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REFERENCE LINKING PLATFORM OF KOREA S&T JOURNALS
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Korean Journal of Sport Biomechanics
Journal Basic Information
Journal DOI :
Korean Society of Sport Biomechanics
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Volume & Issues
Volume 16, Issue 4 - Dec 2006
Volume 16, Issue 3 - Sep 2006
Volume 16, Issue 2 - Jun 2006
Volume 16, Issue 1 - Mar 2006
Selecting the target year
Analysis of golf putting for Elite & Novice golfers Using Jerk Cost Function
Lim, Young-Tae ; Choi, Jin-Sung ; Han, Young-Min ; Kim, Hyung-Sik ; Yi, Jeong-Han ; Jun, Jae-Hun ; Tack, Gye-Rae ;
Korean Journal of Sport Biomechanics, volume 16, issue 1, 2006, Pages 1~10
DOI : 10.5103/KJSB.2006.16.1.001
The purpose of this study was to identify critical parameters of a putting performance using jerk cost function. Jerk is the time rate of change of acceleration and it has been suggested that a skilled performance is characterized by decreased jerk magnitude. Four elite golfers(
) and 4 novice golfers participated in this study for the comparison. The 3D kinematic data were collected for each subject performing 5 trials of putts for each of these distances (random order): 1m, 3m, 5m The putting stroke was divided into 3 phases such as back swing. down swing and follow-through. In this study, it was assumed that there exist smoothness difference between elite and novice golfers during putting. The distance and jerk-cost function of Putting stroke for each phase were analyzed Results showed that there was a significant difference in jerk cost function at putter toe (at media-lateral direction) and at the center of mass between two groups by increasing putting distance. From these it could be concluded that jerk can be used as a kinematic parameter for distinguishing elite and novice golfers.
Relationship between Walking Speed and Smoothness of Movement
Tack, Gye-Rae ; Han, Young-Min ; Choi, Jin-Sung ; Yi, Jeong-Han ; Lim, Young-Tae ; Jun, Jae-Hoon ; Park, Sang-Kyoon ; Stephanyshin, Darren ; Park, Seung-Ha ;
Korean Journal of Sport Biomechanics, volume 16, issue 1, 2006, Pages 11~17
DOI : 10.5103/KJSB.2006.16.1.011
The purpose of this study was to evaluate the smoothness of movement during various walking speeds. Based on the maximum smoothness theory (or the minimum jerk theory), we hypothesized that the walking speed at the maximum smoothness (or minimum normalized jerk) is the same as that at the minimum energy consumption. Eleven university students participated in treadmill walking experiment with 11 different walking speeds (1.11, 1.19, 1.25, 1.33, 1.56, 1.78, 1.9, 2, 211, 233, and 2.47m/sec). Normalized jerk at 15 markers and the center of mass was calculated. Results showed that there existed a quadratic relationship between the normalized jerk of the vertical direction at the center of mass and the walking speed As the walking speed increased, the normalized jerk of all directions at the heel decreased Our hypothesis that the previously published energetically optimal walking speed (
) is the same as the minimum jerk speed (1.78m/s) did not agree with this result. The minimum normalized jerk at the center of mass occurred at the walking speed of 1.78m/s which was the preferred walking speed by subjects' questionaries. Further studies concerning the energetically optimal walking speed, preferred walking speed, and walk-run transition speed or run-walk transition speed are necessary based on actual energy consumption experiment and various multi-dimensional analysis.
The Evaluation of Custom Foot Orthotics for Injury Prevention of Joggers
Kim, Ro-Bin ;
Korean Journal of Sport Biomechanics, volume 16, issue 1, 2006, Pages 19~30
DOI : 10.5103/KJSB.2006.16.1.019
The purpose of this study was to examine the effect of foot orthotics on the overall comfort and muscle activity during running. The subjects were 10 members from the joggers` club which consisted of 2 women and 8 men. These individuals ran on the treadmill by 4.0m/s speed with and without the custom foot orthotics. The data concerning the overall comfort was collected by a questionairre that examined the overall comfort, heel cushioning, forefoot cushioning, medio-lateral control, arch height, heel cup fit, shoe heel width, forefoot width, and shoe length The MegaWin ver. 2.1(Mega Electronics lid, Ma. Finland) was used to gain electromyography signals of the muscle activity; Tibialis anterior, medial gastronemius, lateral gastronemius, vastus lateralis, vastus medialis, biceps femoris, and rectus femoris were measured. The results of the study were as follows. 1. During running the overall comfort was higher for the foot arthotic condition than the nonorthotic condition. Among the inquiries the overall comfort showed the biggest difference comparing the two conditions. and the shoe heel width showed the highest score for contort. 2 The muscle activity of the biceps femoris, and vastus lateralis in the stance period decreased. due to the foot orthotics. The muscle activity of the vastus medialis in the swing period also decreased and the muscle activity tibialis anterior in the stance and swing stance decreased as well During running, orthotics showed positive result in foot comfort. The foot comfort related to decreased stress, muscle activity, and foot arch strain. Overall comfort and the adequate decrease of muscle activity were associated with injury prevention and the best method to prevent injury semms to be the maintenance of foot comfort.
A Biomechanical Comparative Analysis of the Multi-Radius Total Knee Arthroplastry System for Go up Stair and Go down Stair
Jin, Young-Wan ; Yoo, Byung-In ; Kawk, Yi-Sub ;
Korean Journal of Sport Biomechanics, volume 16, issue 1, 2006, Pages 31~41
DOI : 10.5103/KJSB.2006.16.1.031
The primary purpose of a TKA is to restore normal knee function Therefore, ideally, a TKA should: (a) maintain the natural leverage of the knee joint muscles to ensure generating adequate knee muscle moments to accomplish daily tasks such as rising from climbing stairs; (b) provide adequate knee joint stability. A 16-channel MyoResearch XP EMG system was used to collect the differential input surface electromyography signals VM, VL, RF, BF, ST during climbing/descending stair tests. A Peak Motion Measurement System was used to collect the kinematic and kinetic data. AKIN-COM Ill isokinetic dynamometer was used for EMG of VM, VL, RF, BF and ST during maximal voluntary contraction. I Quadriceps EMG results for the VM of the passed 1year group limb demonstrated significant less RMS EMG than that of the passed 3year group limb
of knee flexion(p<0.05). The VL of the passed 1year group limb also demonstrated significants less RMS EMG than that of the passed 3year group limb from
of knee flexion(p<0.05). Similar to the VM and VL, the RF of the passed 1year group limb showed less RMS EMG than that of the passed 3year group limb from
do knee flexion(p<0.05). Hamstring EMG results for the BF of the passed 1year group limb demonstrated less RMS EMG than that of the passed 3year group limb from
of knee flexion(p<0.05). The passed 1year group limb tended to have less ADD displacement(p<0.071) than that of the passed 3year group limb. There was no significant difference of the ABD displacement between the passed 1year group and the passed 3year group limbs(p<0.73). The passed 3year group used compensatory adaptation movement strategies to compensate for the strength deficit of passed 3year group limbs. The passed 3year group limb also increased the quadriceps muscle activation level to produce more knee extension moment to compensate for the short quadriceps moment arm. The passe 3year group limb might have an unstable knee joint in the medio-Iateral direction during the climbing/descending by showing a tendency of more ADD displacement and greater hamming co-activation EMG than the passed 1year group limbs. The TKA design was not able to help the knee joint to produce adequate knee extension moment with less quadriceps muscle effort. I think that old man needs continuous exercise for muscle strength.
A Study on Weight Transfer Sidehill Slopes during Goal Impact : Especially sidehill Slopes with ball above the feet
Lee, Eui-Lin ; Choi, Ji-Young ;
Korean Journal of Sport Biomechanics, volume 16, issue 1, 2006, Pages 43~53
DOI : 10.5103/KJSB.2006.16.1.043
Among several movements that occurred upon a slope, golf swing is the most typical one because environmental conditions dynamically vary with many kinds of slopes. Some studies on the golf swing were performed about a weight transfer on flatland, however, there couldn't be seen any study about the weight transfer on slope elsewhere. Therefore, the purpose of this study was to provide quantified data to objectively test the coaching words and keys about the weight transfer at sidehill slope during goal impact EspeciaIly sidehill Slopes with ball above the feet. Four highschool golfer, who have average handy 5, were recruited for this study. Plantar pressure distribution and cinematographic data were collected during golf swing in the conditions of flatland,
sidehill slope simultaneously. The two data were used to synchronize the two data later. The plantar regions under the foot were divided into 8 regions according to the directly applied pressure pattern of the subject to insole sensor. The 8 foot regions were hullux, medial forefoot, central forefoot, lateral forefoot, medial midfoot, lateral midfoot, medial heel, and lateral heel. And the plantar pressure data was also divided into four movement address, phases-backswing. downswing, and follow-through phases according to the percentage shown to the visual information of film data. Based on the investigations on public golf books and experiences of golfers, it was hypothesized by the authors in the early of this study that the steeper slopes are, the more weight loads on left foot that positions at the higher place. When observing the results of plantar pressure and vertical force curves according to the sidehill slope conditions, the hypothesis could be accepted.
Kinematic Analysis of Deff Motion in High Bars
Back, Jin-Ho ;
Korean Journal of Sport Biomechanics, volume 16, issue 1, 2006, Pages 55~63
DOI : 10.5103/KJSB.2006.16.1.055
The purpose of this study is to prove the kinematical characteristics of Deff motion, the high bar performance, in terms of flying phases so that we can provide basic sources for improving gymnastic performance. To do this, we selected and analyzed the performance of two athletes who did Deff motion in the high bar competition of male artistic gymnastic in the 22nd Universiade 2003 Daegu. We drew the conclusions from the kinematical factors that were came out through analyzing three-dimensional cinematography of the athletes` movements, by using a high speed video camera. To make a successful performance, a performer releases the bar at a height of a high bar vertically and at a height of 82cm horizontally, and the flying performance should be made without moving forward, as maintaining the proper balance, in order to rise over 118cm high during the flying phase. When the performer is releasing the bar, an increase of the vertical speed in the center of the body and extension of a knee joint and a hip joint contribute to increasing a flying height. And when the moving body is twisted, leaning to left side is caused by the winding movement of a knee joint, which causes an unstable bar grasp. To grasp the bar stably, just before releasing the performer should gain propulsive force from twisting rotation through increasing the speed of shoulder rotation. And before the peak point, the performer should make sure of a body rotation distance over
so that he or she can do an aerial rotary performance smoothly. When grasping the high bar, the center of the body should be above the bar and the angle of shoulder rotation should be maintained close to
simultaneously. he high point performance(S1) has more speed on an ascending phase and less speed on a descending phase than the low point performance (S2). At the peak point, both the rotation angle of the body and that of the shoulder in high point performance are big as well. In conclusion, it is shown that a performer can make a jump toward the high bar easily with the body straight because the performer can hold the upper part of the body erect early in a descending phase.
Correctional Function of Custom Foot Orthotics for Foot Diseases related to Excessive Pronation during Gait
Kim, Seung-Jae ;
Korean Journal of Sport Biomechanics, volume 16, issue 1, 2006, Pages 65~79
DOI : 10.5103/KJSB.2006.16.1.065
The purpose of this study was firstly to investigate correctional function of custom semi-rigid foot orthotics for excessively pronated people during gait by observing comfort, navicular movement and leg muscles` activity according to short-term and mid-term wearing duration and secondly to understand positive and/or negative point of view of a recently proposed paradigm related to foot orthotics more profoundly. Sixteen subjects who showed excessive pronation at navicular drop test were recruited for this study. Custom semi-rigid foot orthotics were made fitting for foot characteristics of the subjects by podiatry division of Otto Bock Korea company. While wearing the foot orthotics for two months, comfort of wearing were questioned and vertical navicular movement and electromyography of leg muscles during gait were measured at the condition of both immediately after and 2 months after including a control condition, respectively. The subjects were required to walk on a treadmill at the speed of 1.5m/s and four digital video camera filmed the movement of navicular process at the speed of 60 frames/s. In conclusion, in excessively pronated group continuous increase of comfort from short-term to mid-term wearing of custom foot orthotics is assumed to be closely related with short-term and mid term correctional action, of which are consisted the decrease of the range of navicular drop and navicular raisins- the faster timing of minimum navicular position occurring, and the decrease of leg muscles` activities. This conclusion could lead to positively accept new paradigm related to foot orthotics suggested by Nigg and the author suggest that in the future study the variable which could observe navicular movement would be one of major variables to study preferred path of skeleton in the paradigm.
C Ball speed by a professional baseball player, and study of comparison of uniform rotational speed by the shoulder joint
Park, Sung-Jin ; Park, Young-Jin ;
Korean Journal of Sport Biomechanics, volume 16, issue 1, 2006, Pages 81~88
DOI : 10.5103/KJSB.2006.16.1.081
Present study is to know the relation with throwing speed according to the uniform torque by the shoulder joint, over 20 persons of professional baseball, and were measured the uniform torque by the shoulder joint accordance with throwing speed between (A-low speed) and (B-high speed) of each group. In the present study, three components were measured, and analyzed with having an approximated output value appearing by changing angular velocity, and in
, the maximum strength of muscles was measured, and in
, the points of endurance strength of muscles were measured and analyzed, and the following result could be obtained. 1. In muscles strength (peak torque)of inner rotation, and outer rotation for respect to each speed of shoulder joint, though there did not appear outstanding difference between A group and B group in the
, it showed that group B has priority in a little. Also in outer rotation by shoulder joint, though there appeared the same difference between A group and B group, B group is tended to be prior to A group in a little. 2 In the view of muscles strength (peak torque)of inner rotation, and outer rotation for respect to each speed of shoulder joint, though there did not appear outstanding difference between A group and B group in the
, it showed that group B has priority in a little. Also in outer rotation by shoulder joint, though there appeared the same difference between A group and B group, B group is tended to be prior to A group in a little. 3. In the view of muscles strength(peak torque)of inner rotation, and outer rotation for respect to each speed of shoulder joint, though there did not appear outstanding difference between A group and B group in the
, it showed that B group has priority in a little. Also in outer rotation by shoulder joint, though there appeared the same difference between A group and B group, B group is tended to be prior to A group in a little. 4. In the view of peak torque for respect to the weight accordance with each velocity of shoulder joint, there did not appear outstanding difference between A group and B group. In outer rotation by the shoulder joint, there was not appeared clear difference between A group and B group. 5. In the concern of the peak torque for respect to the weight accordance with each velocity of shoulder joint, there did not appear outstanding difference between A group and B group in
. In outer rotation by the shoulder joint, there was not appeared clear difference between A group and B group. 6. In the concern of the peak torque for respect to the weight accordance with each velocity of shoulder joint, there did not appear outstanding difference between A group and B group in
. In outer rotation by the shoulder joint, there was not appeared clear difference between A group and B group. As conclusion, there did not appear a correlation of uniform torque by shoulder joint versus the speed throwing by a pitcher of professional base ball.
Kinematic Analysis of Acopian in Vault
Lee, Soon-Ho ; Park, Jong-Hoon ; Lee, Chong-Hoon ;
Korean Journal of Sport Biomechanics, volume 16, issue 1, 2006, Pages 89~99
DOI : 10.5103/KJSB.2006.16.1.089
The study were to assess technical factors between the high score group and the low score group, from the subjects of 16 male national gymnasts, and to analyze the kinematical characteristic and main technical cause on technique of Akopian's 3D motion analysis of the male vaulting game in 2001 classification championship. The result of this study is this. There were not so much difference between the two groups in term; of the time of board contact, pre-flight, and total performance, but it takes shorter time when the players who are in the high point group take down the board, and they take long time for post-flight(p<.01). The high point group has a longer perpendicular distance in the moment of horse taking off, 0.05m on the average, than the low point group. The high point group shows 0.16m higher on the average than the other group in term; of the height of post-flight(p<.01). In the phase of board contact, the range of horizontal velocity at board take on were
, but there weren't significantly statistic differences between two groups. The hight score group were 0.68m/s faster than the low point group at the horizontal velocity at board take off event(<.05). About the average horizontal velocity of deceleration, AG1(-1.95m/s) reduces the speed more than AG2(-1.57m/s)(p<.05). And the hight score group were 0.37m/s faster than the low point group at the vertical velocity at horse take off event(<.05). When board taking off, the projectile angle of com were
on the average. the comparative groups show almost same results. When horse taking off, the HPVy of the high point group were 37.6 degree which were a little higher than the low point group. The angular velocities of the players who takes on the horse with a right hand and then takes off with a left hand in the high point group were 14.97rad/sec, 10.82rad/sec in the low point group. However, the angular velocity of the players who takes on the horse with a left hand and then takes off on a right hand with the high point group were 14.97rad/sec, 15.56rad/sec in the low point group.
The Effects of Wearing Roller Shoes on Ground Reaction Force Characteristics During Walking
Chae, Woen-Sik ;
Korean Journal of Sport Biomechanics, volume 16, issue 1, 2006, Pages 101~108
DOI : 10.5103/KJSB.2006.16.1.101
The purpose of this study was to compare GRF characteristics during walking wearing jogging and roller shoes. Twelve male middle school students (age:
) who have no known musculoskeletal disorders were recruited as the subjects. Kinematic data from six S-VHS camcorders(Panasonic AG456, 60 fields/s) and GRF data from two force platform; (AMII OR6-5) were collected while subjects walked wearing roller and jogging shoes in random order at a speed of 1.1 m/s. An event sync unit with a bright LED light was used to synchronize the video and GRF recordings. GRF data were filtered using a 20 Hz low pass Butterworth. digital filter and further normalized to the subject`s body weight. For each trial being analyzed, five critical instants and four phases were identified from the recording. Temporal parameters, GRFs, displacement of center of pressure (DCP), and loading and decay rates were determined for each trial. For each dependent variable, paired t-test was performed to test if significant difference existed between shoe conditions (p <.05). Vertical GRFs at heel contact increased and braking forces at the end of initial double limb stance reduced significantly when going from jogging shoe to roller shoe condition. Robbins and Waked (1997) reported that balance and vertical GRF are closely related It seems that the ankle and knee joints are locked in an awkward fashion at the heel contact to compensate for the imbalance. The DCP in the antero-posterior direction for the roller shoe condition was significantly less than the corresponding value for the jogging shoe condition. Because the subjects tried to keep their upper body weight in front of the hip to prevent falling backward, the DCP for the roller shoe condition was restricted The results indicate that walking with roller shoes had little effect on temporal parameters, and loading and decay rates. It seems that there are differences in GRF characteristics between roller shoe and jogging shoe conditions. The differences in GRF pattern may be caused primarily by the altered position of ankle, knee, and center of mass throughout the walking cycle. Future studies should examine muscle activation patterns and joint kinematics during walking with roller shoes.
The Kinematic Analysis of the Rybalko Motion on the Horizontal Bar
Lee, Byoung-Won ;
Korean Journal of Sport Biomechanics, volume 16, issue 1, 2006, Pages 109~117
DOI : 10.5103/KJSB.2006.16.1.109
The purpose of this study was done in order to investigate the Kinematical variables of the Rybalko motion on the Horizontal bar using the 3-dimensional cinematographic method. For this study, three excellent athletes take part in a 2003 Daegue universid game were chosen. The subject,s Rybalko motion was filmed with S-VHS camera at the speed of 60 fields per second and digitized the each fields. And the Kwon3D 3.1 version program was employed to obtain 3-dimensional data. As a result of this study. 1. A total time spent for performing Rybalko skill was Mean
. From starting down swing to releasing right hand the Mean
was taken. 2. In the event 3 of Rybalko motion, that is, the moment which the right-hand is released on the bar, the center of mass must is employed at the position above the horizontal line of bar. In this research, the average vertical displacement(z axe) of center of mass shows
. 3. In the event 5, that is, the moment which the right-hand is catched again on the bar, the center of mass is employed at the position before the vertical line of bar. In this research, the average horizontal displacement(z axe) of center of mass shows
. 4. It has been seen that, at the moment of release of right-hand, lateral variation of center of mass is 13.395cm, vertical variation of center of mass is 7.41cm Thus, it is concluded that lateral variation of center of mass should be reduced for high grade to be acquired. 5. It has been founded that high speed of down swing influences speed of up swing, and that, in the motion of twist, the horizontal speed is little changed.
Analysis of Ground Reaction Force with Different Soccer Studs
Lee, Joong-Sook ;
Korean Journal of Sport Biomechanics, volume 16, issue 1, 2006, Pages 119~128
DOI : 10.5103/KJSB.2006.16.1.119
This study was performed to see ground reaction force with different soccer studs with twelve players in Human Performance Laboratory(University of Calgary). Running speed was
in straight running as well as vcut running. By using four different kinds of shoes; three different pairs of soccer shoes and one pair of jogging shoes, I reached a conclusion as following. In case of right and left ground reaction force, on the assumption that the positive magnitude of power is inversion and the negative is eversion, vcut running did not occur any inversion, which in the aspect of kinetic mechanics, thought to be decelerating movement. Because when eversion happens, it arises component force of power on heading direction about 8.6 times more than in the movement of straight running. In case of front and rear ground reaction, on the assumption that the positive magnitude of power is suspension power and the negative is propulsion, vcut movement is thought to be decelerating movement in the aspect of kinetic mechanics. Because on heading direction, this movement occurs component force of power about 1.8 times more suspension and 2.2 more propulsion than in the straight running movement. In case of vertical ground reaction, on the assumption that the first peak is the magnitude of power in impact and the second peak is the magnitude of power in active, we judged that the straight running movement performed more efficiently than the vcut movement in the aspect of kinetic mechanics. On the next study, I suppose that vcut running would make up an interesting subject in the aspect of improving kinetic performance ability.
A Study of the prediction of spinning table-tennis balls
Han, Min-Sung ; Lee, Hoon-Sik ;
Korean Journal of Sport Biomechanics, volume 16, issue 1, 2006, Pages 129~138
DOI : 10.5103/KJSB.2006.16.1.129
The motion of a spinning table-tennis ball is investigated in both theory and experiment. The equation of motion of spinning table-tennis ball is made using aerodynamics and calculated by C++ program In theoretical part, gravity, drag force and lift force are regarded as main force. Velocity, angular velocity, mass and Drag and lift coefficients are considered as a independent variable. Experiments are made by a digital stroboscope, a digital camera and a mirror, and snap multi-exposed images were took as a dependent result In experimental part, both magnitude and direction of velocity and angular velocity are changed in each situation. The predicted three-dimensional trajectories of spinning balls are compared with experimental trajectories. As a result the theoretical trajectories were predicted within 10% of experimental trajectories.
A Kinematics Analysis of Inward 1½ Somersault in Platform dives
Lee, Jong-Hee ;
Korean Journal of Sport Biomechanics, volume 16, issue 1, 2006, Pages 139~149
DOI : 10.5103/KJSB.2006.16.1.139
This study is to analyze the kinematic variables of inward
somersault in platform diver. For the manner, 3 people form the national diving team in the year 2000were 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 filterin 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. However, horizontal distance which is the change of the COG, form the point of the jump to the point of Event 3 where the player is out of the board range completely, Subject B showed 105.1cm and 71.1cm of the vertical distance which are shorter horizontal distance and higher vertical distance, thus, took a great advantage of the position to prepare for the entry. Therefore, if a player takes higher position by speeding up the vertical velocity at the moment of the jumping off the board, and stays in the air longer, the player can have more time to show his skill. Because of the use of the characteristics of the inward somersault, keeping the safe distance form the board is important but in order to higher the completeness, it is ideal to keep the horizontal distance little over 100cm. Also, the angles of shoulder and elbow from Event 1 to 4, depending on swing of the arms, motions in the air, getting ready for the entry, showed some difference individual by individual, according to the velocity of the thigh and shank showed much difference while getting ready and take-off, and it`s because of the individual`s different bending and straightening for horizontal and vertical distance.
The Kinematical Characteristics of the Basic Ballet Position
Kim, Eun-Hee ;
Korean Journal of Sport Biomechanics, volume 16, issue 1, 2006, Pages 151~158
DOI : 10.5103/KJSB.2006.16.1.151
The purpose of this study was to find out the kinematical characteristics of arm`s basic position in ballet. In order to achieve the purpose of the study, 3D cinematographic analysis was conducted with a ballerina who might performed the perfect arm`s basic position. According to the results of this study, it was appeared that the shoulder kept about 78%-82%, the elbow kept about 62%-96%, the wrist kept 52%-109%, and finger kept 48%-110% with the height. Also, movement was formed with
of the upper arm angle,
of the elbow,
of the wrist, and
of the shoulder. The left-right ratio of the total arm angle was 98% in the first, second, and third position, and 100% in the forth position. The angle of arm gradient was remained
in the first position,
in the second position,
in the third position, and
in the forth position. Based on the results mentioned above, balance and symmetry of both arms was an important factor in those four positions. Although it is impossible to maintain the position like robot, it may be a good performance if a certain level of extent was remained With respect to this point of view, it may be a good position if the difference between right and left arm in each joint can be remained within 2%. Angle also was an important factor that if the difference in total angle can be remained within 2% it may be an excellent position, there was difference of right and left based on the joint though. Therefore, practice and instruction to make a perfect symmetry as much as possible were needed Also, it would be a good movement if position and angle of joint within 2% difference of right and left arm can be remained In turn, because ballet is movement with expression of the body, beauty of the body and balance of the movement have to be harmonized for beautiful performance. Therefore, it would be a meaningful future study considering the body condition and movement of ballerina to define the beauty.
A Fatigue Analysis on Lumbar Extension Muscle during Repeated Trunk Extention Exercise for Chronic Lumbar Pain
So, Jae-Moo ; Lee, Chul-Kyu ;
Korean Journal of Sport Biomechanics, volume 16, issue 1, 2006, Pages 159~166
DOI : 10.5103/KJSB.2006.16.1.159
The purpose of this study were analysed fatigue character of lumbar extension Muscle during repeated trunk flexion-extension motion we used EMG multi-telemeter (WEB 5000, Nihon Koden, Japan), Medex lumbar extension machine(Ocala, USA). We evaluated 20 persons on chronic low back pain group and 20 persons on control group. We analysed the quantitative variables IMF, MF, decreased ratios of MF to investigate fatigue. As a result, the following conclusion was drawn : 1. Each lumbar IMF of CLBP was L5> L3> L1 in the order of their size. CON group was similar quantitative and same order. But the relationship of two groups were not significantly. 2 The IMF within lumbar position(L1-L3, L1-L5, L3-L5) of two groups was significantly all positions(p<.05). 3. The MF shifting at lumbar position of two groups during repeated trunk flexion-extension motion was decrease shifting pattern with increase repeating motion, especially CLBP group was suddenly dropping than CON at all lumbar positions(L1, L3, L5) on early stage motion(34 set). 4. The lumbar fatigue of CLBP was higher than CON during repeated trunk flexion-extention motion, so CLBP supposed more tired than CON. And it was significantly within two groups at lumbar positions(L1, L3 : p<.05, L5 : P<.01).