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J Korean Soc Phys Med, 2016; 11(2): 41-52 http://dx.doi.org/10.13066/kspm.2016.11.2.41 Online ISSN: 2287-7215 Print ISSN: 1975-311X Research Article Open Access 정상인들의다양한자세에서두부와경부의회전동안경부표층근육들의사용비율 황태연 송현승 1 이남용 1 전남과학대학교물리치료학과, 1 대전대학교일반대학원물리치료학과 Comparison of Multimodal Posture of Healthy Adults on the Usage Rate of the Superficial Neck Muscles during Head and Neck Rotation Tae-Yeun Hwang, PhD, PT Hyun-Seung Song, MSc, PT 1 Nam-Yong Lee, MSc, PT 1 Dept. of Physical Therapy, Chunnam Techno University 1 Dept. of Physical Therapy, Graduate School, Daejeon University Received: February 17, 2016 / Revised: February 20, 2016 / Accepted: March 22, 2016 c 2016 J Korean Soc Phys Med Abstract 1) PURPOSE: This study was conducted to compare the levels of usage of the superficial neck muscles during head rotation in forward head posture and in multimodal postures for improvement of cervical rotation movement impairment. METHODS: To acquire electromyography (EMG) signals from the sternocleidomastoid (SCM-M), upper trapezius (UPT-M), and the splenius capitis (SPC-M) muscles, 11 subjects practiced right rotation of the head in forward head postures (FHP), upright sitting postures (USP), upright sitting postures with supported arms (SUP), standing postures with the arms leaning against the wall (WSP), and four feet postures (FFP), respectively. RESULTS: The left SCM-M was used significantly more in the FFP compared to the FHP, but not in other postures Corresponding Author : sweetlny@naver.com This is an Open Access article distributed under the terms of the Creative Commons Attribution Non-Commercial License (http://creativecommons.org/licenses/by-nc/3.0) which permits unrestricted non-commercial use, distribution, and reproduction in any medium, provided the original work is properly cited. (p<0.01). The left UPT-M was used significantly more in all postures other than the FHP. The right SPC-M was used significantly more in the FFP (p<0.001) and significantly less (p<0.05) in the SUP compared to the FHP. CONCLUSION: During the rotation of the head, although the usage of the SPC-M significantly decreased in SUP compared to FHP but the usage of the SCM-M and UPT-M did not decrease significantly in other postures compared to FHP. Further research is necessary to prove the hypothesis that special postures may reduce the activity of the superficial neck muscles during head rotation. Key Words: Neck Muscle, Head Rotation, Movement impairment, EMG Integration, Posture Ⅰ. 서론경부는두부 (head) 의자세를유지하고여러방향으로두부를움직이는동안중력에대하여공간에서두부를안내하는역할을담당한다. 두부와경부를움직이기

42 J Korean Soc Phys Med Vol. 11, No. 2 위하여경부에는 20쌍이상의심층과표층근육들이복잡하게둘러싸여있으며, 이런복잡한구조속에서경부근육들은등척성수축상태에서해부학적특성과역할에따라특정한방향으로우세하게동원되거나활동동안척추가안정된상태에서원활한동작을수행하도록협력해서수축한다 (Blouin 등, 2007; Keshner 등, 1989; Vasavada 등, 2002). 움직임실행에서적절한움직임패턴과운동조절의결함은만성근골격계기능부전의발달에기여하는요소가될수있다 (Comerford와 Mottram, 2001; Hodges와 Moseley, 2003). 근육활성을평가한근전도연구들에서, 정상성인들은두개경부굴곡과제동안부하가증가될때표층경부굴곡근보다심층두개경부굴곡근의활성이더높은비율로증가되는것으로나타났으며 (Falla, 2003), 또한부하가낮을수록표층근육들이심층근육에비해더낮은비율로활성화되는것으로나타났다 (O'Leary 등, 2007). 그러나경부편타손상 (whiplash injury) 과잠행성경부통증 (insidious neck pain) 을나타내는환자들은표층경부굴곡근이심층두개경부굴곡근의지지와안정성약화를보상하기위해과도한활성을나타내는것으로보고되었다 (Jull 등, 2004). 만성경부통증을가진사람들은표층경부굴곡근이목적있는활동이끝난후에도이완되지않고수축활동이일정시간지속해서나타나거나심층두개경부굴곡근과표층근들에서앞먹임 (feedforward) 활성지연을나타내는것으로알려지고있다 (Barton과 Hayes, 1996; Falla 등, 2004). 또한경부에서기원하는만성긴장성두통을가진환자들은등척성경부굴곡과신전시에표층의경부근육들의길항적활성이과도하게증가되는변화된운동조절전략을보였다 (Fernandezde-las-Penas 등, 2008). 경부척추의압박을증가시켜자세성경부통증의원인이되는것으로알려진구부정하게앉는자세는경부통증이없는대상자들에서도바른자세로앉을때보다경부신전근활성이증가되는것으로알려졌다 (Caneiro 등, 2010; Edmondston 등, 2011). 경부통증과기능장애를개선하기위해전체적인경부근육들의기능을개선하는것은중요하게인식되어지고있다 (O'Leary 등, 2009). 전방두부자세 (forward head posture) 를감소시키고더똑바른자세를취하도록 하는자세교정은경부표층신전근활성을감소시키고심층경부굴곡근의활성을증가시켜경부기능부전을개선하고통증을감소시킬수있는것으로알려져있다 (Caneiro 등, 2010; Choi와 Kim, 2013; Falla 등, 2007; Harms-Ringdahl 등, 1986, Lee 등, 2015). 역으로심층경부굴곡근의강화는자세를교정하고흉쇄유돌근 (sternocleidomastoid muscle) 과같은표층근육들의상대적인활성을감소시켜결과적으로경부통증과기능을개선하는것으로나타났다 (Lee 등, 2015). 이들직접적인경부의운동조절뿐만아니라수동적으로지지된상지자세또한경부회전움직임동안경부의부하를감소시키고통증을줄이면서움직임을가능하게한다고하였다 (Andrade 등, 2008; McDonnell 등, 2005; Van Dillen 등, 2007). Sahrmann (2010) 은가장많은경부운동손상증후군으로알려진경부의신전 / 회전운동손상증후군의개선을위해다양한자세에서두개경부의굴곡과함께두부의치우침없이두부를회전시키거나상지와견갑대의무게를줄이고두부를회전시키는운동들을추천하였다. 이들운동들은두부회전시에경부표층에서신전과측방굴곡의기능을담당하는흉쇄유돌근과상부승모근 (upper trapezius muscle) 의활성을줄이고심층경부근육들의활성을증가시켜경부에가해진압박력을줄임으로통증과기능을개선할수있다고하였다 (Sahrmann, 2010). 이처럼경부근육들의기능을개선하기위한다양한방법들이임상에서활용되고있으며, 이들대부분의움직임손상의개선을위한중재들은표층근육들의활성을감소시키고심층근육들의활성을증가시키는것을목적으로사용되고있다 (Sahrmann, 2010). 그러나움직임손상을개선하기위해활용되고있는훈련방법들을사용하여정상인을대상으로저항없이두부와경부를회전하는움직임동안표층과심층근육들에서활성이역전되는지를확인한연구는부족하며, 대부분근전도연구들이등척성수축활동들이나심층두개경부굴곡근운동연구에집중되어있다. 따라서정상인들을대상으로경부표층근육들의활성을감소시키고심층근육들의활성을증가시킬것이라고알려진다양한자세들에서두부와경부를저항없이회전하는움직임동안근육들이사용되는정

정상인들의다양한자세에서두부와경부의회전동안경부표층근육들의사용비율 43 도에대해알아보는연구는필요하다고생각된다. 이에본연구는경부신전 / 회전운동손상의개선을위하여추천되고있는다양한자세들과부적당한자세로알려진전방두부자세에서두부와경부를회전할때경부표층근육들이사용되는차이를알아보고그결과를임상적기초자료로제공하고자한다. Ⅱ. 연구방법 1. 연구대상자본연구의연구대상자들은최근 1년이내에척추와사지의근골격계기능장애로인한통증과신경학적결함이없는건강한성인들 ( 총 11명, 남 ; 7명, 여 ; 4명 ) 을선정하였다 (Table 1). 대상자들은평균나이 30.27±7.13 세, 평균키 170.18±7.05 cm, 평균체중 62.18±10.78 kg그리고평균체질량지수가 21.33±2.38 kg / m2이었다. 대상자들은근전도검사에서원활한신호획득을위하여체질량지수가 30 이내인대상자들을선정하였다 (Cuesta-Vargas와 González-Sánchez, 2013). 또한오른쪽이우세측인대상자들을선정하였다. 대상자들은연구자로부터연구목적과방법에대한자세한설명을듣고자발적으로연구의참여에동의하였다. Table 1. General characteristics of subjects Variable M±SD a Age (year) 29.54±5.01 Height ( cm ) 170.18±7.05 Weight ( kg ) 62.18±10.78 BMI ( kg / m2 ) 21.33±2.38 a Mean±standard deviation, b Body mass index. 2. 실험도구 1) 근전도시스템본연구는다양한자세에서각각의대상자들이평소에편안하게돌릴수있는속도로전방중립자세에서부터우측회전끝범위까지두부와경부를회전하는동안 흉쇄유돌근, 상부승모근그리고두판상근 (splenius capitis) 이동작을하는데사용되는정도를알아보기위하여델시스무선근전도 (Trigno EMG Sensor, Delsys Inc., Boston, MA, USA) 를사용하였다. Trigno 근전도전극을통하여측정된각근육들의아날로그신호는 Trigno 기지장치 (base station) 로무선전송된후디지털신호로전환하여개인용컴퓨터에서 Delsys EMG Works Acquistion 소프트웨어를통해자료를수집하여처리하였다. 근전도신호의표본추출률 (sample rate) 은 2000 H Z 로설정하였고, 주파수대역폭 (band with) 은근전도신호의잡음제거를위하여 20 H Z 40 H Z 의주파수를사용하였다. 수집된근육들의근전도신호는제곱근평균제곱 (root mean square; RMS) 처리한뒤다시적분 (integration) 처리하여분석하였다. 3. 실험방법 1) 근전도측정대상자들은두부와경부의움직임과근전도신호측정을위해방해되지않도록편안한복장을착용하였다. 표면근전도신호의원활한추출을위해피부저항을최소화하기위하여전극부착부위피부의털을제거한후부드러운사포로피부각질을제거하고, 의료용알코올솜으로청결하게닦아내었다. 그런후에각근육의근섬유방향과동일하게전극을부착하였다. 흉쇄유돌근의신호추출을위한전극은유양돌기에서흉골결절사이의하 1/3 위치에부착하였다 (Falla 등, 2002). 상부승모근의전극은제 7 경추에서견봉 (acromion) 외측단사이에서중앙외측 2cm부위에부착하였다 (Farina 등, 2002). 두판상근은대상자에게두부와경부를회전하게하고검사자가한손으로측두부위에저항을주면서흉쇄유돌근뒤쪽의제 7 경추와귀를잇는선상에서다른손으로근육의수축을촉진하여정확한위치를확인한후에부착하였다 (Joines 등, 2006). 실험전에각각의근육에전극을부착한뒤대상자들에게두부와경부를회전하게하고근전도신호를확인하였다. 근전도표면전극의부착후에, 본실험에앞서근전도값의표준화를위하여대상자들에게편안하게메트리스위에눕게하고이완된상태에서근전도신호를

44 J Korean Soc Phys Med Vol. 11, No. 2 Fig. 1. EMG Measure during resting posture on supine lying. 측정하였다 (Bexander 등, 2005)(Fig. 1). 이완상태에서근전도신호는 1분동안측정하였고, 근전도신호가일정하게유지된 1초동안의신호를분석을위하여 RMS 처리한후에다시적분 (integration) 처리하였다. 이완된자세에서관련신호를측정한후에다양한자세에서대상자들이평소에편안하게돌리는속도로두부와경부를능동적으로회전하는동안양쪽흉쇄유돌근, 상부승모근그리고두판상근의근전도신호를측정하였다. 근전도신호는움직임을시작하는중립전방주시자세에서부터우측회전의끝범위에서머무르게하는시간까지약 3초동안을측정하였고, 순수하게두부와경부의회전하는동안의신호를분석에사용하기위하여시작시에약 50ms의신호를제거한뒤의약 1초동안의신호를 RMS 처리하고다시적분 (Integration) 처리하였다. 근전도신호의정규화는다음과같은방법을사용하여근육의사용비율 (rate) 로사용하였다. 한후대상자들은다음과같은 5가지자세들에서움직임을실행하였다 (Sahrmann, 2010). 첫째, 대상자들에게시각적관찰을통하여평소에등을구부리고편안하게앉은자세인견봉중심보다귀의이개가정중관상면에서전방에위치하는전방두부자세를취하도록하고그자세에서두부와경부를우측으로돌리고 3초후에다시중립위치로되돌아오게하였다 (Fig. 2-A). 둘째, 등을똑바로펴고골반을중립위치가되도록앉게하고가볍게후두골을들어올리고턱을당기게한똑바로앉은자세에서두부와경부를우측으로돌리고 3초후에중립위치로되돌아오게하였다 (Fig. 2-B). 셋째, 등받이가없는의자에똑바로앉은자세에서양쪽팔꿈치의주두 (olecranon) 높이보다약 5cm정도높은받침위에팔꿈치를지지하고앉게한후후두골을가볍게들어올리고턱을당기게한후두부와경부를우측으로돌리고 3초후에중립위치로되돌아오게하였다 (Fig. 3-A). 넷째, 대상자들에게어깨넓이만큼양발을벌리고자신의상완의거리만큼벽에서떨어져서게하고역시어깨넓이만큼양팔을벌려벽에양쪽전완을기대고, 똑바른자세를취하게하고, 가볍게후두골을들어올리고턱을당기게한후두부와경부를우측으로돌리고 3초후에다시중립위치로되돌아오게하였다 (Fig. 3-B). 다섯째, 고관절과견갑상완관절 (glenohumeral joint) 이약 90 가되게하여네발기기자세를취하게 회전시적분값 / 휴식시적분값 = 회전시사용비율 2) 실험과정다양한자세에서두부와경부의우측회전시에흉쇄유돌근, 상부승모근그리고두판상근의근전도신호를획득하기위하여대상자들에게메트로놈에서신호음이울리면평소에자신이편안하게돌리는속도로두부와경부를우측으로회전하고유지하다가메트로놈이 3초를알리면중립자세로되돌아오게하였다. 근전도측정전에연구자의관리하에충분히자세와동작을반복하여숙지하게하였다. 자세와동작을익숙하게 Fig. 2. EMG measure during right rotation of the head and neck on (A) a forward head posture and (B) an upright sitting posture.

정상인들의다양한자세에서두부와경부의회전동안경부표층근육들의사용비율 45 Fig. 3. EMG measure during right rotation of the head and neck on (A) an upright sitting posture with supported arms and (B) a standing posture with the arms learning against the wall. 하고허리와등과두부와경부가일직선에서중립을유지하게하고견갑골이들어올려지지않은상태에서턱을가볍게당기고두부와경부를우측으로돌린후 3초후에중립위치로다시되돌아오게하였다 (Fig. 4). 모든움직임들은 3회를반복하였으며, 각움직임사이에 30초의휴식시간을갖게하였고, 움직임의순서는무작위로하였다. Fig. 4. EMG measure during right rotation of the head and neck on Four foot posture. 4. 자료분석수집된자료의통계처리는 SPSS version 18.0 통계프로그램 (SPSS Inc. Chicago, IL, USA) 을사용하였다. 자세에따른좌측과우측의흉쇄유돌근, 상부승모근그리고두판상근의사용비율을분석하기위하여반복측정분산분석 (repeated measure ANOVA) 을사용하였고, 주효과비교를위하여본페로니 (Bonferroni) 수정을하였다. Mauchly의구형성검정이만족되면개체내효과검정으로그리고만족되지못하면다변량검정분석결과를사용하여분석하였다. 각자세간차이는대응별비교분석의결과를이용하였다. 좌측과우측근육들의사용비율의차이를비교하기위하여맨-휘트니유 (Mann-Whitney U) 검정을사용하여분석하였다. 각분석시통계학적유의수준은 α=0.05로하였다. Ⅲ. 연구결과 1. 자세에따른두부와경부의우측회전시좌측과우측흉쇄유돌근사용비율대상자들의자세에따른두부와경부의우측회전시좌측과우측흉쇄유돌근사용비율의비교는 Table 2에제시되었다. 각자세들사이에서두부와경부의우측회전시좌측흉쇄유돌근의사용비율은유의한차이를나타내었으며 (p<0.05), 대응별비교에서전방두부자세에비해네발기기자세에서사용비율이유의하게높게나타났다 (p<0.01). 각자세들사이에서두부와경부의우측회전시우측흉쇄유돌근의사용비율은유의한차이를나타내지않았다. 각자세들사이에서 Table 2. Comparison of usage rate of sternocleidomastoid muscle during right rotation of head and neck for each postures Muscle FHP a USP b SUP c WSP d FFP e p SCM f Left 11.03±7.56 e 13.46±7.94 10.98±6.02 12.24±4.71 15.45±8.88 * 0.02 Right 1.56±0.68 1.46±0.43 1.58±0.68 2.07±0.86 3.54±1.97 0.10 Diff 9.47±7.67 12.00±8.07 9.43±6.26 10.16±4.52 11.91±9.30 p 0.00 0.00 0.00 0.00 0.00 a Forward head posture, b Upright sitting posture, c Supported sitting posture with supported arms, d Standing posture with the arms leaning against the wall, e Four feet posture, f SCM; sternocleidomastoid muscle, e Mean±standard deviation, * p<0.05.

46 J Korean Soc Phys Med Vol. 11, No. 2 두부와경부의우측회전시좌측과우측흉쇄유돌근의사용비율은모든자세에서유의한차이를나타내었으며 (p<0.001), 모두좌측근육의사용비율이유의하게높게나타났다. 2. 자세에따른두부와경부의우측회전시좌측과우측상부승모근사용비율대상자들의자세에따른두부와경부의우측회전시좌측과우측상부승모근사용비율의비교는 Table 3에제시되었다. 각자세들사이에서두부와경부의우측회전시좌측상부승모근의사용비율은유의한차이를나타내었으나 (p<0.05), 대응별비교에서유의하게사용비율의차이를나타낸자세는없었다. 각자세들사이에서두부와경부의우측회전시우측상부승모근의사용비율은자세에따라유의한차이를나타내었으며 (p<0.05), 대응별비교에서다른자세들에비해네발기기자세에서사용비율이높은것으로나타났다 (p<0.01). 각자세들사이에서좌측과우측상부승모근의사용비율을분석한결과팔을지지하고앉은자세 (p<0.01) 와벽에팔을기대고선자세 (p<0.05) 에서좌측상부승모근이유의하게많이사용되었다. 3. 자세에따른두부와경부의우측회전시좌측과우측두판상근사용비율대상자들의자세에따른두부와경부의우측회전시좌측과우측두판상근사용비율은 Table 4에제시되었다. 각자세들사이에서두부와경부의우측회전시좌측두판상근의사용비율은유의한차이를나타내었다 (p<0.01). 대응별비교에서팔을지지하고앉은자세에비해네발기기자세에서사용비율이높은것으로나타났다 (p<0.05). 각자세들사이에서두부와경부의우측회전시우측두판상근의사용비율은유의한차이를나타내었으며 (p<0.01), 전방두부자세에비해팔을지지하고앉은자세에서사용비율이유의하게낮았으며 (p<0.05), 네발기기자세에서는다른모든자세에비해유의하게사용비율이더높은것으로나타났다 (p<0.001). 각자세에따른두부와경부의우측회전시좌측과우측두판상근의사용비율은전방두부자세 (p=0.001), 똑바로앉은자세 (p<0.01), 팔을지지하고앉은자세와벽에팔을기대고선자세 (p=0.001) 그리고네발기기자세 (p<0.001) 모두에서우측두판상근이더높은것으로나타났다. Table 3. Comparison of usage rate of upper trapezius muscle during right rotation of head and neck for each postures Muscl e FHP a USP b SUP c WSP d FFP e p UPT f Left 2.04±0.89 g 2.42±1.54 5.54±3.63 5.36±3.54 2.62±0.92 0.03 Right 1.57±0.45 1.45±0.47 1.40±0.32 2.23±1.17 3.41±1.53 0.03 Diff 0.47±0.98 0.96±1.56 4.14±3.42 3.12±2.72 0.79±1.70 p 0.25 0.06 0.01 0.05 0.25 a Forward head posture, b Upright sitting posture, c Supported sitting posture with supported arms, d Standing posture with the arms leaning against the wall, e Four feet posture, f UPT; upper trapezius muscle, g Mean±standard deviation, p<0.01. Table 4. Comparison of usage rate of splenius capitis muscle during right rotation of head and neck for each postures Muscle FHP a USP b SUP c WSP d FFP e p SPC f Left 3.49±1.80 g 3.73±2.50 3.33±1.60 3.96±2.38 4.97±2.30 * 0.01 Right 14.47±7.19 12.04±7.13 10.12±4.32 * 9.86±4.88 23.01±8.65 0.01 Diff 10.98±6.83 8.31±7.14 6.79±4.32 5.90±4.59 18.04±8.69 p 0.00 0.01 0.00 0.00 0.00 a Forward head posture, b Upright sitting posture, c Supported sitting posture with supported arms, d Standing posture with the arms leaning against the wall, e Four feet posture, f SPC; splenius capitis, g Mean±standard deviation, * p<0.05, p<0.001.

정상인들의다양한자세에서두부와경부의회전동안경부표층근육들의사용비율 47 Ⅳ. 고찰이연구는정상성인들을대상으로경부의신전 / 회전운동손상증후군의개선을위하여임상에서사용하도록추천된다양한자세들에서후두골을가볍게들어올리고턱을당겨두개경부굴곡자세를유지하면서경부의신전과측방굴곡의보상이발생되지않도록경부를회전하는동안흉쇄유돌근, 상부승모근그리고두판상근의사용비율을알아보기위하여근전도를사용한연구를실행하였다. 본연구의일차적인목표는골반을중립위치를취하고등을똑바로편자세에서팔을지지한자세가축견갑근육들 (axioscapular muscles) 의수동적신장을감소시켜경부의부하를줄일것이며, 후두골을가볍게들어올리고턱을당기는두개경부굴곡자세가경부의표층근육들의부하를감소시키고심층근들의활성을증가시켜경부기능부전을개선할것이라는이론에근거하여추천된자세들에서불량한자세인전방두부자세에비해표층근들의사용이감소되는지를확인하는것이다 (Sahrmann, 2010). 본연구의결과에서두부와경부의우측회전시에좌측흉쇄유돌근은내민두부자세에비해팔을지지하고앉은자세에서는그사용비율이유사하였고, 네발기기자세에서는유의하게사용비율이증가하였으나나머지자세에서는유의한차이는없었지만증가하는경향을보였다. 바른앉기자세의훈련이요추다열근과심층두개경부굴곡근의활성을증가시킨다고하였다 (Falla 등, 2007). 이자세교정은불량한척추와견갑골자세에의해유발된경부의부하를감소시키고심층자세안정화근육을강화하여척추근육의기능적인자세지지역할을개선시키는것으로보고되었다 (Jull 등, 2004). 만성경부통증환자들과편타손상환자들은압력장치를사용한두개경부굴곡근검사동안증상이없는대조군들과비교해서표층근육인흉쇄유돌근의 RMS 값이더높은것으로나타났다 (Jull 등, 2004). 또한 Sterling 등 (2001) 의연구에서는경부통증환자들에게관절가동술후에통증의감소와함께흉쇄유돌근의활성이감소하는것을보여주었다. 이들연구들의주장 하는점은경부통증이있거나부적당한자세를가진대상자들에서는경부움직임에서천층근육들의활성이증가되고, 경부통증이없거나바른자세에서일어나는움직임은천층근육의활성이감소하고심층근육의활성은증가할것이라는가설에근거한것이다. 그러나 Yang와 Oh(2014) 의연구에서는전방두부자세를가진경부통증이없는대상자들에게바르게앉은자세에서시각적피드백을이용하여경부의측방굴곡에대한보상작용을방지하고자연스런움직임으로두부를좌측과우측으로회전하게하고흉쇄유돌근의활성도와측방굴곡의양을측정한결과피드백장치를사용하지않고경부를회전한움직임에비해측방굴곡의양은줄어들었지만흉쇄유돌근의근활성도는감소하지않았다. Yang과 Oh(2014) 의연구와유사하게본연구에서도골반과척추의중립자세와함께두개경부굴곡상태에서두부와경부의회전을시켰음에도전방두부자세보다팔을지지한자세를제외한모든자세에서흉쇄유돌근의사용비율이감소하지않았다. 이런결과는흉쇄유돌근이두부와경부회전에상당한영향을미치는근육이기때문으로생각되며 (Bexander 등, 2005; Williams 등, 1995), 또한정상적으로흉쇄유돌근은경부의굴곡에서전사각근과함께 83% 의역할을담당하고두장근 (longus capitis) 과경장근 (longus colli) 은단지 17% 의역할만을담당한다는근거들과일치하게경부의굴곡에흉쇄유돌근이상당한작용을하기때문이라고생각된다 (Vasavada 등, 1998). 이런근거들에비추어볼때본연구의대상자들은경부통증이없는정상인들로서특별하게표층근의활성이증가되어있지않았었기때문에두개경부굴곡자세를취하고회전하는동안좌측흉쇄유돌근의사용비율이감소하지않았고, 두개경부굴곡과두부의회전에대한정상적인이중협력작업에사용되어졌을것으로생각된다. 한편, 네발기기자세에서그사용비율이유의하게증가한것은앉거나선자세들에비해중력에의해서아래로떨어지는턱을잡아당겨두개경부를굴곡시키기위해흉쇄유돌근이더많은노력을해야했기때문일것으로생각된다. Sahrmann (2010) 은앉은자세또는누운자세에서경부회전이너무어렵거나통증이

48 J Korean Soc Phys Med Vol. 11, No. 2 있다면네발기기자세가대안적으로정교한경부회전을수행하기위하여사용될수있다고하였지만이자세에서운동이경부통증환자들에서표층근의활성을줄이고심층근의활성을증가시켜척추의정렬에더유리하게운동을시킬수있을지에대해서는경부통증환자들을대상으로한연구가더필요할것으로생각된다. 이연구에서좌측흉쇄유돌근이휴식시에비해약 11 15배의사용을보인반면우측흉쇄유돌근은약 1 3.5배의사용으로아주미미하였는데이는반대쪽으로경부를회전시키는흉쇄유돌근의근육특성을잘반영하는것으로이연구에서측정결과들이정상적인근육반응이었음을증명하는것이라고생각된다 (Bexander 등 2005; Williams 등, 1995). 우측흉쇄유돌근은휴식시에비해대부분의자세에서사용비율이미미하였으나네발기기자세에서다른자세들에비해높은사용비율을나타낸것은역시좌측과마찬가지로턱을당기기위한항중력작용에의한결과라고보여진다. 좌측상부승모근은우측회전동안에모든자세에서전방두부자세보다많은사용비율을나타내었으나유의한차이를보이지않았다. 그사용비율에서유의한차이를나타내지않았을지라도나머지자세들에비해팔을지지하고앉은자세와벽에팔을기대고선자세에서좌측상부승모근이더많이사용되었는데이는팔을지지함과동시에바른자세를취하기위해어깨의끝을가볍게말아올리게하였기때문에어깨의높이를유지하는데일부그힘이사용되어나타난결과라고생각된다 (Sahrmann, 2010). 좌측과우측상부승모근의사용비율에서의차이는네발기기자세를제외하고대체로좌측상부승모근이우측에비해더높았다. 이런결과는상부승모근이반대쪽으로경부를회전하는데일부기여하기때문에경부를우측으로회전하는동안좌측이우측보다많이사용되어나타난결과라고생각된다. 그러나네발기기자세에서우측상부승모근의사용비율이좌측보다더높은것은경부를회전할때좌측이아래를향하게될때우측상부승모근이중력에대한저항으로작용하여두부를중립신전과중립우측측방굴곡으로유지하기위함이었을것이다 (Keshner 등, 1989). 상부승모근과견갑거근과같은축견갑근육은경부를포함한척주와상지사이에서부하를동시에전달하고견갑골을안내하는이중역할을담당하는것으로알려져있다 (Cools 등, 2014). 견갑골정렬의결함은경부와견갑상호간에생역학적인영향을미쳐축견갑근육들의긴장을바꾸고, 경부에서압박적인부하를증가시키는것에의하여경부기능을악화시키고, 경부의가동범위의제한과경부통증의원인이될수있다고하였다 (Johnson 등, 1994; Swift과 Nichols, 1984; Szeto 등, 2005; Van Dillen 등, 2007). 이전의연구들에서견갑골자세의교정은경부통증이있는환자들에서경부가동범위와통증의경감에대한즉각적인개선을시킬수있다고보고하였다 (Lluch 등, 2014; Van Dillen 등, 2007). 그러나다른연구에서는건강한대상자들에서견갑골의변형은경부회전에유의한영향을미치지않는것으로나타났다 (Andrade 등, 2008). 또한특발성경부통증을가진사람들에대한상부승모근의근전도연구에관한체계적인고찰연구에서는휴식시와어깨높이아래에서과제수행동안에경부통증을가진사람들과정상인사람들사이에서근전도진폭활동에서유의한차이가없는것으로나타났다 (Castelein 등, 2015). 본연구에서는두부와경부의우측회전동안에좌측흉쇄유돌근이휴식시에비해약 11 15.5배의사용을보인반면, 좌측상부승모근은약 2 5.5배로그사용비율이낮았다. 이는상부승모근이두부의움직임보다는어깨의움직임과더밀접하게관련이있으며, 두부의등척성안정화에미치는영향이미미하다는주장 (Keshner 등, 1989) 과유사하게두부와경부의회전에많은영향을미치지는않는것으로보인다. 본연구의결과에서전방두부자세에비해개선을위해추천된자세들에서좌측상부승모근의사용비율이감소하지않은것은이들자세들에미치는영향이적거나, 경부회전에대한그역할이미미하거나또는본연구의대상자들이정상인이었기때문에근육의활성이비정상적으로증가되어있지않았었기때문일수있다. 따라서추가적으로더많은연구가다양한조건과대상들에게실행되어야할것으로생각된다.

정상인들의다양한자세에서두부와경부의회전동안경부표층근육들의사용비율 49 두판상근은동측으로두부를회전하는데기여하는근육으로흉쇄유돌근과함께협력하여동원된다 (Bexander, 등 2005; Williams 등, 1995). 또한중립두부와경부자세에서후두골에저항을적용하고신전하는자세에서활성이증가하는것으로나타났다 (Schomacher 등, 2012). 본연구에서도우측회전동안에좌측두판상근이휴식시에비해 3 5 배사이에서사용되는것에비해우측두판상근은약 10 23배사용되는것으로나타나동측으로두부를회전할때동원되는결과를보여주었다 (Bexander 등 2005; Williams 등, 1995). 좌측두판상근은네발기기자세에서팔을지지하고앉은자세보다유의하게사용비율이높았고, 다른자세들에비해서도유의하지는않았지만더많은비율로사용되었다. 이는네발기기자세에서좌측두판상근이작지만두개경부의신전근의역할에의해중력에대해떨어지는두부를지지하는데기여한결과라고생각된다 (Elliot 등, 2010; Schomacher 등, 2012). 우측두판상근은팔을지지하고앉은자세에서전방두부자세에비해유의하게더적은비율로사용되었고, 똑바로앉은자세와벽에팔을지지하고앉은자세는전방두부자세에비해유의하지않았지만그사용비율이적은것으로나타나전방두부자세보다두판상근의부하가작은상태에서두부의회전운동이가능한자세들임을보여주었다. 네발기기자세는다른모든자세에비해두판상근의사용비율이유의하게더높은것으로나타났다. 이는역시네발기기자세에서는두부가아래로떨어지는것에대한저항의역할때문에그사용비율이높았을것으로생각된다 (Elliott 등, 2010; Schomacher 등, 2012). 두판상근이사용되는결과를볼때네발기기자세를제외한나머지자세들은동측두판상근의과긴장으로인한신전을동반한회전운동손상이나타날때두판상근의사용을적게하면서회전을실행할수있는운동이될수있을것으로생각된다. 결과적으로정상성인들에서경부회전동안좌측흉쇄유돌근과좌측상부승모근의사용비율은전방두부자세에비해똑바로앉은자세, 팔을지지하고앉은자세, 벽에팔을기대고선자세그리고네발기기자세들에서감소하지않고오히려증가하였다. Sahrmann (2010) 은이들자세들이심부경부근육들의활성을증가시키고표층경부근육들의활성을감소시킬것이라고하였다. 그러나이연구에서는연구대상자들이정상인들이었기때문에경부통증을가진대상자들에서나타나는심층근육의약화로인한표층근육의보상적인과활성이나타나지않았었을것이며 (Jull 등, 2004), 그에따라교정된자세들에서표층근육들의사용비율이감소하지않았을것으로생각된다. 더구나표층근육의사용비율의변화는심층근육의사용비율에대한변화와비교가필요하지만이연구에서는심층근육을측정할수없는제한적인요소때문에표층근육들만을측정하였기때문에표층근육들의증가비율이필연적으로나타날수있는증가비율이었을잠재적가능성을배재할수없다 (Falla 등, 2003; Jull 등, 2009; O'Leary 등, 2007). 또한이연구에서사용된두개경부의굴곡자세를취하고두부와경부를회전하는움직임은단순하게두개경부를굴곡하는움직임에회전움직임이추가되었기때문에회전에많은역할을하는표층근육들의사용비율이더높아졌을것으로보여진다 (Bexander 등, 2005; Williams 등, 1995). 이연구의결과들에서대상자들사이에서표준편차가큰이유는근육의수축에따라발생하는전기신호가미세하기때문에작은변화에도민감하게반응하는근전도의특성때문일것이며, 또한가벼운두개경부굴곡자세를취하고머리의편위가발생하지않도록근전도측정전충분한연습을실행하였지만일상에서본인이편안하게움직이는속도로두부와경부를회전하도록하였기때문에각각대상자들의움직임특성이달라서나타난결과라고생각된다 (Castelein 등, 2015). 이연구는모든사람들에게일반화하기에는연구대상자들의수가너무적었다. 그러나이연구의근전도측정은동일한근육의좌측과우측의사용비율이회전동안분명하게차이가나는결과들에비추어볼때적절하였던것으로생각된다. 추후연구에서는더많은대상자들에게그리고경부통증이있는대상자들과정상인대상자들사이에서사용비율의차이를비교하는연구가필요할것으로생각된다.

50 J Korean Soc Phys Med Vol. 11, No. 2 Ⅴ. 결론본연구는전방두부자세와경부의신전 / 회전운동손상증후군의개선을위하여추천된똑바로앉은자세, 팔을지지하고앉은자세, 벽에팔을지지하고앉은자세그리고네발기기자세를취하고두부와경부를회전할때흉쇄유돌근, 상부승모근그리고두판상근의사용비율을비교하기위하여실행하였으며, 그결과전방두부자세에비해팔을지지하고앉은자세에서두판상근의사용비율의유의한감소를제외하고는모든자세들에서전방두부자세에비해이들근육들의사용비율이유의하게감소하지않았다. 따라서전방두부자세와비교해바르고교정된자세들에서경부의회전동안표층근육들의사용이줄어드는지에대해알아보는더많은연구가필요할것으로생각된다. References Andrade GT, Azevedo DC, De Assis Lorentz I, et al. Influence of scapular position on cervical rotation range of motion. J Orthop Sports Phys Ther. 2008;38(11): 668-73. Barton PM, Hayes KC. Neck flexor muscle strength, efficiency, and relaxation times in normal subjects and subjects with unilateral neck pain and headache. Arch Phys Med Rehabil. 1996;77(7):680-7. Bexander CS, Mellor R, Hodges PW. Effect of gaze direction on neck muscle activity during cervical rotation. Exp Brain Res. 2005;167(3):422-32. Blouin JS, Siegmund GP, Carpenter MG, et al. Neural control of superficial and deep neck muscles in humans. J Neurophysiol. 2007;98(2):920-8. Caneiro JP, O'Sullivan P, Burnett A, et al. The influence of different sitting postures on head/neck posture and muscle activity. Man Ther. 2010;15(1):54-60. Castelein B, Cools A, Bostyn E, et al. Analysis of scapular muscle EMG activity in patients with idiopathic neck pain: a systematic review. J Electromyogr Kinesiol. 2015;25(2):371-86. Choi HW, Kim SY. The effect of functional postural trunk exercise on pain, activities of daily living, range of motion, deep cranio-cervical flexor muscle endurance in neck pain patient by acute whiplash-associated disorders. J Korean Soc Phys Med. 2013;8(4):655-66. Comerford MJ, Mottram SL. Movement and stability dysfunction--contemporary developments. Man Ther. 2001;6(1):15-26. Cools AM, Struyf F, De Mey K, et al. Rehabilitation of scapular dyskinesis: from the office worker to the elite overhead athlete. Br J Sports Med. 2014;48(8):692-7. Cuesta-Vargas AI, Gonzalez-Sanchez M. Differences in muscle activation patterns during sit to stand task among subjects with and without intellectual disability. Biomed Res Int. 2013;173148(10):7. Edmondston SJ, Sharp M, Symes A et al. Changes in mechanical load and extensor muscle activity in the cervicothoracic spine induced by sitting posture modification. Ergonomics. 2011;54(2):179-86. Elliott JM, O'Leary S, Sterling M, et al. Magnetic resonance imaging findings of fatty infiltrate in the cervical flexors in chronic whiplash. Spine. 2010;35(9): 948-54. Falla D, Dall'Alba P, Rainoldi A, et al. Location of innervation zones of sternocleidomastoid and scalene muscles--a basis for clinical and research electromyography applications. Clin Neurophysiol. 2002;113(1):57-63. Falla D, Jull G, Dall'Alba P et al. An electromyographic analysis of the deep cervical flexor muscles in performance of craniocervical flexion. Phys Ther. 2003;83(10): 899-906. Falla D, O'Leary S, Fagan A, et al. Recruitment of the deep cervical flexor muscles during a postural-correction exercise performed in sitting. Man Ther. 2007;12(2): 139-43. Farina D, Madeleine P, Graven-Nielsen T, et al. Standardising

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