The degree of arm elevation impacts the endurance and cardiopulmonary adaptations of COPD patients performing upper-limb exercise: a cross-over study

BACKGROUND: In Chronic Obstructive Pulmonary Disease (COPD), upper limb exercise is widely recommended. However, how the degree of shoulder flexion may influence the exercise response is unknown.

AIM: We compared metabolic, ventilatory and symptomatic responses during constant-load supported and unsupported exercise performed at 80° and 120° arm elevation.

DESIGN: Randomized cross-over study.

SETTING: Pulmonary Pathophysiology Service in an Italian Respiratory Rehabilitative Division, in-patients were enrolled.

METHODS: Twelve patients with moderate-to-severe COPD (FEV1 51%, BMI 26.7 ± 6.3 Kg/m2) performed 4 symptom-limited constant-load tests at 70% of their individual maximal workload: 2 supported and 2 unsupported, respectively at 80° and 120° of glenohumeral joint flexion, executed in a random order.

RESULTS: Time to exhaustion (Tlim), evaluated by Kaplan-Maier curve, was shorter at 120° than 80° arm elevation in both supported (360 vs.. 486 seconds, p=0.031) and unsupported exercise (210 vs.. 375 seconds, p=0.005). No difference in dynamic hyperinflation was found between 80° and 120° elevation, even at the peak of exercise and at iso-ventilation. When normalized to Tlim, 120° arm elevation had a significantly higher metabolic cost, heart rate, minute ventilation and dyspnea/fatigue symptoms compared to 80° elevation, both in unsupported and supported conditions.

CONCLUSIONS: A larger shoulder flexion shortens per se exercise endurance due to the increased metabolic, ventilatory and cardiac response, without worsening dynamic hyperinflation.

CLINICAL REHABILITATION IMPACT: Arm position should be considered when prescribing individual exercise training and may be adjusted to modulate the workload.