Effect of muscle load tasks with maximal isometric contractions on oxygenation of the trapezius muscle and sympathetic nervous activity in females with chronic neck and shoulder pain

Yukiko Shiro,Takako Matsubara,Shunsuke Isogai,Takahiro Ushida,Young-Chang P Arai

doi:10.1186/1471-2474-13-146

Abstract

BackgroundSympathetic nervous activity contributes to the maintenance of muscle oxygenation. However, patients with chronic pain may suffer from autonomic dysfunction. Furthermore, insufficient muscle oxygenation is observed among workers with chronic neck and shoulder pain. The aim of our study was to investigate how muscle load tasks affect sympathetic nervous activity and changes in oxygenation of the trapezius muscles in subjects with chronic neck and shoulder pain.MethodsThirty females were assigned to two groups: a pain group consisting of subjects with chronic neck and shoulder pain and a control group consisting of asymptomatic subjects. The participants performed three sets of isometric exercise in an upright position; they contracted their trapezius muscles with maximum effort and let the muscles relax (Relax). Autonomic nervous activity and oxygenation of the trapezius muscles were measured by heart rate variability (HRV) and Near-Infrared Spectroscopy.ResultsOxyhemoglobin and total hemoglobin of the trapezius muscles in the pain group were lower during the Relax period compared with the control group. In addition, the low frequency / high frequency (LF/HF) ratio of HRV significantly increased during isometric exercise in the control group, whereas there were no significant changes in the pain group.ConclusionsSubjects with neck and shoulder pain showed lower oxygenation and blood flow of the trapezius muscles responding to isometric exercise, compared with asymptomatic subjects. Subjects with neck and shoulder pain also showed no significant changes in the LF/HF ratio of HRV responding to isometric exercise, which would imply a reduction in sympathetic nervous activity.

Highlights

Sympathetic nervous activity contributes to the maintenance of muscle oxygenation
ΔTHb in the pain group was lower during Relax 2 and Relax 3 periods at the right trapezius muscle and each Relax and second rest periods at the left trapezius muscle compared with the control group (Figure 3)
The pain group induced no significant changes in the low frequency / high frequency (LF/high frequency (HF)) ratio of heart rate variability (HRV) responding to isometric exercise

Summary

Introduction

Sympathetic nervous activity contributes to the maintenance of muscle oxygenation. Insufficient muscle oxygenation is observed among workers with chronic neck and shoulder pain. The aim of our study was to investigate how muscle load tasks affect sympathetic nervous activity and changes in oxygenation of the trapezius muscles in subjects with chronic neck and shoulder pain. Several studies showed that metabolic insufficiencies are related to pain perception of workers with trapezius myalgia [7,8]. Impaired regulation of microcirculation occurs in the trapezius muscle in cases of chronic neck pain [4,5] and insufficient muscle blood flow and oxygenation have been observed among workers with chronic neck and shoulder complaints [7,8]. The pathogenic mechanisms of chronic neck and shoulder pain development are likely to be multifactorial

Objectives

Methods

Results

Conclusion