate symptoms during daily arm activities.

Given the evidence, PR programs should include endurance and strength arm training, both to increase arm exercise capacity and alleviate symptoms. However, there remain some questions that should be addressed in future research. The mechanisms underlying improvements in arm exercise capacity and symptoms of dyspnea following upper extremity training in patients with COPD are still unclear. Moreover, except for the study by Costi and colleagues, ² no other trial has examined the long-term effects of upper extremity training in patients with COPD. Further research in these areas is warranted. There is also a need to investigate how the increase in arm exercise capacity following upper extremity training translates into functional improvements during ADL.