The Effect of Auricular and Systemic Acupuncture on the Electromyographic Activity of the Trapezius Muscle with Trigger Points—A Pilot Study

Patrícia Silva de Camargo; Carla Rigo Lima; Maria Luiza de Andrade E Rezende; Adriana Teresa Silva Santos; João Wagner Rodrigues Hernandez; Andréia Maria Silva

doi:10.1016/j.jams.2017.11.003

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The Effect of Auricular and Systemic Acupuncture on the Electromyographic Activity of the Trapezius Muscle with Trigger Points—A Pilot Study

Patrícia Silva de Camargo¹, Carla Rigo Lima¹, Maria Luiza de Andrade E Rezende¹, Adriana Teresa Silva Santos¹, João Wagner Rodrigues Hernandez², Andréia Maria Silva¹^*

¹Federal University of Alfenas (UNIFAL-MG), Brazil
²University Centre of Espírito Santo (UNESC), Brazil

Correspondence to:

Andréia Maria Silva

Received: June 26, 2017; Revised: November 11, 2017; Accepted: November 15, 2017

http://creativecommons.org/licenses/by-nc-nd/4.0/

2018; 11(1): 18-24

Published February 1, 2018 https://doi.org/10.1016/j.jams.2017.11.003

Abstract

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Abstract
1. Introduction
2. Materials and methods
3. Results
4. Discussion
5. Conclusion
Acknowledgments
Disclosure statement
References

The purpose of this study was to analyze and compare intra and intergroup the immediate effect of the auricular and LR8 systemic acupuncture on the electromyographic activity of the trapezius with the trigger points. This is an experimental clinical trial; 40 people were split in 4 distinct groups (n = 10): GI mustard seed application in the auricular acupoint; GII bilateral needle application in the LR8 acupoint; GIII combination of the techniques; GIV/Control Group mustard seed application in an acupoint not linked to the muscle tension. The EMG was used to assess the muscle contraction for 5 seconds during the resting time and during the isometric contraction time. The EMG signal was first collect without the acupuncture intervention; then both techniques were applied for 5 minutes; and the EMG was collected again right after these applications. The Shapiro-Wilk test was used, the t test was paired with the Wilcoxon test to the intragroup comparison; One-way analysis of variance test for intergroup comparison. There was no statistical difference in the intragroup comparison for the groups. The same happened to the intergroup comparison before and after application. Systemic and auricular acupuncture did not promote immediate changes in the EMG activity of the trapezius muscle in individuals with MTrPs.

Keywords

acupuncture, electromyography, muscular tension, rehabilitation, trigger point

1. Introduction

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Abstract
1. Introduction
2. Materials and methods
3. Results
4. Discussion
5. Conclusion
Acknowledgments
Disclosure statement
References

Acupuncture is a Traditional Chinese Medicine technique which has the energy balance of the meridians as the principle [1]. It can be classified as systemic or auricular, and the form of application can be through the insertion of needles at different depths in strategic points of the skin and underlying tissues, as well as in auricular reflex points. These points are referred to as acupoints, and when stimulated, they trigger functional responses such as relief of muscle pain due to exacerbated muscle contraction [2, 3]. In addition to resulting in an energetic balance of the organism, afferent stimulation of acupoints promotes effects based on local or systemic reflex responses [4]. Currently, this technique is well known for its neurophysiological effects such as the inactivation of the neural circuit of myofascial trigger points (MTrPs), reduction of pain, and reduction of muscle contraction among others [2].

MTrPs can be defined as hypersensitivity points present in areas of skeletal muscle tension and are associated with hyperirritable nodules which, on palpation, may produce several local or distant symptoms, such as local cutaneous hyperthermia, dysesthesias, and hypesthesias, restriction of range of motion, referred pain in adjacent and/or distant areas, proprioceptive and coordination disorders, and motor dysfunction during physical examination [5, 6]. In other words, a complex of MTrPs in a certain tense musculature is composed of several contraction “knots” that are palpation sensitive [5-8]. The pathophysiological mechanism of MTrPs is related to changes in muscle activity, blood circulation, and local metabolism [8].

The trapezius muscle–descending fibers are one of the most affected areas by MTrPs due to the frequent presence of acute traumas, tension by chronic lesions, and tissue inflammation by repetitive movements in this muscle. Such tissue changes can lead to biopsychosocial changes, reducing the quality of life and productivity of individuals [8, 9]. It is estimated that 21–93% of the population presents trigger points and that the trapezius muscle with its descending portion is an area of common involvement [10]. Clinically, this area is relatively more symptomatic as to the presence of pain implying muscle imbalances [11]. Different therapeutic approaches are used to treat MTrPs; among them, the use of acupuncture can be highlighted.

Some studies have demonstrated the effect of acupuncture on various biological systems, elucidating the mechanisms of action through neurophysiology [10, 12, 13]. The release of vasoactive substances, the increase in local blood supply, the increase in cellular oxygenation, the metabolic changes, the increase in immune system activation, changes in the lymphatic system, and the release of endogenous opioids that promote analgesia and muscle relaxation are also the results found by means of this therapy [10, 12-15]. The literature does not highlight which technique is the best to alter the electromyographic (EMG) activity of the trapezius muscle with MTrPs. Therefore, the first hypothesis is that the immediate stimulation in the auricular acupoint may act indirectly on the EMG activity of the trapezius muscle with MTrPs, and the systemic acupoint LR8 that presents the relaxation of tendons and muscles as one of the functions. The second hypothesis is the possible enhancement of the combined effects of both techniques and the individual effects of each technique. The last hypothesis was that the immediate effects of the procedures after 5 minutes of application would possibly lead to an alteration in the EMG signal.

Therefore, the purpose of the present study was to analyze and perform the intragroup and intergroup comparisons of the immediate effect of the auricular acupoint and systemic acupuncture LR8 on the EMG activity of the trapezius muscle with MTrPs.

2. Materials and methods

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Abstract
1. Introduction
2. Materials and methods
3. Results
4. Discussion
5. Conclusion
Acknowledgments
Disclosure statement
References

2.1. Study

It was an experimental clinical trial approved by the Research Ethics Committee of the Federal University of Alfenas, under protocol number 192/2011. All participants were properly informed regarding the objectives and procedures and signed a statement of informed consent before testing.

2.2. Sample

A total of 40 volunteers were randomly selected from a pool of 200 participants from the population of undergraduate and graduate students of the Federal University of Alfenas. The inclusion criteria were as follows: volunteers having trigger points in the trapezius muscle; age older than 18 years (average and deviation); both genders (Fig. 1). A physical therapy evaluation was performed to detect the presence of trigger points through anamnesis and manual palpation in the trapezius muscle following the Trigger Point & Referred Pain Guide (http://www.triggerpoints.net/). The exclusion criteria were as follows: participants having no trigger points, pregnancy, or any type of panic reaction to needles.

Figure 1.Flow diagram of the local and adjacent acupuncture. The diagram also includes the number of volunteers who were included and excluded from the trial

After the selection, they were randomized, by simple draw, into four distinct groups with 10 participants each: the first group (GI) was treated with mustard seed (due to low cost/benefit) application in the auricular acupoint; the second group (GII) was treated with bilateral needle application in the LR8 acupoint (point of liver meridian) whose energetic function is to relax muscles and tendons; the third group (GIII) was treated with the combination of the techniques; and the last group (GIV/control group)was treated with a mustard seed application to an acupoint not linked to the muscle tension.

2.3. Equipment used

The electromyography signal was recorded in the upper trapezius muscle. An electromyograph unit model EMG 800 C (EMG System do Brasil Ltda, São José dos Campos, Brazil), with four input channels, 16-bit analog to digital conversion board resolution, electromyography amplifier with total gain of 2,000 times, band pass filter of 20 to 500 Hz, four active monopolar surface electrodes, with gain preamplification of 20 times, shielded cable and pressure at the extremity, common rejection mode ratio > 100 dB, and software for signal collection and analysis with sampling frequency of 2000 Hz per channel, was used. Windows platform, common rejection mode is 100 dB, gain of preamplifiers (cables) is a gain of 20 (with differential amplifier), a gain of each channel is a gain 100 times (configurable), system impedance is an impedance of 109 Ohm with a noise ratio signal less than 3 μV square root of the mean (RMS), band pass filter with a cut-off frequency of 20 to 500 Hz, filtering was performed using a second order Butterworth analog filter.

2.4. EMG data recording

First, the skin asepsis was performed with 70% alcohol to reduce the impedance for better signal acquisition followed by the placement of the electrodes [16]. The individuals remained in a sitting position on a chair with both feet flat on the floor, without shoes, and in a neutral position during the evaluation [17]. The active monopolar electrode was positioned bilaterally on the upper trapezius muscle unclothed on the midpoint of the line between the C7 spinous process and the acromion [18]. The electrode of reference (ground) was placed on the participant's C7 spinous process (this vertebra is quite prominent making it easy to realize the manual palpation). The participant in the seated position performed flexion of the cervical spine, and the spinous processes were individually palpated.

They performed a maximum voluntary contraction (MVC) against the gravity for 5 seconds for the EMG signals recording [19] and then executed an elevation of the shoulder and scapula against the gravity. Three series of MVC of 5 seconds each were recorded, with a minute rest period between efforts (Fig. 2). Only one examiner was responsible for the evaluation of individuals in search of trigger points and subsequent collection of EMG data.

Figure 2.Positioning of the electrodes for the electromyographic data recording. (A) It shows trapezius muscle resting. (B) It shows maximal isometric contraction of the trapezius muscle. Source: personal files.

The recording was done without the application of acupuncture. Afterward, the acupuncture points were applied for 5 minutes and then they were reevaluated with EMG.

The EMG signal processing was obtained as follows: the average between the three collections was calculated, later divided by the greater value, and multiplied by 100%.

2.5. Acupuncture procedures

The asepsis on the application sites was provided by 70% alcohol, and the skin was shaved when necessary. The acupuncture method adopted was the Traditional Chinese Medicine with the application in auricular and systemic acupuncture. It was performed by a physical therapist certified in the Auricular and Systemic Acupuncture by the Brazilian Institute of Acupuncture, having 10 years of clinical experience with the method.

A needle (25 × 30 mm, stainless steel spiral cable, sterilized with plastic mandrel—Qizhou® made in China) was inserted into LR8 (QuQuan) acupoint [20]. The insertion was perpendicular with a depth of approximately 35 mm or until feeling a tissue resistance [20]. The stimulation of the acupoints was manual, and the needle was inserted for 5 minutes. Each patient received only one treatment session, with evaluation and EMG reassessment being performed on the same day.

In the GI group, the mustard seeds were applied on the right ear at the points corresponding to the neck, cervical spine, and thoracic spine, located at the bottom of the antihelix and held with a micropore tape [21] for 5 minutes [18] (Fig. 3). These auricular acupoints produce a therapeutic effect at a distance; the choice of using these tiny seeds was due to its ease in placement and cost effectiveness (cost/benefit ratio).

Figure 3.Insertion points of the mustard seed application, corresponding to the neck, cervical spine, and thoracic spine located in the ear (GI—circles) and the trachea located in the shell of the ear (GIV/control group—square). Also, acupuncture needle in the LR8 acupoint (GII—bilateral) located in the medial end of the transverse crease of the popliteal fossa. Source: personal files.

In the GII group, the needles were inserted bilaterally into the LR8 (QuQuan) [20] located in the region on the medial side of the knee, at the medial end of the popliteal fold, in a depression between the semitendinous muscle tendon and the medial condyle of the tibia; therefore, the energetic functions are the relaxation of the tendons and muscles. This point was stimulated at a distance, for 5 minutes, to trigger the relaxation response [20, 18] (Fig. 3).

In the GIII group, the two techniques described previously were combined.

In the GIV group, mustard seeds were applied in the right ear at the point corresponding to the trachea, located in the cava shell [20] and maintained for 5 minutes [18] (Fig. 3).

2.6. Statistical analysis

Demographic characteristics and EMG data were assessed by the Shapiro–Wilk normality test. Demographic data were compared using the one-way analysis of variance test (intergroups) followed by Bonferroni test. EMG data were compared using the paired t test and the Wilcoxon test (intragroups) and the one-way analysis of variance test for intergroup comparison. The statistical program used was the Statistical Package for the Social Sciences (SPSS, version 20.0). The effect size was classified according to Chen: small effect between 0 and 0.39; mean effect between 0.40 and 0.79; and large effect greater than 0.80 and power >0.80. The sample calculation was performed with a sample and considered the EMG variable on the left side, adopting a statistical power of 0.80 and an alpha level of significance of 0.05, in which a required number of 116 individuals were estimated. The power analysis was performed using the G* Power software (version 3.1).

3. Results

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Abstract
1. Introduction
2. Materials and methods
3. Results
4. Discussion
5. Conclusion
Acknowledgments
Disclosure statement
References

The demographic characteristics of the groups are presented in Table 1. There were statistical differences between the groups for the body mass variable.

Table 1 . Demographic characteristics of the volunteers separated into variables, groups, and power values.

Variables	GI	GII	GIII	GIV	p
Age (y)	20.6 ± 1.64	21.0 ± 1.76	20.4 ± 1.83	21.0 ± 2.98	0.89
Body mass (Kg/cm²)	56.8 ± 4.97	56.6 ± 5.42	58.7 ± 5.27	63.1 ± 6.0	0.03^*
Height (m)	1.64 ± 0.07	1.63 ± 0.07	1.61 ± 0.06	1.62 ± 0.05	0.75
Gender, n (%)	10 (100%) F	10 (100%) F	9 (90%) F; 1 (10%) M	9 (90%) F; 1 (10%) M

F = female; GI, GII, GIII = intervention groups; GIV = control group; M = male.

*p = power value.

Analysis of variance one-way test followed by Bonferroni test.

The results of Table 2 demonstrate that there were no statistical differences in intragroup comparisons for the variables of GI (p = 0.45 R, p = 0.88 L); GII (p = 0.20 R, p = 0.66 E); GIII (p = 0.75 R, p = 0.22 L); GIV (p = 0.38 R, p = 0.66 L). Statistical analyses of all variables indicated a low effect size and a power below 0.8%.

Table 2 . Intragroup comparison of electromyographic variables.

Muscle		GI (n = 10)			GII (n = 10)			GIII (n = 10)			GIV (n = 10)

		Before	After	p^* d	Before	After	p^* d	Before	After	p^* d	Before	After	p^* d

		95% CI	95% CI		95% CI	95% CI		95% CI	95% CI		95% CI	95% CI
Trapezius	R	96.55 ± 12.71	95.22 ± 14.70	0.45^a	85.38 ± 27.96	95.39 ± 16.97	0.20^b	86.82 ± 9.18	85.75 ± 11.27	0.75^a	92.10 ± 17.39	93.30 ± 12.08	0.38^b
	R	87.45–105.64	84.70–105.74	0.09	65.37–105.38	83.24–107.54	0.41	80.25–93.39	77.68–93.81	0.10	79.66–104.54	84.65–101.94	0.07
	L	92.51 ± 11.45	92.84 ± 11.85	0.88^a	95.10 ± 29.34	97.70 ± 19.23	0.66^a	83.02 ± 11.21	87.36 ± 8.45	0.22^a	89.02 ± 5.70	89.74 ± 5.58	0.66^a
	L	84.31–100.71	84.36–101.32	0.02	74.11–116.09	83.93–111.46	0.10	74.99–91.02	81.31–93.42	0.42	84.94–93.10	85.74–93.73	0.12

CI = confidence interval; GI, GII, GIII = intervention groups; GIV = control group; L = left; R = right. *p < 0.05.

^at test paired.

^bWilcoxon test; d: effect size with power <0.89% value.

The results of Table 3 demonstrate that there were no statistical differences in the intergroup comparison before (p = 0.37) and after (p = 0.90) treatment for the EMG variables of GI, GII, GIII, and GIV.

Table 3 . Results of the intergroups EMG analysis.

Muscle	Groups (GI, GII, GIII, and GIV)

		Before	After

		p	p
Trapezius	R	0.509	0.37
Trapezius	L	0.42	0.90

EMG = electromyographic; L = left; R = right.

Analysis of variance one-way, *p < 0.05.

4. Discussion

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Abstract
1. Introduction
2. Materials and methods
3. Results
4. Discussion
5. Conclusion
Acknowledgments
Disclosure statement
References

The main finding of the study was that systemic and auricular acupuncture, after 5 minutes, did not promote changes in the EMG activity of the muscle during MVC.

However, Politti et al [18] demonstrated that in healthy individuals, there is an increase in EMG activity after 1 minute and a reduction in the activity after 5 minutes of MVC intervention, suggesting that auricular acupuncture promotes the modulating mechanism of muscle activity, both in the number of motor units recruited and in the mean discharge frequency of the motor units. This result is in contrary to the present study in which this alteration was not observed, perhaps being related to the insufficient sample size.

As a result, the immediate effects of auricular acupuncture after 5 minutes of application did not present a decrease in the EMG activity of trapezius muscle–descendent fibers. According to Silva et al [22] after 30 minutes of application of auricular acupuncture in healthy individuals and individuals with cervical pain, there is a decrease in the EMG activity of the trapezius muscle, therefore, indicating the immediate effect of auricular acupuncture. However, no similar results to the abovementioned study were found, which may be related to a different postintervention time.

Treatment with systemic acupuncture reestablishes the energy balance between the meridians, being energy channels responsible for conducting the vital energy (Qi) by the body [23]. Costa and Araújo [24] compared the immediate effects of local acupuncture (acupuncture stomach 36—ST36—referring to the anterior tibial muscle) and adjacent (acupoint spleen 9—SP9—referring to the muscular system) in the anterior tibial muscle. They found a reduction in the EMG activity in both acupoints, 20 minutes after the application. However, the acupoint ST36 also decreases muscle strength. Therefore, the current experiment used the acupoint LR8 for distance intervention, and the literature emphasizes that this acupuncture aims to promote tendon and muscle relaxation [20], and this point did not promote changes in the EMG activity.

Ferreira et al [25] obtained an immediate reduction of muscle activity after 20 minutes of application of systemic acupuncture in individuals with pain symptoms in several muscles, including the trapezius muscle. Therefore, the decrease in the EMG activity of the muscles induces muscle relaxation and pain relief. Regarding this study, 5 minutes after the application was not enough to cause changes in the EMG activity; this may be related to the time after the intervention and also to the number of sessions, perhaps the application of more sessions could have effectiveness with this therapy.

Psychological stress also generates muscle tension. Gomes et al [23] found systemic acupuncture effectiveness with the reduction in the EMG activity of the trapezius muscle–descending fibers. However, the aims were not intended to assess psychological stress in relation to muscle tension; this could be an influencing factor in the selection of the sample associated with the presence of trigger points.

Another form of treatment with acupuncture is auricular acupuncture. It stimulates the cerebral cortex inducing immediate, delayed, temporary, or permanent reactions in a reflex way in addition to promoting through peripheral neural stimulation, local and systemic responses, mediated by the immune and endocrine systems, and by the central centers of Central Control [26]. Haker et al [27] analyzed the effect of auricular and systemic acupuncture on the induction of changes in both the sympathetic and parasympathetic nervous systems. They concluded that the stimulation in healthy individuals induces an alteration in the sympathetic and parasympathetic nervous system and that this depends on the place and the period of stimulation. Therefore, the present experiment could have presented late reflex reactions if there was an increase in the period of application of the combined therapy (auricular and systemic acupuncture).

5. Conclusion

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Abstract
1. Introduction
2. Materials and methods
3. Results
4. Discussion
5. Conclusion
Acknowledgments
Disclosure statement
References

In the present study, sample size and treatment with short duration may have been a limiting factor. Given these limitations, a larger sample size and a long-term treatment are suggested, as well as conducting further studies related to the effect of acupuncture on muscle relaxation. Finally, systemic and auricular acupuncture did not promote immediate changes in the EMG activity of the trapezius muscle in individuals with MTrPs.

Acknowledgments

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Abstract
1. Introduction
2. Materials and methods
3. Results
4. Discussion
5. Conclusion
Acknowledgments
Disclosure statement
References

This work was supported by the Federal University of Alfenas with no founding source, FAPEMIG APQ-00349-15, and in part by the Marcelo Lourenço da Silva, PT at the Federal University of Alfenas.

Disclosure statement

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Abstract
1. Introduction
2. Materials and methods
3. Results
4. Discussion
5. Conclusion
Acknowledgments
Disclosure statement
References

I Andréia Maria Silva corresponding author of the manuscript “The Effect of Auricular and Systemic Acupuncture on the Electromyographic Activity of the Trapezius muscle with Trigger Points-pilot Study” declare that we do not divulge in another journal.

References

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Abstract
1. Introduction
2. Materials and methods
3. Results
4. Discussion
5. Conclusion
Acknowledgments
Disclosure statement
References

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