Purpose The purpose of this study was to investigate the three dimensional joint angles of the ankle, knee and hip during basic long turn, carving long turn, basic short turn and carving short turn. Methods Fourteen alpine ski instructors from Korea Ski Instructor Association participated in this study. Each skier asked to perform 4-types of turning technique, classified by radius and level. 8 inertial measurement units were used to measure three-dimensional joint angles of the ankle, knee and hip joint. Results Significant differences were found the lower extremity joint angles on the mediolateral and vertical axis during long-turn and carving-turn (p<.05). significant differences were found the lower extremity joint angles on the anteroposterior axis in the steering phases 1, 2 and complete phase (p<.05). Conclusions In the Alpine skiing, the short turn requires a complex movement of the lower limb joint compared to the long turn. When performing a long turn, the movement of the ankle joint on the vertical axis are required compared to the short turn. And the carving and short turn need to the movements of the lower limb joint on the mediolateral axis.
[Purpose] The purpose of this study was to compare Yeo 2 vault and YANG Hak Seon vault to verify the possibility of YANG Hak Seon vault. [Methods] The YANG Hak Seon vault and Yeo 2 vault performed by five Korean national gymnastic athletes, and the photographic images were collected using a high-speed camera and their kinematic characteristics were analyzed by 3D image analysis. [Results] The main variable of the post-flight phase S1, S4, and S2 were similar to YANG Hak Seon vault. S1 showed the largest at shoulder angle and the highest body center of mass at horse take-off. S4 showed the smallest shoulder angle at horse take-off, slow twisting at the post-flight ascending period, but faster femoral rotation during horse contact. S2 showed the slowest twist velocity in the ascending period of the post-flight and the smallest rotational distance and twist distance at the peak. S3 showed the slowest horse take-off velocity, the least time in the post-flight phase, and the hip joint was flexed at the peak. [Conclusions] S1 is required to increase the twist velocity by narrowing the shoulder angle during post-flight. S4 is required to strong push-up and an increase in the twisting velocity in the post-flight ascending period. S2 is required to shorten the horse contact time and increase the horse take-off angle through powerful femoral rotation after board take-off. S3 will have to get enough power from the preparation phase.
The purpose of this study was to identify the characteristics through technical analysis of dismount to perform the successful landing. The subjects in this study were male gymnastic players of the national team, hish-speed cameras were used to record the salto backward dismount on the parallel bars of the subjects and to study the qualitative and quantitative analysis. The evaluations including feedback of each subjects’problem were as follow: KHH showed early release timing compared to other players. It could be one of factors which can not decelerating the rotational speed, so the correction of posture is needed. NYI didn’t slide to the left at the release phase, and showed big rotation of body compared to other players so the center of mass moved to the rear. The correction of the hand position at flight phase is necessary to perform the V-shaped position. RSD landed in a state where the rotation is insufficient, so the training using elasticity of parallel bars at phase 2, and the correction of hand position are in need. PMS’s rotation angular velocity of body increased consistently, so showed instable land. Therefore the training to ensure the height of flight is required. PEJ showed high vertical position of CM at the release phase which is help for height of flight. He performed ideal V-shaped position, and took a relatively stable landing position. BGR also showed high vertical position of CM and performed ideal V-shaped position, so he landed in a posture in which the most stable. YHS should push vertically rather than horizontally at the moment of release. Especially, the hand position is not on the hamstring but on the back of the knee to perform the ideal V-shaped position. CJY showed little hip angle at the release phase, so he can’t take a position for vertical rise. Also he showed the lowest knee angle and performed rotation and landing in a state that cannot extend the knee. If such problems are corrected, it will be helpful to landing position not only in parallel bars but also in other events.
Purpose The purpose of the study was to perform a comparative analysis of the YANG Hak Seon technique carried out by "K" athlete with the kinematical data of "Y" athlete and propose a method to improve the YANG Hak Seon technique of "K" athlete. Method The subject recruited for the study was a male athlete from Korean national team (Age: 21, height: 1.65 m, body weight: 59.6 kg, and career: 11 years). Four high - speed cameras were used to analyze the 3D motion of the YANG Hak Seon technique performed by "K" athlete. The variables selected for analysis were the velocity of COM, displacement of COM, the rotational & torsional angle of the trunk and rotational & torsional angular velocity of the trunk. The results obtained were compared to the preexisting data of the "Y" athlete (data set from the published research). Results Firstly, the horizontal displacement of the YANG Hak Seon technique of the "K" athlete was observed to be shorter along with lower vertical displacement during landing compared to “Y” athlete. In addition, the overall horizontal velocity was low and vertical velocity was not generated which rises during the BC (board contact) phase. Although the rotational angular velocity of the trunk was lower during the BC, HC (horse contact) phase and LD (landing) phase, torsional angular velocity was higher during the LD. Conclusion In order to improve the completeness of the YANG Hak Seon technique of the K player, it is necessary to enter with a fast and low posture on the footplate during the initial phase. In the BC phase, it is essential to raise the COM simultaneously while landing on the footplate and increase the rotational angular velocity of the trunk.
The aim of this study was to acquire essential information regarding Ri Se Gwang motion(element group Ⅱ, difficulty 6.4 point, double Tsukahara with tucked 1/1 twist), which Ri Se Gwang of North Korea performed during the final vault event of artistic gymnastic at Incheon Asian Game 2014, by analyzing motional characteristics. Firstly, Ri Se Gwang technique had second jump airborne time of 1.07 seconds and airborne height of 2.91m, which have great influences on the success of technique while having horizontal and vertical velocity of 2.73 m/s and 3.87 m/s, respectively, at the takeoff. These were sufficient jump motion for successful accomplishment of the technique however flight pattern was somewhat small which was mainly oriented vertically when compared to previous studies of Yeo and YANG Hak Seon 2 techniques. Secondly, blocking angle of vault contact was small at 9 degrees while having very small takeoff angle of 79 degrees. However, it had fast average trunk rotational velocity of 545 deg./s at the vault contact phase by rapidly bending trunk from the board takeoff until approaching the vault leading to achieve fast trunk rotational velocity of 452 deg./s after the take off in order to complete the airborne rotation successfully. Thirdly, the preparation phase of Ri Se Gwang technique had a distinct characteristics that the trunk was rapidly bent during the approach to the vault attempting aggressive blocking which leads to vertically oriented flight. It showed that this characteristic assists the motion of thigh snatch and the regulation of twist which strengthen airborne rotation for airborne rotational motion. And it also showed that sufficient landing and twist angles at the landing phase are possible with free rotational motion if the height of second jump reaches 3 m.
[Purpose] We examined the influence of reactive neuromuscular training (RNT) on golf swing coordination. RNT aims to induce proper coordinative movement by exaggerating the performer’s mistakes. Therefore, we applied RNT using inertia overloading to golfers who have problems with kinematic sequence during a golf swing. [Methods] To examine the effect of 12 weeks of RNT on golf swing coordination, we employed a ball tracking system (launch monitor) and motion analysis system (inertia sensors) were taken on four consecutive periods (pre-test and post-tests 4, 8, and 13 weeks later). Thirty Korean male cadets were divided into three groups based on inertial loading and practiced 7-iron golf swings combined with specific group tasks twice per week. [Results] At pre-test, most participants reached maximal angular velocity near the impact timing (95-100%). However, the deceleration timing of the maximum angular velocity of the proximal segments gradually moved toward mid-downswing as the training sessions proceeded, with the RNT group ultimately outperforming the two control groups. Additionally, the RNT group showed a significantly higher maximum angular velocity in the thorax and wrist. [Conclusion] Our results suggest that RNT can be sufficient to elicit and effective whole-body coordination pattern. Considerable follow-up research is needed on the use of RNT for various sports tasks and the effects of expertise on RNT results.
[Purpose] A potential issue for wheelchair sports are the characteristics of wheelchair design. The purpose of this review was to investigate the characteristics of design in wheelchair sports including the height of seat, camber and handrim size for improving the performance. [Results] The optimum height of seat related to trunk, arm length and handrim size. The lower seat showed the push efficient highly, while higher seat increased the energy expenditure. In energy expenditure, the optimum height of seat was 100-120° of elbow angle. Handrim size play the role in gear. The smaller handrim size acts like high gear, it gains disadvantages in acceleration, it gains advantages in maximum velocity. On the contrary, the higher handrim size acts like low gear, it gains disadvantages in maximum speed, it gains advantages in acceleration. The ratio of gear consideration in power and velocity. When increased camber enhanced the lateral stability, easier catch the handrim and easier arm motion. So it improved the energy expenditure and push technique. When increased camber enhanced the mechanical efficiency and stability, but it decreased the power. The racing wheelchair camber using the 8° and 10°. [Conclusion] Athletes, coaches and wheelchair experts are provided with insight in the performance effect of key wheelchair design settings, and they are offered a proven sensitive method to apply in sports practice, in their search for the best wheelchair-athlete combination.
