The Acute Effects of Short Static-Stretching on Vertical Jump Performance

Eonho Kim,Chang Young Kim,Yong Dae Choi,Poram Choi,Yongin Cho 한국코칭능력개발원 2017 International Journal of Coaching Science Vol.11 No.2

The purpose of this study was to clarify the acute effects of short static-stretching (10 seconds and 30 seconds) on vertical jump performance. Twenty-six healthy college students (10 males and 16 females) participated in this study. Each subject measured his/her pre-stretching vertical jump height using Vertec and performed 10- or 30-second staticstretching on the four lower-body muscle groups (hamstrings, gastrocnemius, soleus, quadriceps), which are involved in executing a vertical jump. Post-stretching vertical jump height was measured after the static-stretching. No significant differences between the two groups were found in the three variables (pre-stretching jump height, post-stretching jump height, difference in jump height) (p = .478). The mean pre-stretching jump height and the mean post-stretching jump height for both groups were 258.98 ± 26.59 and 258.59 ± 26.59. There was no significant difference in jump height between the pre- and post-stretching (p = .387). These results suggest that static-stretching for 30 seconds or less does not negatively affect vertical jump performance and static-stretching can be used prior to athletic competition as long as the duration of static-stretching is kept under 30 seconds per each muscle group.

Measuring Isometric Strength by Utilizing an Isokinetic Dynamometer and Determining Balance through Limits of Stability and Rhythmic Weight Shift with the Balance Master System

Eonho Kim,Kee-hyun Kim,Hyeri Oh,Kyunghoon Choi 한국코칭능력개발원 2018 International Journal of Coaching Science Vol.12 No.1

The purpose of this study was to properly measure isometric strength through use of an isokinetic dynamometer, as well as to measure balance through the Balance Master System. Isometric strength was measured through peak torque and rate of force development under different breathing conditions and balance was used the Limits of Stability and Rhythmic Weight Shift tests. Healthy college-aged students were used for this survey (n=8, age 23.8±1). Isometric strength test was conducted under 4 breathing conditions with 2 trials for each condition as well as a single test for limit of stability and 6 trials for rhythmic weight shift. The tests showed no significant difference in peak torque or rate of force development under different breathing conditions or in the muscle group × breathing condition interactions. Rhythmic Weight Shift showed significant differences in on-axis velocity as well as speed × movement interaction effects. Limits of stability showed significant difference in movement velocity but no significant differences in directional control between different directions.

런닝화의 미드솔 경도가 하지 근육의 피로와 충격력에 미치는 영향

Kim, Eonho,Lim, Kyuchan,Cho, Seunghyun,Lee, Kikwang 한국운동역학회 2019 한국운동역학회지 Vol.29 No.3

Objective: The aim of this study was to investigate the effect of midsole hardness of running shoe on muscle fatigue and impact force during distance running. Method: Ten healthy college recreational runners who were performing distance running at least three times a week participated in this experiment. They were asked to run for 15 minutes in the treadmill at 10 km/h with running shoes having three different types of midsole hardness (Soft, Medium, Hard). EMG signal and insole pressure were collected during the first and last one minute for each running trials. Data were analyzed using a one-way analysis of variance (ANOVA) with repeated measures. Results: Midsole hardness did not affect the consistency of stride length. For the median frequency of the EMG signal, only VL was affected by midsole hardness; that of medium was greater than other midsoles (p<.05). The loading rate of impact forces increased by midsole hardness (p<.01). Conclusion: Although soft midsole could attenuate impact forces at heel contact, it might have a negative effect on the fatigue of muscle which could decelerate the body after heel contact. Therefore, it is necessary to select the optimum hardness of midsole carefully for both reduction impact forces and muscle fatigue.

런닝화의 미드솔 경도가 하지 근육의 피로와 충격력에 미치는 영향

( Eonho Kim ),( Kyuchan Lim ),( Seunghyun Cho ),( Kikwang Lee ) 한국운동역학회 2019 한국운동역학회지 Vol.29 No.3

Objective: The aim of this study was to investigate the effect of midsole hardness of running shoe on muscle fatigue and impact force during distance running. Method: Ten healthy college recreational runners who were performing distance running at least three times a week participated in this experiment. They were asked to run for 15 minutes in the treadmill at 10 km/h with running shoes having three different types of midsole hardness (Soft, Medium, Hard). EMG signal and insole pressure were collected during the first and last one minute for each running trials. Data were analyzed using a one-way analysis of variance (ANOVA) with repeated measures. Results: Midsole hardness did not affect the consistency of stride length. For the median frequency of the EMG signal, only VL was affected by midsole hardness; that of medium was greater than other midsoles (p<.05). The loading rate of impact forces increased by midsole hardness (p<.01). Conclusion: Although soft midsole could attenuate impact forces at heel contact, it might have a negative effect on the fatigue of muscle which could decelerate the body after heel contact. Therefore, it is necessary to select the optimum hardness of midsole carefully for both reduction impact forces and muscle fatigue.

Abdominal fat accumulation as a potential risk factor for low back pain in adult men

( Bokun Kim ),( Sechang Oh ),( Eonho Kim ) 국민체육진흥공단 한국스포츠정책과학원 2019 International Journal of Applied Sports Sciences Vol.31 No.1

The purposes of this study were twofold: (a) to examine role of body mass index in incidence of low back pain and (b) to investigate more relevant causes of low back pain in body composition. Of the 250 initial subjects, 188 subjects were included for the first analysis and divided into quartiles based on the scores of Japan Low Back Pain Evaluation Questionnaire which was adopted to assess low back pain. We selected 51 subjects (body mass index: 27.4 ± 5.0 kg/m²; age: 47.4 ± 10.9 years) in 1st quartile as a control group and 45 subjects (body mass index: 27.1 ± 2.8 kg/m²; age: 56.4 ± 7.1 years) in 4th quartile as a low back pain group for the final analysis. Assessments of anthropometric characteristics and body composition (by whole-body dual-energy X-ray absorptiometry) were carried out and body composition was evaluated as absolute and relative values. No difference in body mass index between the two groups was detected and waist hip ratio and percentage of trunk fat mass per weight in low back pain group was significantly greater than those in the control group. While low back pain was significantly related to abdominal fat related variables including waist, waist hip ratio and percentage of trunk fat mass per weight, it was not linked to other variables such as weight and body mass index. Abdominal fat accumulation may be a potential risk factor for low back pain in adult men.

A Study of Analysis of Stability and Types of Injury in the Dominant and Non-dominant Feet of Female Ballet Dancers

Chulmin Choi,Eonho Kim 상명대학교 글로벌문화예술교육연구소 2024 Research in Dance and Physical Education Vol.8 No.1

The purpose of this study is to evaluate the stability of the dominant and nondominant feet of ballet dancers and use it as basic data for injury analysis. The subjects of the study were 12 people with more than 10 years of experience majoring in ballet at K University in Seoul. Those who had not undergone lower extremity joint surgery within 6 months from the baseline date of participation and those who had no experience in medical procedures or rehabilitation due to injury were selected. As a result of the study, no significant differences were found in the overall analysis between dorsiflexion and plantarflexion, inversion and eversion, and dominant and non-dominant feet. It was found that instability of dorsiflexion and plantar flexion, which are the most common causes of imbalance and injuries in ballet dancers dominant and non-dominant feet, also affected inversion and eversion. Lastly, the stability and balance of the dominant and nondominant feet were analyzed as important factors in injury prevention, and it is expected that they will be used as basic data in future studies targeting subjects with injury experience.

여자 필드하키 페널티코너 전문 슈터 양성을 위한 Drag Flick 슈팅 동작의 운동학적 분석: 사례 연구

Park, Jongchul,Byun, Kyungseok,Kim, Eonho 한국운동역학회 2019 한국운동역학회지 Vol.29 No.2

Objective: This study aims to propose an efficient technical model through a kinematic analysis of field hockey drag flick shooting motion in laboratory situations and game situations and to build up the basic data on drag flick shooting technique through a comparative analysis of a Korean specialized shooter and specialized shooters of competing Asian countries. Method: This study selected one Korean female national specialized shooter and seven specialized shooters of competing countries, China, Japan, India, and Malaysia, who participated in the 2018 Asian Hockey Champions Trophy as research subjects. In exercise situations, a 3-D motion analysis utilizing an infrared camera was conducted, while in game situations, an image-based 3-D motion analysis utilizing a digital camera was conducted. Results: The Korean specialized shooter had smaller changes in the angles of the trunk and the stick in game situations than in exercise situations. She had a high angular velocity of the trunk and the stick head, and the maximum speed of the ball was high. The Korean specialized shooter had the maximum angular velocity of the trunk higher than the specialized shooters of the competing countries did, and the angular velocity of the stick head and the maximum speed of the ball were in the average level. Conclusion: As for drag flick shooting in game situations, changes in the angle of the trunk and the stick were small, and the angular velocity was high due to the pressure that the shooters should perform the motion fast with the defenders' interruptions, and this high angular velocity of the trunk and the stick head affected the movement of the ball. Thus, the maximum speed of the ball was higher in game situations than in exercise situations. The Korean specialized shooter had the maximum angular velocity higher than the specialized shooters of the competing countries did; however, the maximum speed of the ball was average, and it turned out that the maximum speed of the ball was associated with the angular velocity of the stick head in P3. Therefore, Korean specialized shooters need complementary training for a change to the torque of the stick head, using the strong torque of the trunk.

여자 필드하키 페널티코너 전문 슈터 양성을 위한 Drag Flick 슈팅 동작의 운동학적 분석: 사례 연구

( Jongchul Park ),( Kyungseok Byun ),( Eonho Kim ) 한국운동역학회 2019 한국운동역학회지 Vol.29 No.2

Objective: This study aims to propose an efficient technical model through a kinematic analysis of field hockey drag flick shooting motion in laboratory situations and game situations and to build up the basic data on drag flick shooting technique through a comparative analysis of a Korean specialized shooter and specialized shooters of competing Asian countries. Method: This study selected one Korean female national specialized shooter and seven specialized shooters of competing countries, China, Japan, India, and Malaysia, who participated in the 2018 Asian Hockey Champions Trophy as research subjects. In exercise situations, a 3-D motion analysis utilizing an infrared camera was conducted, while in game situations, an image-based 3-D motion analysis utilizing a digital camera was conducted. Results: The Korean specialized shooter had smaller changes in the angles of the trunk and the stick in game situations than in exercise situations. She had a high angular velocity of the trunk and the stick head, and the maximum speed of the ball was high. The Korean specialized shooter had the maximum angular velocity of the trunk higher than the specialized shooters of the competing countries did, and the angular velocity of the stick head and the maximum speed of the ball were in the average level. Conclusion: As for drag flick shooting in game situations, changes in the angle of the trunk and the stick were small, and the angular velocity was high due to the pressure that the shooters should perform the motion fast with the defenders' interruptions, and this high angular velocity of the trunk and the stick head affected the movement of the ball. Thus, the maximum speed of the ball was higher in game situations than in exercise situations. The Korean specialized shooter had the maximum angular velocity higher than the specialized shooters of the competing countries did; however, the maximum speed of the ball was average, and it turned out that the maximum speed of the ball was associated with the angular velocity of the stick head in P3. Therefore, Korean specialized shooters need complementary training for a change to the torque of the stick head, using the strong torque of the trunk.

사과貯藏에 관한 硏究(Ⅳ)

朴魯豊(Noupoung PARK),崔?浩(Eonho CHoi),金順天(Soonchon Kim) 한국원예학회 1971 Horticulture, Environment, and Biotechnology Vol.10 No.-

핸드볼 슈팅 특성에 따른 골키퍼 방어율 분석: 2019 여자 핸드볼 세계선수권 대회 자료를 중심으로

이승훈(Seung-hun Lee),김언호(Eonho Kim),오성옥(Seong-ok Oh) 한국체육측정평가학회 2021 한국체육측정평가학회지 Vol.23 No.3

본 연구의 목적은 시간의 흐름, 슈팅 유형 등의 환경적 요소를 고려하여 승패로 구분된 집단 간 핸드볼 골키퍼 방어율에 영향을 미치는 요인을 살펴보는데 있다. 2019년 일본에서 열린 여자핸드볼세계선수권대회 91경기에 출전한 전체 골키퍼를 대상으로 승패집단에 따른 슈팅 시간, 슈팅 유형별 골키퍼의 방어율 차이검증을 위해 반복측정 이원배치 분산분석을 이용하였다. 승패집단 간 골키퍼 방어율의 차이는 시간의 흐름에 영향을 받았는데, 특히, 경쟁요소가 극대화되는 전반전 종반부(승리팀: 26.9%, 패배팀: 18.9%)와 후반전 종반부(승리팀: 31%, 패배팀: 17%)에서 가장 큰 차이를 나타냈다. 반면, 승패집단 간 골키퍼 방어율의 차이는 슈팅 유형에 영향을 받지 않았으며, 7m(13.8%), 속공(15.3%), 돌파(15.3%) 슈팅에서의 방어율에 비해 6m(24.4%), 9m(29.6%), 윙슛(29.9%)에서의 방어율이 상대적으로 높게 나타났다. 본 연구의 결과는 골키퍼 방어율의 환경적 요소와 패턴에 기초해 훈련의 초점을 시간과 위치에 맞춰 설정할 필요성을 밝혀냈으며, 향후 진행될 유사연구에서는 자료의 범위를 넓히고, 골키퍼 방어율에 영향을 미칠 수 있는 다양한 변수 간 상관성에 기반 한 분석이 이루어져야 한다고 사료된다. The purpose of this study is to identify factors that affect the intergroup handball goalkeeper"s defensive ratio, which is divided into wins and losses, taking into account the flow of time, environmental factors of the type of shooting. goalkeeper’s who played in 91 games except for five draws at the 2019 Women"s Handball World Championships in Japan, the team used a 2-way ANOVA of repeat measurements to verify the difference in the goalkeeper"s defensive ratio by type of shooting. The difference in goalkeeper defensive ratio between winning and losing groups was influenced by the passage of time, especially at the end of the first half (26.9% for winning team, 18.9% for losing team) and the end of the second half (31% for winning team, 17% for losing team). In addition, the difference in goalkeeper defensive ratio between winning and losing groups was not affected by the type of shooting, with relatively higher defensive ratio in 6m shots (24.4%), 9m shots (29.6%), and wingshots (29.9%) compared to 7m shots(13.8%), fast break (15.3%), Breakthroughs (15.3%). Based on the environmental factors and patterns of goalkeeper defensive ratio, the need to focus training on time and location, and similar studies in the future should broaden the scope of data and analyze correlations among various variables that can affect goalkeeper defensive ratio.