J Korean Soc Phys Med, 2017; 12(4): 113-122 http://dx.doi.org/10.13066/kspm.2017.12.4.113 Online ISSN: 2287-7215 Print ISSN: 1975-311X Research Article Open Access 앉았다일어서기동작수행시발목관절각도에따른근활성도및역학적부하량의비교 이명모 박대성 1 대전대학교물리치료학과, 1 건양대학교물리치료학과 A Comparison of Muscle Activation and Mechanical Loading according to the Degree of Ankle Joint Motion during a Sit-to-stand Task Myung-Mo Lee, PT, PhD Dae-Sung Park, PT, PhD 1 Dept. of Physical Therapy, Daejeon University 1 Dept. of Physical Therapy, Konyang University Received: August 29, 2017 / Revised: September 18, 2017 / Accepted: October 15, 2017 c 2017 J Korean Soc Phys Med Abstract 1) PURPOSE: The purpose of this study was to investigate the comparison of muscle activity and mechanical loading according to the angle of ankle joint during a sit-to-stand (STS) task. METHODS: Thirty-four young participants performed the STS in a randomized trial with the ankle joint at a neutral, 15 degrees dorsiflexion and 15 degrees plantarflexion angle in a fixed sitting posture with the knee in 105 degrees flexion. Muscle activity of the tibialis anterior (TA), rectus femoris (RF), biceps femoris (BF), and gastrocnemius medialis (GCM) was measured, and the parameters calculated in relation to mechanical loading were the STS-time, maximum peak, minimum peak, and total sum of mechanical loading. Corresponding Author : daeric@konyang.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. RESULTS: In the dorsiflexion position, the muscle activity of the TA and GCM showed a significant increase (p<.05), and the STS time, maximum peak and total sum of mechanical loading showed a significant difference compared to that in the neutral position (p<.05). In the plantarflexion position, the muscle activity of the RF and GCM showed a significant increase (p<.05), while that of the TA showed a significant decrease (p<.05) compared to that in the neutral position. And the minimum peak was significantly increased than the neutral position (p<.05), and the maximum peak and total sum of mechanical loading were showed significant difference compared with dorsiflexion position (p<.05). CONCLUSION: These results show that there is a difference in muscle activity and mechanical loading when performing the STS movement according to the change in the ankle joint angle. Key Words: Ankle joint, Electromyography, Range of motion, Time and motion studies
114 J Korean Soc Phys Med Vol. 12, No. 4 Ⅰ. 서론앉았다일어서기 (Sit-to-stand, STS) 는신체중심이안정된앉은자세에서안정성이떨어지는폄된하지위로전위될때균형을잃지않고직립자세를이루는동작으로정의된다 (Roebroeck 등, 1994). 이는일상생활에서많이사용하는동작중하나로걷기, 계단오르기, 물건들기, 옮기기와같이독립적이고기본적인기능을위한필요전제조건이며 (Munton 등, 1984; Cahill 등, 1999), 기능적인능력을확인할수있는지표이다 (Kanai 등, 2016). 이에따라많은임상가들이정확한 STS 동작의필요성을인식하고있으며, 치료적목적으로 STS 과제를응용하고있다 (Schenkman 등, 1990). 정상적인 STS 동작은몸통 (trunk) 과골반 (pelvis) 이앞쪽으로회전되어움직임이시작되는구간, 엉덩이 (hip) 가의자로부터떨어지는시점을시작으로몸전체가앞으로움직이는구간, 발목 (ankle) 이최대발등굽힘 (ankle dorsi-flexion) 되는시점을시작으로엉덩관절 (hip joint) 이완전히폄되는구간, 그리고일어선동작에서자세를안정화하는구간으로세분화하여 4개의구간으로분석할수있다 (Schenkman 등, 1990). 연구자에따라크게몸통을앞으로기울이는구간과선자세를만들기위해몸체를들어올리는구간으로나누기도하며 (Ada와 Westwood, 1992), 이는굴곡단계와서기단계로나누기도한다 (Nuzik 등, 1986). 이러한과정을안정적으로수행하기위해서는충분한관절회전력, 좁아진두발의지지면에압력중심을안정적으로이동시키는능력, 그리고다리와몸통근육의조화로운수축이요구되며, 이를통하여환경적변화에따라일어나는전략을수정하는능력이필요하다 (Mak 등, 2003; Shumway-Cook와 Woollacott, 2007). 의자높이 (Su 등, 1998; Kawagoe 등, 2000), 팔걸이유무 (Munton 등, 1984; Alexander 등, 1991), 초기접지발의위치 (Park와 Lee, 2011), 수행속도 (Mourey 등, 2000; Papa와 Cappozzo, 2000), 무릎관절각도 (Eriksrud 와 Bohannon, 2003) 등과같은 STS 동작에영향을미치는요소들과관련한운동역학적 (kinetic) 분석과운동형상학적 (kinematic) 분석을위한노력들은 1980년대이후 부터지속되어왔다. 이러한연구의결과들을토대로효율적인 STS 동작의수행방법이제시되었고, 기능적제한을지닌대상자들의비정상적인 STS 동작에대한분석도추가적으로이루어졌다 (Nadzadi 등, 2003). STS 동작수행은신체기능적제한이대상자들에게기능적수행평가의용도및훈련수행과제로서도제시되어오고있다 (Boonstra 등, 2010; Mong 등, 2010; Kwon, 2014). 특히, STS 동안무릎과발목관절주변의근육은엉덩이가의자로부터떨어지면서체중을앞으로가속화하여이동시키고, 몸통을일으키는데큰역할을하기때문에, 임상에서환자를기능적으로훈련시킬때중요히여기는부분이기도하다 (Schenkman 등, 1990). STS 동작수행에있어발의위치는운동역학적요소와운동형상항적요소의효율에있어서중요하다. 발의대칭성과발의위치에관한선행연구들이이미임상진단적가치와훈련과제로서의미를제시하고있지만, 다양한조건하에수행되는움직임에대한분석과결과들이지속적으로보고되어야한다. 이에본연구에서는발목관절각도에세가지조건의변화를주어 STS 동작시발생되는근활성도및역학적부하량의변화를살펴보고, 이를임상적기초자료로서활용하고자한다. Ⅱ. 연구방법 1. 연구대상자대전시소재의 D 대학교에재학중인 20대성인남녀 40명을모집하였다. 대상자선정기준은상지의보상작용없이독립적인 STS가가능한자로하였으며, 중재결과에영향을줄수있는관절의가동성제한이있는자, 최근 3개월이내하지의정형외과적질환이나, 수술의경험이있는자는제외하였다. 실험전모든대상자에게연구의목적과절차에대해설명하였으며, 자발적으로연구참여동의서에서명한자만을연구대상자로하였다. 2. 연구절차본연구는발목관절각도변화에따른 STS 동작
앉았다일어서기동작수행시발목관절각도에따른근활성도및역학적부하량의비교 115 수행시발생되는근활성도와역학적부하량의변화를알아보기위한단면적연구설계 (cross-sectional study design) 로실험에앞서대상자들의일반적특성을기록하고, STS의시작자세와방법에대하여설명하였다. STS의시작자세중중립자세는양팔은팔짱을끼고, 궁둥뼈결절 (ischial tuberosity) 부터무릎관절까지의근위부 1/2 영역이전동테이블위에닿게앉는것으로하였다 (Seven 등, 2008). 앉은자세에서양쪽무릎은정면을향하여 105 굽힘하고 (Cheng 등, 1998), 시선은정면을응시하며, 양발은맨발의상태로어깨너비만큼서로평행하게벌린채지면과수평하게위치하도록하였다 (Fig. 1-A). 중립자세에서경사각 15 인경사판을이용하여발목관절각도의변화를주었으며, 각각발등굽힘자세 (Fig. 1-B) 와발바닥굽힘 (ankle plantar- flexion) 자세 (Fig. 1-C) 로설정하였다. 경사판위에서 STS 동작수행시발의이동과미끄럼을방지하기위해미끄럼방지패드를부착하였으며, 경사판유무에따라변화하는발목의높이와무릎의각도 (105 굽힘 ) 를유지하기위해높낮이가조절가능한전동테이블위에대상자들이앉도록하였다. 각시작자세에서 편안한속도로일어나세요. 라는구두지시에따라대상자들은동작을수행하였으며 (Tully 등, 2005), STS 동작수행동안발생한근활성도와역학적부하량의변화를측정하였다. 순서에따른편견을최소화하기위해시작자세는무작위순서로하였으며, 각동작수행및측정간 30초의휴식시간을제공하였다. 3. 측정도구및방법 1) 근활성도측정 STS 동작수행동안하지의근활성도를측정하기위해표면근전도시스템 (LXM 3204, Laxtha Inc., Korea) 를사용하였다. 앞정강근 (tibialis anterior, TA), 넙다리곧은근 (rectus femoris, RF), 넙다리두갈래근 (biceps femoris, BF), 그리고장딴지근 (gastrocnemius, GCM) 에각각 2cm간격으로표면전극을부착하였다. 표면전극부착전부위에피부저항을줄이고전극이피부에잘고정되도록면도하여체모를제거하였으며, 이물질제거를위해소독용알코올로충분히닦아청결을유지하였다 (Hermens 등, 2000). TA의표면전극은무릎관절바깥쪽과발목관절바깥쪽복사뼈 (lateral malleolus) 를연결한몸쪽 1/3지점에부착하였고, RF의전극은넙다리의무릎뼈 (patella) 끝과위앞엉덩뼈가시 (anterior superior iliac spine; ASIS) 사이중간지점에부착하였다. BF의전극은넙다리의뒤쪽, 궁둥뼈결절과정강뼈 (tibia) 안쪽사이의중간지점에부착하였으며, GCM의전극은무릎관절안쪽과발꿈치뼈 (calcaneous) 사이의몸쪽 1/3지점에부착하였다. 접지전극은내측복사뼈에부착하였다 (Rempel, 2000). 각근육의최대등척성수축 (maximal voluntary isometric contraction; MVIC) 값을측정한후 STS 동작수행시해당근육의최대활성전위값을 MVIC의 % 값으로정량화하여데이터를수집하였다. 각조건에대하여 3회측정한평균값을기록하였으며, 자료수집및분석은 Telescan 소프트웨어 (Telescan 3.1, Laxtha Inc., Korea) 를사용하였다. 근전도신호의표본추출률 1,024Hz, 대역통과필터 (band pass filtering) 20~400Hz와 60Hz 노치필터 (notch filter) 를적용하여필터링하였다. Fig. 1. Experimental condition 2) 역학적부하변화량측정 STS 과정에서지면에가해지는힘의변화를역학적부하변화량값으로하였으며, Wii balance Board (WBB) 를이용하여측정하였다. WBB는 4개의로드셀을이용하여체중과신체압력중심점을측정할수있으며, 가격이저렴하고이동이편하여지면반발력 (ground reaction
116 J Korean Soc Phys Med Vol. 12, No. 4 force, GRF) 과신체압력중심점 (center of pressure, COP) 을측정하는데유용하여최근임상연구에서많이활용하고있는장비이다 (Abujaber 등, 2015). 힘판 (force plate) 과비교하여 STS와보행동안지면반발력측정값에있어높은타당도 (ICC=.701~.994)(Jeong와 Park, 2016) 와높은검사- 재검사간신뢰도 (ICC=.676~.946) 를지닌장비이다 (Yang 등, 2016). STS 동안가해지는역학적부하량값은 WBB의로드셀을통해연속적으로수집되어블루투스로연결된컴퓨터에무선으로전송되었다. 대상자들이 STS 동작을개시하기 3초전부터측정을시작하여, 안정되게선상태가유지된이후 3초까지의데이터를수집하였다. 데이터의수집은 Balancia software (Balancia software ver 2.0, Mintosys Inc., Korea) 를사용하였으며, 데이터샘플추출은 100Hz로하였다. 저장된데이터는엑셀을사용하여 STS 수행시간, STS 동안지면에가해지는최대부하값과최소부하값, 그리고부하량의총합을산출하였다. STS 시작전앉은상태에서 3초간 WBB에가해진부하량의역치값 ( 평균 - 2* 표준편차 ) 보다낮아지는시점을 STS의시작지점으로설정하였고 (Fig. 2-A), STS 이후선자세가안정하게 유지된 3초동안 WBB에가해진부하량의역치값 ( 평균 - 2* 표준편차 ) 보다낮아지는마지막시점을 STS의끝지점으로설정하여 (Fig. 2-B) 시작지점부터끝지점까지의시간을 STS 수행시간으로하였다 (Fig. 2-C). STS 동작시행후다리의체중부하가수직방향으로순간적감소되어지면에가해지는체중부하가가장낮은지점을최소부하값으로하였으며 (Fig. 2-D), 엉덩이가들리고하지의폄자세가만들어지는과정에서체중부하가최대로증가한지점을최대부하값으로하였다 (Fig. 2-E). STS동안지면에가해진부하량의총합은 STS 시작과끝지점사이그래프아래의면적으로시간에대한부하값을적분 (pressure-time integration) 하여계산하였으며 (Fig. 2-F), 지면에가해진부하량의각크기와합은체중의백분율 (%) 로표기하였다. 발등굽힘과발바닥굽힘시작자세를위해경사판을이용한경우경사판의무게를뺀값으로데이터를기록하였다. 3회반복측정하여평균값을데이터분석에사용하였으며, 모든측정은사전에훈련된두명의검사자와보조자에의해표준화된방법으로동일하게실시되었다. A: Start of STS, B: End of STS, C: STS time, D: Peak min., E: Peak max., F: Total sum of mechanical loading. Fig. 2. Individual data recording and key indicators during a STS task
앉았다일어서기동작수행시발목관절각도에따른근활성도및역학적부하량의비교 117 4. 분석방법본연구의모든통계학적분석은 SPSS 20.0 (SPSS INc., Chicago, IL, USA) 을사용하였다. STS동작시발목관절각도 ( 중립, 발등굽힘 15도, 발바닥굽힘 15도 ) 에따른근육의활성도, STS 수행시간, 최소부하값, 최대부하값, 그리고부하량의총합의변화를알아보기위하여반복측정일원분산분석 (one-way repeated measures analysis of variance, one-way RM ANOVA) 을사용하였다. 사후검정방법은 Bonferroni검사로하였으며, 자료의모든통계학적유의수준 (α) 은.05이하로하였다. Ⅲ. 연구결과 2. STS 동작시발목관절각도에따른근활성도결과 TA의근활성도는발등굽힘자세에서가장높았고, 발바닥굽힘자세에서가장낮았으며, 발목관절각도에따른유의한차이가있었다 (p<.05). RF의근활성도는발바닥굽힘자세에서가장높았고, 중립자세에서가장낮았으며, 중립자세에대하여발바닥굽힘자세에서만유의한차이가있었다 (p<.05). BF의근활성도는발바닥굽힘자세에서가장높았고, 발등굽힘자세에서가장낮았으나, 발목관절각도에따른유의한차이는나타나지않았다. GCM의근활성도는발등굽힘자세에서가장높았고, 중립자세에서가장낮았으며, 중립자세에대하여발등굽힘자세와발바닥굽힘자세에서각각유의한차이가있었다 (p<.05)(table 2). 1. 연구대상자의일반적특성 STS의시작자세중발등굽힘자세에서근육의단축으로인해발뒤꿈치가경사판바닥에닿지않는 6명을제외하고, 최종 34명의대상자가실험에참가하였다. 대상자들의일반적특성은 Table 1과같다. 3. STS 동작시발목관절각도에따른역학적부하변화량결과 STS에소요되는시간 (STS time) 은, 발바닥굽힘자세에서가장높았고, 발등굽힘자세에서가장낮았으며, 발등굽힘자세와발바닥굽힘자세에서만유의한차이 Table 1. General characteristics of the participants a Male (N=11) Female (N=23) Total (N=34) Age (year) 23.73 ± 3.17 a 21.70 ± 1.20 22.35 ± 2.24 Height (cm) 173.09 ± 4.44 161.7 ± 4.44 165.38 ± 7.41 Weight (kg) 67.84 ± 7.83 58.03 ± 10.81 61.21 ± 10.87 Mean ± Standard deviation Table 2. Comparison of muscle activation according to the ankle joint angle during a STS task (N=34) Neutral Ankle dorsiflexion Ankle plantar flexion F p TA 51.38 ± 17.32 a 75.98 ± 18.83 40.96 ± 13.01 69.51.00 RF 39.91 ± 15.31 42.78 ± 18.12 44.06 ± 16.03 3.53.04 BF 15.98 ± 9.86 18.34 ± 7.96 18.11 ± 13.85 1.58.22 GCM 12.48 ± 7.71 21.26 ± 12.68 16.23 ± 9.04 9.54.01 a Mean ± Standard deviation (%MVIC), TA: Tibialis anterior, RF: Rectus femoris, BF: Biceps femoris, GCM; Gastrocnemius. Significant difference from neutral position, p<.05 Significant difference from ankle dorsiflexion position, p<.05
118 J Korean Soc Phys Med Vol. 12, No. 4 Table 3. Comparison of mechanical loading according to the ankle joint angle during a STS task (N=34) Neutral Ankle dorsiflexion Ankle plantar flexion F p STS time (sec) Peak Min. (weight %) Peak Max. (weight %) 1.89 ±.25 a 1.82 ±.20 1.91 ±.22 6.20.01 9.34 ± 2.85 9.70 ± 3.30 10.25 ± 2.49 3.54.04 115.23 ± 3.62 120.48 ± 5.52 115.55 ± 5.52 18.58.00 Total sum (weight %) 127.58 ± 16.29 121.16 ± 15.04 128.10 ± 20.15 5.15.01 a Mean ± Standard deviation, STS; sit to stand, Min; minimum, Max; maximum. Total sum; Total sum of mechanical loading. Significant difference from neutral position, p<.05, Significant difference from ankle dorsiflexion position, p<.05 가있었다 (p<.05). 최소부하값 (peak min) 은중립자세에서가장낮았고, 발바닥굽힘자세에서가장높았으며, 중립자세에대하여발바닥굽힘자세에서만유의한차이가나타났다 (p<.05). 최대부하값 (peak max.) 은중립자세에서가장낮았고, 발등굽힘자세에서가장높았으며, 발등굽힘자세는중립자세와발바닥굽힘자세에대하여각각유의한차이가있었다 (p<.05). STS 동안지면에가해지는부하량의총합 (total sum) 은발바닥굽힘자세에서가장높았고, 발등굽힘자세에서가장낮았으며, 발등굽힘자세는중립자세와발바닥굽힘자세에대하여각각유의한차이가있었다 (p<.05). 중립자세와발바닥굽힘자세간유의한차이는없었다 (Table 3). Ⅳ. 고찰본연구는발목관절각도에따른 STS동작수행시근활성도의변화와역학적부하량의변화를알아보기위해수행되었으며, 그결과발목관절각도에따라근활성도와역학적부하량에의미있는변화를살펴볼수있었다. STS 동작의초기구간은몸통과골반이앞으로기울어지고엉덩이가의자로부터떨어지기전까지의구간으로 (Ada와 Westwood, 1992), 몸통이전방으로의가속 이발생됨과동시에하지는순간적으로머리쪽으로향하는힘이발생된다. 이러한과정에서 TA와 RF근육들이우세하게사용되며 (Kim 등, 2006), 이구간동안에지면에가해지는부하량은최소값의형태로나타나게된다 (Demura와 Yamada, 2007). TA는 STS 동작시몸을앞으로가져가기전발을안정화시키기위해하지에서가장빠르게작용되는근육으로서 (Goulart와 Valls-Sole, 2001; Jang 등, 2014), 우리의연구결과에서는발등굽힘자세, 중립자세, 발바닥굽힘자세순으로활성도가높게나타났다. 반면, RF는 STS 동작시몸통을전방으로가속화하여이동시키기위해작용되는근육으로서, 연구결과발바닥굽힘자세에서가장높은근활성도를보여주었다. 이러한결과는발등굽힘각도가높아짐에따라 TA의작용이더욱우세하게나타난것으로보이며, 한편, TA의활성도가가장낮았던발바닥굽힘자세에서는이를보상하기위해 RF가상대적으로높은근활성도를나타낸것으로보여진다. STS 동작초기구간에서발목각도에따른 TA와 RF의활성도차이는역학적부하량변수들에도유의한영향을미쳤다. 특히발등굽힘자세에서 TA의우세한작용은 STS 수행시간의단축과부하량총합의감소에영향을주었다. Jacobs 등 (2009) 은보조운동영역 (supplementary motor area) 이선행자세조정시간에영향을미치며, 보조운동영역의활성이증가되면동작시근활성화시점이빨라진다는결과를보고한
앉았다일어서기동작수행시발목관절각도에따른근활성도및역학적부하량의비교 119 바있다. 이러한의미에서해석해볼때, 중립자세에비하여발등굽힘자세로선행된자세가보조운동영역으로작용하면서활성화되었고, 이로인해 TA의활성화를앞당겨결과적으로 STS 소요시간이감소되었으며, 시간의영향을받는부하량총합의값도함께감소된것으로보인다. 한편, 발바닥굽힘자세에서감소된 TA의활성도는 STS 동작시발생되는최소부하값에영향을주었다. STS의초기구간은 TA와 RF의구심성수축에의해발생된다. 특히, TA의수축은 STS 초기발목을중심으로우리의몸을전방으로가져가기위한발의안정성제공뿐만아니라, 동시에지면에가해지는다리의부하를순간적으로감소하는데영향을미친다. 우리의연구결과발바닥굽힘자세에서 TA의근활성도는중립자세보다약 25% 감소하였으며, RF의근활성도는 10% 증가하였다. 이러한결과로볼때발바닥굽힘자세를시작자세로한 STS 동작에서 TA의작용의감소는발에충분한안정성을제공하지못하였고, 이를보상하기위하여 RF의작용이증가된것으로생각된다. 또한 STS 초기 TA의수축으로인한하지의순간적인부하량감소에도영향을주어최소부하값이다른두시작자세에비해상대적으로높게나타난것으로보여진다. STS의초기이후두번째구간은엉덩이가의자로부터떨어져선자세를만들기위해몸체를들어올리는과정이다 (Ada와 Westwood, 1992). 이구간에서는발목관절의최대발등굽힘이일어나며, 엉덩관절과무릎관절의완전한폄이일어난다 (Sun 등, 2012). 이때, 하지대부분의근육이최대로쓰이는데그중 BF와 GCM이우세하게사용된다 (Kim 등, 2006). 또한이구간동안상체가앞쪽으로전이되며, 전이된몸체를들어올리기위한순간발바닥에가해지는부하량이증가되어최대부하값이나타나게된다 (Roebroeck 등, 1994). BF는엉덩이떼기시점이후엉덩관절의굽힘을감소시키고, 신체를편자세로만들어주는데역할을수행한다 (Goulart와 Valls-Sole, 2001). 우리의연구에서발등굽힘자세와발바닥굽힘자세에서 BF의근활성도는중립자세보다각 14%, 13% 증가하였지만, 통계적으로유의한수준은아니었다. GCM은 STS시동안작용되는하 지의근육중가장늦게반응하는근육으로, 엉덩이떼기시점이전마지막구간에서몸이전방으로전이되는속도를제어하며 (Lindemann 등, 2003), 무릎을폄시켜일어서기동안자세안정성에기여한다 (Doorenbosch 등, 1994). 우리의연구결과발등굽힘자세와발바닥굽힘자세에서 GCM의활성도는중립자세보다각각 70.5%, 30% 만큼증가하여통계적으로유의한차이가있었다. 일상적인 STS 조건이아닌발목관절의각도에따라 STS시자세를유지하기위해 BF와 GCM은더많은힘을사용하고있음을알수있다. 발등굽힘자세에서 GCM의근활성도증가는역학적부하량의최대부하값이증가하는데영향을주었다. 최대부하값은 STS 신체의전방이동과동시에엉덩이가테이블에서들리는순간발바닥굽힘을통해지면을누르는힘으로, 몸체를들어올렸을때불안정한발등굽힘자세를보상하기위해 GCM의작용이크게나타나게된다. 또한, STS 소요시간의다른조건에비해단축된것으로보아, 상대적으로큰가속도힘이지면에전달되어, 이로인해지면을누르는힘이일시적으로증가하여최대부하값이커진것으로생각된다. 기능적움직임동안발생되는생체역학적변화에관한연구는많은연구자들의관심사이다. 정상적인움직임에대한이해는엘리트스포츠선수의운동효과를증진시키는방법으로제시할뿐만아니라, 기능적움직임의제한이있는대상자에게적용하여움직임을개선시킬수있는방법을제시하기도한다. STS 동작은선자세에서독립적이고기능적인동작을수행하기앞서앉은자세에이어연결수행되어야할과정이다. 그동안 STS에관한다양한연구들이보고된바있다. 앉은의자의높이 (Su 등, 1998; Kawagoe 등, 2000), 팔걸이유무 (Munton 등, 1984; Alexander 등, 1991), 초기접지발의위치 (Park와 Lee, 2011), STS 수행속도 (Mourey 등, 2000; Papa와 Cappozzo, 2000), 무릎관절각도 (Eriksrud와 Bohannon, 2003) 등은 STS 동작에영향을주는요소로서알려졌지만, 발목관절각도와 STS동작수행에미치는영향을보고한결과는하이힐또는신발굽높이, 인솔높이에관한연구들로제한적이었다 (Lee 등, 2006; Park와 Kim, 2015). 따라서본연구의결과는
120 J Korean Soc Phys Med Vol. 12, No. 4 STS 연구에관한추가적인기초자료로써제시할수있을뿐만아니라, STS 동작수행에어려움이있는신경학적손상환자의기능적움직임개선에효율적인중재방법으로활용할수있으리라사료된다. 안타깝게도본연구에는몇가지제한점이있다. 첫째, 20대의젊은성인만을대상으로실시하였기에모든성인혹은질환을갖은대상자에게일반화하기어려우며, 연구참가자의개인적특성이고려되지못하였다. 둘째, 실험자의구두지시에따라동작을수행하였기에움직임개시와동시에측정되었어야할변수측정간에시간적오차가발생하였을수있다. 셋째, 근활성도측정이 4개의하지근육으로국한되어, STS 동작에관여하는다른근육의작용을고려하지못하였다. 넷째, STS 동작에관여하는각관절의운동형상학적요소에대한측정이수행되지못했다. 따라서향후연구에서는다양한연령층과근골격및신경계질환의환자를대상으로운동역학적요소와운동형상학적요소가결합된분석이요구되며, 결과에영향을줄수있는실험절차에대하여추가적인기술적개선이요구된다. Ⅴ. 결론본연구는 20대의건강한성인남녀 34명을대상으로발목의중립자세, 발등굽힘 15도자세, 발바닥굽힘 15도자세에따라 STS 동작수행시발생되는근활성도와역학적부하량의차이를알아보기위하여수행되었다. 그결과발등굽힘이선행된시작자세는해당근육의작용을앞당겨높은수축력과동시에빠른움직임이개시될수있었다. 이로인해 STS 동작수행에소요되는시간이단축될수있었으며, STS 동안지면에가해지는체중부하량의총합을감소시킬수있었다. 발바닥굽힘이선행된시작자세의경우 STS 초기에사용되는 TA의활성도는중립자세보다낮아졌으나이를보상하기위한 RF의활성도는높게나타난것으로보인다. 발바닥굽힘자세에서 STS 동작수행에소요되는시간은중립자세보다지연되어 STS 동안지면에가해지는체중부하량의총합은세조건중가장크게나타났다. 또한, 발등굽힘자세와발바닥굽힘자세에서 GCM의활성도는중립자세보다높게나타나발목관절각도의변화에따라 STS 동안하지의안정성에기여하는근육의활성도가달라졌음을알수있었다. 이러한결과를바탕으로본연구는 STS 동작분석에관한추가적인기초자료로써정보를제공할수있을뿐만아니라, 기능적평가및움직임개선에효율적인중재방법으로써 STS 동작의다양한적용이가능하리라생각된다. References Abujaber S, Gillispie G, Marmon A, et al. Validity of the Nintendo Wii Balance Board to assess weight bearing asymmetry during sit-to-stand and return-to-sit task. Gait Posture. 2015;41(2):676-82. Ada L, Westwood P. A kinematic analysis of recovery of the ability to stand up following stroke. Aust J Physiother. 1992;38(2):135-42. Alexander NB, Schultz AB, Warwick DN. Rising from a chair: effects of age and functional ability on performance biomechanics. J Gerontol. 1991;46(3):M91-8. Boonstra MC, Schwering PJ, De Waal Malefijt MC, et al. Sit-to-stand movement as a performance-based measure for patients with total knee arthroplasty. Phys Ther. 2010;90(2):149-56. Cahill BM, Carr JH, Adams R. Inter-segmental co-ordination in sit-to-stand: an age cross-sectional study. Physiother Res Int. 1999;4(1):12-27. Cheng PT, Liaw MY, Wong MK, et al. The sit-to-stand movement in stroke patients and its correlation with falling. Arch Phys Med Rehabil. 1998;79(9):1043-6. Demura S, Yamada T. Height of chair seat and movement characteristics in sit-to-stand by young and elderly adults. Percept Mot Skills. 2007;104(1):21-31. Doorenbosch CA, Harlaar J, Roebroeck ME, et al. Two strategies of transferring from sit-to-stand; the activation of
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