Effects of static contraction and cold stimulation on cardiovascular autonomic indices, trapezius blood flow and muscle activity in chronic neck–shoulder pain

Abstract

The aim of the present study was to investigate reactions in trapezius muscle blood flow (MBF), muscle activity, heart rate variability (HRV) and systemic blood pressure (BP) to autonomic tests in subjects with chronic neck-shoulder pain and healthy controls. Changes in muscle activity and blood flow due to stress and unfavourable muscle loads are known underlying factors of work-related muscle pain. Aberration of the autonomic nervous system (ANS) is considered a possible mechanism. In the present study, participants (n = 23 Pain, n = 22 Control) performed autonomic tests which included a resting condition, static hand grip test (HGT) at 30% of maximal voluntary contraction, a cold pressor test (CPT) and a deep breathing test (DBT). HRV was analysed in time and frequency domains. MBF and muscle activity were recorded from the upper trapezius muscles using photoplethysmography and electromyography (EMG). The pain group showed reduced low frequency-HRV (LF) and SDNN during rest, as well as a blunted BP response and increased LF-HRV during HGT (∆systolic 22 mm Hg; ∆LF(nu) 27%) compared with controls (∆systolic 27; ∆LF(nu) 6%). Locally, the pain group had attenuated trapezius MBF in response to HGT (Pain 122% Control 140%) with elevated trapezius EMG following HGT and during CPT. In conclusion, only HGT showed differences between groups in systemic BP and HRV and alterations in local trapezius MBF and EMG in the pain group. Findings support the hypothesis of ANS involvement at systemic and local levels in chronic neck-shoulder pain.

Analysis of scapular muscle EMG activity in patients with idiopathic neck pain: A systematic review

“…Four of the six studies did not find significant differences between the groups (Johnston et al, 2008a;Nilsen et al, 2006;Sjors et al, 2009;Voerman et al, 2007). Hallman et al (2011) found larger UT activity in patients with neck pain during a Cold Pressor Test. Sjogaard et al (2010) found also higher UT activity in the neck pain group while Voerman et al (2007), using a similar task, did not find significant differences between patients with neck pain and healthy controls.…”

“…Seven studies measured the activity of the UT during rest. Six studies (Andersen et al, 2014(Andersen et al, , 2008Hallman et al, 2011;Nilsen et al, 2006;Voerman et al, 2007;Wegner et al, 2010) showed consensus and did not find any difference in EMG amplitude between patients with neck pain and healthy controls during rest. In contrast, the study of Sjors et al (2009) found higher activity in patients with neck pain during rest, in comparison to healthy controls.…”

“…Schulte et al (2006) found lower UT activity in patients with neck pain during sustained isometric shoulder girdle elevation (6 min at 30% MVC) against a force transducer. Hallman et al (2011) found larger UT activity in patients with neck pain during a static hand grip test and Cold Pressor Test. The other studies did not show a difference in amplitude of UT activity during short term (20 s, respectively at 10%, 30%, 50% and 70%) isometric shoulder girdle elevation against a handle connected to a strap attached to a strain gauge dynamometer (Elcadi et al, 2013), during a static arm-holding task (as long as possible) with arm in 45°flexion in the scapular plane (Goudy and McLean, 2006), during step-wise increased contractions (5 force levels, 20, 40, 60, 80 and 100 N, 10 s each) of isometric shoulder elevation (Kallenberg et al, 2007), and during isometric abduction, flexion and external rotation using a purpose built dynamometer (20%, 50%, 100% MVC) (Zakharova-Luneva et al, 2012).…”

“…Six studies measured the amplitude of UT EMG activity during stressful tasks, including pressing one or two keys with their fingers (Nilsen et al, 2006), calling out as fast as possible the color of a print (Johnston et al, 2008a), a Cold Pressor Test (Hallman et al, 2011), the Trier Social Stress Test (Sjors et al, 2009) and a mouse task (Sjogaard et al, 2010;Voerman et al, 2007). Four of the six studies did not find significant differences between the groups (Johnston et al, 2008a;Nilsen et al, 2006;Sjors et al, 2009;Voerman et al, 2007).…”

Cardiac autonomic modulation adjustments in isometric exercise

“…13 Agiovlasitis et al 24 found increased low frequency activity during isometric exercise compared with the resting condition in paraplegic patients. Hallman et al 25 investigated the response of cardiac autonomic modulation in isometric contraction in patients with muscle pain, and found a reduction in the overall modulation of HR analyzed through the SDNN index as the intensity of pain increased. Shiro et al 26 found no significant changes in the LF/HF ratio in patients with pain in the trapezius muscle, concluding that the decrease in muscle blood flow and oxygen in the trapezius muscles can derive from the sympathetic response during isometric exercise.…”