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J Korean Soc Phys Med, 2017; 12(1): 75-81 http://dx.doi.org/10.13066/kspm.2017.12.1.75 Online ISSN: 2287-7215 Print ISSN: 1975-311X Research Article Open Access 앉은자세와한발로선자세에서의발보조기와권양기효과를이용한짧은발운동시엄지벌림근의근활성도비교 김도현 정도영 1 중부대학교인문산업대학케마치료학과, 1 중부대학교물리치료학과, 운동병리과학연구소 Comparison of the Activity of the Abductor Hallucis Muscle during Short-foot Exercises using Foot Orthosis and the Windlass Effect in Sitting and One-leg Standing Positions Do-Hyun Kim, PT Do-Young Jung 1 Dept. of KEMA Therapy, Graduate School of Humanities Industry, Joongbu University 1 Department of Physical Therapy, Kinesiopathologic Institute, Joongbu University Received: November 7, 2016 / Revised: November 8, 2016 / Accepted: November 28, 2016 c 2017 J Korean Soc Phys Med Abstract 1) PURPOSE: The purpose of this study was to compare the activity of the abductor hallucis (AbdH) muscle during short foot exercise (SFE) using foot orthosis (SFE-FO) and the windlass effect (SFO-WE) while sitting and in a one-leg standing position. METHODS: We recruited fourteen subjects with normal feet for this study. Surface electromyography (EMG) was used to measure the muscle activity of the AbdH muscle during SFE, SFE-FO, and SFE-WE while sitting and in a one-leg standing position. Three trials consisting of a 5 s hold for each of the three exercises were performed to measure the Corresponding Author : ptsports@joongbu.ac.kr 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. EMG activity of the AbdH muscle. Exercise type and position were randomly assigned. Two-way repeated-measures ANOVA was used to analyze the effects of exercise type (SFE vs. SFE-FO vs. SFE-WE) and position (sitting vs. one-leg standing position) on AbdH muscle activity. A statistical significance was set at α=.05. RESULTS: The EMG activity of AbdH muscle in the SFE-WE exercise was significantly greater than that during SFE and SFE-FO in both exercise positions (p<.001). In addition, the EMG activity of the AbdH muscle in the one-leg standing position was significantly higher than that while sitting (p<.001) during all three exercises. CONCLUSION: These results suggest that SFE-WE is a more effective strengthening exercise than SFE or SFE-FO for activating the AbdH muscle. Key Words: Abductor hallucis muscle, Plantar intrinsic muscles, Short-foot exercise, Windlass effect

76 J Korean Soc Phys Med Vol. 12, No. 1 Ⅰ. 서론발외재근은종아리에서기시해서발목을가로질러발에정지하는반면에발내재근은발에서기시하여발에서정지한다. 그중발내재근은발등과발바닥모두존재하지만발바닥내재근 (plantar intrinsic muscles) 이발의세로활 (longitudinal arch) 과가로활 (transverse arch) 에기능적으로연결되어있기때문에주로발바닥내재근을발내재근으로간주한다 (Soysa 등, 2012). 발바닥내재근은발바닥널힘줄 (plantar aponeurosis) 로부터 4개의층으로구성된다. 또한발바닥내재근의첫번째와두번째층은발의안쪽과가쪽세로활모양에정렬되어있는반면에깊은층은앞쪽과뒤쪽에있는가로활에정렬되어있다 (Neumann, 2002). 발바닥내재근은체중지지활동동안아치의안정성에기여하고발바닥근막, 발바닥인대및발의외재근과함께작용하여보행시발의목말밑관절 (subtalar joint) 의엎침 (pronation) 을조절한다 (Headlee 등, 2008; Goldmann과 Bruggemann, 2012; Fiolkowski 등, 2003). 이전연구에서과도한발가락굽힘운동으로인한발바닥굽힘근의피로가안쪽세로활의높이를감소시켰으며이를통해발바닥내재근이발안쪽세로활을유지하고엎침을조절하는기능을갖는다고보고하였다 (Headlee 등, 2008). 또한몇몇연구들에서발바닥내재근이자세및균형조절기능과관련있다고보고하였다 (Kelly 등, 2012; Goldmann과 Bruggemann, 2012; Mickle 등, 2009) 그중 Kelly 등 (2012) 은한발로서게되면무게중심이내측으로이동하면서발바닥내재근의근활성도가증가되었다고보고하였다. 발내재근의기능부전 (dysfunction) 은망치발가락 (hammer toe), 갈퀴발가락 (claw toe) 그리고엄지발가락가쪽휨증 (hallux valgus) 과같은발가락기형과 (Myerson 와 Shereff, 1989; Arinci Incel 등, 2003; Kwon 등, 2009), 발바닥근막염 (Plantar fasciitis)(allen과 Gross, 2003; Chang 등, 2012) 과관련이있다. 따라서최근에임상에서발내재근기능부전을예방하고중재하기위한발내재근강화훈련이자주시행되고있다. 임상에서주로시행하는발내재근강화훈련으로 발가락말기 (toe-curl) 운동, 발가락뻗침 (toe-spread) 운동그리고짧은발 (short-foot) 운동이있다. 최근에다양한발내재근강화훈련에대한근활성도를비교하기위한근전도연구와장기간의훈련효과를알아보기위한무작위- 대조군연구들이선행되었다 (Kim 등, 2013; Jung 등, 2011a; Jung 등, 2011b). 다양한발내재근강화운동의근활성도를비교하기위한근전도연구들에서내재근중세로활유지에가장크게기여하는엄지벌림근 (abductor hallucis) 의근활성도를비교한결과, 짧은발운동이발가락말기운동보다그리고발가락뻗침운동이짧은발운동보다근활성도가더유의하게높았다고보고하였다 (Jung 등, 2011a). Lynn 등 (2012) 은 4주간의발가락말기운동과짧은발운동을비교한결과, 발배뼈높이와정적인균형능력에는유의한차이가없었으나비우세다리에서의동적균형능력에는짧은발운동이발가락말기운동보다더효과가있다. 비록다양한발내재근강화훈련에대한효과를비교한연구들이선행되었지만임상에서실제발내재근의기능부전이있는환자에게짧은발운동을교육하고적용했을때발내재근을쉽게활성화시키는데어려움이있다. 따라서본연구에서는쉽게발내재근을활성화시킬수있는운동방법을알아보기위해기존의짧은발운동, 발보조기를이용한짧은발운동그리고권양기효과를이용한짧은발운동시근활성도를비교하고자하였다. Ⅱ. 연구방법 1. 연구대상자본연구대상자는실험전에본연구의목적과방법에대해충분히설명을듣고, 실험참여에동의한자로하였다. 연구대상자는총 14명 ( 남성 : 11명, 여성 : 3명 ) 으로선정기준은다음과같다. 첫째, 발배뼈처짐 (navicular drop) 검사시 10 mm 이하이고편안한기립자세에서의뒤꿈치자세 (RCSP: resting calcaneal stance posture) 가 2 ~+2 인자 (Razeghi과 Batt, 2002; Mahar와 Livinqston, 2009), 둘째로하지의반복적손상이나수술적병력이

앉은자세와한발로선자세에서의발보조기와권양기효과를이용한짧은발운동시엄지벌림근의근활성도비교 77 없는자, 셋째, 당뇨병이나발가락의기형이없는자. 대상자의일반적인특징으로평균키 169.6±5.8cm, 몸무게 64.2±11.3kg, 나이 27.8±4.3세그리고 BMI 22.2±3.1kg/m² 이다. 본연구의결과의수치를가지고파워분석 (power analysis) 을해본결과, 운동간의유의한차이가나는조건중가장낮은평균차이와차이의표준편차수치를대입하여알아본결과파워가.8(80%) 일때대상자크기 (sample size) 가 11명임으로본연구의대상자수는충분하다. 2. 측정도구엄지벌림근의활성도를측정하기위해무선근전도시스템 (TeleMyo 2400T EMG, Noraxon, USA) 을이용하였다. 근전도신호는근전도소프트웨어 (Master Edition 1.06, Noraxon, USA) 를이용하여분석하였다. 자료수집률 (sampling rate) 은 1000 Hz로하였으며원신호는 20~400 Hz의밴드패스필터 (bandpass filter) 를사용하여여과하였다. 또한근전도신호를 RMS (root mean square) 값으로계산하여분석하였다 (Bang, 2015; Yoon 등, 2014). 보조기는발보조기를이용한짧은발운동을위해뒤꿈치에서먼쪽발허리뼈까지길이의길이의견고한발보조기를사용하였다. 3. 실험방법알코올로실험자의우세측발의부착지점을닦아낸부위에전극을붙였다. 엄지벌림근의근전도전극부착부위는발배뼈거친면의뒤쪽 1-2 cm에근섬유의진행방향과평행방향으로 2개를부착하였다. 짧은발 운동은발가락의굽힘없이발허리발가락관절을바닥에붙여발뒤꿈치방향으로당기는동작으로, 앞 뒤방향으로발이작아지고안쪽세로활을높게만드는동작으로이루어진다. 이때발허리발가락관절과뒤꿈치가지면에서떨어지지않도록하고발의안쪽세로활이최대로올라가도록지시하였다 (Fig. 1A). 발보조기를이용한짧은발운동은수동적으로안쪽세로활을높일수있도록발보조기를사용한상태로위에서언급한짧은발운동을수행하였다 (Fig. 1B). 권양기효과를이용한짧은발운동은실험자가대상자의엄지발가락의발허리발가락관절을수동적으로발등굽힘시키면발바닥근막에서발생하는장력에의해안쪽세로활이올라가는것을대상자에게인지하게한후안쪽세로활의높이를유지하면서능동적으로발허리발가락관절을발바닥굽힘시켜짧은발운동을실시하였다 (Fig. 1C). 각각의운동방법을앉은자세와한발서기자세에서측정하였다. 본연구에서두가지자세를선택한이유는체중지지유무에따라지면반발력이발내재근에대해저항으로써작용하기때문이다. 앉은자세는등받이가있는의자에상체를수직으로세운자세로엉덩관절과무릎관절이 90도로유지된상태이고, 한발서기자세는벽을마주보고대상자의팔길이만큼의거리에서한발로서서균형을잡을수있을정도로만손가락으로기대고체간이앞 뒤로기울어지지않게하였다. 그리고체중지지를하지않은다리의무릎관절은 90도로굽힘하였다. 각조건의운동시동일한자세를유지하도록대상자에게지시하였다. 운동방법과운동자세는무작위로할당하였다. 각 A. SFE B. SFE-FO C. SFE-WE SFE: short foot exercise; SFE-FO: short foot exercise using foot orthosis; SFE-WE: short foot exercise using windlass effect. Fig. 1. Exercise type

78 J Korean Soc Phys Med Vol. 12, No. 1 각의운동은 5초간 3회씩수행하면서근활성도를측정하였고, 근활성도분석은 5초간수집된자료에서처음과마지막 1초의근전도값은사용하지않고, 중간 3초동안의평균값을대표값으로하였다. 각운동간에근피로를예방하기위해각조건사이에 3분간의휴식을취하였다. 4. 분석및통계방법평균근활성도의정규화 (normalization) 를위해앉은자세에서뒤꿈치를잡고엄지발가락을벌림과굽힘방향으로최대한의자발적등척성수축에대해실험자의손가락으로몸쪽발가락에저항을주었다. 근전도측정은 5초동안수집되며, 처음과마지막 1초의근전도값은사용하지않고, 3초동안측정된값의평균값을최대자발적등척성수축 (maximal voluntary isometric contraction: MVIC) 으로하였다. 각각의운동에대한평균근활성도를 %MVIC로표현하였다. 이요인반복측정분산분석 (two-way repeated-measures ANOVA) 를이용하여운동방법 (SF vs. SF-FO vs. SF-WE) 과운동자세 ( 앉은자세 vs. 한발서기자세 ) 에따른엄지벌림근의근활성도를분석하였다. 사후분석으로대응표본 t-검정 (paired t-test) 를사용하였고통계학적유의수준 α는.01로정하였다. Table 1. Muscle activities of AbdH during SF exercises (%MVIC) Exercise position Exercise type Mean±SD Sitting One-leg standing Table 2. Results of ANOVA analysis in exercise position and type Source of Variance Exercise position SS df MS F p 26986.1 1 26986.1 5.2.03* Exercise type 17364.4 2 8682.2 23.0.00* Exercise position x type SF 46.35±40.47 SF-FO 32.05±29.61 SF-WE 71.35±47.3 SF 80.62±50.58 SF-FO 73.58±38.94 SF-WE 103.09±55.66 361.2 2 180.6.5.62 * Significant differences in exercise position and type (p<.05) Ⅲ. 연구결과 Table 1에각조건에서의평균근활성도를제시하였다. 이요인반복측정분산분석결과, 운동방법과운동자세에서엄지벌림근의근활성도는유의한차이를보였다 (p<.05)(table 2). 운동방법에따른사후분석결과, 모든자세에서권양기효과를이용한짧은발운동이일반적인짧은발운동과발보조기를이용한짧은발운동보다엄지벌림근의근활성도가유의하게높았다 (p<.01)(fig. 2). 또한운동자세에따른사후분석결과, 모든운동방법에서한발로선자세가앉은자세보다엄지벌림근의근활성도가유의하게높았다 (p<.01)(fig. 2). * Significant differences in exercise type (p<.01); Significant differences in exercise position (p<.01) SFE: short foot exercise; SFE-FO: short foot exercise using foot orthosis; SFE-WE: short foot exercise using windlass effect. Fig. 2. Result of post-hoc analysis in exercise types and positions

앉은자세와한발로선자세에서의발보조기와권양기효과를이용한짧은발운동시엄지벌림근의근활성도비교 79 Ⅳ. 고찰임상에서평발환자의경우운동에대한설명을자세히설명해줌에도불구하고처음에올바른운동의수행이어렵다. 왜냐하면평상시선택적으로사용하는근육들이아니고약해져있는발내재근의수축을수행해야하기때문이다. 그래서발내재근이약한환자의경우에치료사가수동적으로안쪽세로활을잡아주어발을짧게한후수행하기도하지만이것또한쉽지않은운동이다 (Page 등, 2009). 최근연구에서도실험대상자에게는짧은발운동이익숙하지않아서 2주간운동법을연습한후에발가락말기운동 (toe-curl exercise) 과짧은발운동시엄지벌림근의근활성도를측정하였다 (Jung 등, 2011a). 따라서본연구에서는임상에서쉽게할수있는짧은발운동을제시하고자실험전각대상자들에게운동방법들을설명한뒤 3번연습한후운동방법을무작위로배정하여다양한짧은발운동을수행하였다. 본연구결과, 앉은자세와한발서기자세모두권양기효과를이용한짧은발운동이일반적인짧은발운동과발보조기를이용한짧은발운동보다엄지벌림근의근활성도가유의하게높았다. 권양기효과는발허리발가락관절을발등굽힘시키면발바닥근막 (plantar aponeurosis) 의장력이증가하여안쪽세로활의높이를올리고발의안정성을제공해주는역할을한다 (Bolgla와 Malone, 2004). 특히보행중말기입각기시권양기효과는발이뒤침 (supination) 되는중요한요인으로작용하고발을견고하게하여추진할수있도록도와준다 (Hicks, 1954; Kappel-Bargas 등, 1998). 이러한권양기효과를이용하여본연구에서는발허리발가락관절을수동적으로발등굽힘시켜안쪽세로활의높이를올려이를유지하면서발가락을천천히발바닥굽힘시켜짧은발운동을실시하였다. Jung 등 (2011a) 의연구에서짧은발운동의근활성도는앉은자세와한발로선자세에서본연구의결과와비슷한연구결과를보였다. 본연구에서실시한권양기효과를이용한짧은발운동은일반적인짧은발운동보다 앉은자세와한발로선자세에서각각 14%MVIC와 23%MVIC 차이를보였다. Reinold 등 (2004) 의연구에서비록어깨관절에서의근육에관한연구이지만, 임상적으로의미가있기위해서는근활성도의차이가최소한 10%MVIC의차이를보여야한다고보고하였기때문에본연구에서는임상에서환자들이발내재근을쉽게활성화시킬수있는권양기효과를이용한짧은발운동을추천한다. 발보조기는평발환자들에게발의아치를재정렬시키고환자의증상완화를위해자주처방되고제작되어지는중재방법이다 (Hume 등, 2008; Banwell 등, 2014; Evans와 Rome, 2011). 본연구에서는이러한발보조기를이용한쉽게아치를올리고짧은발운동을시행하였으나근활성도가 32.1%MVIC와 73.58%MVIC 로다른짧은발운동중가장낮았다. 그이유는발보조기를착용하면발의아치가올라가면서엄지벌림근의길이가짧아진상태가되어근활성도를최대한으로유발하기에충분한길이가되지못하므로근활성도가낮았을것이라사료된다. Jung 등 (2011b) 은 8주간발보조기를사용한그룹과발보조기와짧은발운동을함께수행한그룹을비교한연구에서두그룹모두근력과엄지벌림근의단면적이증가한결과를바탕으로발보조기가발바닥의피부수용기로부터감각되먹임에의해구심성자극을증가시킬수있고, 늘어난엄지벌림근을정상길이로회복하는것을도울수있다고제안하였다. 본연구와이전연구와는상반된연구결과이지만발보조기를이용한짧은발운동은근피로를쉽게느끼지않고근지구력향상을위한운동방법으로추천한다. 본연구에서는운동자세에따른사후분석결과, 모든짧은발운동방법에서한발로선자세가앉은자세보다엄지벌림근의근활성도가유의하게높았다. 이는체중지지유무에따른지면반발력이발내재근에대해저항으로써작용하기때문이다. 따라서평발환자들에게짧은발운동을수행할때발내재근의수행능력에맞춰운동자세를고려해야한다고사료된다. 본연구와유사한이전연구에서 Kelly 등 (2012) 은한발서기

80 J Korean Soc Phys Med Vol. 12, No. 1 자세에서의발바닥내재근의활성도가앉은자세와두발로서있는자세보다유의하게높게나타났으며한발서기자세에서압력중심의안쪽이동에분명한연관성이있다고보고하였다. 또한 Mulligan과 Cook (2013) 의연구에서는 4주간의짧은발운동후기능적뻗기능력이향상되었다고보고하였다. 따라서본연구는균형능력이떨어지는환자에게짧은발운동을수행할때환자의균형능력에맞추어운동자세및방법을고려하기위한기초자료로활용할수있을것이다. 본연구의첫번째제한점으로는안쪽세로활의높이를측정하지못했다는것이다. 비록권양기효과를이용한짧은발운동시대상자로하여금안쪽세로활이내려가지않고유지하라고지시하였으나이를제대로수행했는지확인하지못했다. 두번째로, 다양한짧은발운동시발내재근의활성도의차이를좀더명확하게알아보기위해발내재근의근활성도와안쪽세로활높이와의상관관계를알아보지못하였다. 세번째로, 보조기를이용한짧은발운동에서각실험자간발의크기와안쪽세로활의높이를고려하지않고같은모양의보조기를이용한점이다. 네번째로는평발환자가아닌일반대상자로하였고대상자수가적어연구결과를일반화 (generalization) 할수없다는것이다. 따라서향후연구에서는발내재근의약화가있는평발환자를대상으로다양한짧은발운동시발내재근의근활성도와안쪽세로활의높이를알아보고장기간의효과를알아볼필요가있을것이다. Ⅴ. 결론본연구에서권양기효과를이용한짧은발운동이기존의짧은발운동이나보조기를이용한짧은발운동보다엄지벌림근의근활성도가유의하게높았다. 따라서임상에서발내재근이약한사람들에게발내재근의근활성화를활성화에좀더효과적이고쉽게적용할수있는권양기효과를이용한짧은발운동을추천한다. Acknowledgements 본결과물는교육과학기술부의재원으로지원을받아수행된산학협력선도대학 (LINC) 육성사업의연구결과입니다. References Allen RH, Gross MT. Toe flexors strength and passive extension range of motion of the first metatarsophalangeal joint in individuals with plantar fasciitis. J Orthop Sports Phys Ther. 2003;33(8):468-79. Arinci Incel N, Genc H, Erdem HR, et al. Muscle imbalance in hallux valgus: an electromyographic study. Am J Phys Med Rehabil. 2003;82(5):345-9. Bang HS. The Effects of Lumbar Stabilization Exercise on Muscle Activity and Isokinetic Muscle Strength of Female Patients with Chronic Low Back Pain. J Korean Soc Phys Med. 2015;10:63-71. Banwell HA, Mackintosh S, Thewlis D. Foot orthoses for adults with flexible pes planus: a systematic review. J Foot Ankle Res. 2014;7:23 Bolgla LA, Malone TR. Plantar Fasciitis and the Windlass Mechanism: A Biomechanical Link to Clinical Practice. J Athl Train. 2004;39(1):77-82. Chang R, Kent-Braun JA, Hamill J. Use of MRI for volume estimation of tibialis posterior and plantar intrinsic foot muscles in healthy and chronic plantar fasciitis limbs. Clin Biomech. 2012;27(5):500-5. Evans AM, Rome KA. Cochrane review of the evidence for non-surgical interventions for flexible pediatric flat feet. J Phys Rehabil Med. 2011;47(1):69-89. Fiolkowski P, Brunt D, Bishop M, et al. Intrinsic pedal musculature support of the medial longitudinal arch: an electromyography study. J Foot Ankle Surg. 2003;42(6):327-33. Goldmann JP, Bruggemann GP. The potential of human toe

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