Effects of neuromuscular electrical nerve stimulation on quadriceps muscle strength and endurance in patients with chronic obstructive pulmonary disease

Abstract

Introduction: Neuromuscular Electric Nerve Stimulation (NMES) is a modality that is gaining interest as part of the management of participants with Chronic Obstructive Pulmonary Disease (COPD). Given the increased knowledge of how the muscle changes structurally as the respiratory condition deteriorates, treatment options are being investigated to help maintain and improve strength and endurance in patients who are limited due to poor exercise tolerance and increased dyspnoea and cannot part-take in rehabilitation. Method: Using a randomised control trial design, 33 participants who required admission to hospital due to an Acute Exacerbation of COPD, with a moderate to severe classification based on the MRC score, were recruited and randomly allocated to an experimental or control group. Quadriceps strength, endurance, COPD Assessment Test Score (CAT Score), 1-minute Sit-to-Stand test (1MSTS), Borg Dyspnoea Scale (BDS) and Rectus Femoris width and thickness were assessed at baseline and on completion of the intervention upon discharge from hospital on all participants. The experimental group received 30 minutes of NMES stimulation on the quadriceps muscles daily throughout their hospitalisation stay, over and above the usual physiotherapy treatment provided to all participants by physiotherapists in the ward. The control group received only Physiotherapy treatment provided in the ward. All outcome measures were repeated prior to discharge. Results: Statistically significant improvements in quadriceps strength (left and right; P < 0.001), quadriceps endurance (left: P < 0.027, right: P < 0.015), Rectus Femoris Cross-sectional Area (left: P < 0.012, right: P < 0.003), Rectus Femoris Thickness (left and right: P < 0.001), Rectus Femoris Width on the right side (P = 0.017) and BDS (P = 0.027) were reported in the experimental group. In contrast, statistically significant declines in mean values for the left and right Rectus Femoris width were registered for the control group (left P = 0.006, right: P< 0.001). The only outcomes which resulted in statistically significant improvements for both groups included the CAT Score (P < 0.001) and the 1MSTS test (P < 0.001); however, a higher mean percentage change in both tests was noted for the experimental group. Conclusions: 30 minutes of daily NMES during a period of hospitalisation due to an AECOPD in moderate to severe participants resulted in significant improvements in all outcome measures for the experimental group. Therefore, NMES can be utilised as an adjunct to the already provided physiotherapy treatments offered to maintain and improve quadriceps strength, endurance and muscle structure, improve the impact of COPD on patients and increase exercise tolerance.