• 한국운동역학회지
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• 제20권2호
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• pp.139-148
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• 2010

The purpose of this study was to comparatively analyze the kinematic variables between the squash backhand and racquetball backhand strokes through three-dimensional cinematography. Three expert racquetball players and three expert squash players were involved in the data gathering process. The horizontal, vertical and lateral displacement of racket and trunk segment, intersegmental angular velocity of the wrist, elbow and shoulder joints, and the linear velocity of the racket were descriptively analyzed, and the followings were concluded. The racket of the squash backhand stroke showed an 'U' shaped movement where the racket moved rapidly downward and moved forward to make an impact and followed through to a front-top finish, while the racket of racquetball backhand stroke showed an 'O' shaped movement where the racket showed circular movement through the rear and bottom positions for the impact, and showed rotation through the lower-front and upper front to a upper-rear-ward finish during the follow-through. The peak velocity of racket was found before the impact point in the squash backhand stroke and at the impact point in the racquetball backhand stroke. For the final conclusion, for the squash backhand stoke, instructors might be better to make the racket move downward to make highest velocity before the impact and finished short follow-through, while for the racquetball backhand stroke, to make the racket move forward to make highest velocity at the impact and finished rather long follow-through.

• 한국운동역학회지
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• 제19권2호
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• pp.337-345
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• 2009

본 연구는 테니스 서브 속도에 따른 라켓의 움직임에 대한 운동학적 변인들의 차이를 비교 분석하는데 있다. 연구문제를 해결하기 위해 국내 실업 테니스선수 3명을 대상으로 3대의 고속카메라를 이용하여 3차원 영상분석을 실시하였으며, 다음과 같은 결론을 얻었다. 첫째, 임팩트 순간 라켓의 속도는 전후축 방향으로의 빠른 속도가 중요하며, 이를 위해 라켓의 전방이동이 필요함을 확인하였다. 또한 임팩트 순간까지 라켓의 상향스윙이 이루어지는 것을 확인하였다. 둘째, 임팩트 순간 라켓의 각속도는 좌우축에서의 빠른 각속도가 중요하며, 이를 위해 손목의 강한 굴곡운동이 필요함을 확인하였다. 또한 수직축에서의 각운동도 필요함을 확인하였다. 셋째, 서브 속도는 라켓 가속구간에서 라켓의 증축과 -X축이 이루는 각의 변화를 작게 하는 것이 중요하며, 이는 가속구간에서 라켓을 볼의 진행 방향과 일치하게 이동시켜야 함과 동시에 라켓 가속구간의 시작인 백스크래칭 순간에 라켓을 지면과 수직이 되도록 하여 가속거리를 최대로 하는 것이 서브 속도를 높이는데 중요함을 알 수 있었다.

• 한국운동역학회지
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• 제17권1호
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• pp.41-52
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• 2007

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.

• 한국운동역학회지
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• 제12권1호
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• pp.221-231
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• 2002

The purpose of this study was to clarify the differences in service patterns of a forward and backward soft tennis players using 3D motion analyzer. Subjects were 4 forward players of $24.0\pm5.23$yrs and 4 backward players of $23.5\pm1.73$yrs. The results were as following: 1. There was no difference among each positions on swinging-time. The longest racket swinging-time was in the phase of takeback, the second one was in follow-through. The shortest one was in the phase of forward-swing so called force production phase, which had an influence on ball's velocity. 2. The racket speed on impact was 16.3m/s in forward subject and 19.53m/s in backward subject, when each velocity of balls was 44.6m/s, 52.9m/s. Although there was no significant difference along by positions, backward subject showed faster result. 3. The maximum speed of each performance was reached before the impact, and the speed at impact along by positions did not show any significant difference. The summation of velocity was measured in good order as following; hip, shoulder, elbow, wrist, top of racket. 4. In the angular velocity of all examine except one, the angular velocity of forearm was bigger than the one of racket top although there was no statistically significant difference between forward and backward subject. 5. The service grip of the forward players was shorter than that of backward players.

• 한국운동역학회지
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• 제17권2호
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• pp.145-156
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• 2007

The purposes of this study were to investigate kinematic parameters of racket head and upper extremities during squash back hand stroke and to provide quantitative data to the players. Five Korean elite male players were used as subjects in this study. To find out the swing motion of the players, the land-markers were attached to the segments of upper limb and 3-D motion analysis was performed. Orientation angles were also computed for angular movement of each segment. The results were as follows. 1) the average time of the back hand swing (downswing + follow-through) was 0.39s (0.24 s + 0.15 s). 2) for each event, the average racket velocity at impact was 11.17m/s and the velocity at the end of swing was 8.03m/s, which was the fastest swing speed after impact. Also, for each phase, 5.10m/s was found in down swing but 7.68m/s was found in follow-through. Racket swing speed was fastest after the impact but the swing speed was reduced in the follow-through phase. 3) in records of average of joints angle, shoulder angle was defined as the relative angle to the body. 1.04rad was found at end of back swing, 1.75rad at impact and it changes to 2.35 rad at the end of swing. Elbow angle was defined as the relative angle of forearm to upper arm. 1.73rad was found at top of backswing, 2.79rad at impact, and the angle was changed to 2.55rad at end of swing. Wrist angle was defined as the relative angle of hand to forearm. 2.48rad was found at top of backswing, 2.86rad at impact, and the angle changes to 1.96rad at end of swing. As a result, if the ball is to fly in the fastest speed, the body has to move in the order of trunk, shoulder, elbow and wrist (from proximal segment to distal segment). Thus, the flexibility of the wrist can be very important factor to increase ball speed as the last action of strong impact. In conclusion, the movement in order of the shoulder, elbow and the wrist decided the racket head speed and the standard deviations were increased as the motion was transferred from proximal to the distal segment due to the personal difference of swing arc. In particular, the use of wrist (snap) may change the output dramatically. Therefore, it was concluded that the flexible wrist movement in squash was very important factor to determine the direction and spin of the ball.

• 한국운동역학회지
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• 제15권3호
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• pp.161-173
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• 2005

Recently among several tennis techniques forehand stroke has been greatly changed in the aspect of spin, grip and stance. The most fundamental factor among the three factors is the stance which consists of open, square and closed stance. The purpose of this study was to investigate the relations between the segments of the body, the three dimensional anatomical angle according to open stance patterns during forehand stroke in tennis. For the movement analysis three dimensional cinematographical method(APAS) was used and for the calculation of the kinematic variables a self developed program was used with the LabVlEW 6.1 graphical programming(Johnson, 1999) program. By using Eular's equations the three dimensional anatomical Cardan angles of the joint and racket head angle were defined 1. In three dimensional maximum linear velocity of racket head the X axis showed $11.41{\pm}5.27m/s$ at impact, not the Y axis(horizontal direction) and the z axis(vertical direction) maximum linear velocity of racket head did not show at impact but after impact this will resulted influence upon hitting ball It could be suggest that Y axis velocity of racket head influence on ball direction and z axis velocity influence on ball spin after impact. the stance distance between right foot and left foot was mean $74.2{\pm}11.2m$. 2. The three dimensional anatomical angular displacement of shoulder joint showed most important role in forehand stroke. and is followed by wrist joints, in addition the movement of elbow joints showed least to the stroke. The three dimensional anatomical angular displacement of racket increased flexion/abduction angle until the impact. after impact, The angular displacement of racket changed motion direction as extension/adduction. 3. The three dimensional anatomical angular displacement of trunk in flexion-extension showed extension all around the forehand stroke. The angular displacement of trunk in adduction-abduction showed abduction at the backswing top and adduction around impact. while there is no significant internal-external rotation 4. The three dimensional anatomical angular displacement of hip joint and knee joint increased extension angle after minimum of knee joint angle in the forehand stroke, The three dimensional anatomical angular displacement of ankle joint showed plantar flexion, internal rotation and eversion in forehand stroke. it could be suggest that the plantar pressure of open stance during forehand stroke would be distributed more largely to the fore foot. and lateral side.

• 한국운동역학회지
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• 제16권2호
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• pp.97-108
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• 2006

C. H. OH, S. N. CHOI, T. G. NAM, The Kinematic Analysis of the Tennis Flat Serve Motion, Korean Jiurnal of Sports Biomechanics, Vol. 16, No. 2, pp. 97-108, 2006. By the comparison and the analysis of the different factors during the tennis flat serve motion such as the required time per section, the movement displacement of the racket, the velocity of the upper limbs joints, the physical center of gravity, and the angle and the angular velocity of the upper limbs joints between an ace player and a mediocre player, these following results were drawn. First, the experiment result of the total time required per section in a tennis flat serve motion showed that an ace player was faster than a mediocre player by 0.4 seconds. This result suggested that it was required to increase the speed of the racket head by a swift swing to perform an effective flat serve motion. Second, the experiment result of the movement displacement of the racket in the tennis flat serve motion showed that an ace player greatly moved toward the left side on an x-axis. But both an ace and a mediocre player were shown to be at the similar points on a y-axis at the moment of the impact of the racket. An ace player was also shown to be located at a higher position on a z-axis by 0.23m. Third, the velocity of the center of gravity of an ace player was faster in every phase than that of a mediocre player in a tennis flat serve motion. Fourth, the velocity of the upper limb joints of an ace player was faster in every phase than that of a mediocre player in a tennis flat serve motion. Fifth, the experiment result of the speed of the racket head in tennis flat serve motion showed that a mediocre player was faster than an ace player in the first phase, but the latter was faster than the former in the second, third, and the fourth phases. Sixth, at the moment of impact of a tennis flat serve, an ace player had greater flexion of the angle of the wrist joints by an 11.8 degree than a mediocre player. An ace player also had greater extension of the angle of the elbow joint and the shoulder joint respectively by a 5.2 degree and a 1.4 degree with a mediocre player. Seventh, an ace player had greater angular velocity of the upper limb joints and the hip joints than a mediocre player at the moment of the impact of tennis flat serve. Eighth, an ace player was shown to have a greater change of the forward and the backward inclination (or the anterior and posterior inclination) of the upper body

• 한국운동역학회지
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• 제13권2호
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• pp.65-74
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• 2003

The purpose of this study was to analyze kinematic variables in the badminton smash motion through 3-dimensional image analysis. The kinematic variables were velocity of joints in upper limbs, the angle of wrist in the impact, and the angular velocity of the top of racket head. The smash motions of four male badminton players in H University and four male students at department of the physical education in K University who were not majoring in badminton were analyzed kinematically and the attained conclusions were as follow. 1. The velocity of segments in upper limbs of the unskilled group was faster than that of the skilled group. The movement pattern was fast back swing-slow impact moment-fast fellow through in the unskilled group, but slow back swing-fast impact moment-slow follow through in the sullied group. 2. As the BS phases, the velocity of segment in right shoulder was different significantly between groups. Right elbow and right wrist segments, velocity of racket head was different significantly between groups(p<.05) by IP phases. As the FT phases, there was no significant difference. 3. The angle of right wrist at the impact, the angle of palm flexion and the angle of palm flexion in aspect were shown that the skilled group was higher than unskilled group. There was no significant difference. 4. The velocity of racket head was shown that the unskilled group has fast velocity, but the angle velocity was shown the unskilled group has slow. 5. The angle velocity of racket head in aspect were no significant difference between groups, but maximal angle velocity was different significantly between groups(p<.05).

• 한국운동역학회지
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• 제19권1호
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• pp.77-85
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• 2009

본 연구는 배드민턴 드라이브 동작의 원리와 현상을 이해함은 물론 운동 시 정확한 동작을 유도하여 상해예방 및 기술향상을 기할 수 있도록 기초자료를 제공하고자 하였다. 라헤드의 이동변위는 모든 연구대상자들에게서 비슷한 패턴으로 나타났지만 다소 차이가 나타난 이유로는 신장, 상완과 전완의 길이, 스윙괘적의 개인적인 성향의 등 외부적인 요인에 의한 결과로 사료된다. 국면별 상지관절의 각도를 살펴보면 어깨 관절, 팔꿈치 관절, 손목 관절의 각도는 드라이브 동작을 수행함에 있어 서로 유기적인 관계로 얽혀 있으며 근위에서 원위로 힘의 전달을 한다는 분절 순서이론도 뒷받침하고 있다. 상지관절의 각속도는 연구대상자 모두에서 임팩트 이후 팔로우스루 동작에서도 크게 나타났는데 이는 배드민턴과 같은 라운동에서 팔로우스루의 중요도를 나타내는 것을 의미한다. 이 팔로우스루 동작은 자세의 안정성 유지, 동작의 자세교정, 관절의 상해예방이라는 측면에서 라운동 시 중요요소로 작용하고 있음을 보여주고 있다. 종합해보면 분절의 순서이론에 따른 스윙이 이루어져야 효율적인 동작을 할 수가 있을 것으로 판단된다.

• 한국운동역학회지
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• 제15권4호
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• pp.85-95
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• 2005

The purpose of this study was to investigate the relations between the segments of the body, the three dimensional anatomical angle during One Hand Backhand Stroke and Two Hand Backhand in tennis. For the movement analysis three dimensional cinematographical method(APAS) was used and for the calculation of the kinematic variables a self developed program was used with the LabVIEW 6.1 graphical programming(Johnson, 1999) program. By using Eular's equations the three dimensional anatomical Cardan angles of the joint and racket head direction were defined. 1. In three dimensional maximum linear velocity of racket head the X axis and Y axis(horizontal direction) showed $-11.04{\pm}2.69m/sec$, $-9.31{\pm}0.49m/sec$ before impact, the z axis(vertical direction) maximum linear velocity of racket head did not show at impact but after impact this will resulted influence upon hitting ball. It could be suggest that Y axis velocity of racket head influence on ball direction and z axis velocity influence on ball spin after impact. The stance distance between right foot and left foot was mean $75.4{\pm}5.86cm$ during one hand backhand stroke and $72.6{\pm}4.67cm$ during two hand backhand stroke. 2. The three dimensional anatomical angular displacement of trunk in interna rotation-external rotation showed most important role in backhand stroke. and is follwed by flexion-extension. the three dimensional anatomical angular displacement of trunk did not show significant difference between one hand backhand stroke and two hand backhand stroke but the three dimensional anatomical angular displacement of trunk was bigger than one hand backhand stroke. 3. while backhand stroke, the flexion-extension and adduction-abduction of right shoulder joint showed significant different between one hand backhand stroke and two hand backhand stroke. the three dimensional anatomical angular displacement of right shoulder joint showed more flex and abduct in one hand backhand stroke. 4. The three dimensional anatomical angular displacement of left shoulder showed flexion, adduction, and external rotation at impact. after impact, The angular displacement as adduction-abduction of left shoulder changed motion direction as abduction. angular displacement of left shoulder as flexion-extension showed bigger than the right shoulder.