스텝 운동 기구를 사용한 운동 시 발의 위치가 하지 근육 활동에 미치는 영향 분석

채원식 한국운동역학회 2005 한국운동역학회지 Vol.15 No.1

W. S. CHAE. Electromyographic Analyses of the effects of different foot positions during exercise on a stair-climbing machine. Korean Journal of Sport Biomechanics, Vol. 15, No. 1, pp. 207-219, 2005. The purpose of this study was to determine the effect of the foot rotation on the lower limb muscles. Fourteen subjects performed step-up/step-down at a cadence of 80 beats/min, exercises with the foot neutral, 35?internally rotated, and 35?externally rotated, respectively. For each variable, a one-way analysis of variance (ANOVA) was used to determine whether there were significant differences between genders and among the eight types of jump. When a significant difference was found in jump type, post hoc analyses were performed using the Tukey procedure. A confidence level of p < .05 was used to determine statistical significance. The results showed that significant changes in averaged IEMG values occurred with the internal rotation of the foot in the lateral gastrocnemius during the knee extension, and in the of the foot produced a significantly lower Averaged IEMG values than the neutral foot position in the medial gastrocnemius. The results also found that the peak IEMG activity of the rectos femoris during the knee extension for the external rotation of the foot was significantly higher than the corresponding values in the neutral position of the foot, while the intenal rotaion of the foot exhibited a significant difference with the neutral position of the foot in the semitendinosus during the knee flexion. In general, the foot rotation position did not influence the average IEMG and Peak IEMG values of most muscles. The practice of adopting foot rotation to selectively strengthen individual muscles of the lower limb was not supported by this study. The external rotation of the foot produced high muscle activities in the quadriceps during the knee extension. For the knee extension, therefore, maintaining a laterally rotated position should be need for stable and comfortable position.

전방십자인대 수술이 시행되어진 슬관절과 정상 슬관절의 유효 모멘트암(effective moment arm) 비교 분석

채원식 한국운동역학회 2003 한국운동역학회지 Vol.13 No.1

Chae, W-S. Bilateral Comparison of Effective Moment Arms of the Quadriceps Force on Unilateral ACL-Reconstructed Individuals. Korean Journal of Sport Biomechanics, Vol. 13, No. 1, pp. 13-21. The purpose of this study is ⒜ to estimate effective moment arms of quadriceps forces and ⒝ to compare the d_e between the ACL-reconstructed and uninjured knees the same individual. One female (20 yrs old, 2 yrs post-op, hamstring tendon autograft) and two males (22 yrs old, 2 yrs post-op; 28 yrs old, 4 yrs post-op; patellar tendon autografts for both). Sagittal view radiographs were obtained for 6-7 different angles (range 5˚-110˚) from each knee. The d_e was determined by the method of Chow et al.(1999a). The results showed that the maximum d_e values ranged from 4.61 to 5.59 cm and 4.59 to 4.89 cm for the ACL-reconstructed and uninjured knees, respectively. The maximum d_e occurred between 35˚ and 50˚ and 20˚ and 50˚ for the ACL-reconstructed and uninjured knees, respectively. The maximum d_e values ranged from 4.12 to 4.35 cm and 3.12 to 3.63 cm for the ACl-reconstructed and uninjured knees, respectively. The effective moment arm of the knee extensor affects the loads on knee ligaments during knee-extension exercises. Because apparent differences in the moment arm of the quadriceps in different participants, it is very important to use personalized knee joint geometry for the computation of knee joint force. In the present study, no noticeable bilateral difference was found in the male subjects. However, apparent bilateral differences in d_e were observed in the female subject. This suggests that the effects of ACL reconstruction surgery on patellar mechanism deserve further investigation.

롤러 신발과 조깅 슈즈 신발 착용 후 보행 시 지면반력의 형태 비교 분석

채원식 한국운동역학회 2006 한국운동역학회지 Vol.16 No.1

Muscle Length and Shortening Velocity Changes during the Different Types of Vertical Jumps

Chae, Woen-Sik 한국운동역학회 2004 한국운동역학회지 Vol.14 No.1

본 연구의 목적은 각기 다른 수직 점프 동작 시 근육의 길이와 근육의 수축속도 변화를 비교 분석하는데 있다. 피험자의 운동학적 변인들을 분석하기 위해 2대의 고감도 카메라를 (60 Hz, Panasonic AG455) 사용하여 점프 동작을 촬영하였다. 대퇴직근, 내측광근, 외측광근, 중간광근, 대퇴이두관 (단두), 내측과 외측 비복근의 길이와 근수축 속도는 Brand et al. (1982)에 의해 제시되어진 하지근 기시 정지점의 3차원 좌표값과 동작분석을 통한 하지 분전간의 회전 및 변환행렬을 사용하여 측정되어졌다. 일반적인 근육 길이와 수축속도의 변화 형태는 각기 다른 점프간에 매우 유사한 형태를 보였다. 상승기 초기에 대퇴사두근의 길이가 최대인 것으로 나타났으며, 이에 반해 대퇴이두근과 내외측 비복근은 공중 동작이 발생하는 시점에 근의 길이가 최대인 것으로 나타났다. 근육의 길이 변화 범위는 대퇴직근이 35.9에서 47.5 cm, 외측광근이 29.4에서 38.8 cm, 중간광근이 31.5에서 38.0 cm, 내측광근이 30.9에서 38.6 cm, 대퇴이두근이 21.3에서 39.1cm, 외측비복근이 31.4에서 33.5cm, 내측비복근이 30.5에서 33.2 cm인 것으로 나타났다. SQ와 CMJ에서는 대퇴사두근의 최대 단축성 수축 속도와 대퇴이두근과 내외측 비복근의 최대 신장성 수축이 공중동작이 발생하기 바로 전에 이루어졌다. 대퇴사두근의 최대 신장성 수축과 대퇴이두근과 내외측 비복근의 최대 단축성 수축은 일반적으로 피험자가 착지하는 순간에 발생되어졌다. 그러나 HJ와 DJ에서는 대퇴사두근의 최대신장성 추축과 대퇴이두근과 내외측 비복근의 최대 신장성 수축이 하강기 초반에 발생되어졌다.

Muscle Activity of Cycling Movements at Different Pedal Shaft Widths

Chae, Woen-Sik,Lee, Min-Hyung 한국운동역학회 2002 한국운동역학회지 Vol.12 No.1

The purpose of this study was to quantify the electromygraphic (EMG) activity of selected lower limb muscles during cycling, and to define the relationship between pedal shaft width and muscular involvement. This study has particular significance to the female cyclists who by virtue of pelvic width may have a less efficient pedalling force, or an imbalance of applied muscular force. Variables analyzed were hip, knee, ankle range of motion (ROM), biceps femoris (BF), vastus lateralis (VL), rectus femoris (RF), and vastus medialis (VMO) muscle activity. Significant differences among three pedal shaft widths were determined through use of repeated measures one-way ANOVA, Newman-Keuls post hoc test. The biceps femoris, and vastus medialis EMG activity results of the present study appeared to indicate that different pedal shaft widths had an effect on changes in EMG activity. This study indicated that an increase in pedal shaft width significantly decreased the muscle activity in the vastus medialis while two inch pedal shaft width significantly decreased the muscle activity in the biceps femoris. Based on the present biomehcanical analysis, cycling with appropriate adjustments of the pedal shaft width may cause alteration in muscular patterns and lead to alteration in joint stresses. Modification in the bicycle system specific for women can be suggested with the result of the present study. Because it was found that different pedal shaft widths had an effect on changes in EMG activity, it seems reasonable to suggest that different pedal shaft widths should be provided for different cyclists.

Kinematics of Shot Putting Performed by Male and Female Wheelchair Athletes

( Chae Woen-sik ) 한국체육학회 1999 한국체육학회지 Vol.38 No.4

본 연구의 목적은 동급 장애를 가진 남녀 휠체어 선수들을 피험자로 선택하여 투포환 투척시 동작의 특성을 분석하고 남녀 선수들의 차이점을 밝히는데 있다. 휠체어 경기 USA (WSUSA)에 의해 조직된 트레이닝 캠프에서 5명의 남자와 4명의 여자 피험자를 선택했으며, 피험자들의 평균연령은 32.9 ±0.7세, 장애등급은 F6 와 F7, 신경 학상의 등급은 요추 2번에서 천추 2번까지이다. 투포환 투척시의 동작을 분석하기 위해 두 대의 고감도 카메라가 사용되었다. 피험자는 각기 6번의 투척을 하였으며, 그중 가장 기록이 좋은 투척 동작만을 선택 분석하였다. 3차원 영상좌표를 구하기 위해 Direct Linear Trangformation 방식이 사용되었다. 투척 순간의 투포환과 상체 각분절, 마지막 투척 동작시의 분절의 동작 범위와 평균 각속도와 같은 동작 변인들을 분석하였다. 남녀 선수들의 통계학적인 차이점을 찾기 위해 독립 t-test를 사용하여 각 변인들을 분석하였다. 비록 여자 선수들이 남자 선수들(4㎏)에 비해 가벼운 투포환(3㎏)을 사용하지만 통계학적으로 여자 선수들의 투척거리는 남자 선수들의 투척거리에 비해 짧았고(p≤.05), 이러한 이유는 남녀의 투척시 투포환의 속도, 각, 그리고 높이 차이 때문이다. 수직방향 속도(p≤.01)에는 남녀의 통계학적인 차이가 있었으나 수평방향의 속도에는 차이점을 찾을 수 없었다. 각기 다른 신체 분절중, 투척 순간 상지의 각속도와 마지막 투척 동작시의 상지의 동작 범위와 평균각속도가 가장 높았다. 이러한 결과는 상지가 투척거리를 결정하는 가장 중요한 신체분절임을 밝혀준다. 높은 표준 편차와 통계학적으로 남녀간의 차이가 없는 신체분절의 동작 변인들에 의해 각 피험자는 각기 다른 고유한 투척방법을 사용한다는 것을 알 수 있다. 앞으로 보다 다양한 장애등급을 가진 피험자를 선택하여 투척방법과 기술을 연구해야 할 것이다. The purposes of this study were to describe selected kinematic characteristics of shot putting performed by male and female wheelchair athletes of similar functional capability and to identify differences in kinematic characteristics between males and females. Wheelchair field athletes of a training camp (5 males and 4 females, age: 32.9 ±0.7 yrs, field classification: F6/F7, neurological level: L2-S2) organized by the Wheelchair Sports, US (WSUSA) served as the subjects. Two S-VHS camcorder (60 fields/s) were used to record the shot put performances. Each subject performed six trials and the best trial was selected for analysis. The direct linear transformatio (DLT) technique was used to obtain three-dimensional coordinates of selected body landmarks and the shot. Selected kinematic variables of the shot and upper body segments at the instant of release, and the range of motio (ROM) and average angular speed of different segments during the final forward thrus (delivery) were determined. For each variable, an independent t-test was conducted to test for the significant difference between males and females. Although female athletes used a lighter sho (3 ㎏ as compared to 4 ㎏ used by males), the put distances for males were significantly greater than the distances attained by female (p≤.05) (Table 1). The greater distances were due to the greater speed, angle, and height of release of the shot. Significant difference between sexes was found in the vertical velocity of releas (p≤.01), but not in the horizontal velocity of release. Among different segments, the upper arm has the greatest angular speed at release, and ROM and average angular speed during the forward thrust. This implies that the upper arm motion is an important determinant of the put distance. The large SD values and non-significant differences between sexes found in segmental kinematics may suggest that the subjects used different techniques(e.g., emphasizing different segments) in their puts. Future studies should investigate the shot putting techniques used by athletes of different functional capabilities.

Muscle Length and Shortening Velocity Changes during the Different Types of Vertical Jumps

( Woen Sik Chae ) 한국운동역학회 2005 한국운동역학회 논문 영문초록집 Vol.2005 No.-

Analysis of Selected Spatial and Temporal Parameters In 100-M Wheelchair Sprinting

( Woen Sik Chae ) 한국체육학회 1999 한국체육학회지 Vol.38 No.1

본 연구의 목적은 회전 카메라 영상분석 방법론을 개발하고 이 방법을 통해 100-m휠체어 경기동안의 시공간적 변수들과 추진 운동시의 특성을 분석하는데 있다. 전체 100-m휠체어 경기중, 각각의 변인들을 분석하기 위해 0-10m 구간, 최대 속도 구간, 90-100m 구간으로 나누었으며, 휠체어 장애등급이 T4인 한 명의 피험자가 본 연구에 참여하였다. 초반 50m와 후반 50m의 각 경기 구간을 두 대의 고감도 카메라에 담기 위해 두 대의 카메라를 각기 피험자의 운동방향으로 수평 회전시킨다. 피험자의 손이 휠체어 추진림에 닿거나 떨어지는 순간의 출발점에 대한 휠체어의 상대거리를 계산하기 위해 저자에 의해 고안된 회전 카메라 영상분석 방법이 사용되었다. 이 분석방법에 의해 계산된 피험자의 100-m 평균속도는 5.96m/s, 최대속도는 7.45m/s이며, 최대속도에 이르는 거리는 출발점으로부터 65.7m이다. 마지막 90-100m 구간 동안의 평균속도는 7.31m/s이며, 0-10m 구간, 최대 속도 구간, 90-100m 구간 동안의 평균 추진 거리와 추진 빈도는 각각 1.56, 3.38, 3.87m와 1.82, 1.92, 1.89㎐이다. 본 연구결과, 마지막 구간에서의 약간 감소된 추진빈도가 피험자의 감속에 보다 중요한 요인이라는 결론을 얻었으며, 정상인의 100-m경기와 비교했을 때 최대속도에 도달하는데 더 많은 시간이 소요되며, 마지막 구간까지 최대속도에 보다 가까운 추진속도를 유지할 수 있는 것으로 나타났다. The purposes of this study were to develop a 2-dimensional panning technique to determine selected spatial and temporal parameters over an entire 100-m wheelchair race and to evaluate selected stroking characteristics during the initial (first 10 m), maximum speed and final (last 10 m) phases of the race. One T4 (functional upper extremities, abdominal and lower back muscles) wheelchair racer served as the subject. Two S-VHS camcorders (60 fields/s) were panned horizontally to cover the first and second 50 m of the 100-m race, respectively. A special videographic technique was used to obtain the locations of the wheelchair relative to the start line at the instants of hand contact and release. The 100-m average speed was 5.96 m/s. The subject attained his maximum speeds (7.45 m/s) at the 65.7 m mark. The average speed in the final phase was 7.31 m/s. The average stroke length and frequency in the initial, maximum speed, and final phases were 1.56, 3.88, and 3.87 m, and 1.82, 1.92, and 1.89 ㎐, respectively. The data suggest that the slight decrease in speed toward the end of the race was attributed to the slight decrease in stroke frequency. When comparing to the able-bodied 100-m race, wheelchair racers reached their maximum speeds later and could maintain greater percentage of their maximum speeds toward the end of the race than their able-bodied counterparts.

Bilateral Comparison of Effective Moment Arms of the Quadriceps Force on Unilateral ACL-Reconstructed Individuals

( Woen Sik Chae ) 한국운동역학회 2005 한국운동역학회 논문 영문초록집 Vol.2005 No.-

The Effects of Computer Game Exposure on Musculoskeletal Pathological Symptoms in Adolescents

( Woen-sik Chae ),( Jae-hu Jung ) 한국운동역학회 2018 한국운동역학회지 Vol.28 No.1

Objective: This study aimed to analyze the effects of computer game exposure on pathological musculoskeletal symptoms in adolescents. Method: This study included 10 male junior high school students who used computers less than 3 times a week for 1 hr per day. The subjects were asked to play computer games for 4 hr. Magnetic resonance imaging of the hand and wrist, from the distal radius and ulnar head to the distal phalanges, and radiography of the cervical vertebrae were performed before and after playing computer games. For each dependent variable, a paired t-test was performed to identify significant changes before and after a 4-hr active computer game (p<.05). Results: The horizontal diameters of the flexor tendons in the index and middle fingers were significantly reduced after playing computer games. The horizontal diameters of the flexor tendons of other fingers did not show any significant differences, but there was a tendency toward a decrease after playing computer games. There was no significant change in the cervical lordosis angle before and after playing computer games. However, the cervical lordosis angle was relatively decreased. Conclusion: The results of this study showed that computer game exposure had direct and indirect effects on morphological changes of flexor tendons. In addition, playing computer games for long periods of time can have a negative effect on normal functioning of the musculoskeletal system, with the possible development of abnormalities. However, computer game exposure in adolescents cannot be decisively identified as a factor causing pathological symptoms, based on the results of this study alone. Thus, longterm longitudinal studies on the overall musculoskeletal system are necessary.