드롭 착지 시 warm-up 유무에 따른 충격흡수 기전의 차이 분석

고영철(Young Chul Koh),김경훈(Kyung Hun Kim),황성우(Sung Woo Hwang),김창영(Chang Young Kim),조상우(Sang Woo Cho),조준행(Joon Haeng Cho) 한국사회체육학회 2013 한국사회체육학회지 Vol.0 No.51

Warm-up is considered to be a critical factor and is regularly used for the prevention injuries and achieve high performance during training and competition. However much of the research through the biomechani-cal analysis about effect of warm-up has either lacked. Therefore, the purpose of this study was to investigate the effect of warm-up during a drop-landing maneuvers which could increase a risk of injuries. Fifteen female college students was participated to evaluate the effect of warm-up through the kinematics and kinetics analysis of lower extremities during a landing from a height of 30 cm. The results are as follows. First, the maximum flexion angle of the knee and hip joints was increased after warm-up. Second, the flexion angular velocity of the ankle joint was decreased, however the knee and hip joints was increased after warm-up. Third, the eccentric work of the ankle joint was decreased, while the knee a nd hip joint was increased after warm-up. These results implies that warm-up is effective to avoid injuries of lower extremities during a drop-landing.

시각 정보의 차단이 드롭랜딩 시 착지 전략에 미치는 영향

고영철 ( Young Chul Koh ),조준행 ( Joon Haeng Cho ),문곤성 ( Gon Sung Moon ),이해동 ( Hae Dong Lee ),이성철 ( Sung Cheol Lee ) 한국운동역학회 2011 한국운동역학회지 Vol.21 No.1

This study aimed to determine the effects of the blockage of visual feedback on joint dynamics of the lower extremity. Fifteen healthy male subjects(age: 24.1±2.3 yr, height: 178.7±5.2 cm, weight: 73.6±6.6 kg) participated in this study. Each subject performed single-legged landing from a 45 cm-platform with the eyes open or closed. During the landing performance, three-dimensional kinematics of the lower extremity and ground reaction force(GRF) were recorded using a 8 infrared camera motion analysis system (Vicon MX-F20, Oxford Metric Ltd, Oxford, UK) with a force platform(ORG-6, AMTI, Watertown, MA). The results showed that at 50 ms prior to foot contact and at the time of foot contact, ankle plantar-flexion angle was smaller(p<.05) but the knee joint valgus and the hip flexion angles were greater with the eyes closed as compared to with the eyes open(p<.05). An increase in anterior GRF was observed during single-legged landing with the eyes closed as compared to with the eyes open(p<.05). Time to peak GRF in the medial, vertical and posterior directions occurred significantly earlier when the eyes were closed as compared to when the eyes were open(p<.05). Landing with the eyes closed resulted in a higher peak vertical loading rate(p<.05). In addition, the shock-absorbing power decreased at the ankle joint(p<.05) but increased at the hip joints when landing with the eyes closed(p<.05). When the eyes were closed, landing could be characterized by a less plantarflexed ankle joint and more flexed hip joint, with a faster time to peak GRF. These results imply that subjects are able to adapt the control of landing to different feedback conditions. Therefore, we suggest that training programs be introduced to reduce these injury risk factors.

경사면에서 골프 스윙 시 양발 간 지면반력의 협응 관계 분석

문곤성(Gon Sung Moon),고영철(Young Chul Koh),이성철(Sung Cheol Lee) 한국사회체육학회 2011 한국사회체육학회지 Vol.0 No.43

The purpose of this study was to determine the inter-foot relations during the golf swing on the flat lie(FL), uphill sidehill lie(USL) and downhill sidehill lie(DSL) of 10°. Ten right-handed professional golfers were selected for the experiment and the 7 iron club was used. We used four force-plates to measure GRF and synchronized with the three-dimensional motion analysis system(VICON). Totally, the inter-foot relation during the golf swing on the FL, is similar to the golf swing on the DSL and USL except the weight transfer, the maximum GRF and the crossing of weight for both feet. This results could effect on the coiling of lower limbs during back swing and the blocking of lower limbs to minimize dispersion of the weight during the down swing. Therefore this results identify that the slopes could effect on the maximum head velocity of club head and the direction of ball.

착지 시 성별과 높이에 따른 무릎 움직임과 각속도의 3차원적 비교 분석

김경훈(Kyoung Hun Kim),고영철(Young Chul Koh),조준행(Joon Haeng Cho) 한국사회체육학회 2012 한국사회체육학회지 Vol.0 No.49

The purpose of this study was to analyse knee movement and angular veloctiy with gender differences and landing height during landing. In this study, 24 participants(12 males, 12 females) dropped from a height of 30cm and 60cm. 8 vicon cameras and 1 force plate were used to anlayze the kinematic data. The results are followings: Females tended to contact the ground in a more knee extended position. Female also exhibited increased valgus and tibia internal rotation at Initial contact and PVGRF time at higher landing height. Third, Female exhibited increased maximum valgus, tibia internal rotation and maximum angular velocities with increased landing height compared to males. The results of this study showed that female might be predisposed to higher incidence of knee injury during landing. Gluteus medius and quadriceps strengthening program can be a important part to prevent injuries and consideration of these strengthening program is needed in sports activities.

골프 드라이버와 아이언 스윙 시 전완근의 근활성도 분석

정일미(Il Mi Chung),고영철(Young Chul Koh) 한국사회체육학회 2014 한국사회체육학회지 Vol.0 No.56

The purpose of this study was to analyze forearm muscle activity throughout phases of the golf swing using the driver and 5 Iron. Sixteen male KPGA golfers was participated to evaluate the forearm muscles activity in the left flexor carpi radialis(FCR), left extensor carpi radialis(ECR), right FCR and right ECR muscles using a wireless surface electrode electromyography(Delsys, Boston, MA) at 2000Hz. The results showed that the cocking angle of the driver was significantly greater than 5 Iron at the E1, E3, E4, and E6. And at those events the forearm muscle activity differs significantly between the driver and 5 Iron swing. We thought it was because of the difference of the moments of inertia by the length of the club shaft. Our results imply that the cocking angle of the driver was greater than 5 Iron for the late-hitting through the more forearm muscle activity.

Downhill Sidehill Lie에서 골프 스윙 시 하지의 운동학적 분석

문곤성(Gon Sung Moon),고영철(Young Chul Koh),최지영(Ji Young Choi) 한국사회체육학회 2010 한국사회체육학회지 Vol.0 No.41

The purpose of this study is to determine the characteristics of the kinematics in golf swing for the flat lie(FL) and the downhill sidehill lie(DSL) of 10 degrees. Ten right-handed professional golfers were selected for the experiment and the 7 iron club was used. We used the three-dimensional motion analysis system(VICON) and set the sampling rate of 250Hz. The maximum club head velocity was showed 36.42±2.71m/s on the FL, 35.99±1.65m/s on the DSL. It showed the slopes didn·t have much effect on the maximum club head velocity. But, the slopes could cause to make the sway of lower limbs which have negative effect on the coiling of lower limbs during the back swing. And the slopes could cause the upper body to incline much to the opposite target direction which have negative effect on the direction of the ball at the impact. Therefore, To swing with the good balance on the DSL, the ankle joint needed to be more plantarflexion than on the FL, Knee joint and hip joint needed to be more flexion than on the FL.

드롭랜딩 시 높이 변화에 따른 인체 분절의 충격흡수 전략에 관한 연구

조준행 ( Joon Haeng Cho ),고영철 ( Young Chul Koh ),이대연 ( Dae Yeon Lee ),김경훈 ( Kyoung Hun Kim ) 한국운동역학회 2012 한국운동역학회지 Vol.22 No.3

The purpose of current study was to investigate the effects of the heights on the lower extremities, torso and neck segments for energy dissipation during single-leg drop landing from different heights. Twenty eight young healthy male subjects(age: 23.21±1.66 yr, height: 176.03±4.22 cm, weight: 68.93±5.36 kg) were participated in this study. The subjects performed the single-leg drop landing from the various height(30, 45 & 60 cm). Force plates and motion-capture system were used to capture ground reaction force and kinematics data, respectively. The results were as follows. First, the ROM at the ankle, knee, hip and trunk was increased with the increased heights but the ROM at the neck was increased in the 60cm. Second, the angular velocity, moment and eccentric work at the ankle, knee, hip, trunk, and neck was increased with the increased heights. Third, the contribution to total work at the knee joint was not significantly different, while the ankle joint rate was decreased and hip and neck rate was increased in the 60cm, and trunk rate was increased with the increased heights. Lastly, the increase in landing height was able to augment the level of energy dissipation not only at the lower extremities but also at the trunk and neck. The findings showed that drop landing affect trunk and neck with lower extremity joints. Therefore, we need to consider that trunk and neck strengthening including stability should be added to reduce sports injury during prevention training.