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An experimental study on the dynamic and static horizontal force of elbow joint
1106
Abstracts-International
Society of Biomechanics
XII Congress 10x0
A COMPARISON OF TECHNIQUES USED BY ELITE MALE AND FEMALE GYMNASTS PERFORMING A HANDSPRING VAULT. Yoshiaki Takei, Department of Physical Education, Northern Illinois University, DeKalb, IL 60115 The purpose of the study was to compare the techniques used by men and women performing the handspring vault at the 1987 Pan American Games. Techniques used by male subjects have been described in the previous article by Takei (in press) and were compared with those used by women. A deterministic model was developed to identify mechanical factors for the subsequent analysis. A high-speed 16 mm motion-picture camera was placed with its optical axis at 90" to runway to record the vaults by 24 women investigated in the present study. Despite a significantly greater horizontal velocity (VH) at takeoff (TO) from the floor for men, length of hurdle for men and women did not differ significantly when it was adjusted for standing height of the subjects. Women achieved significantly smaller gain of vertical velocity (VV) on board and, consequently, significantly smaller VV at TO from the board and touchdown (TD) on the horse than men. Although the angular momentum (L) of Preflight was significantly greater for men, there was no significant difference between them when it was adjusted for height and mass. Women (a) contacted the horse with significantly smaller VH and VV; (b) had significantly longer time of horse contact; (c) had significantly smaller average vertical and horizontal forces and impulses exerted during horse contact; (d) had significantly smaller gain of VV and loss of L on horse; and (e) departed from the horse with significantly smaller VH and VV than men. The significantly smaller VH and VV at TO from horse for women resulted in significantly less height, distance, and time of postflight, even after adjustment for the difference of horse height.
EFFECTS
OF DYNAMIC
FEATURES
OF TENNIS
RACKETS
ON MUSCULAR
LOAD
OF TENNIS
PLAYERS
M. Yoshizawa, M. Kumamoto*, Y. Nemoto*t", T. Itani*** and B. Jonsson"*** Dept. of Educa., Fukui Univ., "Kyoto Univ., **Osaka Kyoiku Univ., it"+eOkayama Univ., Japan, and *-Swedish National Board Occupa. Safe. & Health, Sweden Electromyographical and kinesiological studies were carried out to elucidate effects of dynamic features of various models of tennis rackets on muscular load on the forearm of tennis players. Tennis rackets used were eight types of four models of different manufacturers. Subjects employed were 11 University Tennis Club members who had participated in the official contests and gained good results. Electromyograms (EMGs) with bipolar surface electrodes were recorded from the extensor carpi radialis brevis and the flexor carpi radialis and ulnalis muscles. EMGs, strain curve of the and longus, racket and video motion pictures were simultaneously recorded during forehand and backhand strokes with controlled ball by tennis ball machine, and service. Amplitude probability distribution of the EMGs were examined. The results obtained were as follows. (1) The larger moment of inertia of the test racket induced the higher amplitude level of EMGs during the stroke. (2) The smaller face area of the test racket induced the more prolonged vibration of the shaft and the higher amplitude level of EMGs after the ball impact. (3) The stiffness of the shaft of the test racket affects on the low amplitude level activity. (4) The high gut tension of the test racket induced the middle amplitude levels of EMGs. (5) The double hand strokes could markedlv attenuate the racket vibration and the high amplitude level of EMGs after the ball impact.
AN EXPERIMENTAL STUDY ON THE DYNAMIC AND STATIC HORIZONTAL FORCE OF ELBOW JOINT Yuan Qingcheng - China Shenyang Physical Culture Institute Zou Jihao, Zhao Guangfu. and Sun Zhonavina - China Dalian Polvtechnoloev Universirv The present ar&le’makes dynami~andYstatic test and analy\is of elb&& horizontal pulling force of elbow bending and stretching at different angle positions. Due to the general need for research on movement techniques of the human body, this study provides a basis for research on functional anatomy, biodynamics and sport skills. Its objects are 93 sportsmen of baseball and throwing, jogging and jumping events. Apparatus used for test is Model YL-82A piezoelectrical pulling force meter developed by Dalian Polytechnology University (testing range, O-300 kgf; linearity < 1%; resolving power: 0.5 kgf; inherent frequency: < 9KHz; weight: 50g). It displays the value of static horizontal force through piezoelectric digital meter and scanscrables curves of dynamic horizontal force through light-ray recorder. Tested were 19 groups of data of dynamic and static forces of elbow bending and stretching at five angles: 30°, 60°, 90”, 120” and 150”. At the same time, scan-scrabling were made of the electromyograms of humeral biceps and triceps by means of Model 272 multi-purpose remote measuring meter made the Japanese Sanrong Tester Co. Ltd.
Abstracts-International
Society of Biomechanics
XII Congress 10x0
A COMPARISON OF TECHNIQUES USED BY ELITE MALE AND FEMALE GYMNASTS PERFORMING A HANDSPRING VAULT. Yoshiaki Takei, Department of Physical Education, Northern Illinois University, DeKalb, IL 60115 The purpose of the study was to compare the techniques used by men and women performing the handspring vault at the 1987 Pan American Games. Techniques used by male subjects have been described in the previous article by Takei (in press) and were compared with those used by women. A deterministic model was developed to identify mechanical factors for the subsequent analysis. A high-speed 16 mm motion-picture camera was placed with its optical axis at 90" to runway to record the vaults by 24 women investigated in the present study. Despite a significantly greater horizontal velocity (VH) at takeoff (TO) from the floor for men, length of hurdle for men and women did not differ significantly when it was adjusted for standing height of the subjects. Women achieved significantly smaller gain of vertical velocity (VV) on board and, consequently, significantly smaller VV at TO from the board and touchdown (TD) on the horse than men. Although the angular momentum (L) of Preflight was significantly greater for men, there was no significant difference between them when it was adjusted for height and mass. Women (a) contacted the horse with significantly smaller VH and VV; (b) had significantly longer time of horse contact; (c) had significantly smaller average vertical and horizontal forces and impulses exerted during horse contact; (d) had significantly smaller gain of VV and loss of L on horse; and (e) departed from the horse with significantly smaller VH and VV than men. The significantly smaller VH and VV at TO from horse for women resulted in significantly less height, distance, and time of postflight, even after adjustment for the difference of horse height.
EFFECTS
OF DYNAMIC
FEATURES
OF TENNIS
RACKETS
ON MUSCULAR
LOAD
OF TENNIS
PLAYERS
M. Yoshizawa, M. Kumamoto*, Y. Nemoto*t", T. Itani*** and B. Jonsson"*** Dept. of Educa., Fukui Univ., "Kyoto Univ., **Osaka Kyoiku Univ., it"+eOkayama Univ., Japan, and *-Swedish National Board Occupa. Safe. & Health, Sweden Electromyographical and kinesiological studies were carried out to elucidate effects of dynamic features of various models of tennis rackets on muscular load on the forearm of tennis players. Tennis rackets used were eight types of four models of different manufacturers. Subjects employed were 11 University Tennis Club members who had participated in the official contests and gained good results. Electromyograms (EMGs) with bipolar surface electrodes were recorded from the extensor carpi radialis brevis and the flexor carpi radialis and ulnalis muscles. EMGs, strain curve of the and longus, racket and video motion pictures were simultaneously recorded during forehand and backhand strokes with controlled ball by tennis ball machine, and service. Amplitude probability distribution of the EMGs were examined. The results obtained were as follows. (1) The larger moment of inertia of the test racket induced the higher amplitude level of EMGs during the stroke. (2) The smaller face area of the test racket induced the more prolonged vibration of the shaft and the higher amplitude level of EMGs after the ball impact. (3) The stiffness of the shaft of the test racket affects on the low amplitude level activity. (4) The high gut tension of the test racket induced the middle amplitude levels of EMGs. (5) The double hand strokes could markedlv attenuate the racket vibration and the high amplitude level of EMGs after the ball impact.
AN EXPERIMENTAL STUDY ON THE DYNAMIC AND STATIC HORIZONTAL FORCE OF ELBOW JOINT Yuan Qingcheng - China Shenyang Physical Culture Institute Zou Jihao, Zhao Guangfu. and Sun Zhonavina - China Dalian Polvtechnoloev Universirv The present ar&le’makes dynami~andYstatic test and analy\is of elb&& horizontal pulling force of elbow bending and stretching at different angle positions. Due to the general need for research on movement techniques of the human body, this study provides a basis for research on functional anatomy, biodynamics and sport skills. Its objects are 93 sportsmen of baseball and throwing, jogging and jumping events. Apparatus used for test is Model YL-82A piezoelectrical pulling force meter developed by Dalian Polytechnology University (testing range, O-300 kgf; linearity < 1%; resolving power: 0.5 kgf; inherent frequency: < 9KHz; weight: 50g). It displays the value of static horizontal force through piezoelectric digital meter and scanscrables curves of dynamic horizontal force through light-ray recorder. Tested were 19 groups of data of dynamic and static forces of elbow bending and stretching at five angles: 30°, 60°, 90”, 120” and 150”. At the same time, scan-scrabling were made of the electromyograms of humeral biceps and triceps by means of Model 272 multi-purpose remote measuring meter made the Japanese Sanrong Tester Co. Ltd.