Association Between Muscle Activity of Upper Limbs and Respiratory Parameters During Functional Performance in People With Chronic Obstructive Pulmonary Disease

Background: Few studies have examined the activity of the accessory inspiratory muscles as well as respiratory function simultaneously in individuals with chronic obstructive pulmonary disease (COPD) while performing activities of daily living (ADLs). This cross-sectional study is aimed at understanding the differences in the demands for respiratory expenditure and activity of the upper limbs and accessory inspiratory muscles during functional performance in individuals with and without COPD. Methods: Thirteen patients with mild to moderate COPD and 10 healthy adults were enrolled. All participants were asked to complete the requested ADL tasks involving upper limb elevation while recording activities of muscles of the accessory inspiratory muscles, as well as respiratory expenditure via the Delsys Trigno electromyography and Ultima CardiO2 system, respectively. Results: Muscle activity of the pectoralis major (PM) in the COPD group was significantly higher than that in the non-COPD group during washing both sides of the head (p < 0.05) and storing 2- and 4-kg objects on a shoulder-height shelf (p < 0.05). Ventilatory inefficiency and metabolic expenditure were significantly higher during the storage of objects at head height in the COPD group. A positive correlation was observed between sternocleidomastoid muscle activity and metabolic/ventilatory expenditure in the non-COPD group. However, muscle activity of the upper trapezius was significantly correlated with metabolic/ventilatory expenditure in the COPD group. Higher PM muscle activity and ventilatory inefficiency in the COPD group were found during performing ADLs involving upper limb elevation. Conclusions: Individuals with COPD demonstrated increased accessory inspiratory muscle activity, reduced ventilatory efficiency, and higher metabolic expenditure during ADLs involving upper limb elevation compared to healthy controls. The PM in the COPD group was the major accessory inspiratory muscle for performing ADLs involving upper limb elevation. These findings could inform recommendations for individuals with COPD to adjust their strategies for upper limb elevation while performing ADLs. Training of the larger accessory inspiratory muscles in rehabilitation programs has also been considered to enhance ADL performance in individuals with COPD. Trial Registration: ClinicalTrials.gov identifier: NCT04146948.