• Korean Journal of Applied Biomechanics
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• v.22 no.2
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• pp.151-158
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• 2012

The purpose of this study was to investigate variables of significantly difference as the structure of the spine, pelvic deviation and foot pressure between undergraduates and golf player subjects. The subjects of study were composed of 20 male golf players and 20 male undergraduates. Both groups were right handed persons. The measurement tools of this study were Formetric 4D(Diers, Germany) which is a three dimensional measure. The result are the follows: there were a significant difference between golf players and general students of trunk imbalance, pelvic tilt, pelvic torsion, pelvic rotation, surface rotation, lumbar lordotic curve, foot pressure(fore & behind foot), weight distribution(right & left foot). In conclusion, golf players might cause transform of spine and foot pressure due to golf exercise for several years. Such as imbalance affect to induce functional impairment and pain of musculoskeletal system, and appropriate evaluation and treatment were necessary for golf players.

• Korean Journal of Applied Biomechanics
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• v.19 no.3
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• pp.499-508
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• 2009

The purpose of this study was to compare and analyze flick shooting motion in penalty corner between high school players and national players in field hockey. Five high school players and six national players participated in this study. The 3D kinematic data were collected for each subject performing the penalty corner stroke. The results of the study were as follows: 1) The national players had higher stick head and ball velocity than the high school players. 2) The forward length between ball and support foot during ball catching with stick head was longer in the national players than the high school players. 3) At the Z axis of the E5 event, the center of gravity of the national players was lower than that of the high school players. 4) At the Z axis of the E5 event, left hip angle of the national players was lower than that of the high school players. 5) The national players had longer drag length of ball than the high school players. 6) The national players had higher hand and lower arm angular momentum than the high school players.

• Korean Journal of Applied Biomechanics
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• v.23 no.2
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• pp.109-116
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• 2013

The purpose of this study was to provide fundamental information for the enhancement of performance through kinematic analysis of cornering according to the radius of curve course in short track speed skating. To perform this study, six skaters: three narrow radius players(N, body mass: $56.0{\pm}7.2$ kg, height: $163.7{\pm}5.1$ cm, age: $21.3{\pm}1.5$ yrs) and three wide radius players(W, body mass: $61.0{\pm}9.5$ kg, height: $169.0{\pm}4.4$ cm, age: $20.0{\pm}1.7$ yrs). Three-dimensional motion analysis was performed on the section from the forth block starting to show the change of radius to the sixth block using eight infrared cameras(sampling frequency of 100 Hz for N and W players). The time of push-off was greater for N than for W(p<.05) while the radius of center of mass was greater for W than for N(p<.05). The flexion and extension of knee and hip joint were greater for N than for W(p<.05). The external rotation of left knee joint was greater for N than for W(p<.05). Based on the findings, a small radius by increasing the range of the flexion and extension of knee and hip joint with greater external rotation of left knee joint would be related to more efficient run at curve. It is expected that these results will be useful in developing a training program for enhancing performance of short track speed skating athletes.

• Korean Journal of Applied Biomechanics
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• v.20 no.2
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• pp.205-212
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• 2010

The purpose of this study was to compare the efficiency of visual perception and impulse according to the three types of Taekwondo players to be able to supply an efficient training method, for this a total of 12 representative Taekwondo players of the Korean National team, 4 poomsae players, 4 kyokpa players and 4 kyorugi players weighting between 68 to 74 kg, and the results from the motion analysis system, eye tracker and Electronic hogu are as follows. For the visual perceptual function, the total body reaction time was slowest for the kyokpa group, and for the visible reaction and vision fixation time was longest of the poomsae group, while the performance movement was fastest for the kyorugi group. As for description of the two kicking motions dollyo chagi and dolgae chagi the longer visual fixation helps the accuracy of the kick. In conclusion, as there was a difference between the groups, this information could help to train the visual perception of players according to what event they are participating in.

• Korean Journal of Applied Biomechanics
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• v.22 no.3
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• pp.285-293
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• 2012

The aim of this study is to identify the appropriate movement for maintaining postural balance during Front Kick and Turning Side Kick motions. To do so, ten Taekwondo athletes: five skilled players(S, body mass: $65.0{\pm}5.8kg$, height: $172.3{\pm}3.7cm$, age: $20.0{\pm}1.2yrs$, career: $9.0{\pm}1.9yrs$) and five less-skilled players(LS, body mass: $67.1{\pm}5.5kg$, height: $173.2{\pm}5.1cm$, age: $19.4{\pm}1.7yrs$, career: $9.6{\pm}1.7yrs$) participated in this study. A three-dimensional motion analysis was performed on the participants using eight infrared cameras and two force plate(sampling frequency of 200 Hz and 2000 Hz for S and LS players, respectively). The participants' motions were divided into: a front-kick phase(P1) and a turning-side-kick phase(P2). For P2(p<.05), the range and root mean square(RMS) of the ground reaction torque and the M-L mean velocity of COP were greater for LS than for S; similarly, for P2(p<.05), the M-L range, A-P range, and velocity of the COP were greater for LS than for S. Further, the M-L range and maximum velocity of the COP was greater for failure than for success(p<.05). The femoral biceps muscle for bending the knee joint was significantly stronger in S than in LS(p<.05). It is expected that these results will be useful in developing a training program for improving the balance and stability of Taekwondo poomsae athletes and improve their front-kick and turning-side-kick motions.

• Korean Journal of Exercise Nutrition
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• v.13 no.3
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• pp.211-216
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• 2009

This study was conducted to investigate the changes of exercise-induced stress response with acute anaerobic exercise in elite soccer players of university. The subjects were divided into elite soccer players of university (SG, n=10) and control group (CG, n=10). Subjects were tested three consecutive Wingate test for 30 seconds involving 2 times of 3 mins of resting time. In addition, whole blood and capillary blood were collected at rest, immediately post-exercise and 60 mins. of recovery time. Obtained results were as follows: Evaluated mean power and peak power of SG group was significantly higher than that of CG group in the all phase of Wingate test, respectively (p<.01). Although resting serum TG, TC, HDLC levels were not significant difference between SG and CG group, resting serum glucose of SG group was significantly lower than that of CG group. In addition, serum CRP levels of SG group were significantly lower than that of CG group at rest, immediately post-exercise and 60 mins of recovery time, respectively (p<.01). In serum cytokines, in spite of no significant differences in IL-1β levels between SG and CG group, IL-6 levels of SG group were significantly lower than that of CG group at immediately post-exercise and 60 mins. of recovery time, respectively (p<.05, p<.01). From these results, long-term combination training have a crucial role in amelioration of acute exerciseinduced stress response in elite soccer players.

• Korean Journal of Applied Biomechanics
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• v.20 no.1
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• pp.1-12
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• 2010

The purposes of this study were to determine the effects of lower extremity plyometric training on the proprioception and postural stability of collegiate soccer players with postural instability. The study was conducted from April 17, 2009 to September 28, 2009(for a total of 6 weeks). Ten male collegiate soccer players were enrolled into the study, then divided into two groups: the plyometric training group(PMT) and the classical postural stability training group(CPT). Plyometric training on the lower extremities showed statistically significant improvement on proprioception and postural stability(p<.05). Although not all neurophysiologic mechanisms underlying such an effect were revealed, it is proposed that plyometric training can be used as an effective training program to improve functional postural stability in soccer players with preexisting postural instability.

• Korean Journal of Applied Biomechanics
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• v.17 no.4
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• pp.107-113
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• 2007

The purpose of this study were to investigate the effects of knee brace on the knee muscular neuro-biomechanical variables during the rebound in female highschool basketball players. Twelve high school female ($17.9{\pm}0.8years$) basketball players rebound jumped for maximal vertical height to sufficiently stress the anterior cruciate ligament with and without knee brace. Kinematic data were collected to estimate the knee flexion, abduction angles and jump height. The EMG data from the biceps femoris and rectus femoris was used to estimate the ratio of quadriceps muscle activity. Female athletes with knee brace showed more reduced the knee abduction angle and the ratio of quadriceps muscle activity at foot contact phase than without knee brace. In conclusion, Female athletes with brace reduced knee anterior cruciate ligament loads.

• Korean Journal of Applied Biomechanics
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• v.13 no.2
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• pp.29-47
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• 2003

This study is to analyze the kinematic variables in release motion of discuss throwing. For the matter, 5 people from the national team and collegiate discuss throwing in the year 2001 were chosen as the subjects and two S-VHS video cameras set in 60frames/sec were used for recording their motions. Coordinated raw positions data through digitizing are smoothing by butter-worth 's low-pass filtering method at a cut off frequency 6.0Hz. and the direct linear transformation(DLT) method was employed to obtain 3-D position coordinates. The conclusions were as follows; 1. The better record players showed the shorter approach time in the last support phase. 2. In the displacement CG, the better record players showed the shorter displacement in medial-lateral direction, and the longer displacement in horizontal direction. In the motion, the COG showed longer displacement vertical direction. 3. The better record players showed the faster horizontal velocity than vertical velocity in the release. 4. The better record players showed to take the posture of vertical axis in the release.

• Korean Journal of Applied Biomechanics
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• v.13 no.1
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• pp.173-184
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• 2003

The purpose of this study was to investigate the batting characteristics in elite baseball players. Seven skilled collegiate players hit the ball which was thrown by a pitching machine linearly and strongly to the center of the field. Time, velocity, angle and pound reaction force variables were measured by using high-speed video cameras and pound reaction force analyzer. The results were as follows: 1. The elite players finished their stride performance in a short time and they stayed longer in a swing phase. The increases in the range of trunk rotation were associated with the delay of the swing phase. 2. The 'take-back' phenomenon in the trunk was showed after the stride phase. 3. The down swing demonstrated powerful line drives. 4. Equivalent body weights were placed on both feet during the ready phase. 95% of the body weights were moved to the rear foot during the stride phase, whereas the body weights were driven to the front foot during the swing phase. 95% of the body weights were placed on the front foot at impact.