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was found to be larger (p0.001) in SR (0.44±0.03) than in OR (0.39±0.02). Significant relationships were found between C and/or η
and the temporal and spatial (vertical and forward direction) variability of the BCOM: the higher the variability, the larger C and the lower η. Discussion. The “apparent” efficiency of running (η) is larger in SR than in OR and this has to be attributed to differences in W rather than in C. In turn, the observed differences in W can be attributed to differences in the “active stiffness” of the lower leg: the higher the stiffness, the larger the BCOM vertical displacement and hence the larger W (and η). Larger η values are also associated with a lower intra step variability (both spatial and temporal) of the BCOM. These findings could tentatively be explained by a more symmetrical gait pattern in skilled runners in comparison with occasional ones.
References  Minetti et al. (1993) Mechanicals determinants of gradient walking energetics in man. J. Physiol. 471: 725-735.
CHARACTERISTICS OF THE SUPPORT LEG MOVEMENT IN THE START AND TOP SPEED PHASES OF ELITE SPRINTERSKIJIMA, K., FUKUDA, K., ITO, A., ISHIKAWA, M.
OSAKA UNIVERSITY OF HEALTH AND SPORT SCIENCES
The purpose of the present study was to examine the characteristic of the sprint start movement of elite sprinters.
The measurement was performed at the 100-m event of the 11th IAAF World Championships in Athletics, Osaka, Japan. The movements of four male and three female elite sprinters, whose results were 9.85-10.20 sec in male and 10.99-11.98 sec in female, recorded by four high-speed cameras (200 fps) and analyzed with direct linear transformation method. The analysis phases were during start phase (6 steps from start) and middle phase (around the 60m from start). Their running velocity, step length, and step frequency as well as the angles of joints, segments and leg during the supporting phase. The peak angular, segment and leg swing velocities were calculated.
The leg swing angle of the supporting leg was defined as the angle between a line from the trochanter major to the lateral malleolus and a perpendicular line from the trochanter major to the ground.
Results and Discussion:
The leg swing velocity and forward rotation velocities of the thigh and shank segments were higher with increasing steps. During the start phase, the forward rotation velocity of the thigh segment was already reached those during the middle phase. However, the forward
rotation velocity of the shank segment was significantly lower during the start phase than during the middle phase. Therefore, the leg swing velocity during the start phase can be obtained mainly due to the increment of the forward rotation velocity of the thigh segment.
The previous study had reported that the knee joint during the foot contact phase should not be extended to transfer the hip extension velocity effectively to the leg swing velocity during the middle phase (Ito et al., 1998). During the start phase, however, the extension velocity of the knee joint and the amplitudes of the knee joint changes were greater in the start phase than in the middle phase. In addition, the angle of the shank segment was smaller as compared to that during the middle phase. It is likely that the elite sprinters could obtain the leg swing velocity by the knee extension due to the forward rotation of the thigh segment during the start phase.
ITO.A et al (1998) Relationship between sprint running movement and velocity at full speed phase during a 100 m race. Japan Journal of Physical Education 43, 260-273 (in Japanese).
THE RELATION ANALYSIS ON THROWING ANGLE AND MOTION IN JAVELIN THROWTAZUKE, S.
DOSHISHA UNIVERSITYIntroduction: Throwing angle is important for better performance in track & field javelin throw. Javelin throwers tend to throw higher than optimal angle. Coach instructs athlete to throw lower, and thrower tries to throw the javelin lower. However, it is difficult for throwers to throw the javelin in lower angle. In this study the factors of the throwing angle in javelin throw were examined from the viewpoint of the throwing motions.
Methods: Subjects were 9 javelin throwers (aged 19.33 years+-1.414, best performance 55.75m+-8.047, career of javelin throw
48.22month+-1.563, body height 171.04cm+-8.042, body weight 68.39kg+-10.925), 2 female and 7 male throwers. The experiment was carried out from the throwing gate, which enables measuring the throwing angle, initial velocity and attack angle immediately, right after throwing. Subjects got their throwing angle after throwing from this gate. For the first throw, they threw the javelin normally. From the second to sixth throw, they were to declare their target throwing-angle beforehand, e.g. “higher” or “lower”, those were recorded. Every throwing motion was filmed with two high-speed video cameras, film rate 250 / sec. by NAC. 21 out of 54 feasible throwing motions were analyzed by the three-dimensional analysis with motion analysis software, Dynas-3D by Shin-Osaka Shokai Co., Ltd. The correlation of the analyzed data, initial velocity of javelin (IVJ), velocity of body gravity (VBG), throwing angle (THA), attack angle (ATA), trunk angle (TRA), arm angle (ARA), arm-trunk angle (A-TA) and elbow angle (EA) etc. at release (R); last (LFC), second (SFC) and third foot contact (TFC) before releasing; third foot takeoff (TFT) before releasing were analyzed with the statistic software, SPSS.
Results and Discussion: A clear interactive relation was observed throwing angle and IVJ (r=-0.787, p=.01), VBG at R (r=-0.666, p=.01), THA on the XZ plane at TFT (r=-0.711, p=.01) and at TFC (r=-0.882, p=.01), TRA on the XY plane at TFC (r=0.642, p=.05), TRA on the XZ plane at R (r=0.593, p=.05) and SFC (r=0.700, p=.01), ARA on the XY plane at R (r=0.585, p=.05), and ARA on the XZ plane at SFC (r=0.552, p=.05), at TFT (r=0.803, p=.01) and at TFC (r=0.724, p=.01), and left ARA on the XY plane at R (-0.597, p=.05), at LFC (r=-0.787, p=.01) and at SFC (r=0.795, p=.01), left ARA on the XZ plane at RFC (r=0.550, p=.05) and at TFT (r=0.623, p=.05), A-TA at LFC (r=0.754, p=.01), TRA on the ZY plane at R (r=0.700, p=.01) and at TFT (r=0.561, p=.05).
3 followings were mainly suggested from the experiment. 1) When the direction of javelin leans toward X axis at TFC, the throwing angle is lower. 2) When the trunk leans toward horizontal line at TFC, the throwing angle is higher. 3) When the throwing arm leans toward horizontal line at R, the throwing angle is higher.
1) Paavo V. Komi et al., Biomechanical Analysis of Olympic Javelin Throwers, INTERNATIONAL JOURNAL OF SPORT BIOMECHANICS, Vol.1, Nr. 2, pp 139-150, 1985
BIOMECHANICAL ANALYSIS OF SPRINT RUNNING MOVEMENT OF ELITE SPRINTERS: THE THIGH AND SHANK SEGMENT’S MOVEMENT DURING THE CONTACT PHASEFUKUDA, K., KIJIMA, K., ITO, A.
OSAKA UNIVERSITY OF HEALTH AND SPORT SCIENCES
The purpose of the present study was to examine the characteristics of lower limb’s movements around the top sprint speed phase of elite sprinters. Especially, it focused on the movements of the thigh and shank segments during the contact phase.
The subjects were 6 male (9.85-11.24 sec) and 6 female (10.99-13.10 sec) sprinters, who participated in a 100-m races in 11th IAAF World Championships in Athletics, Osaka, Japan. Their running movements of one stride at approximately 60-m point were recorded by two
high-speed video cameras (200fps) and calculated the following parameters with three-dimensional direct linear transformation method:
average running velocity during the one stride, step length and step frequency as well as the average segment and joint angles of legs during the contact phase. The contact phase was divided into the ratio of 43% and 57% as the deceleration and acceleration phases, respectively. These phases were defined by the previous study (Fukuda et al., 2004) which calculated from the horizontal components of the ground reaction forces.
Results and Discussion:
The average angular velocity of the shank segment during the deceleration and acceleration phases were positively related to their running velocity. In these subjects, the average angular velocity of the shank during the deceleration phase was slightly higher than that of the thigh. It is likely that the greater forward rotation velocity of the shank segment could be occurred by the deceleration force of the initial impact. Consequently, the angular velocity of the knee joint showed a flexor direction during the deceleration phase. During the acceleration phase, on the other hand, the average angular velocity of the thigh segment increased, especially for the lower sprint velocity group, and did not showed any significant difference with that of shank segment. However, the average angular velocity of shank segment decreased similarly to all of them from the deceleration to acceleration phase. Consequently, the knee joint extended during the acceleration phase in the lower sprint velocity group. These results suggest that the elite sprinters can be hardly extended of the knee during the acceleration phase due to the greater angular velocity of shank segment. This is likely that elite sprinters could be transferred angular velocity of thigh segment effectively to the leg swing velocity.
Fukuda, K., Ito, A. (2004) Relationship between sprint running velocity and changes in the horizontal velocity of the body’s center of gravity during the foot contact phase. Japan J. Phys. Educ. Hlth. Sport Sci. 49: 29-39 (in Japanese).
INITIAL ROTATIONAL VELOCITY OF HIPS IS A KEY FACTOR IN DISCUS THROWYAMAMOTO, D., ITO, A.
OSAKA UNIVERSITY OF HEALTH AND SPORT SCIENCESThe purpose of this study was to investigate relationships between the official discus throwing distance and the movements of discus throw or the release conditions of discus. The throwing movements of 18 male discus throwers were recorded by two digital video cameras (60 Hz) in the 11th World Championships in Athletics in Osaka and the Japan Track and Field National Championships, and also in experimental trials. From the video data of trials when each athlete had thrown the longest distance, real-life three-dimensional coordinates of their body landmarks and the center of the discus were calculated with the direct linear transformation method. The throwing movements were divided into six instants and analyzed.
The initial velocity and the height of discus at the moment of release showed a positive correlation with the throwing distance. The throwing distance had no relation with the release height normalized by the body height and the release angle. These results suggested that the initial velocity and the release height of discus must be important to take longer throws, however the release height was dependent on the body height. At the right-foot takeoff (R-off) and the left-foot touchdown (L-on), both discus velocity and rotational velocity of hips indicated positive correlations with the throwing distance. Positive relations were shown between the discus velocity at R-off and rotational velocity of shoulders and hips at the same instants. The discus velocity at L-on had a positive relationship with the rotational velocity of shoulders at that time. The higher discus velocity at R-off of longer-distance throwers suggested that increase of rotational velocity of the whole body at the beginning of throwing movements is important. The translational velocity of the center of mass including thrower and discus (CM) at left-foot takeoff (L-off), right-foot touchdown (R-on) and L-on were recognized as a negative correlation with the official distance. The translational velocity of CM showed a negative relation with the rotational velocity of hips at L-off, and also velocity of CM indicated a negative correlation with torsion angle of trunk at R-on. These results suggested that longer-distance throwers might keep lower translational velocity of CM to obtain lager torsion angle of trunk during the flight phase.