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REFERENCE LINKING PLATFORM OF KOREA S&T JOURNALS
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Korean Journal of Sport Biomechanics
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Journal DOI :
Korean Society of Sport Biomechanics
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Volume & Issues
Volume 17, Issue 4 - Dec 2007
Volume 17, Issue 3 - Sep 2007
Volume 17, Issue 2 - Jun 2007
Volume 17, Issue 1 - Mar 2007
Selecting the target year
Accuracy and Reliability of Ground Reaction Force System and Effect of Force Platform Mounting and Environment
Park, Young-Hoon ; Youm, Chang-Hong ; Sun, Sheng ; Seo, Kook-Woong ; Kim, Eui-Hwan ; Kim, Tae-Whan ;
Korean Journal of Sport Biomechanics, volume 17, issue 1, 2007, Pages 1~8
DOI : 10.5103/KJSB.2007.17.1.001
Ground reaction force (GRF) measures are one of the most commonly used in biomechanical study. GRF system is very useful educational tool to explain and demonstrate the Newton's law of universal gravitation and laws of motion as well. However, accuracy, intra- and inter- force platform measures' consistency, reliability, noise, and the effect of platform mounting to GRF measures were not clearly viewed. The aim of this study was to examine the above. GRFs of a plastic dummy and two subjects' quiet upright standing were collected at four university laboratories eight force platforms. The types of platforms, analysis programs, and platform set-up were various. Three 100s-trials were conducted with sampling frequency of 100 Hz. First two trials' vertical component of GRFs, Fz, and CoP sway ranges of mid-60s-portion of 100s trials were analyzed by the paired t-tests and one-way ANOVA. Six of eight platforms' 1st and 2nd trial dummy Fz were statistically different (p<.05) and all platforms ICC were poor (<.28). Fz of the two platforms in every four laboratories were statistically different (p<.05). There were white noises and/or very distinctive noises at specific frequency ranges in all Fz measures. 5 Hz low-pass filtering made clear the Fz differences. CoP ranges of dummy were less than 0.5 cm and the best was 0.02 cm. This CoP range finding agrees with previous results suggests the importance of force platform mounting and A/D card resolution.
The Analysis of Joint Motion of Lower Extremities to Running Velocities and Cutting Angles
Kwon, Oh-Bok ; Jung, Chul-Jung ;
Korean Journal of Sport Biomechanics, volume 17, issue 1, 2007, Pages 9~16
DOI : 10.5103/KJSB.2007.17.1.009
Cutting movements frequently occur in sports and influence much Lower Extremity injuries. The purpose of this study was to compare joint motion of lower extremities to cutting angles and running velocities. Seven male subjects performed cutting movements to three angles(
). Subjects were instructed to run five meters at a speed of 2.5m/s and 4.5m/s before contacting their right foot on the force plate and then change direction to the left. The Peak hip, knee and ankle joint kinematics were influenced according to the running velocities and cutting angles. In conclusion, Fast running velocity and cutting angle will may influence on the lower extremity joint instability on real game situation.
The Effects of Start and Finish Distance on the Gait Variables during Walking
Lim, Bee-Oh ; An, Seung-Hyun ; Lee, Sang-Woo ; Do, In-Young ;
Korean Journal of Sport Biomechanics, volume 17, issue 1, 2007, Pages 17~27
DOI : 10.5103/KJSB.2007.17.1.017
It is essential for gait analysis to know the distance information. The purpose of this study was to investigate the effects of start and finish distance on the gait variable during walking. Six adolescent participated in this study. Start condition was given by six conditions.: walking forward from (1) one step, (2) three steps, (3) five steps, (4) ten steps, (5) one step after standing walk, and (6) three steps after standing walk, before contacting the force plate. Stop condition was given by four conditions. : stop after (1) one step, (2) two steps, (3) three steps, and (4) ten steps, passing force plate. Repeated measured one-way ANOVA was utilized for data analysis, and the significant level was set at .05. The largest change from the difference of gait velocity exists between the variables of ground reaction force. There were no significant differences in spatio-temporal and posture(angle) variables, as well as ground reaction force variables with walking over the three steps. There were significant differences in gait velocity, knee angle at heel contact, vertical impulse and ankle angle at toe off in short distance.
An Analysis on Kinematically Contributing Factors at Impact of Forehand Drive Motion in Squash
Lee, Kyung-Il ; Lee, Hee-Kyung ;
Korean Journal of Sport Biomechanics, volume 17, issue 1, 2007, Pages 29~39
DOI : 10.5103/KJSB.2007.17.1.029
This study were obtained elapsed time phase-by-phases, displacement, user angle, velocity and angular velocity to analyse kinematically contributing factors at impact of forehand drive motion, on targeting three male players. The results of the study were presented as follows; In the forehand drive swing, the elapsed time by phases was a total of .52 seconds: .30 seconds from backswing to impact and .22 seconds from impact to follow-through, Considering the mean change in locations of COM of each(part
body segment) at impact, racket head, left shoulder, right wrist and left hip, the left-right directions(X-axis) were showm to be each
. The displacement differences of COM of each body segment were shown to be -.57, -.05, -.33, and .16m. For the vertical direction(Z-axis), the center of mass was lowest at impact and highest at E3. For the displacement of the right wrist on the left hip, the right wrist moved to .82m to the lower direction without change in the locations of the hip from E1 from E2. When the left hip moved .02m from E2 to E3, the right wrist moved .7m in the upper direction. In respect to the velocity of each body segment, the hip and the shoulder joint accelerated and then the wrist followed. Then the right wrists of all the subjects and their racket heads showed maximum speed, and an effective swing was observed. At the angle of each part, the angle of the right wrist was the smallest at the backswing and the largest at the moment of the impact. Then it increased gradually in the follow-through section. In respect of angular velocity for subject A, the hip moved and the largest change occurred. Immediately before the impact, the subject made a swing using his right wrist, his hip, and the shoulder joint, showing the maximum value, which was judged to be effective.
A Kinematic Analysis of Two Hand Backhand Stroke Swings in Tennis
Kang, Sang-Hack ; Son, Won-Il ;
Korean Journal of Sport Biomechanics, volume 17, issue 1, 2007, Pages 41~52
DOI : 10.5103/KJSB.2007.17.1.041
The present study analyzed the two hand backhand stroke motion of six female high school tennis players who won the championship at the National Athletic Meeting in 2006, and drew conclusions as follows. The open angle of the racket at the moment of impact was 90 degree without significant difference among the players, making a wide contact between the ball and the racket. The racket angle was 43 degree at take back and 91 at impact, showing a style of holding the racket rather upright in general. In back swing from the top to the impact, the shoulders and the hips turned by 97 degree and 40 degree, respectively. At the moment of impact, the height of the impact was 54%H, and the position of the impact was 10%H ahead of and 37%H left from the central axis of the body. The right hand made a continental grip and the left hand made a Western or semi Western grip. Through the entire swing motion, the grip angle of the left hand was smaller than that of the right hand, and those who maintained a large grip angle of the right hand at the moment of take back put the racket head slightly farther from the body. In the swing of the racket head from the lowest point to the impact, the vertical length of movement was 11%H and the horizontal length of movement was 60%H, quite long.
Analysis of Racket Head Velocity of Tennis Forehand Stroke by Stance Patterns
Seo, Kuk-Woong ; Kang, Young-Teak ; Lee, Kyung-Soon ; Seo, Kook-Eun ; Kim, Jung-Tae ;
Korean Journal of Sport Biomechanics, volume 17, issue 1, 2007, Pages 53~60
DOI : 10.5103/KJSB.2007.17.1.053
Recently tennis techniques has been changed in stance patterns. Stance is consist of square stance, open stance and semi-open stance. The purpose of this study was to analyze the kinematics variables of racket head velocity during forehand stroke by stance patterns. Eight high school tennis players were chosen for the study who use semi western grip right-handed person more than career 7 years. They performed horizontal swing and vertical swing that it was done each five consecutive trial in the condition of square, open and semi-open stance. The results showed that racket head velocity significant difference was not observed in stance types between swings at impact. Y and Z components of racket head velocity for horizontal and vertical swing at second prior to impact and at impact were that y components velocity was faster horizontal swing than vertical swing and z components velocity was later horizontal swing than vertical swing. Statistically significant variable to racket head velocity and Pearson's correlation were drawn as follows. 1. Z components of racket head velocity in square stance was significant correlation by right knee joint. 2. Y components of racket head velocity in semiopen stance was significant correlation by left hip joint. 3. Y components of racket head velocity in open stance was significant correlation by left ankle joint.
An Analysis of Shoulder Joint Torque and Muscle Pattern Duing Tennis Serve by Isokinetic Motions on Isomed 2000
Kim, Sung-Sup ; Kim, Eui-Hwan ; Sung, Young-Ho ; Kim, Tae-Whan ; Chung, Jae-Wook ;
Korean Journal of Sport Biomechanics, volume 17, issue 1, 2007, Pages 61~68
DOI : 10.5103/KJSB.2007.17.1.061
The purpose of this study was to analyze the shoulder joint torque and muscle pattern performing as Tennis serve by Isokinetic motions on Isomed 2000. The subject, who was 5 males Korean national high school tennis players. By analyzing the flexion/extension of the shoulder, the peak torque of the internal/external rotation motion(at 60,180 and 300 degree/sec) at peak torque degree, the weight, peak torque, and power. combined with the timing of the electrode of the attached trapezius and posterior deltoid at the three part. From the data analysis & discussion the following conclusions were drawn. When doing a shoulder extension, the peak torque can be widely seen at 60degree per second. However the degree may be different depending on angular velocity. When doing an internal rotation at 90degree abduction, peak torque per weight was seen at 60degree per second. The degree of peak torque was at 31.6-44.2 and peak power was faster when angular velocity was increased. The aspect of muscle pattern was seen more at the internal rotation in the 90degree abduction rather than the shoulder extension. However the angular velocity was not influenced by muscle mobilization(in order of anterior deltoid, posterior deltoid and trapezius. To properly apply the above conclusion, when tennis players serve it is better the elbow be impacted by the extension. when doing isokinetic motion it is better to increase angular velocity and improve muscle power. also the anterior deltoid amongst the shoulder muscle should be improved to develop serve speed.
The Biomechanical Analysis of Throwing Motion for the Elementary Students - Developmental Approach -
Lee, Dong-Woo ;
Korean Journal of Sport Biomechanics, volume 17, issue 1, 2007, Pages 69~79
DOI : 10.5103/KJSB.2007.17.1.069
The purpose of this study was to examine the characteristics of throwing motion in the elementary school students from the developmental point of view. For the purpose of this, total of nine subjects(each of three students in five, third, and first grades) were participated. They were asked to throw the ball as far as they can and the motions were videotaped with the 30frames/sec and 1/500 shutter speed. The successful motions for each subject were selected for three dimensional analysis. The collected data were analyzed using DV express 1.0 and Kwon3D 3.0 softwares. The results obtained from this study were as follows; 1. Total time for the throwing motion of the first grade was longer than that of the fifth and third grades. 2. The resultant displacement and velocity of COM for the fifth and third grades were greater than that of the frist grade. 3. The first grade tended to flex the trunk forward excessively during the throwing motion. 4. The fifth grade tended to place the upper arm close to the sagital plane and move the forearm and hand freely. 5. Looking at the greater variability of the angular velocity of the hand segment, the fifth grade seemed to have faster and more flexible movement of the wrist. 6. There were somewhat differences in the patterns and magnitudes of ground reaction forces among the different grades.
Development of Auto Tracking System for Baseball Pitching
Lee, Ki-Chung ; Bae, Sung-Jae ; Shin, In-Sik ;
Korean Journal of Sport Biomechanics, volume 17, issue 1, 2007, Pages 81~90
DOI : 10.5103/KJSB.2007.17.1.081
The effort identifying positioning information of the moving object in real time has been a issue not only in sport biomechanics but also other academic areas. In order to solve this issue, this study tried to track the movement of a pitched ball that might provide an easier prediction because of a clear focus and simple movement of the object. Machine learning has been leading the research of extracting information from continuous images such as object tracking. Though the rule-based methods in artificial intelligence prevailed for decades, it has evolved into the methods of statistical approach that finds the maximum a posterior location in the image. The development of machine learning, accompanied by the development of recording technology and computational power of computer, made it possible to extract the trajectory of pitched baseball from recorded images. We present a method of baseball tracking, based on object tracking methods in machine learning. We introduce three state-of-the-art researches regarding the object tracking and show how we can combine these researches to yield a novel engine that finds trajectory from continuous pitching images. The first research is about mean shift method which finds the mode of a supposed continuous distribution from a set of data. The second research is about the research that explains how we can find the mode and object region effectively when we are given the previous image's location of object and the region. The third is about the research of representing data into features that we can deal with. From those features, we can establish a distribution to generate a set of data for mean shift. In this paper, we combine three works to track baseball's location in the continuous image frames. From the information of locations from two sets of images, we can reconstruct the real 3-D trajectory of pitched ball. We show how this works in real pitching images.
Changes of Various Balls Velocity under the Different Surface Conditions after Impact
Park, Jin ;
Korean Journal of Sport Biomechanics, volume 17, issue 1, 2007, Pages 91~97
DOI : 10.5103/KJSB.2007.17.1.091
The purpose of this study was to investigate the changes of various balls velocity under the different surface conditions after impact. For this study, four different balls were used which are golf ball, tang-tang ball, table tennis ball, and iron ball. And two different types of ground conditions were used which are artificial grass green and glass green. Movements of putter head and ball were recorded with 2 HD video cameras(60 Hz, 1/500s shutter speed). Small size control object(
) was used in this study. To transfer the same amount of kinetic energy to the ball, pendulum putting machine was used. Analyzing the process of impact and the ball movement, a putter was digitized the whole movement but the ball was digizited within the 50cm movement. Velocities were calculated by the first central difference method(Hamill & Knutzen, 1995). Putter head velocities were about 112.2cm/s-116.2cm/s at impact. Maximum ball velocities were appeared 0.08s-0.10s after impact no matter what the ground conditions are. Table tennis ball recorded higher ball velocities than the other ball velocities and iron ball recorded the lowest ball velocity in this group. But Table tennis ball was influenced with the frictional force and immediately was decreased at the artificial grass green condition. If an object is received the kinetic energy under the static condition(v
The Kinematical Comparative Analysis Between Spring Shoe and General Shoe
Lee, Chong-Hoon ; Sung, Bong-Ju ; Song, Joo-Ho ;
Korean Journal of Sport Biomechanics, volume 17, issue 1, 2007, Pages 99~109
DOI : 10.5103/KJSB.2007.17.1.099
The purpose of the study is to examine the effect of the spring shoe through the comparison of spring shoe to general shoe. For this, 12 healthy females in the age from 20 to 30 years participated in the E.M.G. experiment with testing kinematic variables. Results indicated that there was significant differences in angle of ankel between the general and spring shoe. Specifically, the spring shoe showed a bigger angle of take on and a smaller angle of take off in walking than the general shoe. This mesns that the spring shoe does not have a significant effect to produce efficient and smooth walking. In addition, the spring shoes revealed a bigger rear-foot angle than the general shoe in the evaluation of rear-foot control function. This means that the rear-foot control function of the spring shoe is low compared to trhe general shoe. Meanwhile, there is no significant differences in angle of knee and angle of Achilles tendon between both shoes. In an analysis of E.M.G., the significant differences were found in gastrocnemius muscle, anterior tibial musculi, musculi rectus femoris, biceps muscle of thigh between both the general and spring shoe groups by the section. In the case of gastrocnemius muscle, the spring shoe showed a low muscle production of anterior tibial musculi than the general shoe. This is a result from structural nature of the sole of a foot of the spring shoe. The spring shoe performs a rolling movement through slightly large pronation toward front-foot from rear-foot in supprt time before taking-off of toe and the power for this movement is mainly produced from musculi rectus femoris.
A Comparative Study of Characters of Muscle Activity in Lower Limb and Gait Pattern on Type of Heel Rockers
An, Song-Y ; Kim, Sang-Bum ; Lee, Ki-Kwang ;
Korean Journal of Sport Biomechanics, volume 17, issue 1, 2007, Pages 111~119
DOI : 10.5103/KJSB.2007.17.1.111
The purpose of this study was to investigate muscle activity and gait pattern in lower limb depending on the outsole of heel rockers. Fifteen healthy men volunteered for this experiment. Each subject performed totally three trails with two pairs of different heel rocker shoes and a pair of normal running shoes at speed of 1.33m/s for 1 minute during walking on a treadmill. Kinematic data gathered in 100Hz was recorded and analyzed by using the 3D motion capture system to measure the trunk tilt and joint angle of the right lower limb. And the lower extremity muscle activities were simultaneously recorded in 1000Hz and assessed by using EMG. The statistical analysis was the one-way ANOVA with the repeated measures to compare among the three kinds of shoes. The level of statistical significance for all tests was 0.05. Joint angle of lower limb was showed statistically significant different in MST(hip joint), LHS(ankle joint), and RTO(knee and ankle joint). Muscle activity of rectus femoris and biceps femoris was statistically increased in both heel rocker shoes during gait cycle on treadmill. The maximum peak time of tibialis anterior in the negative heel rocker showed the delay of approximately 23.8%time than normal shoes. Gait pattern variability of the negative heel rocker was increased in the first half of the stance phase and the variability of the positive heel rocker was increased in the terminal stance phase. In Conclusion, stability was decreased in between joints of lower limb on positive heel rocker than negative heel rocker. This study found that there were different joint angle, muscle activity, gait pattern and coordinate system of the lower limb in each kind of shoes. These unstability affected the lower extremity and the whole body. A further study has to be continued with study of rehabilitation and exercise for a long-term.
Mechanical Behavior of the Soleus Aponeuroses during Voluntary Contraction Using Magnetic Resonance Imaging Technique
Lee, Hae-Dong ;
Korean Journal of Sport Biomechanics, volume 17, issue 1, 2007, Pages 121~127
DOI : 10.5103/KJSB.2007.17.1.121
Muscle force produced by muscle fibers is transmitted to bones via tendinous structures(aponeuroses and tendon), resulting in joint(s) movement. As force-transmitting elements, mechanical behavior of aponeuroses and tendon are closely related with the function of muscle-tendon complex. The purpose of this study was to determine strain characteristics of aponeuroses for in-vivo human soleus muscle during submaximal voluntary contractions using an advanced medical imaging technique, velocity-encoded phase-contrast magnetic resonance imaging (VE-PC MRI). VE-PC MRI of the soleus muscle-tendon complex was acquired during submaximal isometric plantarflexion contraction-relaxation cycle (n
Analysis of Variability for the Components of VGRF Signal via Increasing the Number of Attempt during Running
Ryu, Ji-Seon ;
Korean Journal of Sport Biomechanics, volume 17, issue 1, 2007, Pages 129~134
DOI : 10.5103/KJSB.2007.17.1.129
The purpose of this study was to determine the variability of components of the vertical ground reaction force signal to seek the suitable number of attempt datum to be analyzed during running at 2m/s and 4m/s. For this study, six subjects (height mean:
) were selected and asked to run at least 3 times each run condition randomly. FFT(fast Fourier transform) was used to analyze the frequency domain analysis of the vertical ground reaction forces signal and an accumulated PSD (power spectrum density) was calculated to reconstruct the certain signal. To examine the deviation of the vertical ground reaction between signals collected from an different number of attempt, variability of frequency, magnitude of passive peak, time up to the passive peak and maximum load rate were determined in a coefficient of variance. The variability analysis revealed that when analyze the vertical reaction force components at 2m/s speed running, which belongs to slow pace relatively, it would be good to calculate these components from signal of one attempt, but 4m/s speed running needs data collected from two attempts to decrease the deviation of signal between attempts. In summary, when analyzing the frequency and passive peak of the vertical reaction force signal during the fast run, it should be considered the number of attempt.
Analysis of Biomechanical Effect of the Subtalar Sling Ankle Taping
Choi, Mun-Suk ; Jeon, Hye-Seon ; Kim, Young-Ho ;
Korean Journal of Sport Biomechanics, volume 17, issue 1, 2007, Pages 135~144
DOI : 10.5103/KJSB.2007.17.1.135
The purpose of this study was to identify the effect of the subtalar sling ankle taping, by measuring changes in peak plantar pressure and subtalar angle during jump landing and walking in healthy subjects with subtalar sling ankle taping applied of the ankle joint. Fifty healthy subjects(8 males and 7 female, aged 22 to 25) were randomly divided into a participated in this study. They were free of musculoskeletal injury and neurologic deficit in lower extremity. The subjects were asked to perform 5M walking and single leg jump landing by under the guidance of physical therapists. Subtalar motions were typically measured as the angle made between the posterior aspect of the calcaneous and the posterior aspect of the lower leg during walking with taping or not. This measurement were made using a video system (30Hz sampling rate, rectified 60 Hz sampling rate). At the same time, peak lateral and vertical pressure were investigated using pressure distribution platforms(MatScan system) under foot during walking and single leg jump landing with taping or not. Statistical analysis was done by paired t-test and intraclass correlation coefficient [ICC(3.1)], using software SPSS. We have recently demonstrated significantly altered patterns of subtalr joint and peak plantar pressure when applied subtalar sling ankle taping(p<.05). Inversion angle of subtalar joint significantly decreased with taping(p<.05). The result suggest that pressure patterns observed in subjects are likely to result due to significant decrease in stress on ankle joint structures during jump landing and walking. Also, the result that the subtalar sling ankle taping procedure provides greater restiction of motion associated with ankle inversion. However, this study involved asymptomatic subjects without history of ankle inversion injury, further research is needed to assess the motion restraining effect of the subtalar sling ankle taping in subjects with lateral ankle instability.
The Kinematic Analysis of Handspring Salto Forward Piked
Kwon, Oh-Seok ;
Korean Journal of Sport Biomechanics, volume 17, issue 1, 2007, Pages 145~153
DOI : 10.5103/KJSB.2007.17.1.145
The purpose of this study is to compare and analyze the phase-by-phase elapsed time, the COG, the body joint angle changes and the angular velocities of each phase of Handspring Salto Forward Piked performed by 4 college gymnasts through 3D movement analysis program. 1. The average elapsed time for each phase was .13sec for Phase 1, .18sec for Phase 2, .4sec for Phase 3, and .3sec for Phase 5. The elapsed time for Phase 1 to Phase 3 handspring was .35sec on average and the elapsed time for Phase 4 to Phase 5 handspring salto forward piked was .7sec on average. And so it showed that the whole elapsed time was 1.44sec. 2. The average horizontal changes of COG were 93.2 cm at E1, 138. 5 cm at E2, 215.7 cm at E3, 369.2 cm at E4, 450.7 cm at E5, and 553.1 cm at E6. The average vertical changes of COG were 83.1 cm at E1, 71.3 cm at E2, 78.9 cm at E3, 93.7 cm at E4, 150.8 cm at E5, and 97.2 cm at E6. 3. The average shoulder joint angles at each phase were 131.6 deg at E1, 153.5 deg at E2, 135.4 deg at E3, 113.4 deg at E4, 39.6 deg at E5, and 67.5 deg at E6. And the average hip joint angles at each phase were 82.2 deg at E1, 60 deg at E2, 101.9 deg at E3, 161.2 deg at E4, 97.7 deg at E5, and 167 deg at E6. 4. The average shoulder joint angular velocities at each phase were 130.9deg/s E1, 73.1 deg/s at E2, -133.9 deg/s at E3, -194.4 deg/s at E4, 29.4 deg/s at E5, and -50.1 deg/s at E6. And the average hip joint angular velocities at each phase were -154.7 deg/s E1, -96.5 deg/s at E2, 495.9 deg/s at E3, 281.5 deg/s at E4, 90.3 deg/s at E5, and 181.7 deg/s at E6. The results shows that, as for the performance of handspring salto forward piked, it is important to move in short time and horizontally from the hop step to the point to place the hands on the floor and jump, and to stretch the hip joints as much as possible after the displacement of the hands and to keep the hip joints stretched and high in the vertical position at the takeoff. And it is also important to bend the shoulder joints and the hip joints fast and spin as much as possible after the takeoff, and to decrease the speed of spinning by bending he shoulder joints and the hip joints quickly after the highest point of COG and make a stable landing.
A Kinematic Analysis of the Defence Types during Body Lock Technique in the Ground Wrestling
Hah, Chong-Ku ; Ryu, Ji-Seon ;
Korean Journal of Sport Biomechanics, volume 17, issue 1, 2007, Pages 155~164
DOI : 10.5103/KJSB.2007.17.1.155
This study is to find out effective defensive type by analysis on differences among three different defence types of the body lock technique in the ground wrestling. The subjects are 5 athletes who are in 60kg weight class. To get the kinematic analysis seven ProReflex MCU-240(Motion Capture Unit), infrared rays cameras, which was produced by Qualisys, were used to get a two-dimensional coordinate. Following are the analysis result from kinematic factors such as time element, speed element and angular element. 1. During position of ground wrestling, the average necessary time until defender's hip joint touches the mat for Phase1 was
at side position was the shortest space of time out of three types, and Phase2 was
at front position was the shortest space of time out of three types. Moreover, side defence position was the shortest for total average necessary time with
. 2. The movement change for hip joint was
for rear, and
for side at Phase1 and
for front, and
for rear at Phase2. 3. Movement speed of hip joint at defensive type were most effective in success and fail rate at Phase 1 and its frontal average speed was fastest with
for side, and
for rear. The average for total change of speed is
for side, and
for rear. 4. The joint angle gets smaller in a order by rear, front, and side for the size of hip joint angle and knee angle for different defensive type. 5. As a result of one-way ANOVA on linear velocity for hip joint in frontal defence(phase1) was significance (
=.05), but phase 2 was not significance. Synthetically, analyzing on differences among three different defence types which were front, rear, and side of the body lock technique in the ground wrestling, front defensive type was the most effective. In future, there should be more studies regarding on defence at not a laboratory study but a field study to help out wrestler to pertinent techniques to improve the game of wrestling.
Kinematical Analysis of Basket with 1/2 Turn to Handstand on Parallel Bars
Back, Jin-Ho ; Park, Jong-Chul ; Lee, Yong-Sik ;
Korean Journal of Sport Biomechanics, volume 17, issue 1, 2007, Pages 165~174
DOI : 10.5103/KJSB.2007.17.1.165
The subject of this study was male apparatus gymnastics athlete who had scored high points doing basket with 1/2 turn on parallel bars. Then 3D motion analysis were used to calculate & analyse kinematic variables of Basket with 1/2 turn to Handstand. 1. The total average time spent for Basket with 1/2 turn took
, at the downward upward phase took
, at flight phase took
, at connected area phase took
, at rotation area phase took
. To have a successful performance, there should be faster speed and velocity to rotate at the downward upward phase, then the upward velocity and height must be used adequately. Moreover, the speed must be faster at the flight connect phase to stabilize Center of Mass(CM) for the body, and must secure more time at the rotation area to have more stable performance. 2. After handstand on parallel bars while moving CM to right hand side, and It must be performed with big and magnificent performance with putting both hand's center to far away from the parallel bars. 3. Furthermore, CM must be moved fast from downwards to right hand side, and CM must be moved fast in vertical movement at upward and flight phase to avoid CM from moving back and forth, and left and right. 4. At downwards, the subject must rotate as bis as possible using hip-joint as wide as possible and at upwards, must put his body to vertical to have stable performance. While rotating or turning, it is better to do with bigger shoulder angle and have to make sure that trunk angle must be not scattered. To perform better and more positive in basket with 1/2 turn on parallel bars, the centrifugal force must be used big and fast at downward, and at upward and flight phase, downward movement must change to vertical movement as soon as possible while turning movement must happen at handstand position. Time spent must be shorten at connected area to stabilize CM and turning must be natural as possible while securing the necessary time of movement to well-balanced. Also, the body must be vertically closed from the ground.
The Effect of Upper Extremity Usage and Length of Training to the Function of Dance Turn
Park, Yang-Sun ; Lim, Young-Tae ;
Korean Journal of Sport Biomechanics, volume 17, issue 1, 2007, Pages 175~184
DOI : 10.5103/KJSB.2007.17.1.175
The first purpose of this study was to compare kinematic variables during spinning motion with or without upper extremity and identify the most effective spinning method. The second purpose of this study was to compare functional difference between novice and elite dancers with the term of training. Ten experienced female dancers and ten novices were recruited as subjects for this study. Elite group was asked to perform turn motion with three types of upper extremity. Novice group has taken training of spotting technique for five weeks. Four Falcon HiRES cameras were used to analyze kinematic variables including head angular velocity and CG displacement during spinning. These data were sampled before training, after 3-week, and 5-week of training. Eight different events in two consecutive turns were defined for statistical comparison. One-way ANOVA was performed to compare among the kinematics of turning motion with three types of upper extremity. Independent t-test also used to compare kinematics between elite and novice at three different length of training. As results, spinning with both arm increased angular velocity and stability compared to the turning motion with one arm or with arm strapped and found out that the turn with both arm was the most effective way of spin. Also, for novice dancers, three weeks of training were needed to complete spinning motion.
Does the Control of Breathing Help a Dancer to Perform a Smoother Ballet Pour de Bra?
Chung, Kui-In ; Nam, Ki-Jeong ;
Korean Journal of Sport Biomechanics, volume 17, issue 1, 2007, Pages 185~190
DOI : 10.5103/KJSB.2007.17.1.185
The purpose of this study was to investigate the effects that breathing, thoracic and abdominal, had on the smoothness while performing ballet pour de bra. Five skilled ballet dancers(age:
) with experience of over 10 years participated in this study. Each participant performed the ballet movement three times with abdominal respiration and with thoracic respiration. The kinematic data was recorded at 60 Hz with three digital cameras (Sony VX-2100). The pour de bra movement consists of two phases, up and down. The up phase is defined as the movement from the en bas through the en avant to the en haut. The down phase is defined as the movement from the en haut through the
la seconde to the en bas. During these two phases the Jerk Cost (JC) factor was calculated for the shoulder, elbow and wrist to quantify the smoothness. The group who performed the movement while abdominal respiration had a lower JC factor and so it was concluded that while abdominal respiration the smoothness of the movement was increased as opposed to the thoracic respiration.
Kinematical Analysis of Angle and Angular Velocity of the Body Segment on Spike in Volleyball
Cho, Phil-Hwan ;
Korean Journal of Sport Biomechanics, volume 17, issue 1, 2007, Pages 191~199
DOI : 10.5103/KJSB.2007.17.1.191
This study was conducted to examine the biomechanical characteristics of open spike in the volleyball to improve the technique of the volleyball spike. The subjects were six male college and high school athletes. The motions of volleyball spike were filmed by using two Sony VX 2000 Video Cameras. The mechanical factors were angle and angular velocity of body segments in the upper and the lower limbs. The conclusions were as follows; 1. The angle of the shoulder joint of the skilled showed larger than that of the unskilled in impacting of the volley ball spike. 2. The angle of the elbow joint of the skilled showed larger than that of the unskilled in impacting of the volley ball spike. 3. The angle of the wrist joint of the skilled showed smaller than that of the unskilled in impacting of the volley ball spike. 4. The angle of the hip joint of skilled showed larger than that of unskilled in impacting of the volley ball spike. 5. The angle of the knee joint of the skilled and the unskilled showed same in take off and impacting of the volley ball spike, and that of the skilled showed smaller than that of the unskilled in take-off touchdown and touchdown after impact of the volley ball spike. 6. The angle of the ankle joint of skilled showed larger than unskilled in take-off of the volley ball spike. 7. The angular velocity of the shoulder joint, elbow joint, wrist joint of the skilled showed faster than that of the unskilled in impacting of the volley ball spike. Taken together the result of them, I have come to conclusion that knee joint angle in touchdown of the take off should be decreased and knee joint angle in take off should be increased, and then stability of the take off should be made and, and that extension of the elbow joint should be made and wrist joint angle decreased and shoulder and hip joint angle increased, and then C.O.G of the arm and hand should be positioned ahead C.O.G of the body in impacting for effective impact of the spike, and that the transfer of the angular velocity of body segments for effective impact of the spike make from the proximal segment to the distal segment at spike in volleyball.