CHANGES IN THE TRANSFER OF ANGULAR MOMEMTUM THROUGH FATIGUE AFTER 120 BASEBALL PITCHES

The purpose of this study was to clarify the changes in the angular momentum of the system in three stages (early stage, middle stage and final stage) of fatigue during 120 baseball pitches, and to compare the transmission of angular momentum to the arm-plus-ball system in the three stages of fatigue

A BIOMECHANICAL STUDY OF TIMING IN BASEBALL BATTING AGAINST A PITCHED FASTBALL: COMPARISON OF BATTING SITUATIONS WITH AND WITHOUT PRIOR KNOWLEDGE OF THE TYPE OF PITCH

The aim of the study was to examine the differences in the timing of the batting motion between a situation in which the batter knew beforehand the type of incoming pitch and a situation in which he did not. Nine pitchers and 9 batters participated in this study. Batters were requested to hit the pitched ball in known-pitch and unknown-pitch situations. A successful trial of the batter was one in which the ball was hit squarely; a failed trial was one that produced a glancing blow. Pitching and batting motions were recorded with video cameras and a motion capture system. In the known-pitch situation, significant positive correlations were found between four batting phases and three pitching phases. The results suggested that the timing strategy of the batting motion in the unknown situation is different from that of the known situation

A BIOMECHANICAL ANALYSIS OF COMPETITIVE AND RECREATIONAL PLAYERS IN RELATION TO THE DARTS THROWING TECHNIQUE

The aim of this study was to clarify the difference of the darts throwing motion (technique) between competitive (CG) and recreational (RG) groups. The darts throwing motions for each group were analyzed using an automatic motion capture system and force platforms. The performance (distance) of CG was statistically superior to RG. Shoulder and elbow joint movement indexes were smaller in CG than in RG. CG threw the dart with the static position that body weight was mostly distributed to the forward leg. However, RG started from the static position that distributed two thirds of body weight on the forward leg, and subsequently threw the dart while transmitting most of the remaining body weight from backward leg to forward leg. It is concluded that CG had the less movement of body segments involved in the darts throwing motion to achieve a high level of performance

ANGULAR MOMENTUM ANALYSIS OF MEN’S DISCUS THROWERS IN 1998 USA TRACK & FIELD CHAMPIONSHIPS

Twenty-five discus throwers for USA Track & Field Championships 1998 were videotaped and analyzed using the three-dimensional (3D) DLT method. 3D coordinates of body segments and discus were then obtained. Angular momentum (H) of the thrower and discus was calculated using the link-segmental inverse dynamics approach. Positive HZ for the thrower-plus-discus system was produced during the initial double-support and first single-support phases. Negative HX for the system was a large increase, prior to, or in correspondence with the increase of the negative HY, during the latter half of the second single-support phase and the delivery phase. It seems reasonable to conclude that the increase of vertical speed of the discus (negative HY of the system) results from the interaction between the positive HZ and the negative HX of the system during the second single-support and delivery phases. This paper discusses the mechanism (“Gyro Model”) for the discus throwing motion, based on the principle of the gyroscope

A KINEMATIC COMPARISON OF THE DELIVERY MOTIONS OF CATCHERS AND INFIELDERS IN BASEBALL

The aim of this study was to compare the delivery motions of baseball catchers and infielders. Thirteen catchers and 16 infielders participated in the study. 3D analysis was used to analyze the release parameters, the durations of 4 phases, and trunk, pelvis and throwing arm kinematics in the two groups. No statistical difference in ball velocity and angle of release was found between the groups. Of the 45 angular position and angular velocity parameters tested at key instants in the throws, 15 showed significant differences between the groups. The only significant differences in maximum angular velocities and in their times of occurrence were in the maximum pelvis forward rotation angular velocity and in the time of occurrence of the maximum elbow extension angular velocity. These results should be useful for the improvement of baseball throwing motions

A BIOMECHANICAL COMPARISON OF THE CROSSOVER STEP AND JAB STEP TECHNIQUES IN THE PUSHOFF OF BASE STEALING STARTS IN BASEBALL

The aim of this study was to compare the effectiveness of the crossover step (CS) and jab step (JS) start techniques in baseball base stealing. Fourteen varsity fielders participated in the study. An automatic motion capture system and synchronized force platforms were used to analyze the two start techniques, performed at full effort by each individual. No statistical difference was found in the start time (duration of the start phase) between the two techniques. However, the start velocity (forward velocity of the body CG at the end of right leg push-off phase) was significantly larger in JS than in CS. It was found that the difference in the start velocity between the two step techniques comes from the difference in the forward impulse generated by the left leg push-off

LINEAR AND ANGULAR CONTRIBUTIONS TO BALL VELOCITY IN THE DELIVERY MOTION AMONG VARIOUS LEVELS OF BASEBALL INFIELDER

The purpose of this study was to investigate the linear and angular contributions to ball velocity of the delivery motion among junior high school (group J), high school (group H), and collegiate (group C) baseball infielders by using 3D videography. A total of 54 infielders were asked to throw a baseball quickly and accurately with full effort. Our results indicated that the ball velocity increased with progression in player level (group J, 28.3 m/s; group H, 31.8 m/s; group C, 33.2 m/s). Angle and height of ball release were significantly larger in group J than in groups H and C. Contributions of the forward and upward translations of the body to the ball velocity were, respectively, 6% and 10−15%, with the rest due to the rotations of the body. These results indicate that the rotations of the body are crucial for the increase of ball velocity

CLASSIFICATION OF FOUR DELIVERY STYLES OF PITCHING MOTON IN YOUNG BASEBALL PLAYERS

The purpose of this study was to examine the release positions of the throwing arm and of the trunk in four delivery styles (overarm, three-quarter arm, sidearm and underarm) of the baseball pitching motion, and to identify criteria to define the four delivery styles based upon the positions of both the trunk and throwing arm (upper arm) segments. Thirty-four pitching motions were videotaped using the 3D DLT method. These motions were qualitatively classified by coaches’ observation into 15 overarm, 7 three-quarter arm, 7 sidearm and 5 underarm deliveries. The angles for the trunk lateral tilt and upper arm elevation in the global coordinate system were quantified, and regression analysis revealed a linear relationship between the two angles. Criteria based on these angles were developed that matched the coaches’ observations well, demonstrating that the baseball pitching motion could be quantitatively classified into the four delivery styles

DIFFERENCES AMONG THE OVERHAND, THREE-QUARTER, SIDEARM AND UNDERHAND DELIVERY STYLES IN BASEBALL PITCHERS

The aim of the study was to clarify the biomechanical differences among the overhand (OS), three-quarter (TS), sidearm (SS) and underhand (US) styles of baseball pitching. About 700 pitches were videotaped using the 3D DLT method. The fastest pitch of each pitcher was used to establish criteria for the separation of the pitches into the four styles based on coaches’ observation and on trunk lateral tilt and upper arm elevation angles. Forty-nine pitches were selected for analysis, and classified into 18 OS, 10 TS, 10 SS and 11 US deliveries. Twenty-six kinematic and kinetic variables were calculated and analyzed. Trunk lateral tilt and upper arm elevation angles were significantly larger in the order OS-TS-SS-US. Ball velocity was significantly slower in the US group than in the other three. Significant differences were found among the groups in six kinematic and five kinetic variables. The slow ball velocity in the US group may have been causally linked to the significantly smaller forces and torques of the US group in relation to the other three

Attendance in the 40th Conference of the International Society of Biomechanics in Sports with a visit to the University of Lincoln

departmental bulletin pape