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1 Clinical Article The Korean Journal of Sports Medicine 2011;29(1):26-36 DOI: /kjsm 여자축구선수의사이트커팅동작시방향예측과피로가하지관절의부하에미치는영향 국민대학교체육학과 1, 아주대병원정형외과 2, 중앙대학교체육교육과 3, 경남대학교체육교육과 4 박은정 1 ㆍ이용석 2 ㆍ임비오 3 ㆍ김용운 4 ㆍ이기광 1 Effect of Anticipation and Fatigue on Lower Extremity Joint Loads during Side-cutting in Female Soccer Player Eun-Jung Park, MS 1, Yong-Seuk Lee, MD, PhD 2, Bi-O Lim, PhD 3, Yong-Woon Kim, PhD 4, Ki-Kwang Lee, PhD 1 1 Department of Sport Science, Kookmin University, Seoul, 2 Department of Orthopedic Surgery, Ajou University Hospital, Suwon, 3 Department of Physical Education, Chungang University, Seoul, 4 Department of Physical Education, Kyungnam University, Changwon, Korea To investigate effect of fatigue and anticipation on lower extremity joint load during a side-cutting maneuver in female collegiate soccer players, thirteen female collegiate soccer players whose right leg dominant participated in this study. Three dimensional motion analysis system and a force plate were used to record the 45 o side cutting maneuver. In the first, anticipated and unanticipated cutting were measured in the pre-fatigue condition. Second, participations performed the fatigue protocol by the squat exercise with weight lifting. And then, two different type of cutting task were measured again after fatigue condition. The cutting direction let known before start their running in case of the anticipated cutting, the random signal of cutting direction were presented in the unanticipated condition. In the results, the most influential variable was anticipation factor. Lower limb angles represented significantly flexed posture during unanticipated cutting than anticipated condition. Maximum knee flexion moment represented significantly higher in unanticipated cutting than anticipated cutting. Adduction and internal rotation moment of lower limb joint decreased in unanticipated cutting. Fatigue factor was influenced by the initial contact angles of the ankle joint. Lower limb angles at the initial ground contact indicated more erect posture in post-fatigue condition. The unanticipation factor had more effect on locomotors ability of lower limb in this study. Therefore, the sensory-motor training to adapt to unanticipated situation should be considered for the injury prevention training program. Key Words: Soccer, Cutting maneuver, Anticipation, Anterior Cruciate Ligament, Joint load 접수 : 수정 : 승인 : 책임저자 : 이기광 , 서울시성북구정릉동 국민대학교체육학과운동역학연구실 Tel: , Fax: kklee@kookmin.ac.kr 본논문은한국연구재단의지원에의한논문임 (KRF ). 서론축구선수들에있어하지의부상은전체의 68-88% 로가장높은부상비율을차지하며 1), 훈련시발생하는하지부상은운동기구나다른선수와의접촉으로인한부상보다는비접촉성부상 (non-contact injury) 이더많이보고되고있다 1). 또한여자선수들은커팅 (cutting) 이나착지 (landing) 동작시남자선 26 대한스포츠의학회지

2 박은정외. 여자축구선수의사이드커팅동작시방향예측여부와피로유무가하지관절의부하에미치는영향 수들보다더큰무릎의외전각도와모멘트를나타내며, 이는비접촉성전십자인대 (anterior cruciate ligament) 의부상이여자선수에서보다빈번하게일어나는원인이된다 2-6). 대부분의비접촉성전십자인대부상은갑작스러운방향전환, 감속 (deceleration) 및착지 (landing) 동작에서발생하며 1,7), 이러한부상으로인해많은선수들이훈련이나경기를수개월동안할수없거나, 심지어는다시시합에나갈수없게될수도있으며 4), 전십자인대의파열병력이있는선수들은상대적으로어린나이에무릎에관절염이발병하는경향이있는것으로보고되었다 8). 그러므로축구선수에있어무릎관절의부상기전을정확히분석하고, 부상을예방하기위한방안을연구하는것은매우중요하다고할수있다. 운동선수의무릎부상기전을규명하기위하여주로방향전환및착지동작시무릎의기전을분석한연구가많이진행되었다. 방향전환동작에있어서는커팅동작의시기, 방법및커팅각도에따라하지에미치는영향에대한연구가많이진행되었는데, 사전에방향을예측하지못하거나미리계획되지않은방향전환및착지동작에서미리계획된경우보다무릎관절의부상위험이더큰것으로나타났다 4,5,7,9). 또한, 피로발생과부상위험률의상관관계에대한연구도많이진행되어왔는데 10,11), 최근 James 등 10) 의연구에서는피로는무릎관절주변부근육의운동조절 (movement control) 을변화시키며, 반응시간 (reaction time) 을지연시킬뿐아니라, 피로중에발생한신경근변화 (neuromuscular alterations) 는부상의위험을증가시킬수있다고하였다. 그러나축구선수의무릎부상기전에관한연구는대부분의경우, 착지동작시의자높이에따른영향을비교하거나, 단순히커팅진행방향의각도에따른비교, 또는사전에계획된커팅과미리예측하지못한커팅동작의비교, 피로발생전후의착지동작비교, 남자와여자의커팅및착지동작수행에대한비교등단적인변인으로분석하여그결과를실제경기상황에대입하여해석하는경우가많았다. 그러나실제경기상황에서는이러한모든변인들이종합적으로작용하여부상의원인이되므로, 좀더복합적인상황으로구성된커팅동작연구는보다의미있는결과를제시할것이다. 또한여자축구선수는남자보다무릎관절의부상비율이높다는것이여러연구들에서밝혀졌으므로, 부상에노출될수있는다양한상황에따른여자선수의동작수행에연구가면밀히이루어질필요가있고, 세계적으로축구선수의부상기전에대한다양한연구들이이루어지고있으나아직까지부족한실정이며 12), 국내에서는여자축구선수에대한부상기전과 예방에대한훈련현실이더욱미흡한실정이다. 본연구에서는선수가미리예측할수있는경우와예측하지못하고반사적으로대처해야하는경우의관절각도및관절모멘트와지면반력변인과더불어경기초반과다르게후반에발생되는피로의요인까지추가하여부상요인에대해복합적으로실험조건을구성하고이를종합적으로분석함으로써, 여자축구선수의커팅동작시피로의유무와방향예측여부가하지관절에미치는영향을규명하고, 부상예방및재활프로그램의개발시기초자료로활용하는것이목적이다. 연구방법 1. 연구대상자서울시소재 H대학여자축구팀선수중오른쪽다리가우성인 13명 ( 평균연령 19.2±0.4년, 신장 162.5±5.2 cm, 체중 55.2±4.4 kg, 운동경력 7.5±1.4년 ) 을대상으로하였다. 본연구의취지를이해하고실험에동의한참가자들로구성되었으며, 실험전 6개월이내수술및부상이력이없고, 실험당시하지에진단받은질환이없으며자각적인통증이없는선수에한하여진행하였다. 2. 실험장비영상분석카메라 6대 (Vicon MX-T40, Vicon, Oxford, UK) 와포토센서 (BX5M-MDT, Autonics, Seoul, Korea), 지면반력기 1대 (AMTI MSA-6, AMTI, Watertown, MA, USA), 인조잔디를사용하였다. 지면반력기는실험실바닥에매장한후그위에인조잔디를덮고위치를알아볼수있도록표시하였고, 6대의영상분석카메라를측정공간에적합하도록원형으로배치하였다. 포토센서는피험자의진행경로내에서지면반력기와 2 m 떨어진지점에설치하여 4) 피험자가이지점을통과하면피험자의진행방향앞쪽에놓인노트북컴퓨터로신호가전송되어무작위방향지시신호를제시할수있도록하였다. 실험장비배치는 Fig. 1과같다. 3. 실험절차대상자는짧고달라붙는반바지를착용하고자연스러운동작재연을위해평소본인이신고훈련하는축구화를착용하도록하였다. 바이콘하지보행모델 (Vicon plug in gait Lower limb model) 에상응하는부착부위에총 16개 ( 직경 15 mm) 의반사마커를부착하였으며, 발의움직임측정을위한마커들은 제 29 권제 1 호

3 EJ Park, et al. Effect of Anticipation and Fatigue on Lower Extremity Joint Loads during Side-cutting Fig. 1. Experimental equipments. 축구화를신은상태로부착하였다. 수행과제는 45 o 좌측과우측방향으로의커팅동작으로, 실험참가자는지면반력기를향하여최대속도로달려오다가점프후지면반력기위에착지함과동시에빠르게좌측또는우측 45 o 로방향전환을시도하였다. 피험자들이수행과제를무리없이수행할수있도록충분히연습하게한후실험을진행하였다. 실험은크게피로발생전과피로발생후의상황으로구분하여진행하였으며, 각각의상황에서출발전이미커팅방향을알고시작하는경우 (anticipated cutting, AC) 와출발후지면반력기에착지하기직전, 즉공중에도약된상태에서무작위로방향신호를제시함으로써사전에방향을예측할수없는경우 (unanticipated cutting, UC) 로나누어진행하였다. 각각의상황에서 3회의데이터를수집한후, 사전에방향을알려준커팅 (AC) 의경우는성공적인 1회의데이터를분석에활용하였고, 미리방향을예측하지못한커팅 (UC) 의경우는동작이더불규칙적일것으로생각되어성공적인 2회의데이터의평균값을분석에활용하였다. 본연구에서는오른발착지후왼쪽으로방향전환하는경우를사이드커팅 (side-cutting) 으로지칭하며, 결과분석에는사이드커팅의자료만활용하였다. Gehring 등 3) 은레그프레스운동기구 (leg press weight machine) 를이용한최대하피로프로토콜 (sub-maximal fatigue protocol) 은무릎의굴곡과신전의닫힌사슬 (closed-kineticchain) 운동으로써기능적피로프로토콜로사용될수있다고하였으며, 그의연구에서피험자가선택된무게에서더이상수행할수없을때까지스쿼트운동을수행하고, 피로유발운동직후에피로후상황에대한측정을수행하였다. 따라서본연구에서도피로전 (pre-fatigue) 조건의측정이끝난직후 1분이내에피로프로토콜을수행하였으며, 스미스머신 (Smith machine) 을이용한스쿼트동작을, 30 kg의무게로 5회 1세트, 15세트반복을기준으로개인별능력에따라더이상수행하기힘든수준까지반복하였다. 또한개인별피로회복정도에따른격차를줄이고피로를유지하기위하여피로프로토콜이후수행동작의측정중간에 10회씩프리스쿼트동작을수행하도록하였다 5). 4. 자료분석 6대의영상분석카메라의샘플링주파수는 200 Hz로설정하였으며, 지면반력기의샘플링주파수는 2,000 Hz로설정하였다. 수집된자료의필터링은넥서스 (Nexus) ver. 1.4 프로그램 28 대한스포츠의학회지

4 박은정외. 여자축구선수의사이드커팅동작시방향예측여부와피로유무가하지관절의부하에미치는영향 내에포함된 Woltring filter기능을활용하였으며, MSE 수준은 10으로하였다. 지면반력값의역치는수직성분 (Fz) 10 N으로하였으며, 각피험자들간몸무게차이에의한오차를없애기위하여각피험자들의 % 신체질량 (Body mass) 으로표준화하여지면반력값을사용하였다. 분석구간은각도와모멘트의경우, 착지 (initial contact, IC) 순간, 각도및모멘트가최대치에도달한순간 (maximum values, Max), 이지 (toe off, TO) 순간으로나누어분석하였다. 이시점들에대한각관절의각도, 모멘트값을비교하였으며, 지면반력최대값, 지면접촉시간을두가지변인이다르게적용된상황에대해서비교하였다. 5. 통계처리 PASW ver (SPSS Inc., Chicago, IL, USA) 통계프로그램을이용하여반복측정이원분산분석 (two-way repeated measure ANOVA) 을실시하였다. 독립변인은피로와예측두가지로, 피로요인에대한영향, 예측요인에대한영향과피로와예측의상호작용에대한영향을분석하였다. 유의수준은 α=0.05로하였다. 결과 1. 관절각도 1) 엉덩이관절각도착지시엉덩이관절의굴곡각도는피로후보다피로전에더크게나타났다 (p=0.030). 이시기의엉덩이관절외회전도피로한경우에더큰각도를보였으며 (p=0.028), 피로전 후모두 AC에서더큰외회전각도를보여예측요인에대해서도유의한차이가있었다 (p=0.006). 엉덩이관절굴곡의최대각은피로전 후모두 AC보다 UC에서더크게나타나, 예측요인에대해유의한차이를보였다 (p=0.007). 이지시점에는모든동작에서통계적인차이가없었다. Table 1은각시점별엉덩이관절의굴곡및신전, 내전및외전, 회전각도를제시한것이다. 2) 무릎관절각도착지시무릎의내전각은피로후더감소하는경향을보여, Table 1. Hip joint angles at each of the event Mean (SD) angles of hip joint ( o ) Flx (+)/Ext (-) IC * (7.80) (7.81) (8.37) (6.92) Max * (8.63) (9.92) (11.69) (8.27) TO (7.81) (8.09) (7.78) (6.88) Add (+)/Abd (-) IC (4.74) (4.97) (8.09) (5.72) Max (4.27) (6.21) (5.96) (6.75) TO (3.51) (3.59) (4.71) (4.26) Int-Rot (+)/ IC * Ext-Rot (-) (9.72) (9.43) (10.02) (10.64) Max (9.12) (8.85) (9.76) (9.88) TO (9.57) (8.06) (8.08) (9.04) significant difference within anticipate, F*A: significant difference within fatigue*anticipate, IC: initial contact, Max: maximum, TO: toe off. *p<0.05, p<0.01. 제 29 권제 1 호

5 EJ Park, et al. Effect of Anticipation and Fatigue on Lower Extremity Joint Loads during Side-cutting Table 2. Knee joint angles at each of the event Mean (SD) angles of hip joint ( o ) Flx (+)/Ext (-) IC (5.41) (4.74) (4.54) (4.58) Max (7.68) (6.19) (4.30) (6.76) TO (7.04) (6.39) (4.92) (5.32) Add (+)/Abd (-) IC (4.74) (4.94) (4.18) (4.16) Max (6.84) (7.69) (7.76) (8.75) TO (3.02) (3.24) (3.06) (3.58) Int-Rot (+)/ IC Ext-Rot (-) (6.76) (4.74) (6.60) (6.28) Max *0.026 * (5.10) (5.78) (5.58) (5.09) TO (4.61) (4.41) (3.47) (3.29) significant difference within anticipate, F*A: significant difference within fatigue*anticipate, IC: initial contact, Max: maximum, TO: toe off. *p<0.05, p<0.01. 피로요인에따른유의한차이가있는것으로나타났다 (p=0.008). 그외에굴곡과내회전의착지시각도에대해서는유의한차이가없었다. 무릎의최대굴곡각 (p=0.000) 과최대외전각 (p=0.004) 및최대내회전각 (p=0.025) 은모두 UC에서더크게나타나, 예측요인에대해통계적차이를보였다. 또한최대내회전은피로전보다피로후에더크게일어나피로요인에대해서도유의한차이를보였다 (p=0.026). 이지시점에서는모든동작에서유의한차이가없었다. Table 2는무릎관절의각시점별굴곡및신전, 내전및외전과회전각도를제시한것이다. 3) 발목관절각도착지시발목관절은대체로피로후에더크게회내 (pronation) 되는경향을보여, 피로요인에대해통계적으로유의한차이가있었다 (p=0.003). 또한착지시발목의외회전은피로전보다피로후에더적게나타나, 피로요인에대한차이를보였으며 (p=0.028), 예측요인에대해서도통계적차이를나타냈다 (p=0.006). 최대배측굴곡 (p=0.010) 과내회전 (p=0.010) 각도에서도 AC 보다 UC에서더큰각도를보여, 예측요인에대해유의한차이가있음을알수있었다. 이지시점에서발목의회내 (p=0.025) 와내회전 (p=0.015) 각도는피로전 후모두 UC에서더큰값을보여, 예측요인에대해서통계적차이를나타냈다. Table 3은발목의배측굴곡및저측굴곡, 회내또는회외, 그리고회전각도를제시한것이다. 2. 관절모멘트 1) 엉덩이관절모멘트착지와이지시점에서엉덩이관절의모멘트변인모두에서통계적으로유의한차이가없었다. 엉덩이관절의최대내전모멘트는 AC보다 UC에서더낮게나타나, 예측요인에서유의한차이를보였으며 (p=0.001), 피로와예측요인의상호작용에대해서도통계적차이를나타냈다 (p=0.015). 최대굴곡모멘트와회전모멘트에서는유의한차이가없었다. 다음의 Table 4에서는엉덩이관절의굴곡, 내전및외전과회전모멘트를제시하였다. 30 대한스포츠의학회지

6 박은정외. 여자축구선수의사이드커팅동작시방향예측여부와피로유무가하지관절의부하에미치는영향 Table 3. Ankle joint angles at each of the event Mean (SD) angles of hip joint ( o ) DF (+)/PF (-) IC (13.92) (17.90) (16.39) (18.20) Max * (4.08) (5.17) (4.74) (4.71) TO (5.83) (5.88) (7.47) (5.57) Sup (+)/Pro (-) IC (1.47) (1.49) (1.37) (1.57) Max (3.96) (1.85) (2.18) (1.64) TO * (1.48) (1.88) (1.35) (1.66) Int-Rot (+)/ IC * Ext-Rot (-) ( 9.15) (9.58) (9.25) (9.61) Max * (8.00) (11.42) (7.80) (10.49) TO * (6.19) (8.72) (6.39) (7.93) significant difference within anticipate, F*A: significant difference within fatigue*anticipate, IC: initial contact, max: maximum, TO: toe off, DF: dorsi flexion, PF: plantar flexion, Sup: supination, Pro: pronation. *p<0.05 p<0.01. Table 4. Hip joint moments at each of the event Mean (SD) moments of hip joint (Nm/kg) Flx (+)/Ext (-) IC (0.74) (0.82) (0.72) (0.79) Max (0.99) (1.59) (0.98) (1.27) TO (0.62) (0.35) (0.37) (0.33) Add (+)/Abd (-) IC (0.37) (0.45) (0.51) (0.62) Max *0.015 (0.38) (0.46) (0.61) (0.53) TO (0.36) (0.34) (0.27) (0.33) Int-Rot (+)/ IC Ext-Rot (-) (0.03) (0.04) (0.05) (0.07) Max (0.25) (0.30) (0.21) (0.24) TO (0.05) (0.06) (0.06) (0.05) significant difference within anticipate, F*A: significant difference within fatigue*anticipate, IC: initial contact, Max: maximum, TO: toe off. *p<0.05, p<0.01. 제 29 권제 1 호

7 EJ Park, et al. Effect of Anticipation and Fatigue on Lower Extremity Joint Loads during Side-cutting Table 5. Knee joint moments at each of the event Mean (SD) moments of knee joint (Nm/kg) Flx (+)/Ext (-) IC (0.21) (0.21) (0.21) (0.30) Max * (0.58) (0.57) (0.61) (0.56) TO (0.16) (0.16) (0.20) (0.14) Add (+)/Abd (-) IC * (0.08) (0.11) (0.16) (0.20) Max (0.33) (0.69) (0.46) (0.41) TO (0.19) (0.18) (0.16) (0.16) Int-Rot (+)/ IC Ext-Rot (-) (0.04) (0.05) (0.03) (0.04) Max * (0.15) (0.15) (0.20) (0.13) TO (0.06) (0.07) (0.07) (0.05) significant difference within anticipate, F*A: significant difference within fatigue*anticipate, IC: initial contact, Max: maximum, TO: toe off. *p<0.05, p<0.01. Table 6. Ankle joint moments at each of the event Mean (SD) moments of ankle joint (Nm/kg) DF (+)/PF (-) IC (0.10) (0.06) (0.12) (0.11) Max (0.44) (0.34) (0.54) (0.35) TO * (0.08) (0.05) (0.04) (0.04) Sup (+)/Pro (-) IC (0.02) (0.03) (0.03) (0.03) Max (0.15) (0.15) (0.18) (0.16) TO (0.03) (0.02) (0.02) (0.01) Int-Rot ( +)/ IC Ext-Rot (-) (0.05) (0.05) (0.04) (0.04) Max * (0.17) (0.16) (0.26) (0.18) TO (0.07) (0.06) (0.07) (0.06) significant difference within anticipate, F*A: significant difference within fatigue*anticipate, IC: initial contact, max: maximum, TO: toe off, DF: dorsi flexion, PF: plantar flexion, Sup: supination, Pro: pronation. *p<0.05 p< 대한스포츠의학회지

8 박은정외. 여자축구선수의사이드커팅동작시방향예측여부와피로유무가하지관절의부하에미치는영향 2) 무릎관절모멘트착지시점에서는피로전 후모두내전 (p=0.033) 과내회전 (p=0.005) 모멘트가 UC에서약간더크게나타나, 예측요인에대해유의한차이가있는것으로밝혀졌다. 최대굴곡모멘트는 UC에서더크게나타난것과달리 (p=0.032), 내전 (p=0.000) 및내회전 (p=0.010) 의최대모멘트는 AC에서더크게나타나예측요인에대한차이를알수있었다. 이지시점에서는모든모멘트변인에서유의한차이가없었다. Table 5는무릎관절의최대굴곡과내전및외전, 회전모멘트를제시한것이다. 3) 발목관절모멘트착지시발목은전 후모두 UC에서더외회전되려는경향을보여, 예측요인에대해차이가있는것을알수있었다 (p= 0.005). 이시기에발목의배측굴곡과회외모멘트는유의한 차이가없었다. 발목의배측굴곡 (p=0.001), 회외 (p=0.000), 내회전 (p=0.014) 의최대모멘트는피로전 후모두 AC에서더큰값을보여, 예측요인에대해서유의한차이를나타내었다. 이지시에는피로후에발목이더욱저측굴곡 (plantar flexion) 되는경향을보여, 피로요인에대한통계적차이를나타내었으나 (p=0.028), 그외에는통계적차이가없었다. 다음의 Table 6은발목관절의최대배측굴곡과회외및회내, 회전모멘트를제시한것이다. 3. 지면반력최대값지면반력좌 우성분 (Fx) 의최대값 (peak) 과전 후성분 (Fy) 의최대값, 그리고수직성분 (Fz) 의첫번째최대값과두번째최대값을비교하였다. 좌 우성분 (p=0.001) 과수직성분의두번째최대값 (p=0.008) 이 UC에서더적게나타나, 예측요인에따른유의한차이를보였다. 다음 Table 7은각성분의지면반력 Fig. 2. Fz First and Second Peak and Ground contact time comparison between anticipated cutting (AC) and unanticipated cutting (UC) in one subject. BW: body weight. Fig. 3. Fx Peak value and Ground contact time comparison between anticipated cutting (AC) and unanticipated cutting (UC) in one subject. BW: body weight. Table 7. GRF mean (SD) and significant level GRF (%body weight) Fx 0.73 (0.14) 0.65 (0.16) 0.76 (0.15) 0.65 (0.16) * Fy 0.92 (0.21) 1.08 (0.39) 1.06 (0.46) 1.10 (0.33) Fz (0.64) 4.27 (0.92) 4.39 (0.72) 4.30 (0.85) Fz (0.22) 2.57 (0.29) 2.72 (0.33) 2.55 (0.21) GRF: ground reaction force, SD: standard deviation, AC: anticipated cutting, UC : un-anticipated cutting, F: significant difference within fatigue, A: significant difference within anticipate, F*A: significant difference within fatigue*anticipate, Fx: mediolateral ground reaction force, Fy: anterioposterior ground reaction force, Fz1: first peak of vertical ground reaction force, Fz2: second peak of vertical ground reaction force. *p<0.05, p<0.01. 제 29 권제 1 호

9 EJ Park, et al. Effect of Anticipation and Fatigue on Lower Extremity Joint Loads during Side-cutting Table 8. Ground contact time at each phase Ground contact time (s) Flx 0.12 (0.02) 0.15 (0.04) 0.13 (0.03) 0.14 (0.02) * Ext 0.15 (0.02) 0.17 (0.03) 0.15 (0.02) 0.17 (0.03) AC: anticipated cutting, UC: un-anticipated cutting, F: significant difference within fatigue, A: significant difference within anticipate, F*A: significant difference within fatigue*anticipate, Flx: flexion, Ext: extension. *p<0.05 p<0.01. 최대값을제시한것이며, Fig. 2와 Fig. 3은한명의피험자에대한지면반력좌 우성분과수직성분을제시한것이다. 4. 지면접촉시간지면접촉시간은충격을흡수하는구간인굴곡구간 (flexion phase; 착지에서무릎굴곡각도가최대가되는시점까지 ) 과도약을위해지면을밀어내는신전구간 (extension phase; 무릎의굴곡각도가최대가되는시점에서발이지면에서떨어지는시점까지 ) 으로나누어분석하였다. 굴곡구간 (p=0.012) 과신전구간 (p=0.002) 모두 UC에서더긴접촉시간을보여예측요인에대해서만통계적으로차이가있었으며, 피로요인에대한효과는없었다. 아래의 Table 8은구간별지면접촉시간을제시한것이다. 고찰본연구에서는 13명의대학여자축구선수들을대상으로, 사전방향예측과피로적용여부가커팅동작에서하지관절의역학적요인에미치는영향을알아보았다. 분석결과, 하지관절의최대각도와최대모멘트및지면반력에유의하게영향을주는요인은예측요인으로밝혀졌다. 피로요인은착지시의하지각도와모멘트에영향을주었지만, 예측요인에비해서상대적으로낮은영향력을나타내었다. 1. 관절각도결과에대한해석첫번째로, 예측요인에대해서통계적으로차이가있었던변인은엉덩이관절의착지시내회전과최대굴곡, 무릎관절의굴곡, 외전, 내회전의최대값, 착지시발목관절의내회전과배측굴곡및내회전의최대각도, 그리고이지시점에서발목관절의회외와내회전각도이다. 대체적으로각관절의최대각도에서예측요인에대해통계적으로유의한차이가나타났으 며, 사전에커팅방향을예측하지못한경우에굴곡패턴의각도가더크게나타나는경향을보였다. Borotikar 등 5) 는사전에커팅방향을예측하지못한경우에입각기에서무릎의외전및내회전각도가증가한다고하였으며, 이는본연구의결과와일치한다. Landry 등 7) 은커팅또는착지시덜직립적인자세 (less erect posture) 는무릎관절에가해지는부하를줄여주고전십자인대를보호하는데도움이된다고하였다. 특히이시기에증가된대퇴직근의활성도는엉덩이관절의굴곡에도움을주어위험성이더큰직립적인자세를방지하며, 무릎관절이과굴곡 (hyper-flexion) 된상태에서슬괵근 (hamstring) 의수축은전십자인대에길항근으로작용하여무릎관절의안정성을높여줄수있다고하였다. 이는본연구에서사전에방향을예측하지못한커팅시에하지관절이더굴곡되는경향을보인것과관련이있으며, 미리계획되지않은불안정한운동상황은관절을더불안정하게만들게되고, 신체는이에적응하고관절을보호하기위해굴곡각도를더크게만드는일종의자동반사반응을하는것으로생각된다. 또한, 본연구에서는무릎의외전각도역시사전에방향을예측하지못한커팅에서더크게나타나는경향을보였는데, 이는여자축구선수의무릎부상과과도한무릎외전각도와의상관성에대해언급한연구들 5,6,13) 과일치하는결과라고할수있으며, 미리계획되지않은갑작스러운커팅동작은무릎의부상증가와매우밀접한관련이있다는것을의미한다. 두번째로, 피로요인에대해서통계적으로차이가있었던변인은엉덩이관절의착지시굴곡과내회전, 무릎관절의착지시내전과내회전의최대각도, 착지시발목관절의회외와내회전각도였다. 사전에방향을예측한커팅과예측하지못한커팅모두에서피로발생후의착지시하지관절의굴곡이덜일어나는경향을보여, 피로요인은착지시관절의운동에영향을미치는것을알수있었다. 34 대한스포츠의학회지

10 박은정외. 여자축구선수의사이드커팅동작시방향예측여부와피로유무가하지관절의부하에미치는영향 이와관련하여, James 등 10) 은피로는지면에닿는순간의지면반력 (GRF) 의크기와운동제어활동 (locomotors activities) 시기에서근육의원심성제어를변화시키며, 근피로가근육의충격흡수용량 (shock absorbing capacity) 과운동조절체계 (locomotor system) 의협응력 (coordination) 을통해변화되며, 잠재적으로는수동적인구조물 (passive structure) 에더큰스트레스로작용한다고하였다. 또한 Landry 등 7) 은커팅과랜딩동작의초기지지기 (early stance phase) 동안근육반응에대해초점을맞추는것이중요하다고하였는데, 그이유는이시기에대부분의비접촉성전십자인대손상이일어나기때문이라고하였다. 따라서, 본연구에서피로전보다피로후에초기접촉시하지의관절각도가작게나타난것은피로로인해근육의원심성제어가변화되어충격흡수를위한적절한조절이충분히이루어지지않았기때문으로생각된다. 또한이는피로조건에서보다직립적인자세의착지로연결되면서관절의부하를높여비접촉성무릎부상을일으키는기전으로작용할것으로생각된다. 2. 관절모멘트결과에대한해석관절모멘트의분석결과, 예측요인에대해서는엉덩이관절의최대내전모멘트, 무릎관절의최대굴곡, 내전모멘트및초기접촉시내전모멘트, 그리고발목관절의최대회외모멘트와최대내회전모멘트, 착지시내회전모멘트에서통계적으로유의한차이가있었다. Besier 등 14) 은무릎관절에서외적인굴곡및신전모멘트 (external flexion or extension moments) 는미리계획된경우 (pre-planned) 와예측하지못한경우 (un-anticipated) 간에비슷하다고하였으나, 외반 / 내반과내회전 / 외회전모멘트는미리계획된경우보다예측하지못한경우에서두배이상증가한다고하였다. 그러나본연구에서는미리방향을예측하지못했을때무릎의최대굴곡모멘트에있어서만미리방향을예측한커팅보다더크게나타났고, 나머지관절의모멘트는미리방향을예측하지못한커팅에서더작게나타나위연구결과와반대의경향을보였다. 이는예측하지못함으로인한불안정한상황에서충격흡수에직접적으로영향을미치는무릎의굴곡모멘트는증가한반면, 한다리로서서균형을잡고, 왼쪽방향으로의추진을위해미세한균형조절에필요로하는하지관절의내전과내회전모멘트는충분히사용되지못했기때문인것으로생각된다. 3. 지면접촉시간과지면반력값에대한해석사람이달릴때수직지면반력 (vertical ground reaction force) 은보통두개의최대값 (peak) 을보이는데, 첫번째값은충격력최대값 (impact force peak) 이고, 두번째값은능동적힘의최대값 (active force peak) 이다 15). 첫번째값과두번째값에차이가생기는이유는, 충격력 (impact force) 의구간 (time duration) 이충격 (impact) 동안발생되는감각신호 (sensory signal) 에재반응 (react) 하기위해근육에요구되는시간보다짧기때문이다 15). 따라서본연구에서 AC의평균지면접촉시간이더짧게나온것은, 미리계획된움직임일때충격발생에대응하는재반응시간이더짧게나타난것으로볼수있다. Besier 등 9) 의연구에서, 운동의예측은움직임의변화를최소화하고, 적절한자세를유지하기위한반사반응 (reflex response) 과자세조절 (postural adjustments) 을변화시킬수있다고하였으며, 예측하지못한상황은자세조절전략을적절하게하는데더많은시간을필요로하며무릎에적용된외적모멘트 (external moments) 를변화시킨다고하였다. 이는본연구에서지면접촉시간외에각도와모멘트의변화의결과를종합해보았을때, 불안정하고예측하지못한운동상황이신체의근신경계재반응과운동조절에밀접한관련이있음을의미한다고할수있다. 지면반력값의좌 우성분 (Fx) 과수직성분 (Fz) 의두번째최대값에서예측요인으로인한유의한차이가있었다. Nigg와 Liu 15) 는충격흡수구간 (impact force) 동안최대충격력 (impact force peak) 을줄이기위해서관절의경직 (stiffness) 과완충 (damping) 의변화가중요하다고하였다. 이는두번째지면반력최대값이 UC에서더낮게나온것과관련이있다고할수있겠다. 관절의각도와모멘트부분에서논의한것과마찬가지로, 방향을미리예측하지못한불안정한커팅상황 (UC) 에서관절을보호하기위한자동반사기전으로써능동적으로조절할수있는시기인두번째지면반력구간에서관절의굴곡을더크게하여하지의경직성을낮추고완충기능을높여지면으로부터오는충격력을낮췄기때문인것으로보인다. 이외에도, Houck 16) 은직진달리기와사이드커팅, 크로스커팅을비교하는연구를하였는데, 그결과수직지면반력값 (Fz) 에대해서는세가지변인사이에유의한차이가없었으나, 좌우성분 (Fx) 에서는유의한차이가나타났다고보고하였는데, 이는직진달리기에비하여, 방향전환이요구되는커팅은지면반력좌우성분에영향을미친다는것을의미한다고할수있다. 제 29 권제 1 호

11 EJ Park, et al. Effect of Anticipation and Fatigue on Lower Extremity Joint Loads during Side-cutting Bahr와 Krosshaug 17) 는한발착지시상해가발생하는기전은무릎의굴곡 (flexion) 과경골회전 (tibialrotation), 그리고외반 (valgus) 에의해나타난다고하였는데, 본연구결과 UC에서동일한결과를보여예측요인은착지시무릎부상에밀접한관련이있다고할수있겠다. 또한본연구의지면접촉시간과지면반력결과로유추해볼때, 미리방향을예측하지못한커팅은근신경계의재반응에소요되는시간을지연시켜다음상황에대처하기위한효율을저하시킨다고할수있다. 착지직전에하지의근육활성변화는하지의역학적특성을바꾸며, 그러한변화는착지시골격의움직임및충격력을조절하는데사용될수있는데 15), 본연구에서하지의관절각도가피로후에더신전되는경향을보인것은피로로인해충격력을조절하는능력이저하된것으로해석할수있다. 따라서선수의무릎부상예방을위해서는, 피로발생을예방하기위한근력및지구력훈련은물론, 이와함께비예측성시각자극또는다양한자극에대해신속하게재반응할수있도록, 계획되지않은움직임에빠르게대처하는데익숙해지도록반복하는훈련프로그램을함께고려하는것이좋은대안이될수있을것이다. 참고문헌 1. Agel J, Palmieri-Smith RM, Dick R, Wojtys EM, Marshall SW. Descriptive epidemiology of collegiate women's volleyball injuries: National Collegiate Athletic Association Injury Surveillance System, through J Athl Train 2007;42: Han KH, Lim BO. Mechanism and risk factors of anterior cruciate ligament injuries in female athletes. Kinesiology 2009;11: Gehring D, Melnyk M, Gollhofer A. Gender and fatigue have influence on knee joint control strategies during landing. Clin Biomech (Bristol, Avon) 2009;24: Beaulieu ML, Lamontagne M, Xu L. Lower limb muscle activity and kinematics of an unanticipated cutting manoeuvre: a gender comparison. Knee Surg Sports Traumatol Arthrosc 2009;17: Borotikar BS, Newcomer R, Koppes R, McLean SG. Combined effects of fatigue and decision making on female lower limb landing postures: central and peripheral contributions to ACL injury risk. Clin Biomech (Bristol, Avon) 2008;23: Ford KR, Myer GD, Toms HE, Hewett TE. Gender differences in the kinematics of unanticipated cutting in young athletes. Med Sci Sports Exerc 2005;37: Landry SC, McKean KA, Hubley-Kozey CL, Stanish WD, Deluzio KJ. Gender differences exist in neuromuscular control patterns during the pre-contact and early stance phase of an unanticipated side-cut and cross-cut maneuver in years old adolescent soccer players. J Electromyogr Kinesiol 2009;19:e Lohmander LS, Ostenberg A, Englund M, Roos H. High prevalence of knee osteoarthritis, pain, and functional limitations in female soccer players twelve years after anterior cruciate ligament injury. Arthritis Rheum 2004;50: Besier TF, Lloyd DG, Ackland TR, Cochrane JL. Anticipatory effects on knee joint loading during running and cutting maneuvers. Med Sci Sports Exerc 2001;33: James CR, Scheuermann BW, Smith MP. Effects of two neuromuscular fatigue protocols on landing performance. J Electromyogr Kinesiol 2010;20: Kernozek TW, Torry MR, Iwasaki M. Gender differences in lower extremity landing mechanics caused by neuromuscular fatigue. Am J Sports Med 2008;36: Benjaminse A, Gokeler A, Fleisig GS, Sell TC, Otten B. What is the true evidence for gender-related differences during plant and cut maneuvers? A systematic review. Knee Surg Sports Traumatol Arthrosc 2011;19: Gerbino PG, Griffin ED, Zurakowski D. Comparison of standing balance between female collegiate dancers and soccer players. Gait Posture 2007;26: Besier TF, Lloyd DG, Ackland TR. Muscle activation strategies at the knee during running and cutting maneuvers. Med Sci Sports Exerc 2003;35: Nigg BM, Liu W. The effect of muscle stiffness and damping on simulated impact force peaks during running. J Biomech 1999;32: Houck J. Muscle activation patterns of selected lower extremity muscles during stepping and cutting tasks. J Electromyogr Kinesiol 2003;13: Bahr R, Krosshaug T. Understanding injury mechanisms: a key component of preventing injuries in sport. Br J Sports Med 2005;39: 대한스포츠의학회지

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