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J Acupunct Meridian Stud 2014;--(-):--e--
Available online at www.sciencedirect.com
Journal of Acupuncture and Meridian Studies journal homepage: www.jams-kpi.com
- RESEARCH
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Electromyographic and Strength Analyses of Activation Patterns of the Wrist Flexor Muscles after Acupuncture Marı´lia Silva Zanin, Juliana Morales Ronchi, Tainan de Castro Silva, Amanda Cunha Fuzaro, Joa ˜o Eduardo de Araujo* Laboratory of Neuropsychobiology and Motor Behavior, Department of Biomechanics, Medicine, and Rehabilitation of the Locomotor System, School of Medicine, University of Sa˜o Paulo, Ribeira˜o Preto (USP-RP), Brazil Available online - - -
Received: Sep 23, 2013 Revised: Jan 15, 2014 Accepted: Jan 21, 2014 KEYWORDS acupuncture; electromyography; muscle activation; strength
Abstract This study analyzed the electromyographic and strength responses of the flexor muscles of the wrist following stimulation of acupuncture points. A total of 52 participants were randomly divided into four groups: local (heart 3, HT3), distant (heart 4, HT4), control (bladder 60, BL60), and naı¨ve control groups. To obtain the root mean square electromyographic activity, we placed surface electrodes over the wrist flexors. To obtain kilogram force (kgf) values, we attached a force transducer to the floor and to the hands of participants. Both values were recorded over three repetitions of maximal isometric wrist flexion contractions. Data were analyzed using one-way analyses of variance, followed by Dunnett’s post-hoc tests. We found reductions in electromyographic activity contralateral to the stimulated point in the distant group 10 minutes after removal of the needles (F3,48 Z 3.25; p < 0.05). Regarding muscle strength, ipsilateral and contralateral stimulation in the distant group produced kgf levels prior to and 10 minute and 20 minutes after withdrawal of the acupuncture needle that were lower than that obtained prior to insertion of the needle (F3,48 Z 5.82; p < 0.05). Thus, stimulation of the acupuncture points distant from the wrist flexors reduced ipsilateral and contralateral muscle strength and decreased the root mean square values contralateral to the site of stimulation.
* Corresponding author. Laboratory of Neuropsychobiology and Motor Behavior, Department of Biomechanics, Medicine, and Rehabilitation of the Locomotor System, School of Medicine, University of Sa ˜o Paulo, Ribeira ˜o Preto (USP-RP), Avenida dos Bandeirantes 3900, Ribeira ˜o Preto (SP) 14049-900, Brazil. E-mail: [email protected] (J.E.deAraujo). pISSN 2005-2901 eISSN 2093-8152 http://dx.doi.org/10.1016/j.jams.2014.02.005 Copyright ª 2014, International Pharmacopuncture Institute. Please cite this article in press as: Zanin MS, et al., Electromyographic and Strength Analyses of Activation Patterns of the Wrist Flexor Muscles after Acupuncture, Journal of Acupuncture and Meridian Studies (2014), http://dx.doi.org/10.1016/j.jams.2014.02.005
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1. Introduction Acupuncture is a therapeutic method that has been used in traditional Chinese medicine for over 3000 years [1]. Unlike other procedures that were used in ancient times and are no longer employed, acupuncture has been continuously practiced and is currently one of the most popular treatments worldwide [2e4]. Clinical and experimental studies based on the modern scientific model have demonstrated the efficacy of acupuncture in various biological systems [2,5,6]. Neurochemical, histological, and neurophysiological studies have attempted to elucidate the mechanisms of action of acupuncture [7e10]. These studies have thoroughly documented the release of vasoactive substances, increases in local blood supply, increases in cellular oxygenation, metabolic changes, increases in immune system activation, changes in the lymphatic system [11], and the release of endogenous opiates that promote analgesia and muscle relaxation. Thus, Zhao and Zhu [12] suggested that acupuncture directly affects the peripheral regulation of the release of mediators of inflammation and pain and promotes a reduction in the peripheral release of substance P. Regarding the muscular system, some studies have indicated favorable results in the treatment of conditions that include facial paralysis [13], tension headaches [14], rotator cuff tendinitis [15], and impaired motor responses following stroke [16]. In general, the studies that have sought to investigate the effects of acupuncture on the muscular system have used electromyography (EMG) [17]. This technique enables the identification and description of the function of motor units in terms of muscle activation, and the amplitude and frequency of electrical activation [18]. EMG can be divided into two types: depth EMG in which the electrodes are placed within the muscle in direct contact with the muscle fibers, and surface EMG in which the electrodes are placed under the skin and capture the sum of the electrical activities of all active muscle fibers [19]. Surface EMG is a noninvasive and simple technique that is widely used in kinesiology and muscle neurophysiology studies [19]. Load cells can also be attached to EMG equipment to generate information about the forces produced by muscle contractions [20]. The contractions of the upper trapezius and temporalis muscles after acupuncture have been investigated using this technique, and these investigations have revealed changes in activation patterns [16]. In our laboratory, we have shown that the tibialis anterior muscle exhibits modifications in muscle contraction and force generation following acupuncture [21]. Thus, the aim of this study was to investigate the activation patterns and the strength responses of the flexor muscles of the wrist following stimulation of the heart 3 (HT3; local) and heart 4 (HT4; distant) acupuncture points using surface EMG and load cells.
2. Materials and methods The participants in this study were 52 right-handed healthy individuals of both genders between the ages of 18 years and 30 years who were recruited through advertisements
M.S. Zanin et al. placed on bulletin boards in classrooms and through electronic invitations. The participants were randomly allocated into four groups. The randomization process entailed the following. After the selection of the overall sample (52 participants), we created 15 sealed envelopes containing the name of each experimental group (resulting in a total of 60 sealed envelopes). Prior to the initiation of the experiment, each participant choose one of the 60 sealed envelopes and were assigned to the corresponding experimental group. Of the four experimental groups, three underwent acupuncture at specific points as follows: the local group (LG) received acupuncture at the HT3 point (n Z 15), the distant group (DG) received acupuncture at the HT4 point (n Z 14), and the control group (CG) received acupuncture at the bladder 60 (BL60) point (n Z 15). The participants in the fourth group, that is, the naı¨ve control group (NCG; n Z 8) did not receive any acupuncture (Fig. 1). The heart meridian points were chosen based on their anatomical locations and relationships with the wrist flexor muscles. The BL60 acupuncture point was selected because it is located at the end of the lower limb and has no anatomical relationship with the wrist flexors. The participants received written and verbal information detailing the procedures and read and voluntarily signed consent forms that were written in accordance with Resolution 196-96 prior to the procedures. We excluded participants who did not meet our age criteria, were lefthanded, had pain in their upper limbs, had histories of muscle disease, connective tissue disease, uncontrolled epilepsy, immunosuppression, fear of needles, epithelial allergies, and those who were pregnant. The project was approved by the Ethics Committee on Human Research and Experimentation, HCFMRP Protocol number 8864/2010 and is registered in the National System of Information Ethics and Research Involving Human Subjects CAAE0301.0.004.000-10 as ethically and methodologically appropriate according to the precepts of Resolution 196/96 of the National Health Council. We used a portable surface EMG machine with six channels (model 400c-200c; EMG System, Sa ˜o Jose ´ dos Campos, Sa ˜o Paulo, Brazil). The electrodes were active, double, bipolar (with fixed inter-electrode distances), adhesive, and disposable. A force transducer (EMG System) was coupled to one of the channels of the EMG equipment and used as a dynamometer to convert the traction force applied to the load cell to kilogram force (kgf). EMG electrodes were placed on the muscle bellies of the wrist flexors parallel to the muscle fibers (Fig. 2). The hands of the volunteers were connected to the force transducer to enable the analyses of muscle activation and force during maximal isometric flexion contraction of the wrist as described in the Surface Electromyography for the NonInvasive Assessment of Muscles (SENIAM) project [22]. In this test, the volunteers maintained maximal isometric contraction for 20 seconds in each trial. A dispersive electrode was fixed to the bony prominence of the left lateral malleolus. The volunteers sat in a chair with both arms in the supine position propped on the chair arms and their trunks supported by the back of the chair. After being positioned, the participants performed three maximal isometric contractions against resistance provided by nonelastic bands that were tied to the wrist flexors and the
Please cite this article in press as: Zanin MS, et al., Electromyographic and Strength Analyses of Activation Patterns of the Wrist Flexor Muscles after Acupuncture, Journal of Acupuncture and Meridian Studies (2014), http://dx.doi.org/10.1016/j.jams.2014.02.005
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Activation patterns of wrist flexor muscles after acupuncture
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Random allocation of volunteers into the experimental groups.
load cell (Fig. 2). There was no change in position throughout the procedure, and the room was locked to restrict the access of nonparticipants. The LG, DG, and CG groups underwent the same evaluation and acupuncture procedures, with the exception that the acupuncture point was varied across groups (Fig. 3). The NCG group only underwent the evaluation stages without any type of acupuncture intervention. Skin tricotomizations were initially performed at the site at which the electrodes would be placed. This procedure involved scraping hair, removal of dead cells and skin, and removal of oil with 70% alcohol. The maximal isometric contractions of the wrist required from the participants were as follows: three maximal isometric contractions of the right arm, three maximal isometric contractions of the left arm, and three bilateral maximal isometric contractions. The acquisition of the EMG data during maximal isometric contractions occurred as follows: EMG signals and muscle strength data were collected prior to needle insertion (i.e., the prior to condition); a stainless steel needle (0.25 40 mm) was then inserted into the appropriate acupuncture point (i.e., HT3, HT4, or BL60); the needle remained in place for a total of 20 minutes and was rotated at 2 minutes, 5 minutes, 10 minutes, 15 minutes, and 19 minutes after insertion; the needle was immediately removed after 20 minutes; the participant immediately reperformed the muscle contraction protocol (20 minutes); and 10 minutes after the removal of the needle, the muscle assessment protocol was
repeated (after). A physiotherapist specializing in acupuncture participated in the project and inserted the acupuncture needles according to the regulations of the Brazilian Society of Physiotherapists and Acupuncturists; this organization ensures the quality of acupuncture performed by physiotherapists in Brazil. The data were acquired with DATAQ Instruments Hardware Manager software (Akron, Ohio, U.S.A.), and the values were obtained in units of root mean square (RMS) and kgf (Fig. 3). The RMS and kgf values were transferred to a computer program for organization. Because the data were normally distributed, one-way analysis of variance (ANOVA) was performed, and significant between group differences were further evaluated with Dunnett’s post-hoc tests.
3. Results We did not find any significant differences in the RMS measures from the segment ipsilateral to the site of acupuncture stimulation (i.e., the right upper limb) in any group [LG (F3,48 Z 1.39; p Z 0.25), DG (F3,48 Z 1.66; p Z 0.20), CG (F3,48 Z 0.30; p Z 0.73), and NCG (F3,48 Z 0.11; p Z 0.89)]. Furthermore, no significant differences were observed in the RMS results obtained from the upper limb contralateral to the acupuncture stimulation site (i.e., the left upper limb) in any group [LG (F3,48 Z 0.50; p Z 0.60), CG (F3,48 Z 0.27; p Z 0.76), and NCG (F3,48 Z 0.05; p Z 0.94)]. However, analysis of the
Please cite this article in press as: Zanin MS, et al., Electromyographic and Strength Analyses of Activation Patterns of the Wrist Flexor Muscles after Acupuncture, Journal of Acupuncture and Meridian Studies (2014), http://dx.doi.org/10.1016/j.jams.2014.02.005
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M.S. Zanin et al.
Figure 2
Positioning of the electrodes (A and B) and positioning of the volunteer (C).
data obtained after contralateral insertion of the needle into the DG revealed a decrease in RMS value at 10 minutes after the withdrawal of the acupuncture needle compared with the evaluation prior to the insertion of the acupuncture needle (F3,48 Z 3.25; p < 0.05). The intergroup comparisons across the evaluation time points did not reveal any statistically significant differences in the ipsilateral (right) arm between the prior to (F3,48 Z 1.00; p Z 1.00), 20 minute (F3,48 Z 0.71; p Z 0.55), and 10 minute time points after withdrawal of the acupuncture needle (F3,48 Z 1.31; p Z 0.28). The results for the contralateral (i.e., left) arm were similar [prior to condition (F3,48 Z 1.00; p Z 1.00), 20 minutes (F3,48 Z 0.18; p Z 0.90), and 10 minutes after withdrawal of the acupuncture needle (F3,48 Z 0.62; p Z 0.60)] (Fig. 4). No significant differences in kgf were found in the NCG (F3,48 Z 0.34; p Z 0.71), CG (F3,48 Z 1.81; p Z 0.17), or LG (F3,48 Z 0.33; p Z 0.71) groups for ipsilateral stimulation (right arm). In the DG group, we found reductions in kgf values at 20 minutes and 10 minutes after the withdrawal of
the acupuncture needle compared with the values obtained in the prior to condition (F3,48 Z 5.82; p < 0.05). The same pattern was found for kgf results in contralateral stimulation (i.e., the left arm); no significant differences were found for the NCG (F3,48 Z 0.06; p Z 0.94), CG (F3,48 Z 0.48; p Z 0.61), or LG (F3,48 Z 0.92; p Z 0.40) groups, but similar reductions in kgf values of the DG group at 20 minutes and 10 minutes after the withdrawal of the acupuncture needle compared with the values obtained in the prior to condition were found (F3,48 Z 3.42; p < 0.05). The intergroup comparisons for kgf values ipsilateral to the stimulation (right arm) prior to (F3,48 Z 1.00; p Z 1.00), 20 minutes (F3,48 Z 0.34; p Z 0.79), and 10 minutes after withdrawal of the acupuncture needle (F3,48 Z 0.32; p Z 0.80) did not reveal any significant differences. Similarly, the kgf values contralateral to the stimulation (left arm) prior to (F3,48 Z 1.00; p Z 1.00), 20 minutes (F3,48 Z 0.21; p Z 0.88), and 10 minutes after the withdrawal of the acupuncture needle (F3,48 Z 0.58; p Z 0.62) were not significantly different (Fig. 5).
Please cite this article in press as: Zanin MS, et al., Electromyographic and Strength Analyses of Activation Patterns of the Wrist Flexor Muscles after Acupuncture, Journal of Acupuncture and Meridian Studies (2014), http://dx.doi.org/10.1016/j.jams.2014.02.005
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Figure 3 Acupuncture points examined in this study and their respective anatomical locations. The images were taken, with permission, by the ACUPUNCTURE software (SAEMP; The Instituto Paulista de Estudos Siste ˆmicos, Ribeira ˜o Preto, Sa ˜o Paulo, Brazil).
4. Discussion The present work revealed that the stimulation of acupuncture points distant from the wrist flexors was able to reduce ipsilateral and contralateral muscle strengths and to decrease the RMS values contralateral to the stimulated point. In our previous work, we showed that stimulation of the spleen 9 acupuncture point, which is adjacent to the motor point of the tibialis anterior muscle, is able to reduce ipsilateral RMS values without interfering with the generation of muscle force [21]. In this respect, our data are consistent with previously published data; however, the present study provides new information that may enable the advancement of the understanding of the somatic and energy mechanisms underlying this phenomenon. As shown previously, the reduction in strength ipsilateral to the stimulated point may be related to reductions in muscle fiber recruitment due to interference in proprioceptive feedback that prevents the recruitment of new fibers through the spinal reflex arc [21]. However, this study provides the novel finding that this reduction in strength reduction is also present in the contralateral wrist flexor. Contralateral effects of acupuncture are possible. In a recent study of analgesia in rats with ankle sprains, it was
found that electroacupuncture in the contralateral small intestine six point but not the ipsilateral stomach 36 point is effective in producing analgesia [23]. Although such acupuncture-related analgesia phenomena are primarily sensory, our results are related to changes in motor responses. Motor behavior is generated by a hierarchy of interleaved circuit modules composed of interneurons in the spinal cord, sensory feedback loops, and bilateral communication with supraspinal centers [24]. Thus, the effects of acupuncture can be related to the stimulation of one specific peripheral nerve located at the acupuncture point [23], because the motor and sensory nerves arise from the spinal cord in a segmental manner to form superimposed patterns of innervation of the muscles and skin of the body [25]. Such patterns could provide a somatic explanation of our findings. Another possible explanation of our findings is related to the energy perspective. This perspective provides evidence that the effect is generated in the contralateral acupuncture meridian; that is, the left branch of the heart meridian [26]. Physiological explanations of this phenomenon are also attractive. For example, the use of the concept of acupuncture meridians to explain the modifications of muscle responses may be valid. The authors of another study have also utilized acupuncture meridians to explain changes in the EMG responses of some muscles [27].
Please cite this article in press as: Zanin MS, et al., Electromyographic and Strength Analyses of Activation Patterns of the Wrist Flexor Muscles after Acupuncture, Journal of Acupuncture and Meridian Studies (2014), http://dx.doi.org/10.1016/j.jams.2014.02.005
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Figure 4 Electromyographic ipsilateral (A) and contralateral (B) activation in response to stimulation. The data are presented as mean SD. ) Indicates a p value < 0.05 compared with the prior to condition in the same group; analysis of variance followed by Dunnett’s test. BL60 Z bladder 60; CG Z control group, acupuncture point BL60 (n Z 15); DG Z distant group, acupuncture point HT4 (n Z 14); HT3 Z heart 3; HT4 Z heart 4; LG Z local group, acupuncture point HT3 (n Z 15); NCG Z naı¨ve control group, without acupuncture stimulation (n Z 8).
It is well known that acupuncture treatments often employ the contralateral acupuncture meridian to treat pathological disorders. Some techniques also utilize the lower half of the body to treat the upper half or use the shoulder to treat the hip according to the concept of high/ low opposition [28]. In this context, our work demonstrated that this phenomenon can also interfere with both RMS activation and force generation. This evidence is also corroborated by the findings of another study that evaluated resting masseter and temporal RMS activities and found that these activities can be reduced by acupuncture at local points (i.e., the stomach 4, stomach 6, stomach 7, small intestine 19, governor vessel 26, conception vessel 24, and large intestine 20 points) and distant points (i.e., the gall bladder 34, liver 3, stomach 36, large intestine 4, and small intestine 3 points) [29]. In comparison to the results of the present study with those of our previous work, we failed to observe effects of the stimulation of local acupuncture points (i.e., motor points) in the present study. This discrepancy may be due to the specificity of the stimulated point because we observed reductions in RMS levels and strength after stimulation of the stomach 36 point. The stomach 36 point, also referred to as three miles and tired leg, has the function of relaxing the leg, specifically the tibialis anterior muscle. The fact that HT3 has no specific action on the flexor muscle may
M.S. Zanin et al.
Figure 5 Muscle strength ipsilateral (A) and contralateral (B) to the stimulation. The data are presented as mean SD. ) Indicates a p value < 0.05 compared with the prior to condition in the same group; analysis of variance followed by Dunnett’s test. BL60 Z bladder 60; CG Z control group, acupuncture point BL60 (n Z 15); DG Z distant group, acupuncture point HT4 (n Z 14); HT3 Z heart 3; HT4 Z heart 4; LG Z local group, acupuncture point HT3 (n Z 15); NCG Z naı¨ve control group, without acupuncture stimulation (n Z 8).
explain the absence of an effect. Alternately, the points in the lower limbs (i.e., the yin region) may produce a pattern of muscle responses that differs from that of the points of the upper limbs (i.e., the yang region). Further investigations utilizing electrophysiological techniques are required to fully understand this mechanism and elucidate these important questions. Moreover, our study has some limitations because we only analyzed the responses in healthy participants and did not evaluate the effects of acupuncture over a longer period of time. This study revealed that stimulation of the HT4 point produced a contralateral inhibition of the muscles in the upper limb. Thus, we provide evidence that it is possible to decrease the muscle activities of the wrist flexors. Moreover, it is not necessary to stimulate the site at which a therapeutic effect is desired. This type of stimulation can be extremely helpful in reducing pathological flexor patterns in the upper limbs due to motor neuron disorders.
Acknowledgments M.S.Z. and J.M.R. are recipients of scientific initiation scholarships granted by Fundac ¸a ˜o de Amparo a ` Pesquisa do Estado de Sa ˜o Paulo (FAPESP; process numbers 2010/195442 and 2011/09253-3).
Please cite this article in press as: Zanin MS, et al., Electromyographic and Strength Analyses of Activation Patterns of the Wrist Flexor Muscles after Acupuncture, Journal of Acupuncture and Meridian Studies (2014), http://dx.doi.org/10.1016/j.jams.2014.02.005
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References [1] Ulett GA, Han S, Han JS. Electroacupuncture: mechanisms and clinical application. Biol Psychiatry. 1998;44:129e138. [2] Kaptchuk TJ. Acupuncture: theory, efficacy, and practice. Ann Intern Med. 2002;136:374e383. [3] White A, Cummings M, Filshie J. An Introduction to Western Medical Acupuncture. London: Churchill Livingstone; 2008. [4] Vanderploeg K, Yi X. Acupuncture in modern society. J Acupunct Meridian Stud. 2009;2:26e33. [5] Cheng KJ. Neurobiological mechanisms of acupuncture for some common illnesses: a clinician’s perspective. J Acupunct Meridian Stud; 2013. http://dx.doi.org/10.1016/j.jams.2013. 07.008. [6] List T, Helkimo M. Acupuncture in the treatment of patients with chronic facial pain and mandibular dysfunction. Swed Dent J. 1987;11:83e92. [7] Ehrlich D, Haber P. Influence of acupuncture on physical performance capacity and haemodynamic parameters. Int J Sports Med. 1992;13:486e491. [8] Maioli C, Falciati L, Marangon M, Perini S, Losio A. Short- and long-term modulation of upper limb motor evoked potentials induced by acupuncture. Eur J Neurosci. 2006;23:1931e1938. [9] Cho ZH, Hwang SC, Wong EK, Son YD, Kang CK, Park TS, et al. Neural substrates, experimental evidences and functional hypothesis of acupuncture mechanisms. Acta Neurol Scand. 2006;113:370e377. [10] Akimoto T, Nakahori C, Aizawa K, Kimura F, Fukubayashi T, Kono I. Acupuncture and responses of immunologic and endocrine markers during competition. Med Sci Sports Exerc. 2003;8:1296e1302. [11] Xinnong C. Chinese Acupuncture and Moxibustion. 1st ed. Beijing: Foreign Languages Press; 1987. [12] Zhao F, Zhu L. Effect of eletroacupuncture on neurogenic inflammation. Chen Tzu Yen Chiu. 1992;17:207e211. [13] Daowu Z, Quiqwei G. Treatment of facial paralysis with laser and acupuncture: report of 76 cases. Int J Clin Acupunct. 1993;4:327e329. [14] Vickers AJ, Rees RW, Zollman CE, McCarney R, Smith CM, Ellis N, et al. Acupuncture for chronic headache in primary care: large, pragmatic, randomized trial. BMJ. 2004;328: 744e750. [15] Kleinhenza J, Streitbergera K, Windelerb J, Gueu ˆbacherc A, Mavridisc G, Martina E. Randomised clinical trial comparing
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the effects of acupuncture and a newly designed placebo needle in rotator cuff tendinitis. Pain. 1999;83:235e241. Johansson K, Lindgren I, Widner H, Wiklund I, Johansson BB. Can sensory stimulation improve the functional outcome in stroke patients? Neurology. 1993;43:2189e2192. Regalo SCH, Vitti M, Oliveira AS, Santos CM, Sie ´ssere S. Interfaces da Medicina, Odontologia e Fonoaudiologia no Complexo Ce´rvico-Craniofascial. vol. 1. Barueri: Pro ´-fono; 2008. De Luca CJ. The use of surface electromyography in biomechanics. J Appl Biomechanics. 1997;13:135e163. Correia PP, Santos PM, Veloso A. Electromiografia. Fundamentac¸a˜o Fisiolo´gica, Me´todos de Recolha e Processamento. Aplicac¸o˜es Cinesiolo´gicas. Lisboa: FMH; 1993 [in Portuguese]. Turker KS. Electromyography: some methodological problems and issues. Phys Ther. 1993;73:698e710. Costa LA, de Araujo JE. The immediate effects of local and adjacent acupuncture on the tibialis anterior muscle: a human study. Chin Med. 2008;3:17. SENIAM. Surface Electromyography for the Non-Invasive Assessment of Muscles. Available at: http://www.seniam.org Accessed 04.09.10. Kim JH, Kim HY, Chung K, Chung JM. Electroacupuncture reduces the evoked responses of the spinal dorsal horn neurons in ankle-sprained rats. J Neurophysiol. 2011;105:2050e2057. Arber S. Motor circuits in action: specification, connectivity, and function. Neuron. 2012;74:975e989. Ladak A, Tubbs RS, Spinner RJ. Mapping sensory nerve communications between peripheral nerve territories. Clin Anat; 2013. http://dx.doi.org/10.1002/ca.22285. Longhurst JC. Defining meridians: a modern basis of understanding. J Acupunct Meridian Stud. 2010;3:67e74. Moncayo R, Moncayo H. Evaluation of applied kinesiology meridian techniques by means of surface electromyography (sEMG): demonstration of the regulatory influence of antique acupuncture points. Chin Med. 2009;4:9. De Araujo JE. Acupuntura e Efeito Kirlian: A Visualizac¸a˜o da Energia Vital. Ribeira ˜o Preto: IPES; 1997 [in Portuguese]. de Sousa RA, Semprini M, Vitti M, Borsatto MC, Hallak Regalo SC. Electromyographic evaluation of the masseter and temporal muscles activity in volunteers submitted to acupuncture. Electromyogr Clin Neurophysiol. 2007;47: 243e250.
Please cite this article in press as: Zanin MS, et al., Electromyographic and Strength Analyses of Activation Patterns of the Wrist Flexor Muscles after Acupuncture, Journal of Acupuncture and Meridian Studies (2014), http://dx.doi.org/10.1016/j.jams.2014.02.005
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J Acupunct Meridian Stud 2014;--(-):--e--
Available online at www.sciencedirect.com
Journal of Acupuncture and Meridian Studies journal homepage: www.jams-kpi.com
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Electromyographic and Strength Analyses of Activation Patterns of the Wrist Flexor Muscles after Acupuncture Marı´lia Silva Zanin, Juliana Morales Ronchi, Tainan de Castro Silva, Amanda Cunha Fuzaro, Joa ˜o Eduardo de Araujo* Laboratory of Neuropsychobiology and Motor Behavior, Department of Biomechanics, Medicine, and Rehabilitation of the Locomotor System, School of Medicine, University of Sa˜o Paulo, Ribeira˜o Preto (USP-RP), Brazil Available online - - -
Received: Sep 23, 2013 Revised: Jan 15, 2014 Accepted: Jan 21, 2014 KEYWORDS acupuncture; electromyography; muscle activation; strength
Abstract This study analyzed the electromyographic and strength responses of the flexor muscles of the wrist following stimulation of acupuncture points. A total of 52 participants were randomly divided into four groups: local (heart 3, HT3), distant (heart 4, HT4), control (bladder 60, BL60), and naı¨ve control groups. To obtain the root mean square electromyographic activity, we placed surface electrodes over the wrist flexors. To obtain kilogram force (kgf) values, we attached a force transducer to the floor and to the hands of participants. Both values were recorded over three repetitions of maximal isometric wrist flexion contractions. Data were analyzed using one-way analyses of variance, followed by Dunnett’s post-hoc tests. We found reductions in electromyographic activity contralateral to the stimulated point in the distant group 10 minutes after removal of the needles (F3,48 Z 3.25; p < 0.05). Regarding muscle strength, ipsilateral and contralateral stimulation in the distant group produced kgf levels prior to and 10 minute and 20 minutes after withdrawal of the acupuncture needle that were lower than that obtained prior to insertion of the needle (F3,48 Z 5.82; p < 0.05). Thus, stimulation of the acupuncture points distant from the wrist flexors reduced ipsilateral and contralateral muscle strength and decreased the root mean square values contralateral to the site of stimulation.
* Corresponding author. Laboratory of Neuropsychobiology and Motor Behavior, Department of Biomechanics, Medicine, and Rehabilitation of the Locomotor System, School of Medicine, University of Sa ˜o Paulo, Ribeira ˜o Preto (USP-RP), Avenida dos Bandeirantes 3900, Ribeira ˜o Preto (SP) 14049-900, Brazil. E-mail: [email protected] (J.E.deAraujo). pISSN 2005-2901 eISSN 2093-8152 http://dx.doi.org/10.1016/j.jams.2014.02.005 Copyright ª 2014, International Pharmacopuncture Institute. Please cite this article in press as: Zanin MS, et al., Electromyographic and Strength Analyses of Activation Patterns of the Wrist Flexor Muscles after Acupuncture, Journal of Acupuncture and Meridian Studies (2014), http://dx.doi.org/10.1016/j.jams.2014.02.005
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1. Introduction Acupuncture is a therapeutic method that has been used in traditional Chinese medicine for over 3000 years [1]. Unlike other procedures that were used in ancient times and are no longer employed, acupuncture has been continuously practiced and is currently one of the most popular treatments worldwide [2e4]. Clinical and experimental studies based on the modern scientific model have demonstrated the efficacy of acupuncture in various biological systems [2,5,6]. Neurochemical, histological, and neurophysiological studies have attempted to elucidate the mechanisms of action of acupuncture [7e10]. These studies have thoroughly documented the release of vasoactive substances, increases in local blood supply, increases in cellular oxygenation, metabolic changes, increases in immune system activation, changes in the lymphatic system [11], and the release of endogenous opiates that promote analgesia and muscle relaxation. Thus, Zhao and Zhu [12] suggested that acupuncture directly affects the peripheral regulation of the release of mediators of inflammation and pain and promotes a reduction in the peripheral release of substance P. Regarding the muscular system, some studies have indicated favorable results in the treatment of conditions that include facial paralysis [13], tension headaches [14], rotator cuff tendinitis [15], and impaired motor responses following stroke [16]. In general, the studies that have sought to investigate the effects of acupuncture on the muscular system have used electromyography (EMG) [17]. This technique enables the identification and description of the function of motor units in terms of muscle activation, and the amplitude and frequency of electrical activation [18]. EMG can be divided into two types: depth EMG in which the electrodes are placed within the muscle in direct contact with the muscle fibers, and surface EMG in which the electrodes are placed under the skin and capture the sum of the electrical activities of all active muscle fibers [19]. Surface EMG is a noninvasive and simple technique that is widely used in kinesiology and muscle neurophysiology studies [19]. Load cells can also be attached to EMG equipment to generate information about the forces produced by muscle contractions [20]. The contractions of the upper trapezius and temporalis muscles after acupuncture have been investigated using this technique, and these investigations have revealed changes in activation patterns [16]. In our laboratory, we have shown that the tibialis anterior muscle exhibits modifications in muscle contraction and force generation following acupuncture [21]. Thus, the aim of this study was to investigate the activation patterns and the strength responses of the flexor muscles of the wrist following stimulation of the heart 3 (HT3; local) and heart 4 (HT4; distant) acupuncture points using surface EMG and load cells.
2. Materials and methods The participants in this study were 52 right-handed healthy individuals of both genders between the ages of 18 years and 30 years who were recruited through advertisements
M.S. Zanin et al. placed on bulletin boards in classrooms and through electronic invitations. The participants were randomly allocated into four groups. The randomization process entailed the following. After the selection of the overall sample (52 participants), we created 15 sealed envelopes containing the name of each experimental group (resulting in a total of 60 sealed envelopes). Prior to the initiation of the experiment, each participant choose one of the 60 sealed envelopes and were assigned to the corresponding experimental group. Of the four experimental groups, three underwent acupuncture at specific points as follows: the local group (LG) received acupuncture at the HT3 point (n Z 15), the distant group (DG) received acupuncture at the HT4 point (n Z 14), and the control group (CG) received acupuncture at the bladder 60 (BL60) point (n Z 15). The participants in the fourth group, that is, the naı¨ve control group (NCG; n Z 8) did not receive any acupuncture (Fig. 1). The heart meridian points were chosen based on their anatomical locations and relationships with the wrist flexor muscles. The BL60 acupuncture point was selected because it is located at the end of the lower limb and has no anatomical relationship with the wrist flexors. The participants received written and verbal information detailing the procedures and read and voluntarily signed consent forms that were written in accordance with Resolution 196-96 prior to the procedures. We excluded participants who did not meet our age criteria, were lefthanded, had pain in their upper limbs, had histories of muscle disease, connective tissue disease, uncontrolled epilepsy, immunosuppression, fear of needles, epithelial allergies, and those who were pregnant. The project was approved by the Ethics Committee on Human Research and Experimentation, HCFMRP Protocol number 8864/2010 and is registered in the National System of Information Ethics and Research Involving Human Subjects CAAE0301.0.004.000-10 as ethically and methodologically appropriate according to the precepts of Resolution 196/96 of the National Health Council. We used a portable surface EMG machine with six channels (model 400c-200c; EMG System, Sa ˜o Jose ´ dos Campos, Sa ˜o Paulo, Brazil). The electrodes were active, double, bipolar (with fixed inter-electrode distances), adhesive, and disposable. A force transducer (EMG System) was coupled to one of the channels of the EMG equipment and used as a dynamometer to convert the traction force applied to the load cell to kilogram force (kgf). EMG electrodes were placed on the muscle bellies of the wrist flexors parallel to the muscle fibers (Fig. 2). The hands of the volunteers were connected to the force transducer to enable the analyses of muscle activation and force during maximal isometric flexion contraction of the wrist as described in the Surface Electromyography for the NonInvasive Assessment of Muscles (SENIAM) project [22]. In this test, the volunteers maintained maximal isometric contraction for 20 seconds in each trial. A dispersive electrode was fixed to the bony prominence of the left lateral malleolus. The volunteers sat in a chair with both arms in the supine position propped on the chair arms and their trunks supported by the back of the chair. After being positioned, the participants performed three maximal isometric contractions against resistance provided by nonelastic bands that were tied to the wrist flexors and the
Please cite this article in press as: Zanin MS, et al., Electromyographic and Strength Analyses of Activation Patterns of the Wrist Flexor Muscles after Acupuncture, Journal of Acupuncture and Meridian Studies (2014), http://dx.doi.org/10.1016/j.jams.2014.02.005
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Figure 1
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Random allocation of volunteers into the experimental groups.
load cell (Fig. 2). There was no change in position throughout the procedure, and the room was locked to restrict the access of nonparticipants. The LG, DG, and CG groups underwent the same evaluation and acupuncture procedures, with the exception that the acupuncture point was varied across groups (Fig. 3). The NCG group only underwent the evaluation stages without any type of acupuncture intervention. Skin tricotomizations were initially performed at the site at which the electrodes would be placed. This procedure involved scraping hair, removal of dead cells and skin, and removal of oil with 70% alcohol. The maximal isometric contractions of the wrist required from the participants were as follows: three maximal isometric contractions of the right arm, three maximal isometric contractions of the left arm, and three bilateral maximal isometric contractions. The acquisition of the EMG data during maximal isometric contractions occurred as follows: EMG signals and muscle strength data were collected prior to needle insertion (i.e., the prior to condition); a stainless steel needle (0.25 40 mm) was then inserted into the appropriate acupuncture point (i.e., HT3, HT4, or BL60); the needle remained in place for a total of 20 minutes and was rotated at 2 minutes, 5 minutes, 10 minutes, 15 minutes, and 19 minutes after insertion; the needle was immediately removed after 20 minutes; the participant immediately reperformed the muscle contraction protocol (20 minutes); and 10 minutes after the removal of the needle, the muscle assessment protocol was
repeated (after). A physiotherapist specializing in acupuncture participated in the project and inserted the acupuncture needles according to the regulations of the Brazilian Society of Physiotherapists and Acupuncturists; this organization ensures the quality of acupuncture performed by physiotherapists in Brazil. The data were acquired with DATAQ Instruments Hardware Manager software (Akron, Ohio, U.S.A.), and the values were obtained in units of root mean square (RMS) and kgf (Fig. 3). The RMS and kgf values were transferred to a computer program for organization. Because the data were normally distributed, one-way analysis of variance (ANOVA) was performed, and significant between group differences were further evaluated with Dunnett’s post-hoc tests.
3. Results We did not find any significant differences in the RMS measures from the segment ipsilateral to the site of acupuncture stimulation (i.e., the right upper limb) in any group [LG (F3,48 Z 1.39; p Z 0.25), DG (F3,48 Z 1.66; p Z 0.20), CG (F3,48 Z 0.30; p Z 0.73), and NCG (F3,48 Z 0.11; p Z 0.89)]. Furthermore, no significant differences were observed in the RMS results obtained from the upper limb contralateral to the acupuncture stimulation site (i.e., the left upper limb) in any group [LG (F3,48 Z 0.50; p Z 0.60), CG (F3,48 Z 0.27; p Z 0.76), and NCG (F3,48 Z 0.05; p Z 0.94)]. However, analysis of the
Please cite this article in press as: Zanin MS, et al., Electromyographic and Strength Analyses of Activation Patterns of the Wrist Flexor Muscles after Acupuncture, Journal of Acupuncture and Meridian Studies (2014), http://dx.doi.org/10.1016/j.jams.2014.02.005
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M.S. Zanin et al.
Figure 2
Positioning of the electrodes (A and B) and positioning of the volunteer (C).
data obtained after contralateral insertion of the needle into the DG revealed a decrease in RMS value at 10 minutes after the withdrawal of the acupuncture needle compared with the evaluation prior to the insertion of the acupuncture needle (F3,48 Z 3.25; p < 0.05). The intergroup comparisons across the evaluation time points did not reveal any statistically significant differences in the ipsilateral (right) arm between the prior to (F3,48 Z 1.00; p Z 1.00), 20 minute (F3,48 Z 0.71; p Z 0.55), and 10 minute time points after withdrawal of the acupuncture needle (F3,48 Z 1.31; p Z 0.28). The results for the contralateral (i.e., left) arm were similar [prior to condition (F3,48 Z 1.00; p Z 1.00), 20 minutes (F3,48 Z 0.18; p Z 0.90), and 10 minutes after withdrawal of the acupuncture needle (F3,48 Z 0.62; p Z 0.60)] (Fig. 4). No significant differences in kgf were found in the NCG (F3,48 Z 0.34; p Z 0.71), CG (F3,48 Z 1.81; p Z 0.17), or LG (F3,48 Z 0.33; p Z 0.71) groups for ipsilateral stimulation (right arm). In the DG group, we found reductions in kgf values at 20 minutes and 10 minutes after the withdrawal of
the acupuncture needle compared with the values obtained in the prior to condition (F3,48 Z 5.82; p < 0.05). The same pattern was found for kgf results in contralateral stimulation (i.e., the left arm); no significant differences were found for the NCG (F3,48 Z 0.06; p Z 0.94), CG (F3,48 Z 0.48; p Z 0.61), or LG (F3,48 Z 0.92; p Z 0.40) groups, but similar reductions in kgf values of the DG group at 20 minutes and 10 minutes after the withdrawal of the acupuncture needle compared with the values obtained in the prior to condition were found (F3,48 Z 3.42; p < 0.05). The intergroup comparisons for kgf values ipsilateral to the stimulation (right arm) prior to (F3,48 Z 1.00; p Z 1.00), 20 minutes (F3,48 Z 0.34; p Z 0.79), and 10 minutes after withdrawal of the acupuncture needle (F3,48 Z 0.32; p Z 0.80) did not reveal any significant differences. Similarly, the kgf values contralateral to the stimulation (left arm) prior to (F3,48 Z 1.00; p Z 1.00), 20 minutes (F3,48 Z 0.21; p Z 0.88), and 10 minutes after the withdrawal of the acupuncture needle (F3,48 Z 0.58; p Z 0.62) were not significantly different (Fig. 5).
Please cite this article in press as: Zanin MS, et al., Electromyographic and Strength Analyses of Activation Patterns of the Wrist Flexor Muscles after Acupuncture, Journal of Acupuncture and Meridian Studies (2014), http://dx.doi.org/10.1016/j.jams.2014.02.005
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Figure 3 Acupuncture points examined in this study and their respective anatomical locations. The images were taken, with permission, by the ACUPUNCTURE software (SAEMP; The Instituto Paulista de Estudos Siste ˆmicos, Ribeira ˜o Preto, Sa ˜o Paulo, Brazil).
4. Discussion The present work revealed that the stimulation of acupuncture points distant from the wrist flexors was able to reduce ipsilateral and contralateral muscle strengths and to decrease the RMS values contralateral to the stimulated point. In our previous work, we showed that stimulation of the spleen 9 acupuncture point, which is adjacent to the motor point of the tibialis anterior muscle, is able to reduce ipsilateral RMS values without interfering with the generation of muscle force [21]. In this respect, our data are consistent with previously published data; however, the present study provides new information that may enable the advancement of the understanding of the somatic and energy mechanisms underlying this phenomenon. As shown previously, the reduction in strength ipsilateral to the stimulated point may be related to reductions in muscle fiber recruitment due to interference in proprioceptive feedback that prevents the recruitment of new fibers through the spinal reflex arc [21]. However, this study provides the novel finding that this reduction in strength reduction is also present in the contralateral wrist flexor. Contralateral effects of acupuncture are possible. In a recent study of analgesia in rats with ankle sprains, it was
found that electroacupuncture in the contralateral small intestine six point but not the ipsilateral stomach 36 point is effective in producing analgesia [23]. Although such acupuncture-related analgesia phenomena are primarily sensory, our results are related to changes in motor responses. Motor behavior is generated by a hierarchy of interleaved circuit modules composed of interneurons in the spinal cord, sensory feedback loops, and bilateral communication with supraspinal centers [24]. Thus, the effects of acupuncture can be related to the stimulation of one specific peripheral nerve located at the acupuncture point [23], because the motor and sensory nerves arise from the spinal cord in a segmental manner to form superimposed patterns of innervation of the muscles and skin of the body [25]. Such patterns could provide a somatic explanation of our findings. Another possible explanation of our findings is related to the energy perspective. This perspective provides evidence that the effect is generated in the contralateral acupuncture meridian; that is, the left branch of the heart meridian [26]. Physiological explanations of this phenomenon are also attractive. For example, the use of the concept of acupuncture meridians to explain the modifications of muscle responses may be valid. The authors of another study have also utilized acupuncture meridians to explain changes in the EMG responses of some muscles [27].
Please cite this article in press as: Zanin MS, et al., Electromyographic and Strength Analyses of Activation Patterns of the Wrist Flexor Muscles after Acupuncture, Journal of Acupuncture and Meridian Studies (2014), http://dx.doi.org/10.1016/j.jams.2014.02.005
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Figure 4 Electromyographic ipsilateral (A) and contralateral (B) activation in response to stimulation. The data are presented as mean SD. ) Indicates a p value < 0.05 compared with the prior to condition in the same group; analysis of variance followed by Dunnett’s test. BL60 Z bladder 60; CG Z control group, acupuncture point BL60 (n Z 15); DG Z distant group, acupuncture point HT4 (n Z 14); HT3 Z heart 3; HT4 Z heart 4; LG Z local group, acupuncture point HT3 (n Z 15); NCG Z naı¨ve control group, without acupuncture stimulation (n Z 8).
It is well known that acupuncture treatments often employ the contralateral acupuncture meridian to treat pathological disorders. Some techniques also utilize the lower half of the body to treat the upper half or use the shoulder to treat the hip according to the concept of high/ low opposition [28]. In this context, our work demonstrated that this phenomenon can also interfere with both RMS activation and force generation. This evidence is also corroborated by the findings of another study that evaluated resting masseter and temporal RMS activities and found that these activities can be reduced by acupuncture at local points (i.e., the stomach 4, stomach 6, stomach 7, small intestine 19, governor vessel 26, conception vessel 24, and large intestine 20 points) and distant points (i.e., the gall bladder 34, liver 3, stomach 36, large intestine 4, and small intestine 3 points) [29]. In comparison to the results of the present study with those of our previous work, we failed to observe effects of the stimulation of local acupuncture points (i.e., motor points) in the present study. This discrepancy may be due to the specificity of the stimulated point because we observed reductions in RMS levels and strength after stimulation of the stomach 36 point. The stomach 36 point, also referred to as three miles and tired leg, has the function of relaxing the leg, specifically the tibialis anterior muscle. The fact that HT3 has no specific action on the flexor muscle may
M.S. Zanin et al.
Figure 5 Muscle strength ipsilateral (A) and contralateral (B) to the stimulation. The data are presented as mean SD. ) Indicates a p value < 0.05 compared with the prior to condition in the same group; analysis of variance followed by Dunnett’s test. BL60 Z bladder 60; CG Z control group, acupuncture point BL60 (n Z 15); DG Z distant group, acupuncture point HT4 (n Z 14); HT3 Z heart 3; HT4 Z heart 4; LG Z local group, acupuncture point HT3 (n Z 15); NCG Z naı¨ve control group, without acupuncture stimulation (n Z 8).
explain the absence of an effect. Alternately, the points in the lower limbs (i.e., the yin region) may produce a pattern of muscle responses that differs from that of the points of the upper limbs (i.e., the yang region). Further investigations utilizing electrophysiological techniques are required to fully understand this mechanism and elucidate these important questions. Moreover, our study has some limitations because we only analyzed the responses in healthy participants and did not evaluate the effects of acupuncture over a longer period of time. This study revealed that stimulation of the HT4 point produced a contralateral inhibition of the muscles in the upper limb. Thus, we provide evidence that it is possible to decrease the muscle activities of the wrist flexors. Moreover, it is not necessary to stimulate the site at which a therapeutic effect is desired. This type of stimulation can be extremely helpful in reducing pathological flexor patterns in the upper limbs due to motor neuron disorders.
Acknowledgments M.S.Z. and J.M.R. are recipients of scientific initiation scholarships granted by Fundac ¸a ˜o de Amparo a ` Pesquisa do Estado de Sa ˜o Paulo (FAPESP; process numbers 2010/195442 and 2011/09253-3).
Please cite this article in press as: Zanin MS, et al., Electromyographic and Strength Analyses of Activation Patterns of the Wrist Flexor Muscles after Acupuncture, Journal of Acupuncture and Meridian Studies (2014), http://dx.doi.org/10.1016/j.jams.2014.02.005
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