육상 단거리 선수와 장거리 선수의 체간과 하지의 근기능 및 근전도 비교 분석

정재후 ( Jae Hu Jung ),김정태 ( Jung Tae Kim ) 한국운동역학회 2012 한국운동역학회지 Vol.22 No.1

The purpose of this study was to compare and analyze muscle function and EMG of the trunk and the lower extremity in short and long distance athletes and in order to determine difference in peak torque per unit weight, muscle power per unit weight, endurance ratio, and %MVIC classified by muscle. For that purpose, isokinetic muscle function tests for waist, knee, and ankle joints and EMG measurements for the trunk and the lower extremity muscle with running motion were conducted for 7 short and long distance high school athletes respectively. The study over muscle function of waist, knee, and ankle joints indicates that peak torque per unit weight of short distance athletes is higher than that of long distance athletes in extension and flexion of waist joint, plantar flexion of right ankle joint, and dorsi flexion of left ankle joint. In case of the muscle power per unit weight of short distance athletes is also higher than long distance athletes in waist, knee, and ankle joints. No difference in endurance ratio of waist, knee, and ankle joints between the two groups was founded. The results of the test over EMG of the trunk and the lower extremity show that %MVIC of erector spinae, rectus femoris, vastus medialis, vastus lateralis, and tibialis anterior is higher than that of long distance athletes in support phase. The above results proved to be the same in flight phase except for %MVIC of medial gastrocnemius. In other words, %MVIC of medial gastrocnemius for short distance athletes turned out to be higher than that of long distance athletes in flight phase.

비디오 게임이 청소년의 상지 근골격계에 미치는 영향

김동수 ( Dong-soo Kim ),정재후 ( Jae-hu Jung ),채원식 ( Woen-sik Chae ) 한국스포츠정책과학원(구 한국스포츠개발원) 2016 체육과학연구 Vol.27 No.4

본 연구의 목적은 비디오 게임이 청소년의 상지 근골격계에 미치는 영향을 정량적으로 평가하는데 있다. 이를 위해 남자 중학생을 대상으로 비디오 게임 실시 전과 실시 후에 대한 3차원 동작분석, 근육활동분석을 실시하여 비디오 게임 전과 후의 운동역학적 변인을 비교 분석하였다. 본 연구에서는 근골격계에 이상이 없고 정신 및 정서적 문제가 없는 남자 중학생 14명을 피험자로 선정하였다. 신체적 요소에 미치는 영향을 평가하기 위해 2대의 고감도 카메라(100 Hz, Motion Master100, Visol Inc.)와 근전도 측정기기(1024 Hz, QEMG8, Laxtha Inc.)를 사용하였다. 본 연구에서는 마우스의 좌측 클릭 후 드래그 동작(Task1), 우측클릭 동작(Task2), 스크롤 동작(Task3)의 3차원 동작분석과 근전도 분석을 실시하였다. 비디오 게임 전·후의 생체역학적 변인에 대한 통계적 유의성을 검증하기 위해 SPSS 22.0을 이용하여 대응표본 t-검정을 실시하였다(p<.05). 본 연구의 결과를 살펴보면, 마우스 조작 동작에 따른 관절 각도와 각속도에서는 비디오 게임실시 전·후에 통계적인 유의차가 나타나지 않았지만, 대부분의 관절에서 비디오 게임 실시 전에 비해 실시 후의 관절 각도와 각속도는 상대적으로 증가한 것으로 나타났다. 또한 대부분의 근육에서 Task1과 Task2 동작에 따른 근전도값은 비디오 게임 실시 전에 비해 실시 후에 상대적으로 증가한 것으로 나타났다. 이에 반해 Task3 동작에 따른 승모근의 근활성도는 비디오 게임 실시 후 통계적으로 유의하게 감소한 것으로 나타났다. 이는 손과 손가락을 이용한 장시간의 작업 수행 시 전완 및 승모근의 근활성도가 감소된다고 보고한 Aaras et al.(1998)의 연구 결과와 같이 장시간의 비디오 게임이 승모근의 근육 활동을 감소시켜 작업 수행력 및 근골격계에 부정적인 영향을 미치는 것으로 사료된다. 본 연구의 결과, 장시간 비디오 게임이 직·간접적으로 청소년들의 근골격계에 부정적인 영향을 미치는 것으로 판단된다. 또한 본 연구를 통해 비디오 게임에 대한 과도한 몰입으로 인해 청소년들에게 나타나는 신체적 이상 징후를 줄일 수 있는 적절한 방법을 모색하고 올바른 사용방법을 제시할 수 있을 것으로 사료된다. The purpose of this study was to determine how acute active pc-video game affects kinematic variables and muscle activities of adolescents. Fourteen middle school students(age: 15.9±0.7 yrs, height: 171.3±6.1cm, weight: 60.0±5.4 kg, right handed) who have no musculoskeletal disorder were recruited as the subject according to having experience in using the pc-video game for more than six months. Maximum angle, angular velocity, and muscle activity of the upper extremity were determined for each trial. For each dependent variable, a paired t-test was performed to test if significant difference existed between pre- and post a 60 minute active pc-video game(p<.05). This study found that one hour pc-video game hour may not affect on movement and ROM of the finger and the wrist, whereas it may have an effect on muscle activity of the upper extremity. It seems that repetitive movement pattern during an active pc-video game may hinder muscle activity of adolescents` upper extremity. Part of the increase in musculoskeletal disorders is linked to the amount of time adolescents are allowed to play video games. This study found that an active pc-video game appears to have negative effects on the upper extremity muscles. Since wrist movements are continually repeated throughout the video game, carpal tunnel syndrome may possibly be caused by long-term exposure to video games.

내림 경사로 보행 시 전족부 탈-부착형 아웃솔의 각도 및 형태 변화가 하지 근활성도에 미치는 영향

이행섭 ( Haeng-seob Lee ),정재후 ( Jae-hu Jung ),채원식 ( Woen-sik Chae ) 한국스포츠정책과학원(구 한국스포츠개발원) 2017 체육과학연구 Vol.28 No.2

[목적] 본 연구의 목적은 내림 경사로 보행 시 발 전족부 탈-부착형 아웃솔의 각도 및 형태 변화가 하지근골격계에 미치는 영향에 있다. [방법] 본 연구에 참여한 연구 대상자는 근골격계에 질환이 없는 K대학교남학생 15명(나이: 23.5±2.1 yrs, 키: 175.7±4.6 cm, 몸무게: 651.9±55.5 N)을 선정하였으며, 피험자는 전족부 탈-부착 아웃솔의 각도(5°, 10°, 20°) 및 형태(Type-A, Type-B)에 따른 아웃솔을 착용하여 무작위순으로 보행하였다. 근전도 자료 수집을 위해 유선 근전도기기(QEMG8, Laxtha Inc. korea, sampling frequency = 1,024 Hz, gain = 1,000, input impedance > 1012 Ω, CMRR > 100 dB)를 사용하였다. 내림 경사로 보행 시 전족부 탈-부착형 아웃솔의 각도 변화가 하지 근육과 척추기립근의 근활성도에 미치는 영향을 분석하기 위해 좌측 척추기립근, 왼쪽 하지의 대퇴직근, 내측광근, 외측광근, 대퇴이두근, 전경골근, 외측비복근, 내측비복근에 표면전극을 부착하였다. 통계 처리는 아웃솔의 두 가지 형태(A, B)와 세 가지각도(5°, 10°, 20°) 변화가 근활성도 어떠한 영향을 미치는지 분석하기 위해 반복측정을 통한 이원배치분산분석(two-way ANOVA with repeated measure)을 실시하였다. 이 때 유의 수준은 p<.05로 하였고 Mauchly의 구형성을 만족하지 않을 경우 Greenhouse-Geisser로 검정하였다. 상호작용 효과가 통계적으로 유의하지 않을 경우 사후검정(post-hoc test)은 bonferroni를 통해 다중비교를 하였으며, 상호작용 효과가 통계적으로 유의할 경우 단순 주 효과(simple main effect)를 알아보기 위해 집단간 변인인 아웃솔의 형태는 일원분산분석(one-way ANOVA)으로 검증하였고, 집단내 변인인 아웃솔의 각도는 대응표본 t-검증(pairedt-test)을 실시하였다. [결과] 본 연구의 결과 IDLS 구간에서 대퇴직근의 경우 B형태의 아웃솔은 10° 아웃솔이 5° 아웃솔과 비교하여 대퇴직근의 근육활동이 통계적으로 유의하게 증가하였다. 5° 아웃솔에서 A형태가 B형태보다 대퇴직근의 근육활동이 통계적으로 유의하게 증가하였고, 20° 아웃솔에서도 A형태가 B형태보다 대퇴직근의 근육활동이 통계적으로 유의하게 증가하였다. [결론] 이러한 결과는 B형태 아웃솔이 A형태 아웃솔보다 신체의 균형과 안정성을 높이는 것으로 판단되며, 과도한 전족부 말단부의 높이는 불안정성을 증가시키는 것으로 사료된다. 5°-B 아웃솔은 내림 경사로 보행 중 안정성 향상과 인체 중량 부하에 따른 동작 제어에 가장 유용성 있는 아웃솔로 판단되지만 아웃솔 착용이 입각기 말의 발의 이지 동작과 이지 후, 하지 근육의 원활한 근육 활동을 통한 적절한 힘 분배에 있어서는 효용성이 떨어진다고 판단된다. [Purpose] The purpose of this study was to evaluate the effect of detachable forefoot outsole on muscle activity of the lower extremity during downhill walking. [Methods] Thirteen male university students (age: 23.5±2.1 yrs, height: 175.7±4.6 cm, weight: 651.9±55.5 N) who have no musculoskeletal disorder were recruited as the subjects. Each subject walked down 20° ramp with forefoot`s design for the detachable outsole`s angle(5°, 10° and 20°) and type(A and B). To assess the myoelectric activities of selected muscles, six of surface EMG(QEMG8, Laxtha Inc. korea, sampling frequency = 1,024 Hz, gain = 1,000, input impedance > 1012 Ω, CMRR > 100 dB) electrodes with on-site pre-amplification circuitry were attached to ES, RF, BF, TA, LG, and MG. For each dependent variable, two-way ANOVA with repeated measures was used to determine whether there were significant differences among forefoot`s design for the detachable outsole`s angle and type (p<.05). When correlation effect was not statistically significant, post hoc analyses were performed using the multiple comparison through bonferroni, and if correlation effect was statistically significant, one-way ANOVA was performed as for the form of outsole which is an inter-group variable in order to find out simple main effect, and the paired t-test was performed to find out the angle of outsole, which is an intra-group variable. [Results] In IDLS phase, In terms of Rectus Femoris, 10°-B outsole showed statistically higher muscle movement than 5°-B, 5°-A outsole showed statistically higher muscle movement than 5°-B, 20°-A outsole showed statistically higher muscle movement than 20°-B. Among these outsoles, [Conclusion] 5°-B outsole was found to the most useful outsole for improving stability and controlling the bodily movement due to the body weight load when walking down the ramp.

근피로 유발에 따른 FES 적용이 노인의 하지 등속성 근기능 및 관절위치감각에 미치는 영향

채원식(Chae, Won-Sik),정재후(Jung, Jae-Hu),이한얼(Lee, Han-All),김종근(Kim, Jong-Geun) 한국코칭능력개발원 2020 코칭능력개발지 Vol.22 No.3

드롭 착지 시 탄소나노튜브 소재의 인솔 착용이 하지의 합성 관절 모멘트 및 근활성도에 미치는 영향

채원식 ( Woen Sik Chae ),정재후 ( Jae Hu Jung ) 한국스포츠정책과학원(구 한국스포츠개발원) 2015 체육과학연구 Vol.26 No.3

본 연구의 목적은 드롭 착지동작 시 탄소나노튜브 소재의 충격흡수 인솔 착용에 따른 하지의 합성 관절 모멘트 및 근활성도를 분석하는데 있다. 본 연구를 위해 하지 근골격계에 이상이 없는 20대 남성 10명을 연구대상자로 선정하였다. 2대의 디지털 캠코더와 1대의 지면반력기를 사용하여 드롭 착지동작 시 탄소나노튜브(CNT) 소재의 인솔과 EVA 소재의 인솔 착용에 따른 3차원 동작분석과 합성 관절 모멘트를 산출하였으며, 5개의 표면전극을 우측 하지 근육에 부착하여 근활성도 분석을 실시하였다. 착용된 인솔의 종류에 따른 운동역학적 변인들의 통계적 유의차를 검증하기 위해 paired t-test를 실시하였으며, 유의성 수준은 p<.05 로 설정하였다. 본 연구의 결과, 모든 합성 관절 모멘트에서는 인솔 착용에 따른 통계적 유의차가 나타나지 않았지만, 무릎관절의 신전근 모멘트에서 CNT 인솔 착용 조건이 EVA 인솔 착용 조건에 비해 상대적으로 감소한 것으로 나타났다. 평균 및 최대 적분근전도에서는 두 조건 간 통계적 유의차가 나타나지 않았지만, 대퇴이두근을 제외한 모든 근육에서 CNT 인솔 착용 조건이 EVA 인솔 착용 조건에 비해 상대적으로 근육 활성이 감소한 것으로 나타났다. 이러한 결과는 CNT 소재의 인솔 착용이 착지동작 시 무릎관절의 굴곡 동작을 적절히 제어하고, 발생되는 충격력을 감소시키는데 긍정적인 효과를 발생시키는 것으로 판단된다. The purpose of this study was to investigate effects of carbon nanotube-based insole on the resultant joint moment and muscle activity of the lower extremity during drop landing. Ten males with no known musculoskeltal disorders were recruited as the subjects. Two digital camcorders and one force plate were used to obtain 3-D kinematics and kinetics of the lower extremity. To assess the myoelectric activities of selected muscles, five surface electrodes were attached to the right side of the lower extremity. For each dependent variable, paired t-test was performed to test if significant difference existed between with carbon nanotube-based insole(CNT) and ethylene vinyl acetate-based insole(EVA) conditions(p<.05). The results showed that average and peak IEMG values from RF, TA, MG, and LG in CNT were lower than corresponding values in EVA. Although no significant difference in resultant joint moment was found between two conditions, a decrease in the knee extension moment was found with CNT. This indicates that wearing carbon nanotube-based insole may help to decrease impact force and to control excessive flexion movement of the knee joint during landing.

탄소나노튜브 인솔 착용에 따른 드롭 착지 동작의 생체역학적 분석

채원식 ( Woen Sik Chae ),정재후 ( Jae Hu Jung ),이행섭 ( Haeng Seob Lee ) 한국운동역학회 2012 한국운동역학회지 Vol.22 No.4

The purpose of this study was to determine the biomechanical effect of wearing carbon nanotube-based insole on cushioning and muscle tuning during drop landing. Twenty male university students(age: 21.2±1.5 yrs, height: 175.4±4.7 cm, weight: 70.2±5.8 kg) who have no musculoskeletal disorder were recruited as the subjects. Average axial strain, average shear strain, inversion angle, linear velocity, angular velocity, vertical GRF and loading rate were determined for each trial. For each dependent variable, a one-way analysis of variance(ANOVA) with repeated measures was performed to test if significant difference existed among different three conditions(p<.05). The results showed that Average axial strain of line 4 was significantly less in CNT compared with EVA and PU during IP phase. The average shear strain was less in CNT compared with EVA and PU during other phases. The inversion angle was increased in CNT compared with EVA and PU during all phase. In linear velocity, angular velocity, vertical GRF and loading rate, there were no significant difference between the three groups. This result seems that fine particle of carbon nanotube couldn`t make geometric form which can absolve impact force by increasing density through eliminating voids of forms, Thus, searching for methods that keep voids of forms may play a pivotal role in developing of insole. This has led to suggestions the need for further biomechanical analysis to these factors.

드롭 착지동작 시 마우스가드 착용이 운동역학적 변인에 미치는 영향

채원식 ( Woen Sik Chae ),이규복 ( Kyu Bok Lee ),정재광 ( Jae Kwang Jung ),이행섭 ( Haeng Seob Lee ),김동수 ( Dong Soo Kim ),정재후 ( Jae Hu Jung ) 한국운동역학회 2013 한국운동역학회지 Vol.23 No.4

The purpose of this study was to determine the biomechanical effect of wearing the mouthguard on the lower limb during drop landing. Nine male university students who have no musculoskeletal disorder were recruited as the subjects. Linear velocity, angular velocity, vertical GRF, loading rate, joint moment, and lower extremity muscle activity were determined for each subject. For each dependent variable, paired t-test was performed to test if significant difference existed between with mouthguard (WM) and without mouthguard (WOM) conditions (p<.05). The results showed that linear velocity, angular velocity, vertical GRF and loading rate were no significant difference between the two groups. The inversion moment of the ankle joint was increased in WM compared to WOM. Average IEMG values from BF, TA, and LG in WM were significantly greater than corresponding values in WOM during IP phase. This indicates that wearing mouthguard played a vital role in muscle tuning for maintaining joint stability of the lower limb and preventing injury.

내림 경사로 보행시 배낭 무게에 따른 하지 움직임의 운동역학적 분석

채원식 ( Woen Sik Chae ),이행섭 ( Haeng Seob Lee ),정재후 ( Jae Hu Jung ),김동수 ( Dong Soo Kim ) 한국운동역학회 2015 한국운동역학회지 Vol.25 No.2

Objective: The purpose of this study was to conduct biomechanical analysis of varying backpack loads on the lower limb movements during downhill walking over -20° ramp. Method: Thirteen male university students (age: 23.5±2.1 yrs, height: 175.7±4.6 cm, weight: 651.9±55.5 N) who have no musculoskeletal disorder were recruited as the subjects. Each subject walked over 20° ramp with four different backpack weights (0%, 10%, 20% and 30% of body weight) in random order at a speed of 1.0±0.1 m/s. Five digital camcorders and two force plates were used to obtain 3-d data and kinetics of the lower extremity. For each trial being analyzed, five critical instants were identified from the video recordings. Ground reaction force, loading rate, decay rate, and resultant joint moment of the ankle and the knee were determined by the inverse dynamics analysis. For each dependent variable, one-way ANOVA with repeated measures was used to determine whether there were significant differences among four different backpack weight conditions ( p<.05). When a significant difference was found, post hoc analyses were performed using the contrast procedure. Results: The results of this study showed that the medio-lateral GRFs at RHC in 20% and 30% body weight were significantly greater than the corresponding value in 0% of body weight. A consistent increase in the vertical GRFs as backpack loads increased was observed. The valgus joint movement of the knee at RTO in 30% body weight was significantly greater than the corresponding values in 0% and 10% body weight. The increased valgus moment of 30% body weight observed in this phase was associated with decelerating and stabilizing effects on the knee joint. The results also showed that the extension and valgus joint moments of the knee were systematically affected by the backpack load during downhill walking. Conclusion: Since downhill walking while carrying heavy external loads in a backpack may lead to excessive knee joint moment, damage can occur to the joint structures such as joint capsule and ligaments. Therefore, excessive repetitions of downhill walking should be avoided if the lower extremity is subjected to abnormally high levels of load over an extended period of time.

휴대전화 파지방법이 엄지손가락의 운동학적 변인과 근활성도에 미치는 영향

김동수 ( Dong Soo Kim ),채원식 ( Woen Sik Chae ),정재후 ( Jae Hu Jung ),이행섭 ( Haeng Seob Lee ) 한국운동역학회 2014 한국운동역학회지 Vol.24 No.3

The purpose of this study was to determine whether there are significant differences in kinematic variables and muscle activities of the thumb between two smartphone holding techniques. Twelve right handed university students(age 25.4±3.9 yrs, height 176.2±5.1 cm, weight 75.8±11.4 kg, hand length 19.2±1.1 cm) who have no musculoskeletal disorder were recruited as the subjects and had experience in using a smartphone for more than one year. Maximum joint angle, angular velocity, muscular activities were determined for each trial. For each dependent variable, paired t-test was used to determine whether there were significant differences between one hand (OH) and two hands ([TH], ρ<.05). The results of this study showed that there were no significant differences between OH and TH in the maximum joint angle of the thumb. The angular velocity of each joint was not statistically significant between OH and TH. The statistical analysis revealed that the main effect of the smartphone holding conditions was significant in the peak normalized muscular activities of FDI and APL. Although smartphone holding technique doesn``t affect on mobility and movement of the thumb joint, it may affect on active degree of the thumb and the upper extremity in directly and indirectly.

12분 달리기 시 속도 변화에 따른 몸통과 넙다리근육의 활성도 및 피로도 비교

박성현(Sung-Hyun Park),박정배(Jeong-Bae Park),신정훈(Jeong-Hun Shin),정재후(Jae-Hu Jung) 한국엔터테인먼트산업학회 2013 한국엔터테인먼트산업학회논문지 Vol.7 No.4

본 연구의 목적은 12분 달리기 시 속도 변화에 따른 몸통과 넙다리근육의 활성도 및 피로도를 비교하여 그 차이를 규명하는 것이다. 연구대상자는 I대학교의 건강한 남학생 9명으로 구성하였다. 12분 달리기의 속도는 개인의 100 M 달리기 기록을 기준으로 하였으며, 이 기록의 60%, 70% 및 80%의 속도로 구분하여 실시하였다. 근활성도는 최대적분근전도값을 근거로 각 근육의 신호를 표준화하였고, 근피로도는 평균주파수(MPF) 방법을 사용하였다. 이에 대한 자료 검증은 반복측정에 의한 일원변량분석을 실시하였고, 그 결론은 다음과 같다. 먼저, 근활성도의 변화를 살펴보면 큰볼기근과 중간볼기근은 80%에 비해 60%에서 높은 수준을 보인 반면, 안쪽넓은근과 가쪽넓은근 및 넙다리두갈래근은 60%에 비해 80%에서 높은 수준을 보였다. 다음으로, 근피로도의 변화를 살펴보면 배곧은근과 척추세움근 및 중간볼기근은 60%와 70%에 비해 80%에서 높은 수준을 보였고, 배가로근은 60%에 비해 80%에서 높은 수준을 보였다. 반면, 안쪽넓은근은 80%에 비해 60%와 70%에서 높은 수준을 보였다. 결론적으로 달리기의 속도가 증가할수록, 넙다리근육은 활성 수준이 높아지는 반면에 몸통근육은 피로 수준이 높아지는 것으로 나타났다. The purpose of this study was to compare and analyze the muscle activation and fatigue on muscles of core and thigh according to different running speed during 12 minutes run. The subjects of this study were 9 men. The speed of 12 minutes run standardized a record to run with the personal 100 M, and divided into 60%, 70% and 80% of this record. Peak integrated electromyogram was used to measure muscle activities and mean power frequency was used to measure muscle fatigue. Signals of EMG of each muscle was standardized. The results were analyzed by one-way ANOVA with repeated measure. The results of muscle activation, 60% level in gluteus maximus and gluteus medius were higher than 80% level. However, 80% level in vastus medialis, vastus lateralis, and biceps femoris were higher than 60% level. In muscle fatigue, 80% level in rectus abdominis, erector spinae, and gluteus medius were higher than 60% and 70% levels. The 80% level in transverse abdominis were higher than 60% level. However, 60% and 70% levels in vastus medialis were higher than 80% level. In conclusion, according to the increase of the running speed whereas the muscle activation of the thigh were increased, the muscle fatigue of the core muscle became higher than before.