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The use of surface electromyography for the study of auricular acupuncture
Journal of Bodywork & Movement Therapies (2010) 14, 219e226
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NEUROPHYSIOLOGY
The use of surface electromyography for the study of auricular acupuncture* Fabiano Politti a,b,*, Cesar Ferreira Amorim c, Lilian Calili a, Adriano de Oliveira Andrade d, Evanisi T. Palomari a a
Department of Anatomy, University of Campinas (Unicamp), Brazil Department of Physical Therapy, Rehabilitation Sciences Biomechanics Lab, University of Vale do Sapucaı´ (Univa´s), Brazil c Department of Mechanical Engineering, Sa˜o Paulo State University (UNESP - FEG), Guaratingueta´ - SP, Brazil d Biomedical Engineering Laboratory (BioLab), Federal University of Uberlandia, Brazil b
Received 13 June 2008; received in revised form 11 November 2008; accepted 22 November 2008
KEYWORDS Electromyography; Auricular acupuncture; Neurophysiology
*
Summary The advancement of knowledge in neurophysiology has demonstrated that acupuncture is a method of peripheral neural stimulation that promotes local and systemic reflexive responses. The purpose of this study was to determine if surface electromyography can be used as a tool to study the action of auricular acupuncture on striated skeletal muscle. The electromyographic amplitudes of the anterior, middle and posterior deltoid muscle and the upper trapezium muscle with 20%, 40% and 60% of maximal voluntary contraction of 15 healthy volunteers, were analyzed after the individuals were submitted to the auricular acupuncture treatment. The non-parametric Friedman test was used to compare Root Mean Square values estimated by using a 200 ms moving window. Significant results were further analyzed using the Wilcoxon signed rank test. In this exploratory study, the level of significance of each comparison was set to p < 0.05. It was concluded in this study that a surface electromyography can be used as a tool to investigate possible alterations of electrical activity in muscles after auricular acupuncture. However there is still a lack of adequate methodology for its use in this type of study, being that the method used to record the electromyographic signal can also influence the results. ª 2008 Elsevier Ltd. All rights reserved.
Work accomplished at the State University of CampinaseUNICAMP, Institute of Biology, Department of Anatomy. * Correspondence to: Fabiano Politti, Universidade Estadual de Campinas, UNICAMP, Depto of Anatomia, Instituto de Biologia, Cx Postal 6109, CEP: 13084-971, Campinas - SP, Brazil. E-mail address: [email protected] (F. Politti).
Introduction Acupuncture has recently been recognized by western science as a procedure that can be used supplementary to medicine, especially in the treatment of chronic pain syndrome (NIH, 1998). Advances in the knowledge of
1360-8592/$ - see front matter ª 2008 Elsevier Ltd. All rights reserved. doi:10.1016/j.jbmt.2008.11.006
220 neurophysiology have made it possible to establish that this is a neural peripheral stimulation method that promotes local and systemic reflexive responses, mediated by endocrine and immune systems and by superior centers of central control (Mayer, 2000; Carlsson, 2002). A reflexive response is caused by a gauging stimulus located in the somatic nerve fibers, which is triggered by insertion of a needle (Andersson and Lundeberg, 1995) in specific points of the skin and muscles, called acupoints (Li et al., 2004). These acupoints, found in greater concentration in specific areas such as the ear, can be used in a combined fashion with points on the body (Ellis, 1994). The most frequent use of acupuncture treatment is in muscular relaxation (Lewith and Kenyon, 1984); in the systemic regulation of motor dysfunctions (Ulett et al., 1998) and in the control of skeletal muscle pain, considering that its analgesic effects are mediated by central mechanisms that involve neural standards (Sim, 1997; Pomeranz, 2001). However, results are still questionable regarding acupuncture’s action in pain control. Studies carried out on the effects of chronic pain have indicated that individuals who received treatment with sham acupuncture, demonstrated better results than the individuals receiving real treatment (effective treatment of chronic pain), generating much criticism about the methodology applied in these types of studies (Ezzo et al., 2000). In general, the methodology utilized to demonstrate the effects of acupuncture has concerned several authors (Birch, 2003; Hopwood and Lewith, 2003), who rate many of these studies inconsistent, partial and likely to overestimate the positive effects of the treatment (Moher et al., 1996; Jadad and Rennie, 1998; Ezzo et al., 2000). Due to the existence of different techniques for the insertion of the needle, combined with different strategies for the localization of the insertion points and the existence of several treatment methods for the same type of diseases (Birch, 2003), it is essential for this type of study to consider the appropriate selection of a specific treatment for each type of pathology, and the selection of the control group, the choice of the participants and the choice of the acupuncturists (Sherman and Cherkin, 2003). Recent review articles have concluded that acupuncture still requires investigation. This is due to the fact that the neuromodulating mechanisms of nociception resulting from the stimulus caused by acupuncture, which happen at the three levels of the central nervous system (spinal, troncoencephalic and diencephalic), needs greater clarification (Moya, 2005), as do the methodological standards such as appropriate sample sizes, well-defined inclusion and exclusion criteria, and collection of data on safety and side effects (Sherman and Cherkin, 2003). An important note of observation about these revision articles is that, as of yet, there exists no standardized method for each area of investigation into acupuncture activity. Since it is an acceptable method in the investigation of muscular function in various types of analysis such as in muscular biomechanics (Finley et al., 2005), muscular skeleton fatigue (Ebaugh et al., 2006), strength (Kamibayashi and Muro, 2006), rehabilitation (Barak et al., 2006) and neuromuscular disorders (Hogrel, 2005), surface electromyography can be a reliable tool to validate the
F. Politti et al. effects of acupuncture, because it is then possible to investigate the amplitude and occurrence of electrical activity in the muscle while a task is being performed (Robertson et al., 2004) The aim of the present study was to determine if surface electromyography can be utilized as a tool to study the action of auricular acupuncture on striated skeletal muscles. Additionally, the behavior of the electrical activity was verified from anterior, middle and posterior deltoid muscles and upper trapezium muscle at different levels of exertion in a single test position.
Methods Subjects The volunteers taking part in the study were selected by means of a blind draw from the population of undergraduate and graduate students from the Anatomy Department of the University of Campinas Biology Institute. Fifteen volunteers, between ages 20 and 28, were selected and of those, eight were females (average 20.63 2.97) and seven were males (average 26.33 5.68). Included in the study were healthy, non-obese, sedentary volunteers having no history of previous shoulder pain. The volunteers were examined by a physical therapist familiar with musculoskeletal disorders of the upper limbs and scapular waist and neck. All volunteers signed a Term of Consent as required by resolution 196/96 issued by the National Health Council and previously approved by the Ethical Committee in Research from the State University of Campinas. Each subject was informed of the purpose and potential risks of the study before their written voluntary consent was obtained.
Equipment Myoelectric signals were obtained using an 8-channel module (EMG System do Brazil Ltda.), consisting of a band pass filter of 20e500 Hz, an amplifier gain of 1000, and a common rejection mode ratio >100 dB. All data were acquired and processed using a 16-bit Analog to Digital converter (EMG System do Brazil Ltda), with a sampling frequency 1.33 kHz. The system was composed of active bipolar electrodes displaying a pre-amplification gain of 20. A channel of the acquisition system was enabled for the utilization of the load cell (Alfa Instruments), having an output between 0 and 20 mV and a range up to 1 kN.
Procedure and data collection In western culture, the use of the auricular microsystems developed in France by neurologist and acupuncturist Paul Nogier gave another perspective to the understanding of some of the mechanisms by which acupuncture works. The concept of the technique is based upon the somatotopic organization of the external auricular pavilion and principally on its direct relation to the central nervous system, which is hypothesized to function through the branches of pairs of cranial nerves innervating the whole auricular pavilion (Nogier, 1969, 1972, 1983).
The use of surface electromyography Nogier’s original discovery led to the identification of the body mapping on the auricle which presented remarkable consistency with respect to anatomic and embryological considerations. Thus, the ‘‘inverted fetus’’ presents with the musculoskeletal (mesodermal) projections in the upper aspect of the ear, including the anti-helix, scaphoid fossa, and triangular fossa (Nogier, 1969). According to the theory and body mapping proposed by Nogier, it is possible to conclude that the needle stimulus in the specific external auricular pavilion can influence in a reflexive manner specific regions of the body. However, this hypothesis is yet to be tested in a blind, placebocontrolled clinical trial. In order to verify this hypothesized reflexive action of auricular acupuncture on the musculoskeletal activity, we used the acupuncture point referring to the scapular waist and shoulder, as proposed by Nogier (Figure 1). Consequently, the possible reflexive action of the scapular waist and shoulder acupuncture point was verified through activity from the upper trapezius and deltoid muscles respectively. Muscle activity was recorded from the upper trapezius, selected because they are the primary muscles used to elevate the arm (Michels and Boden, 1992; Campos et al., 1994) and because they are commonly related to tension pain of the head and neck. The anterior, middle and posterior deltoid muscles were chosen because they assist in the elevation and stabilization of the shoulder during this elevation (Hagberg, 1981; Kronberg et al., 1991; McCann et al., 1993). Self-adhesive disposable surface electrodes (Ag/AgCl e Medical Trace) of 10 mm of diameter were used for the surface recording of electromyography with a center to center distance of 20 mm. Prior to the fixation of the
Figure 1 Insertion points of the acupuncture needle in the ear, corresponding to the shoulder (a) and the scapular waist (b) used in the experimental group and the point located in the shell of the ear (c) used for the placebo group.
221 electrodes, the skin was cleansed with 70% alcohol for the elimination of residual fat; cleansing was followed by exfoliation using a specific sand paper for skin (Bio-logic Systems Corp) and a second cleaning with alcohol. The electrodes were affixed 2 cm laterally in reference to the mid point of a line traced from the posterior lateral edge of the acromion to the 7th cervical vertebra (Matthiassen et al., 1995) in the upper trapezium muscle. For the anterior, middle and posterior deltoid electrodes were positioned in the lower half of the distance from the acromion to the deltoid tuberosity (Nannucci et al., 2002). A reference rectangular electrode (3 cm 2 cm), was lubricated with electro-conductor gel (Pharmaceutical Innovations) and fastened to the left wrist of the volunteers. During the experiments, the individuals remained comfortably seated in the test chair. Before beginning the recording of electromyographic signals, each individual subject was asked to carry out a series of three maximum force elevations of the shoulder ipsi-lateral to the auricular acupuncture treatment, with duration of 3 s each, against the resistance offered by the load cell (Figure 2). A 2-min rest period was given between efforts. Verbal encouragement was given to the subject especially during the task. The mean value from the three trials represented a subject’s 100% maximum voluntary contractions (MVC) force, and the 20%, 40% and 60% values of MVC were calculated from that number. Mean muscle output was used to determine MVC as it was believed to be a more accurate representation of a subject’s strength than a single contraction. The three sub-maximal contractions (20%, 40% and 60% MVC) were used in the analysis of the auricular acupuncture action on the shoulder muscle.
Figure 2 Test position as the individual elevates the shoulder ispi-lateral to the auricular acupuncture (A) against the resistance of the load cell (B).
222 Due to the necessity of having an appropriate control group for this type of study, the same volunteers served as the control. Consequently, the experiment was run in two stages with a fixed, 7-day interval between the two tests. The results obtained with the needles placed in the points specific to the treatment of shoulder region problems were assigned to the experimental group and the placebo group served as the control. A blind draw determined the order of the individual subjects sampled. As suggested by Sherman and Cherkin (2003), the real function of each acupuncture point was masked from the participants. Likewise, the participants were requested not to visualize the application site of the needle. Communication with the patient was not permitted during the experiment, and the acupuncturists were not aware of the specific purpose of the study. Questions about the study were noted by one of the authors, but were answered only at the conclusion of the research, when all data had been collected. Electromyographic signals were recorded at three distinct moments, the first, pre-acupuncture (ACP), served as comparison to the signal obtained after the insertion of the acupuncture needle. Five minutes after the first sample (ACP), disposable sterile acupuncture needles 0.25 13 mm (Suchou Huanqiu Acupuncture Medical Appliance Co. Ltd.) were inserted at previously established points of the outer ear and were maintained without manipulation until the end of the experiment. After a 1-min interval, a second electromyographic signal sample was recorded with acupuncture (ACP1), and after 5 min, the third and last sample electromyographic signal (ACP2) was recorded, followed by immediate removal of the needle. The criteria for the recording of the electromyographic signals were always the same for all stages of the experiment. At each moment (ACP, ACP1 and ACP2), 20%, 40% and 60% sub-maximum MVC samples were collected and maintained through visual feedback provided by a line drawn on the computer screen. The duration of each electromyographic signal sample was 5 s. In order to avoid a learning effect, the order of the sample collection was also determined by blind draw. Possible risks of bodily compensation during the traction of the load cell and of patterning in the whole experiment were prevented through training before all the tests. Of greatest concern during the experiment was that the head and neck be always maintained in the same position, so as to avoid interference from the upper trapezius muscle in the activity.
F. Politti et al. waist (Nogier and Boucinhas, 2001). Asepsis by means of alcohol was provided at the location of the acupuncture needle insertion. A physical therapist certified in the Nogier Method of Auricular Acupuncture by the Regional Physical Therapy Council (CREFITO-4) and having 5 years of clinical experience with the Nogier Method, performed the auricular acupuncture treatment.
Processing and analysis of the signals For this study, the EMG signals obtained during the 20%, 40% and 60% sub-maximal MVC contractions under the conditions ACP, ACP1 and ACP2, were normalized by the medium values of the three repetitions at maximal effort with fixed resistance for each muscle analyzed, as used by McLean (2005). Each sample lasted 4 s with a rest interval of 2 min. The position and action of each muscle studied was thus: i) upper trapezium and medium deltoid: individual subject seated, performing static contraction of the limb in abduction of 90 and neutral rotation of the shoulder, against the resistance of a strap positioned near the elbow joint (McLean et al., 2003); ii) posterior deltoid: individual subject seated, with a slight abduction, extension and medial rotation of the shoulder, performing extension of the limb with isometric contraction during the traction of a fixed strap attached near the elbow joint (Kendall et al., 1993); iii) anterior deltoid: individual subject seated, with slight abduction, flexion and lateral rotation of the shoulder, performing flexion of the limb in isometric contraction during the traction of a fixed strap attached near the elbow joint (Kendall et al., 1993). After data were normalized for each muscle the root mean square (RMS) was calculated using a 200 ms moving window technique. Electromyographic Analysis Software, Version 1.01 (EMG System do Brasil, Ltda.) was used.
Statistical analysis Data are presented as means and standard deviations (SD). The non-parametric Friedman test was used to compare intraclass results in root mean square amplitude (RMS). Significant results were further analyzed using the Wilcoxon signed rank test. In this exploratory study, the level of significance of each comparison was set to p < 0.05. The entire analysis was conducted using the software SPSS (Version 12.0).
Needle insertion points on the ear
Results In the experimental group, the needles were inserted on the ear at the points corresponding to the scapular waist, located in the sixth of seven spaces contained between the posterior fold of the anti-tragus (in the region of its junction with the anti-helix and the second depression located on the anti-helix), and to the shoulder, located approximately 3 mm above the furrow which separates the anti-helix from the anti-tragus as indicated in Figure 1 (Nogier and Boucinhas, 2001). In relation to the placebo group, the needles were inserted on the shell of the ear as placebo treatment (Figure 1), being that this region does not present any somatotropic relationship to the shoulder and the scapular
The intraclass analysis (Friedman test) of anterior, middle and posterior deltoid muscle (Table 1) did not present a statistically significant difference (p > 0.05) of the values of RMS amplitude, under pre-acupuncture conditions and post-acupuncture, tested under each sub-maximum force level (20%, 40% and 60% of MVC). The same analytical criteria were adopted for the upper trapezium muscle, which, in accordance with the Friedman test displayed significant difference (p < 0.003) for values corresponding to 60% of the MVC in the experimental group. In the multiple comparisons, using the Wilcoxon test, a significant difference (p < 0.003),
The use of surface electromyography
223
Table 1 Mean and standard deviation (SD) of RMS (mV) from the anterior, middle and posterior deltoid muscle from experimental group and placebo group. ACP indicates the pre-acupuncture condition and ACP1 and ACP2 indicate the acupuncture condition tested under three levels of sub-maximum force (20%, 40% and 60% MVC). Muscles
ACP
ACP1
ACP2
Mean (SD)
Mean (SD)
Mean (SD)
60% 40% 20%
0.29 (0.18) 0.18 (0.12) 0.14 (0.09)
0.28 (0.18) 0.21 (0.12) 0.14 (0.11)
0.32 (0.22) 0.17 (0.14) 0.15 (0.11)
0.76 0.42 0.54
Middle Deltoid
60% 40% 20%
0.83 (0.58) 0.52 (0.49) 0.47 (0.41)
0.80 (0.59) 0.56 (0.42) 0.46 (0.41)
0.86 (0.55) 0.54 (0.42) 0.48 (0.40)
0.81 0.81 0.62
Posterior Deltoid
60% 40% 20%
0.88 (0.56) 0.58 (0.52) 0.28 (0.16)
0.86 (0.68) 0.49 (0.43) 0.28 (0.19)
0.90 (0.69) 0.52 (0.41) 0.31 (0.19)
0.93 0.12 0.48
60% 40% 20%
0.21 (0.06) 0.17 (0.06) 0.10 (0.03)
0.20 (0.10) 0.21 (0.19) 0.11 (0.04)
0.20 (0.06) 0.20 (0.19) 0.10 (0.03)
0.72 0.28 0.76
Middle Deltoid
60% 40% 20%
0.67 (0.39) 0.42 (0.17) 0.35 (0.15)
0.63 (0.36) 0.47 (0.22) 0. 39 (0.20)
0.67 (0.35) 0.46 (0.21) 0.38 (0.19)
0.62 0.62 0.86
Posterior 2Deltoid
60% 40% 20%
0.71 (0.68) 0.43 (0.23) 0.27 (0.12)
0.62 (0.51) 0.41 (0.28) 0.26 (0.11)
0.63 (0.41) 0.43 (0.23) 0.28 (0.12)
0.63 0.21 0.70
Experimental Group Anterior Deltoid
Placebo Group Anterior Deltoid
% MVC
*p value
*A Friedman test did not show a significant difference (p > 0.05) in the intraclass comparison.
was identified in the RMS values corresponding to the ACP and ACP2 (Figure 3). These results indicate an increase of the RMS amplitude in the upper trapezium muscle at 60% MVC, after 5 min of the insertion of the acupuncture needle in the ear. For values regarding 20% and 40% MVC in the experimental group, no significant differences were found (Friedman test, p > 0.05). Under these same test conditions, no statistically significant differences were found in the analysis of the trapezium muscle in the placebo group (Figure 3).
Discussion Based on the advances in neurophysiology, it is possible to define acupuncture as a neural peripheral stimulation method aimed at promoting changes in the sensorial, motor, hormonal and cerebral functions (Nishijo et al., 1997; Mayer, 2000). Such changes originate from the reflex response caused by the afferent stimuli in the somatic nerve fibers after the insertion of the needle (Andersson and Lundeberg, 1995).
Figure 3 Mean of the RMS (mV) value computed over 5 seg from the upper trapezium muscle. The intraclass tests accomplished in the placebo group, did not demonstrate significant statistical differences (Friedman test, p > 0.05) between the pre-acupuncture (ACP) and with acupuncture (ACP1 and ACP2) in each one of the tree tested levels of sub-maximum force (20%, 40% and 60% MVC). * Indicates a significant difference between ACP and ACP2 (Wilcoxon, p < 0.003).
224 Knowledge about the reflex response is concentrated in experimental studies carried out on the pathways of the sensory nerve system responsible for the modulation and inhibition of pain (Mayer, 2000; Carlsson, 2002) in the three levels of the central nervous system: spinal cord (Lewith and Kenyon, 1984; Cao, 2002), encephalic trunk (Cao, 2002) and cerebral cortex (Zhang et al., 2004). However, the action of auricular acupuncture on the motor apparatus is not frequently discussed in scientific studies, which makes a difficult discussion of the results presented in this work. With respect to the results obtained by means of the methodology used in this study, it is not possible to state that auricular acupuncture can influence the activity of the muscles studied because, although a significant increase (p < 0.05) in electromyographic activity of the upper trapezius muscle was observed in the experimental group with 60% of MVC there was no alteration of the electromyographic signal with 20% and 40% of MVC. The significant alteration observed only in the upper trapezius muscle in the experimental group with 60% of MVC, requires extra care in its interpretation. To affirm a possible effect of auricular acupuncture on the muscle activity would be possible only if statistically significant alterations of the electromyographic signal with 20% and 40% of MVC had been found. Factors such as type (Tarkka, 1984) and time duration of contraction (DeVries et al., 1982; Tarkka, 1984) can also alter the muscle activity and should be considered in the analysis of the results obtained in this study. In general, during an isometric exercise at constant load, there is a time related increase of the electromyographic signal (Tarkka, 1984) which could be related to changes in the recruiting pattern of motor units after the first seconds of contraction, as well as to the increase of the amplitude of the action potential and to the recruitment of motor units or the firing of the motor neurons (DeVries et al., 1982; Tarkka, 1984); however, this fact is not enough to justify the increased amplitude of the electromyographic signal in the experimental group, since the same experimental conditions were maintained for the two groups studied. Another argument that would contradict this outcome is that acupuncture has as one of its more frequent clinical uses, muscular relaxation (Lewith and Kenyon, 1984) and, in this case, the electromyographic signal is reduced. All the consulted therapists using the Nogier method relate muscle relaxation and a reduction or an elimination of pain as principle therapeutic effects. As such, the results of this study open to questioning the affirmation that auricular acupuncture has muscular relaxation as one of its effects. This contradiction indicates that the clinical treatment results are not the same as those present in the controlled study, suggesting that further investigation is necessary. One possible explanation for the appearance of the significant difference found in the experimental group at 60% of MVC could be related to the methodology employed during the experiment. Since the collection sequence of electromyographic signal was by blind draw, the data referring to the sub-maximum contraction of 60% of MVC could have randomly been the last to be collected under the ACP2 condition of the experimental group, but there is
F. Politti et al. no way of proving this, each possibility of sub-maximum contraction (20%, 40% and 60% MVC) having been determined by the draw which preceded each of the samples. If this really occurred, the increased electromyographic signal amplitude could be related to the onset of fatigue (Masuda et al., 1999), which can happen during a repetitive or sustained activity (Mannion & Dolan, 1996), as was the case during the experiment. This points to a possible fault in the method used in this study. Thus, the duration of data collection and the number of repetitions of the experiment also need to be well planned to avoid alterations of the amplitude electromyographic signal as a result of biological factors such as muscular fatigue. During the development of this study, a constant source of concern for the authors was the use of methodological rigor in the collection and treatment of data. This concern arose mainly after the literature review indicated potential problems involving sample size, nature of the study, inadequate control groups and absence of long-term responses (Mclellan et al., 1993; Moher et al., 1996; Ezzo et al., 2000; Sherman and Cherkin, 2003; Moya, 2005). To ensure confidence in the results obtained, a blind clinical trial was carried out by means of a draw. The trial aim was to compare the action of the true points in the treatment experimental group versus the action of the false points in the placebo group, in random distribution, as suggested in the literature (Carroll et al., 1996; Filshie and White, 1998) and described in the methodology of the present study. The use of false points is possible due to the fact that points on the ear are highly specific and there are differences between the stimuli effect from the real and false points (Farber et al., 1995; Tavares et al., 1996). It is important to mention that is impossible to carry out a double blind study in acupuncture since the acupuncturist cannot be blinded (Filshie and White, 1998; Carlsson, 2002). Consequently, the volunteers who participated in this study, as well as the author of the evaluations of the electromyographic signals, were not informed of the specific function of the auricular acupuncture treatments adopted in the experiment, as suggested by Filshie and White (1998) and Carlsson et al. (2000). Even with all these cautionary measures, it was observed that the methodology used for electromyographic signal recording of the deltoid muscle was not the most appropriate. Previous studies indicate that the action of the three portions of the deltoid muscle is directly related to the movements of abduction, flexing and the dislocation of the upper limb in different angular movements (Michels and Boden, 1992; Campos et al., 1994). Since this experiment was conducted without angular shoulder movement (Figure 2), the electromyographic signal amplitude obtained from the three portions of the deltoid muscle was very low and possibly not sufficient to show a possible influence of auricular acupuncture on this muscle. With relation to the upper trapezius muscle, the position adopted for the tests (Figure 2) permitted that this muscle performed its functions as a prime mover during elevation and rotation of the scapula and as a stabilizer of the scapula during glenohumeral movements (Schenkman and De Cartaya, 1987) and during glenohumeral torque production (Mathiassen and Winkel, 1990). Consequently, it
The use of surface electromyography is important to respect the muscular function because the firing frequency of the motor units varies according to the levels of force exerted during the isometric contraction (Maton, 1981) and it is possible that the greater the motor engagement, the greater the chance that alterations will be observed in the pattern of the electromyographic signal.
Conclusions Based on the results found, it is not yet possible to state that auricular acupuncture can influence the electrical activity of the muscle. A suitable methodology needs to be developed to allow the utilization of auricular acupuncture as a research tool in the investigation of the action of auricular acupuncture on the electrical activity of the muscle. Factors such as the duration of collection, main action of the muscle and the number of test repetitions during the same experiment can influence the amplitude of the electromyographic signal leading to wrong conclusions about the answers obtained from the tests. To avoid misleading results in future investigations that involve the use of surface electromyographic in the analysis of the effects of auricular acupuncture, the experiments should be carried out while the muscles perform their main action to increase the chances of detecting any alteration of the electromyographic signal caused by the use of auricular acupuncture. However, it is important to mention that this work is an initial study that focuses only on the auricular acupuncture as proposed by the Nogier method. For this reason, the results found in the study are specific to the Nogier method and should not be considered for other methods of treatment by acupuncture.
Acknowledgements This study was partly supported by the FAPESP (2002/ 13559-1) and FAEPEX/Unicamp (0098/02), Brazil.
References Andersson, S., Lundeberg, T., 1995. Acupuncture e from empiricism to science: functional background to acupuncture effects in pain and disease. Medical Hypotheses 45, 271e281. Barak, Y., Ayalon, M., Dvir, Z., 2006. Spectral EMG changes in vastus medialis muscle following short range of motion isokinetic training. Journal of Electromyography and Kinesiology 16 (5), 403e412. Birch, S., 2003. Controlling for non-specific effects of acupuncture in clinical trials. Clinical Acupuncture and Oriental Medicine 4, 59e70. Campos, R.G.E., De FreiTas, V., Vitti, M., 1994. Electromyographic study of the trapezius and deltoideus in elevation, lowering, retraction and protraction of the shoulders. Electromyography and Clinical Neurophysiology 34, 243e247. Cao, X., 2002. Scientific bases of acupuncture analgesia. Acupuncture & Electro-Therapeutics Research 27 (1), 1e14. Carlsson, C., 2002. Acupuncture mechanisms for clinically relevant long-term effects-reconsideration and a hypothesis. Acupuncture in Medicine 20 (2e3), 82e99. Carroll, D., Tramer, M., McQuay, H., et al., 1996. Randomization is important in studies with pain outcomes: systematic review of
225 transcutaneous electrical nerve stimulation in acute postoperative pain. British Journal of Anaesthesia 77, 798e803. DeVries, H.A., Moritani, T., Nagata, A., 1982. The relation between critical power and neuromuscular fatigue as estimated from electromyographic data. Ergonomics 25, 783e791. Ebaugh, D.D., McClure, P.W., Karduna, A.R., 2006. Effects of shoulder muscle fatigue caused by repetitive overhead activities on scapulothoracic and glenohumeral kinematics. Journal of Electromyography and Kinesiology 16, 224e235. Ellis, N., 1994. Acupuncture in Clinical Practice: a Guide for Health Professionals. Chapman & Hall, London. Ezzo, J., Berman, B., Hadhazy, V.A., et al., 2000. Is acupuncture effective for the treatment of chronic pain? A systematic review. Pain 86, 217e225. Farber, P.L., Neves, F.G., Tavares, A.G., et al., 1995. O aumento do limiar da dor com acupuntura auricular na cervicobraquialgia aguda: estudo placebo controlado. Revista Me ´dica e Cientı´fica de Acupuntura 1, 1e3. Filshie, J., White, A., 1998. Medical Acupuncture, a Western Scientific Approach. Churchill Livingstone, Singapore. Finley, M.A., McQuade, K.J., Rodgers, M.M., 2005. Scapular kinematics during transfers in manual wheelchair users with and without shoulder impingement. Clinical Biomechanics 20, 32e40. Hagberg, M., 1981. Electromyographic sings of shoulder muscular fatigue in two elevated arm positions. American Journal of Physical Medicine 60, 111e121. Hogrel, J.Y., 2005. Clinical applications of surface electromyography in neuromuscular disorders. Neurophysiologie Clinique 35, 59e71. Hopwood, V., Lewith, G., 2003. Acupuncture trials methodological considerations. Clinical Acupuncture and Oriental Medicine 3, 192e199. Jadad, A.R., Rennie, D., 1998. The randomized controlled trial gets a middle aged checkup. Journal Of the American Medical Association 279, 319e320. Kamibayashi, K., Muro, M., 2006. Modulation of pre-programmed muscle activation and stretch reflex to changes of contact surface and visual input during movement to absorb impact. Journal of Electromyography and Kinesiology 16, 432e439. Kendall, F.P., Kendall, E., McCreary, P., 1993. Muscles, Testing, and Function, fourth ed. Williams &Wilkins, Baltimore. Kronberg, M., Brostro ¨m, L.A., Nemeth, G., 1991. Differences in shoulder muscle activity between patients with general joint laxity and normal controls. Clinical Orthopaedics and Related Research 269, 181e192. Lewith, G.T., Kenyon, J.N., 1984. Physiological and psychological explanation for the mechanism of acupuncture as a treatment for chronic pain. Social Science & Medicine 19 (12), 1367e1378. Li, A., Zhang, J., Xie, Y., 2004. Human acupuncture points mapped in rats are associated with excitable muscle/skin-nerve complexes with enriched nerve endings. Brain Research 1012, 154e159. Mannion, A.F., Dolan, P., 1996. Relationship between myoelectric and mechanical manifestations of fatigue in the quadriceps femoris muscle group. European Journal of Applied Physiology and Occupational Physiology 74 (5), 411e419. Mathiassen, S.E., Winkel, J., 1990. Electromyographic activity in the shouldereneck region according to arm position and glenohumeral torque. European Journal of Applied Physiology and Occupational Physiology 61, 370e379. Matthiassen, S.E., Winkel, J., Ha ¨gg, G.M., 1995. Normalization of surface EMG amplitude from the upper trapezius muscles in ergonomic studies e a review. Journal of Electromyography and Kinesiology 5, 197e226. Masuda, K., Masuda, T., Sadoyama, T., et al., 1999. Changes in surface EMG parameters during static and dynamic fatiguing contractions. Journal of Electromyography and Kinesiology 9 (1), 39e46.
226 Mayer, D.J., 2000. Biological mechanisms of acupuncture. Program Brain Research 122, 457e477. Maton, B., 1981. Human motor unit activity during the onset of muscle fatigue in submaximal isometric isotonic contractions. European Journal of Applied Physiology 46, 271e281. McCann, P.D., Wootten, M.E., Kabada, M.P., et al., 1993. Kinematic and electromyographic of shoulder rehabilitation exercises. Clinical Orthopaedics and Related Research 288, 179e188. McLean, L., Chislett, M., Keith, M., 2003. The effect of head position, electrode point, movement and smoothing window in the determination of reliable maximum voluntary activation of the upper trapezius muscle. Journal of Electromyography and Kinesiology 13, 169e180. McLean, L., 2005. The effect of postural correction on muscle activation amplitudes recorded from the cervicobrachial region. Journal of Electromyography and Kinesiology 15, 527e535. Mclellan, A.T., Grossman, D.S., Blaine, J.D., 1993. Acupuncture treatment for drug abuse: a technical review. Journal of Substance Abuse Treatment 10, 569e576. Michels, I., Boden, F., 1992. The deltoid muscle: an electromyographical analysis of its activity in arm abduction in various body postures. International Orthopedics 16 (3), 268e271. Moher, D., Fortin, P., Jadad, A.R., et al., 1996. Completeness of reporting of trials published in languages other than English: implications for conducting and reporting of systematic reviews. The Lancet 347, 363e369. Moya, E.G., 2005. Bases cientı´ficas de la analgesia acupunctural. Revista Me ´dica del Uruguay 21, 282e290. Nannucci, L., Merlo, A., Merletti, R., et al., 2002. Atlas of the innervation zones of upper and lower extremity muscles. In: Proceedings of the XIV Congress of the International Society of Electrophysiology and Kinesiology, Vienna, Austria. NIH, 1998. Consensus conference. Acupuncture. The Journal of the American Medicine Association 280, 1518e1524. Nishijo, K., Mori, H., Yoshikawa, K., et al., 1997. Decreased heart rate by acupuncture stimulation in humans via facilitation of
F. Politti et al. cardiac vagal activity and suppression of cardiac sympathetic nerve. Neuroscience Letters 227, 165e168. Nogier, P.F.M., 1969. Traite ´ d’Auriculothe ´rapie. Maisonneuve, Paris, France. Nogier, P.F.M., 1972. Treatise of Auriculotherapy. Moulins-les-Metz, France, Maisonneuve. Nogier, P., 1983. From Auriculotherapy to Auriculomedicine. Moulins-les-Metz, France, Maisonneuve. Nogier, R., Boucinhas, J.C., 2001. Pra ´tica Fa ´cil de Auriculoterapia e Auriculomedicina, second ed. ´Icone Editora Ltda, Sa ˜o Paulo. Pomeranz, B., 2001. Acupuncture analgesia-basic research. In: Stux, G., Hammerschlag, R. (Eds.), Clinical Acupuncture Scientific Basis. Springer-Verlag, Berlin, Heidelberg, New York. Robertson, D.G.E., Caldwell, G.E., Hamill, J., et al., 2004. In: Kamen, G., Whittlesey, S.N. (Eds.), Research Methods in Biomechanics. Human Kinetics, United States. Schenkman, M., De Cartaya, V., 1987. Kinesiology of the shoulder complex. Journal of Orthopaedic and Sports Physical Therapy 8 (9), 438e450. Sherman, K.J., Cherkin, D.C., 2003. Challenges of acupuncture research: study design considerations. Clinical Acupuncture and Oriental Medicine 3, 200e206. Sim, J., 1997. The mechanism of acupuncture analgesia: a review. Complementary Therapies in Medicine 5, 102e111. Tarkka, M., 1984. Power spectrum of electromyography in arm and leg muscles during isometric contractions fatigue. Journal of Sports Medicine and Physical Fitness 24 (3), 189e194. Tavares, A., Moran, C., Farber, P., et al., 1996. Protocolos de ˜o bibpesquisas clı´nicas controladas em acupuntura. Revisa liogra ¸a ´fica e avaliac ˜o crı´tica. Revista Medica e Cientı´fica de Acupuntura 2, 13e14. Ulett, G.A., Han, J., Han, S., 1998. Traditional and evidence based acupuncture: history, mechanisms and present status. Southern Medical Journal 91 (12), 1115e1120. Zhang, W.T., Jin, Z., Luo, F., Zhang, L., Zeng, Y.W., Han, J.S., 2004. Evidence from brain imaging with fMRI supporting functional specificity of acupoints in humans. Neuroscience letters 354 (1), 50e53.
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NEUROPHYSIOLOGY
The use of surface electromyography for the study of auricular acupuncture* Fabiano Politti a,b,*, Cesar Ferreira Amorim c, Lilian Calili a, Adriano de Oliveira Andrade d, Evanisi T. Palomari a a
Department of Anatomy, University of Campinas (Unicamp), Brazil Department of Physical Therapy, Rehabilitation Sciences Biomechanics Lab, University of Vale do Sapucaı´ (Univa´s), Brazil c Department of Mechanical Engineering, Sa˜o Paulo State University (UNESP - FEG), Guaratingueta´ - SP, Brazil d Biomedical Engineering Laboratory (BioLab), Federal University of Uberlandia, Brazil b
Received 13 June 2008; received in revised form 11 November 2008; accepted 22 November 2008
KEYWORDS Electromyography; Auricular acupuncture; Neurophysiology
*
Summary The advancement of knowledge in neurophysiology has demonstrated that acupuncture is a method of peripheral neural stimulation that promotes local and systemic reflexive responses. The purpose of this study was to determine if surface electromyography can be used as a tool to study the action of auricular acupuncture on striated skeletal muscle. The electromyographic amplitudes of the anterior, middle and posterior deltoid muscle and the upper trapezium muscle with 20%, 40% and 60% of maximal voluntary contraction of 15 healthy volunteers, were analyzed after the individuals were submitted to the auricular acupuncture treatment. The non-parametric Friedman test was used to compare Root Mean Square values estimated by using a 200 ms moving window. Significant results were further analyzed using the Wilcoxon signed rank test. In this exploratory study, the level of significance of each comparison was set to p < 0.05. It was concluded in this study that a surface electromyography can be used as a tool to investigate possible alterations of electrical activity in muscles after auricular acupuncture. However there is still a lack of adequate methodology for its use in this type of study, being that the method used to record the electromyographic signal can also influence the results. ª 2008 Elsevier Ltd. All rights reserved.
Work accomplished at the State University of CampinaseUNICAMP, Institute of Biology, Department of Anatomy. * Correspondence to: Fabiano Politti, Universidade Estadual de Campinas, UNICAMP, Depto of Anatomia, Instituto de Biologia, Cx Postal 6109, CEP: 13084-971, Campinas - SP, Brazil. E-mail address: [email protected] (F. Politti).
Introduction Acupuncture has recently been recognized by western science as a procedure that can be used supplementary to medicine, especially in the treatment of chronic pain syndrome (NIH, 1998). Advances in the knowledge of
1360-8592/$ - see front matter ª 2008 Elsevier Ltd. All rights reserved. doi:10.1016/j.jbmt.2008.11.006
220 neurophysiology have made it possible to establish that this is a neural peripheral stimulation method that promotes local and systemic reflexive responses, mediated by endocrine and immune systems and by superior centers of central control (Mayer, 2000; Carlsson, 2002). A reflexive response is caused by a gauging stimulus located in the somatic nerve fibers, which is triggered by insertion of a needle (Andersson and Lundeberg, 1995) in specific points of the skin and muscles, called acupoints (Li et al., 2004). These acupoints, found in greater concentration in specific areas such as the ear, can be used in a combined fashion with points on the body (Ellis, 1994). The most frequent use of acupuncture treatment is in muscular relaxation (Lewith and Kenyon, 1984); in the systemic regulation of motor dysfunctions (Ulett et al., 1998) and in the control of skeletal muscle pain, considering that its analgesic effects are mediated by central mechanisms that involve neural standards (Sim, 1997; Pomeranz, 2001). However, results are still questionable regarding acupuncture’s action in pain control. Studies carried out on the effects of chronic pain have indicated that individuals who received treatment with sham acupuncture, demonstrated better results than the individuals receiving real treatment (effective treatment of chronic pain), generating much criticism about the methodology applied in these types of studies (Ezzo et al., 2000). In general, the methodology utilized to demonstrate the effects of acupuncture has concerned several authors (Birch, 2003; Hopwood and Lewith, 2003), who rate many of these studies inconsistent, partial and likely to overestimate the positive effects of the treatment (Moher et al., 1996; Jadad and Rennie, 1998; Ezzo et al., 2000). Due to the existence of different techniques for the insertion of the needle, combined with different strategies for the localization of the insertion points and the existence of several treatment methods for the same type of diseases (Birch, 2003), it is essential for this type of study to consider the appropriate selection of a specific treatment for each type of pathology, and the selection of the control group, the choice of the participants and the choice of the acupuncturists (Sherman and Cherkin, 2003). Recent review articles have concluded that acupuncture still requires investigation. This is due to the fact that the neuromodulating mechanisms of nociception resulting from the stimulus caused by acupuncture, which happen at the three levels of the central nervous system (spinal, troncoencephalic and diencephalic), needs greater clarification (Moya, 2005), as do the methodological standards such as appropriate sample sizes, well-defined inclusion and exclusion criteria, and collection of data on safety and side effects (Sherman and Cherkin, 2003). An important note of observation about these revision articles is that, as of yet, there exists no standardized method for each area of investigation into acupuncture activity. Since it is an acceptable method in the investigation of muscular function in various types of analysis such as in muscular biomechanics (Finley et al., 2005), muscular skeleton fatigue (Ebaugh et al., 2006), strength (Kamibayashi and Muro, 2006), rehabilitation (Barak et al., 2006) and neuromuscular disorders (Hogrel, 2005), surface electromyography can be a reliable tool to validate the
F. Politti et al. effects of acupuncture, because it is then possible to investigate the amplitude and occurrence of electrical activity in the muscle while a task is being performed (Robertson et al., 2004) The aim of the present study was to determine if surface electromyography can be utilized as a tool to study the action of auricular acupuncture on striated skeletal muscles. Additionally, the behavior of the electrical activity was verified from anterior, middle and posterior deltoid muscles and upper trapezium muscle at different levels of exertion in a single test position.
Methods Subjects The volunteers taking part in the study were selected by means of a blind draw from the population of undergraduate and graduate students from the Anatomy Department of the University of Campinas Biology Institute. Fifteen volunteers, between ages 20 and 28, were selected and of those, eight were females (average 20.63 2.97) and seven were males (average 26.33 5.68). Included in the study were healthy, non-obese, sedentary volunteers having no history of previous shoulder pain. The volunteers were examined by a physical therapist familiar with musculoskeletal disorders of the upper limbs and scapular waist and neck. All volunteers signed a Term of Consent as required by resolution 196/96 issued by the National Health Council and previously approved by the Ethical Committee in Research from the State University of Campinas. Each subject was informed of the purpose and potential risks of the study before their written voluntary consent was obtained.
Equipment Myoelectric signals were obtained using an 8-channel module (EMG System do Brazil Ltda.), consisting of a band pass filter of 20e500 Hz, an amplifier gain of 1000, and a common rejection mode ratio >100 dB. All data were acquired and processed using a 16-bit Analog to Digital converter (EMG System do Brazil Ltda), with a sampling frequency 1.33 kHz. The system was composed of active bipolar electrodes displaying a pre-amplification gain of 20. A channel of the acquisition system was enabled for the utilization of the load cell (Alfa Instruments), having an output between 0 and 20 mV and a range up to 1 kN.
Procedure and data collection In western culture, the use of the auricular microsystems developed in France by neurologist and acupuncturist Paul Nogier gave another perspective to the understanding of some of the mechanisms by which acupuncture works. The concept of the technique is based upon the somatotopic organization of the external auricular pavilion and principally on its direct relation to the central nervous system, which is hypothesized to function through the branches of pairs of cranial nerves innervating the whole auricular pavilion (Nogier, 1969, 1972, 1983).
The use of surface electromyography Nogier’s original discovery led to the identification of the body mapping on the auricle which presented remarkable consistency with respect to anatomic and embryological considerations. Thus, the ‘‘inverted fetus’’ presents with the musculoskeletal (mesodermal) projections in the upper aspect of the ear, including the anti-helix, scaphoid fossa, and triangular fossa (Nogier, 1969). According to the theory and body mapping proposed by Nogier, it is possible to conclude that the needle stimulus in the specific external auricular pavilion can influence in a reflexive manner specific regions of the body. However, this hypothesis is yet to be tested in a blind, placebocontrolled clinical trial. In order to verify this hypothesized reflexive action of auricular acupuncture on the musculoskeletal activity, we used the acupuncture point referring to the scapular waist and shoulder, as proposed by Nogier (Figure 1). Consequently, the possible reflexive action of the scapular waist and shoulder acupuncture point was verified through activity from the upper trapezius and deltoid muscles respectively. Muscle activity was recorded from the upper trapezius, selected because they are the primary muscles used to elevate the arm (Michels and Boden, 1992; Campos et al., 1994) and because they are commonly related to tension pain of the head and neck. The anterior, middle and posterior deltoid muscles were chosen because they assist in the elevation and stabilization of the shoulder during this elevation (Hagberg, 1981; Kronberg et al., 1991; McCann et al., 1993). Self-adhesive disposable surface electrodes (Ag/AgCl e Medical Trace) of 10 mm of diameter were used for the surface recording of electromyography with a center to center distance of 20 mm. Prior to the fixation of the
Figure 1 Insertion points of the acupuncture needle in the ear, corresponding to the shoulder (a) and the scapular waist (b) used in the experimental group and the point located in the shell of the ear (c) used for the placebo group.
221 electrodes, the skin was cleansed with 70% alcohol for the elimination of residual fat; cleansing was followed by exfoliation using a specific sand paper for skin (Bio-logic Systems Corp) and a second cleaning with alcohol. The electrodes were affixed 2 cm laterally in reference to the mid point of a line traced from the posterior lateral edge of the acromion to the 7th cervical vertebra (Matthiassen et al., 1995) in the upper trapezium muscle. For the anterior, middle and posterior deltoid electrodes were positioned in the lower half of the distance from the acromion to the deltoid tuberosity (Nannucci et al., 2002). A reference rectangular electrode (3 cm 2 cm), was lubricated with electro-conductor gel (Pharmaceutical Innovations) and fastened to the left wrist of the volunteers. During the experiments, the individuals remained comfortably seated in the test chair. Before beginning the recording of electromyographic signals, each individual subject was asked to carry out a series of three maximum force elevations of the shoulder ipsi-lateral to the auricular acupuncture treatment, with duration of 3 s each, against the resistance offered by the load cell (Figure 2). A 2-min rest period was given between efforts. Verbal encouragement was given to the subject especially during the task. The mean value from the three trials represented a subject’s 100% maximum voluntary contractions (MVC) force, and the 20%, 40% and 60% values of MVC were calculated from that number. Mean muscle output was used to determine MVC as it was believed to be a more accurate representation of a subject’s strength than a single contraction. The three sub-maximal contractions (20%, 40% and 60% MVC) were used in the analysis of the auricular acupuncture action on the shoulder muscle.
Figure 2 Test position as the individual elevates the shoulder ispi-lateral to the auricular acupuncture (A) against the resistance of the load cell (B).
222 Due to the necessity of having an appropriate control group for this type of study, the same volunteers served as the control. Consequently, the experiment was run in two stages with a fixed, 7-day interval between the two tests. The results obtained with the needles placed in the points specific to the treatment of shoulder region problems were assigned to the experimental group and the placebo group served as the control. A blind draw determined the order of the individual subjects sampled. As suggested by Sherman and Cherkin (2003), the real function of each acupuncture point was masked from the participants. Likewise, the participants were requested not to visualize the application site of the needle. Communication with the patient was not permitted during the experiment, and the acupuncturists were not aware of the specific purpose of the study. Questions about the study were noted by one of the authors, but were answered only at the conclusion of the research, when all data had been collected. Electromyographic signals were recorded at three distinct moments, the first, pre-acupuncture (ACP), served as comparison to the signal obtained after the insertion of the acupuncture needle. Five minutes after the first sample (ACP), disposable sterile acupuncture needles 0.25 13 mm (Suchou Huanqiu Acupuncture Medical Appliance Co. Ltd.) were inserted at previously established points of the outer ear and were maintained without manipulation until the end of the experiment. After a 1-min interval, a second electromyographic signal sample was recorded with acupuncture (ACP1), and after 5 min, the third and last sample electromyographic signal (ACP2) was recorded, followed by immediate removal of the needle. The criteria for the recording of the electromyographic signals were always the same for all stages of the experiment. At each moment (ACP, ACP1 and ACP2), 20%, 40% and 60% sub-maximum MVC samples were collected and maintained through visual feedback provided by a line drawn on the computer screen. The duration of each electromyographic signal sample was 5 s. In order to avoid a learning effect, the order of the sample collection was also determined by blind draw. Possible risks of bodily compensation during the traction of the load cell and of patterning in the whole experiment were prevented through training before all the tests. Of greatest concern during the experiment was that the head and neck be always maintained in the same position, so as to avoid interference from the upper trapezius muscle in the activity.
F. Politti et al. waist (Nogier and Boucinhas, 2001). Asepsis by means of alcohol was provided at the location of the acupuncture needle insertion. A physical therapist certified in the Nogier Method of Auricular Acupuncture by the Regional Physical Therapy Council (CREFITO-4) and having 5 years of clinical experience with the Nogier Method, performed the auricular acupuncture treatment.
Processing and analysis of the signals For this study, the EMG signals obtained during the 20%, 40% and 60% sub-maximal MVC contractions under the conditions ACP, ACP1 and ACP2, were normalized by the medium values of the three repetitions at maximal effort with fixed resistance for each muscle analyzed, as used by McLean (2005). Each sample lasted 4 s with a rest interval of 2 min. The position and action of each muscle studied was thus: i) upper trapezium and medium deltoid: individual subject seated, performing static contraction of the limb in abduction of 90 and neutral rotation of the shoulder, against the resistance of a strap positioned near the elbow joint (McLean et al., 2003); ii) posterior deltoid: individual subject seated, with a slight abduction, extension and medial rotation of the shoulder, performing extension of the limb with isometric contraction during the traction of a fixed strap attached near the elbow joint (Kendall et al., 1993); iii) anterior deltoid: individual subject seated, with slight abduction, flexion and lateral rotation of the shoulder, performing flexion of the limb in isometric contraction during the traction of a fixed strap attached near the elbow joint (Kendall et al., 1993). After data were normalized for each muscle the root mean square (RMS) was calculated using a 200 ms moving window technique. Electromyographic Analysis Software, Version 1.01 (EMG System do Brasil, Ltda.) was used.
Statistical analysis Data are presented as means and standard deviations (SD). The non-parametric Friedman test was used to compare intraclass results in root mean square amplitude (RMS). Significant results were further analyzed using the Wilcoxon signed rank test. In this exploratory study, the level of significance of each comparison was set to p < 0.05. The entire analysis was conducted using the software SPSS (Version 12.0).
Needle insertion points on the ear
Results In the experimental group, the needles were inserted on the ear at the points corresponding to the scapular waist, located in the sixth of seven spaces contained between the posterior fold of the anti-tragus (in the region of its junction with the anti-helix and the second depression located on the anti-helix), and to the shoulder, located approximately 3 mm above the furrow which separates the anti-helix from the anti-tragus as indicated in Figure 1 (Nogier and Boucinhas, 2001). In relation to the placebo group, the needles were inserted on the shell of the ear as placebo treatment (Figure 1), being that this region does not present any somatotropic relationship to the shoulder and the scapular
The intraclass analysis (Friedman test) of anterior, middle and posterior deltoid muscle (Table 1) did not present a statistically significant difference (p > 0.05) of the values of RMS amplitude, under pre-acupuncture conditions and post-acupuncture, tested under each sub-maximum force level (20%, 40% and 60% of MVC). The same analytical criteria were adopted for the upper trapezium muscle, which, in accordance with the Friedman test displayed significant difference (p < 0.003) for values corresponding to 60% of the MVC in the experimental group. In the multiple comparisons, using the Wilcoxon test, a significant difference (p < 0.003),
The use of surface electromyography
223
Table 1 Mean and standard deviation (SD) of RMS (mV) from the anterior, middle and posterior deltoid muscle from experimental group and placebo group. ACP indicates the pre-acupuncture condition and ACP1 and ACP2 indicate the acupuncture condition tested under three levels of sub-maximum force (20%, 40% and 60% MVC). Muscles
ACP
ACP1
ACP2
Mean (SD)
Mean (SD)
Mean (SD)
60% 40% 20%
0.29 (0.18) 0.18 (0.12) 0.14 (0.09)
0.28 (0.18) 0.21 (0.12) 0.14 (0.11)
0.32 (0.22) 0.17 (0.14) 0.15 (0.11)
0.76 0.42 0.54
Middle Deltoid
60% 40% 20%
0.83 (0.58) 0.52 (0.49) 0.47 (0.41)
0.80 (0.59) 0.56 (0.42) 0.46 (0.41)
0.86 (0.55) 0.54 (0.42) 0.48 (0.40)
0.81 0.81 0.62
Posterior Deltoid
60% 40% 20%
0.88 (0.56) 0.58 (0.52) 0.28 (0.16)
0.86 (0.68) 0.49 (0.43) 0.28 (0.19)
0.90 (0.69) 0.52 (0.41) 0.31 (0.19)
0.93 0.12 0.48
60% 40% 20%
0.21 (0.06) 0.17 (0.06) 0.10 (0.03)
0.20 (0.10) 0.21 (0.19) 0.11 (0.04)
0.20 (0.06) 0.20 (0.19) 0.10 (0.03)
0.72 0.28 0.76
Middle Deltoid
60% 40% 20%
0.67 (0.39) 0.42 (0.17) 0.35 (0.15)
0.63 (0.36) 0.47 (0.22) 0. 39 (0.20)
0.67 (0.35) 0.46 (0.21) 0.38 (0.19)
0.62 0.62 0.86
Posterior 2Deltoid
60% 40% 20%
0.71 (0.68) 0.43 (0.23) 0.27 (0.12)
0.62 (0.51) 0.41 (0.28) 0.26 (0.11)
0.63 (0.41) 0.43 (0.23) 0.28 (0.12)
0.63 0.21 0.70
Experimental Group Anterior Deltoid
Placebo Group Anterior Deltoid
% MVC
*p value
*A Friedman test did not show a significant difference (p > 0.05) in the intraclass comparison.
was identified in the RMS values corresponding to the ACP and ACP2 (Figure 3). These results indicate an increase of the RMS amplitude in the upper trapezium muscle at 60% MVC, after 5 min of the insertion of the acupuncture needle in the ear. For values regarding 20% and 40% MVC in the experimental group, no significant differences were found (Friedman test, p > 0.05). Under these same test conditions, no statistically significant differences were found in the analysis of the trapezium muscle in the placebo group (Figure 3).
Discussion Based on the advances in neurophysiology, it is possible to define acupuncture as a neural peripheral stimulation method aimed at promoting changes in the sensorial, motor, hormonal and cerebral functions (Nishijo et al., 1997; Mayer, 2000). Such changes originate from the reflex response caused by the afferent stimuli in the somatic nerve fibers after the insertion of the needle (Andersson and Lundeberg, 1995).
Figure 3 Mean of the RMS (mV) value computed over 5 seg from the upper trapezium muscle. The intraclass tests accomplished in the placebo group, did not demonstrate significant statistical differences (Friedman test, p > 0.05) between the pre-acupuncture (ACP) and with acupuncture (ACP1 and ACP2) in each one of the tree tested levels of sub-maximum force (20%, 40% and 60% MVC). * Indicates a significant difference between ACP and ACP2 (Wilcoxon, p < 0.003).
224 Knowledge about the reflex response is concentrated in experimental studies carried out on the pathways of the sensory nerve system responsible for the modulation and inhibition of pain (Mayer, 2000; Carlsson, 2002) in the three levels of the central nervous system: spinal cord (Lewith and Kenyon, 1984; Cao, 2002), encephalic trunk (Cao, 2002) and cerebral cortex (Zhang et al., 2004). However, the action of auricular acupuncture on the motor apparatus is not frequently discussed in scientific studies, which makes a difficult discussion of the results presented in this work. With respect to the results obtained by means of the methodology used in this study, it is not possible to state that auricular acupuncture can influence the activity of the muscles studied because, although a significant increase (p < 0.05) in electromyographic activity of the upper trapezius muscle was observed in the experimental group with 60% of MVC there was no alteration of the electromyographic signal with 20% and 40% of MVC. The significant alteration observed only in the upper trapezius muscle in the experimental group with 60% of MVC, requires extra care in its interpretation. To affirm a possible effect of auricular acupuncture on the muscle activity would be possible only if statistically significant alterations of the electromyographic signal with 20% and 40% of MVC had been found. Factors such as type (Tarkka, 1984) and time duration of contraction (DeVries et al., 1982; Tarkka, 1984) can also alter the muscle activity and should be considered in the analysis of the results obtained in this study. In general, during an isometric exercise at constant load, there is a time related increase of the electromyographic signal (Tarkka, 1984) which could be related to changes in the recruiting pattern of motor units after the first seconds of contraction, as well as to the increase of the amplitude of the action potential and to the recruitment of motor units or the firing of the motor neurons (DeVries et al., 1982; Tarkka, 1984); however, this fact is not enough to justify the increased amplitude of the electromyographic signal in the experimental group, since the same experimental conditions were maintained for the two groups studied. Another argument that would contradict this outcome is that acupuncture has as one of its more frequent clinical uses, muscular relaxation (Lewith and Kenyon, 1984) and, in this case, the electromyographic signal is reduced. All the consulted therapists using the Nogier method relate muscle relaxation and a reduction or an elimination of pain as principle therapeutic effects. As such, the results of this study open to questioning the affirmation that auricular acupuncture has muscular relaxation as one of its effects. This contradiction indicates that the clinical treatment results are not the same as those present in the controlled study, suggesting that further investigation is necessary. One possible explanation for the appearance of the significant difference found in the experimental group at 60% of MVC could be related to the methodology employed during the experiment. Since the collection sequence of electromyographic signal was by blind draw, the data referring to the sub-maximum contraction of 60% of MVC could have randomly been the last to be collected under the ACP2 condition of the experimental group, but there is
F. Politti et al. no way of proving this, each possibility of sub-maximum contraction (20%, 40% and 60% MVC) having been determined by the draw which preceded each of the samples. If this really occurred, the increased electromyographic signal amplitude could be related to the onset of fatigue (Masuda et al., 1999), which can happen during a repetitive or sustained activity (Mannion & Dolan, 1996), as was the case during the experiment. This points to a possible fault in the method used in this study. Thus, the duration of data collection and the number of repetitions of the experiment also need to be well planned to avoid alterations of the amplitude electromyographic signal as a result of biological factors such as muscular fatigue. During the development of this study, a constant source of concern for the authors was the use of methodological rigor in the collection and treatment of data. This concern arose mainly after the literature review indicated potential problems involving sample size, nature of the study, inadequate control groups and absence of long-term responses (Mclellan et al., 1993; Moher et al., 1996; Ezzo et al., 2000; Sherman and Cherkin, 2003; Moya, 2005). To ensure confidence in the results obtained, a blind clinical trial was carried out by means of a draw. The trial aim was to compare the action of the true points in the treatment experimental group versus the action of the false points in the placebo group, in random distribution, as suggested in the literature (Carroll et al., 1996; Filshie and White, 1998) and described in the methodology of the present study. The use of false points is possible due to the fact that points on the ear are highly specific and there are differences between the stimuli effect from the real and false points (Farber et al., 1995; Tavares et al., 1996). It is important to mention that is impossible to carry out a double blind study in acupuncture since the acupuncturist cannot be blinded (Filshie and White, 1998; Carlsson, 2002). Consequently, the volunteers who participated in this study, as well as the author of the evaluations of the electromyographic signals, were not informed of the specific function of the auricular acupuncture treatments adopted in the experiment, as suggested by Filshie and White (1998) and Carlsson et al. (2000). Even with all these cautionary measures, it was observed that the methodology used for electromyographic signal recording of the deltoid muscle was not the most appropriate. Previous studies indicate that the action of the three portions of the deltoid muscle is directly related to the movements of abduction, flexing and the dislocation of the upper limb in different angular movements (Michels and Boden, 1992; Campos et al., 1994). Since this experiment was conducted without angular shoulder movement (Figure 2), the electromyographic signal amplitude obtained from the three portions of the deltoid muscle was very low and possibly not sufficient to show a possible influence of auricular acupuncture on this muscle. With relation to the upper trapezius muscle, the position adopted for the tests (Figure 2) permitted that this muscle performed its functions as a prime mover during elevation and rotation of the scapula and as a stabilizer of the scapula during glenohumeral movements (Schenkman and De Cartaya, 1987) and during glenohumeral torque production (Mathiassen and Winkel, 1990). Consequently, it
The use of surface electromyography is important to respect the muscular function because the firing frequency of the motor units varies according to the levels of force exerted during the isometric contraction (Maton, 1981) and it is possible that the greater the motor engagement, the greater the chance that alterations will be observed in the pattern of the electromyographic signal.
Conclusions Based on the results found, it is not yet possible to state that auricular acupuncture can influence the electrical activity of the muscle. A suitable methodology needs to be developed to allow the utilization of auricular acupuncture as a research tool in the investigation of the action of auricular acupuncture on the electrical activity of the muscle. Factors such as the duration of collection, main action of the muscle and the number of test repetitions during the same experiment can influence the amplitude of the electromyographic signal leading to wrong conclusions about the answers obtained from the tests. To avoid misleading results in future investigations that involve the use of surface electromyographic in the analysis of the effects of auricular acupuncture, the experiments should be carried out while the muscles perform their main action to increase the chances of detecting any alteration of the electromyographic signal caused by the use of auricular acupuncture. However, it is important to mention that this work is an initial study that focuses only on the auricular acupuncture as proposed by the Nogier method. For this reason, the results found in the study are specific to the Nogier method and should not be considered for other methods of treatment by acupuncture.
Acknowledgements This study was partly supported by the FAPESP (2002/ 13559-1) and FAEPEX/Unicamp (0098/02), Brazil.
References Andersson, S., Lundeberg, T., 1995. Acupuncture e from empiricism to science: functional background to acupuncture effects in pain and disease. Medical Hypotheses 45, 271e281. Barak, Y., Ayalon, M., Dvir, Z., 2006. Spectral EMG changes in vastus medialis muscle following short range of motion isokinetic training. Journal of Electromyography and Kinesiology 16 (5), 403e412. Birch, S., 2003. Controlling for non-specific effects of acupuncture in clinical trials. Clinical Acupuncture and Oriental Medicine 4, 59e70. Campos, R.G.E., De FreiTas, V., Vitti, M., 1994. Electromyographic study of the trapezius and deltoideus in elevation, lowering, retraction and protraction of the shoulders. Electromyography and Clinical Neurophysiology 34, 243e247. Cao, X., 2002. Scientific bases of acupuncture analgesia. Acupuncture & Electro-Therapeutics Research 27 (1), 1e14. Carlsson, C., 2002. Acupuncture mechanisms for clinically relevant long-term effects-reconsideration and a hypothesis. Acupuncture in Medicine 20 (2e3), 82e99. Carroll, D., Tramer, M., McQuay, H., et al., 1996. Randomization is important in studies with pain outcomes: systematic review of
225 transcutaneous electrical nerve stimulation in acute postoperative pain. British Journal of Anaesthesia 77, 798e803. DeVries, H.A., Moritani, T., Nagata, A., 1982. The relation between critical power and neuromuscular fatigue as estimated from electromyographic data. Ergonomics 25, 783e791. Ebaugh, D.D., McClure, P.W., Karduna, A.R., 2006. Effects of shoulder muscle fatigue caused by repetitive overhead activities on scapulothoracic and glenohumeral kinematics. Journal of Electromyography and Kinesiology 16, 224e235. Ellis, N., 1994. Acupuncture in Clinical Practice: a Guide for Health Professionals. Chapman & Hall, London. Ezzo, J., Berman, B., Hadhazy, V.A., et al., 2000. Is acupuncture effective for the treatment of chronic pain? A systematic review. Pain 86, 217e225. Farber, P.L., Neves, F.G., Tavares, A.G., et al., 1995. O aumento do limiar da dor com acupuntura auricular na cervicobraquialgia aguda: estudo placebo controlado. Revista Me ´dica e Cientı´fica de Acupuntura 1, 1e3. Filshie, J., White, A., 1998. Medical Acupuncture, a Western Scientific Approach. Churchill Livingstone, Singapore. Finley, M.A., McQuade, K.J., Rodgers, M.M., 2005. Scapular kinematics during transfers in manual wheelchair users with and without shoulder impingement. Clinical Biomechanics 20, 32e40. Hagberg, M., 1981. Electromyographic sings of shoulder muscular fatigue in two elevated arm positions. American Journal of Physical Medicine 60, 111e121. Hogrel, J.Y., 2005. Clinical applications of surface electromyography in neuromuscular disorders. Neurophysiologie Clinique 35, 59e71. Hopwood, V., Lewith, G., 2003. Acupuncture trials methodological considerations. Clinical Acupuncture and Oriental Medicine 3, 192e199. Jadad, A.R., Rennie, D., 1998. The randomized controlled trial gets a middle aged checkup. Journal Of the American Medical Association 279, 319e320. Kamibayashi, K., Muro, M., 2006. Modulation of pre-programmed muscle activation and stretch reflex to changes of contact surface and visual input during movement to absorb impact. Journal of Electromyography and Kinesiology 16, 432e439. Kendall, F.P., Kendall, E., McCreary, P., 1993. Muscles, Testing, and Function, fourth ed. Williams &Wilkins, Baltimore. Kronberg, M., Brostro ¨m, L.A., Nemeth, G., 1991. Differences in shoulder muscle activity between patients with general joint laxity and normal controls. Clinical Orthopaedics and Related Research 269, 181e192. Lewith, G.T., Kenyon, J.N., 1984. Physiological and psychological explanation for the mechanism of acupuncture as a treatment for chronic pain. Social Science & Medicine 19 (12), 1367e1378. Li, A., Zhang, J., Xie, Y., 2004. Human acupuncture points mapped in rats are associated with excitable muscle/skin-nerve complexes with enriched nerve endings. Brain Research 1012, 154e159. Mannion, A.F., Dolan, P., 1996. Relationship between myoelectric and mechanical manifestations of fatigue in the quadriceps femoris muscle group. European Journal of Applied Physiology and Occupational Physiology 74 (5), 411e419. Mathiassen, S.E., Winkel, J., 1990. Electromyographic activity in the shouldereneck region according to arm position and glenohumeral torque. European Journal of Applied Physiology and Occupational Physiology 61, 370e379. Matthiassen, S.E., Winkel, J., Ha ¨gg, G.M., 1995. Normalization of surface EMG amplitude from the upper trapezius muscles in ergonomic studies e a review. Journal of Electromyography and Kinesiology 5, 197e226. Masuda, K., Masuda, T., Sadoyama, T., et al., 1999. Changes in surface EMG parameters during static and dynamic fatiguing contractions. Journal of Electromyography and Kinesiology 9 (1), 39e46.
226 Mayer, D.J., 2000. Biological mechanisms of acupuncture. Program Brain Research 122, 457e477. Maton, B., 1981. Human motor unit activity during the onset of muscle fatigue in submaximal isometric isotonic contractions. European Journal of Applied Physiology 46, 271e281. McCann, P.D., Wootten, M.E., Kabada, M.P., et al., 1993. Kinematic and electromyographic of shoulder rehabilitation exercises. Clinical Orthopaedics and Related Research 288, 179e188. McLean, L., Chislett, M., Keith, M., 2003. The effect of head position, electrode point, movement and smoothing window in the determination of reliable maximum voluntary activation of the upper trapezius muscle. Journal of Electromyography and Kinesiology 13, 169e180. McLean, L., 2005. The effect of postural correction on muscle activation amplitudes recorded from the cervicobrachial region. Journal of Electromyography and Kinesiology 15, 527e535. Mclellan, A.T., Grossman, D.S., Blaine, J.D., 1993. Acupuncture treatment for drug abuse: a technical review. Journal of Substance Abuse Treatment 10, 569e576. Michels, I., Boden, F., 1992. The deltoid muscle: an electromyographical analysis of its activity in arm abduction in various body postures. International Orthopedics 16 (3), 268e271. Moher, D., Fortin, P., Jadad, A.R., et al., 1996. Completeness of reporting of trials published in languages other than English: implications for conducting and reporting of systematic reviews. The Lancet 347, 363e369. Moya, E.G., 2005. Bases cientı´ficas de la analgesia acupunctural. Revista Me ´dica del Uruguay 21, 282e290. Nannucci, L., Merlo, A., Merletti, R., et al., 2002. Atlas of the innervation zones of upper and lower extremity muscles. In: Proceedings of the XIV Congress of the International Society of Electrophysiology and Kinesiology, Vienna, Austria. NIH, 1998. Consensus conference. Acupuncture. The Journal of the American Medicine Association 280, 1518e1524. Nishijo, K., Mori, H., Yoshikawa, K., et al., 1997. Decreased heart rate by acupuncture stimulation in humans via facilitation of
F. Politti et al. cardiac vagal activity and suppression of cardiac sympathetic nerve. Neuroscience Letters 227, 165e168. Nogier, P.F.M., 1969. Traite ´ d’Auriculothe ´rapie. Maisonneuve, Paris, France. Nogier, P.F.M., 1972. Treatise of Auriculotherapy. Moulins-les-Metz, France, Maisonneuve. Nogier, P., 1983. From Auriculotherapy to Auriculomedicine. Moulins-les-Metz, France, Maisonneuve. Nogier, R., Boucinhas, J.C., 2001. Pra ´tica Fa ´cil de Auriculoterapia e Auriculomedicina, second ed. ´Icone Editora Ltda, Sa ˜o Paulo. Pomeranz, B., 2001. Acupuncture analgesia-basic research. In: Stux, G., Hammerschlag, R. (Eds.), Clinical Acupuncture Scientific Basis. Springer-Verlag, Berlin, Heidelberg, New York. Robertson, D.G.E., Caldwell, G.E., Hamill, J., et al., 2004. In: Kamen, G., Whittlesey, S.N. (Eds.), Research Methods in Biomechanics. Human Kinetics, United States. Schenkman, M., De Cartaya, V., 1987. Kinesiology of the shoulder complex. Journal of Orthopaedic and Sports Physical Therapy 8 (9), 438e450. Sherman, K.J., Cherkin, D.C., 2003. Challenges of acupuncture research: study design considerations. Clinical Acupuncture and Oriental Medicine 3, 200e206. Sim, J., 1997. The mechanism of acupuncture analgesia: a review. Complementary Therapies in Medicine 5, 102e111. Tarkka, M., 1984. Power spectrum of electromyography in arm and leg muscles during isometric contractions fatigue. Journal of Sports Medicine and Physical Fitness 24 (3), 189e194. Tavares, A., Moran, C., Farber, P., et al., 1996. Protocolos de ˜o bibpesquisas clı´nicas controladas em acupuntura. Revisa liogra ¸a ´fica e avaliac ˜o crı´tica. Revista Medica e Cientı´fica de Acupuntura 2, 13e14. Ulett, G.A., Han, J., Han, S., 1998. Traditional and evidence based acupuncture: history, mechanisms and present status. Southern Medical Journal 91 (12), 1115e1120. Zhang, W.T., Jin, Z., Luo, F., Zhang, L., Zeng, Y.W., Han, J.S., 2004. Evidence from brain imaging with fMRI supporting functional specificity of acupoints in humans. Neuroscience letters 354 (1), 50e53.