SPIN, TRAJECTORY, AND MOTION - IN THE CASE OF BASEBALL AND SOFTBALL PITCHERS –

Using mechanical principles as the basis, the trajectory of a pitched ball is determined by its initial linear and rotational velocities, the angle of release, the direction of the ball’s axis of rotation, and the air density. Among the parameters required to determine the pitched baseball trajectory, ball velocity has attracted the most attention from biomechanics researchers. However, ball velocity is only one aspect of the factors for evaluating the pitching performance. In order to make hitting more difficult for batters, the pitcher introduces spin and alters the trajectory from a simple parabolic trajectory to one in which aerodynamic forces play a significant role. In this paper, relationship between spin, trajectory and the motion will be discussed for fastball and curveball in baseball pitch. In the presentation, softball pitching will be also referred to, so far as time permits

THROWING ARM MOTION TO DETERMINE SPIN AXIS OF PITCHED BASEBALL

The purpose of the present study was to investigate a throwing arm kinematics to determine the direction of spin axis of pitched baseball. The baseball was filmed immediately after ball release using a high-speed video camera (250 Hz). The direction of the spin axis and the spin rate were calculated based on the positional changes of the marks on the ball. The throwing motion was recorded with 3-D motion analysis system (Vicon), and angles of wrist flexion/extension, radial/ulnar deviation, and forearm pronation/supination were calculated as kinematic parameters. The direction of the hand segment in global reference frame was also obtained. The spin axis direction significantly correlated with the hand direction, while, there were no special relationship between the spin axis of the ball and joint angular kinematics obtained in this study. It follows from what has been reported that pitched ball trajectory is associated with attitude of the hand when a ball was released from the fingertip

PRONATE GLOBALLY BUT SUPINATE LOCALLY: EVIDENCE OF RADIO-ULNAR SUPINATION AT BALL RELEASE

The purpose of this study was to investigate the radio-ulnar longitudinal rotation during baseball pitching. We captured movements of nine skilled pitchers during pitching by using a system with 16 high-speed cameras (Vicon MX, 1000 Hz). Ten fastest trials which hit a target were averaged to obtain representative data for each participant. We found that the radio-ulnar joint supinated at around the moment of ball release (BRL), although the wrist continued rotating in the direction of pronation at around BRL in the global coordinate. The supination occurred due to the influence of the combination of elbow extension and shoulder internal rotation

STERNOCLAVICULAR JOINT MOVEMENT DURING BACKSWING IN BASEBALL PITCHING MAY BE A GOOD INDICATOR OF SHOULDER INJURY

The purpose of this study was to demonstrate the characteristics of joint movements performed by the pitchers who suffered from throwing shoulder injuries. Fourteen semiprofessional baseball pitchers participated in our longitudinal study. We captured their pitching using an optical motion capture system. We investigated their disease history once a year, for 5 years, in order to investigate the relationship between baseball-related throwing injuries and pitching mechanics. T w of the players suffered from shoulder pain and had to take a "no throw" rest for several weeks during the season. Both pitchers had a reduced range of motions for retraction at the sternoclavicular joint during backswing. However, they presented the same range of motions for shoulder horizontal abduction, as the other healthy pitchers

野球のピッチング動作における踏み出し脚の運動がボール初速度に与える影響

This study deals with how stepping leg and waist motion are related to initial velocity, while practicing baseball pitching. Six pitchers belonging to the university baseball team did the actual pitching for this study and were filmed using the direct linear transformation method of three-dimensional (3D) videography. Several factors determine the initial velocity. Toyoshima^ mentions that the sharp rotation of the waist is one of the big factors. Moreover, the importance of the lower limbs is frequently mentioned on the actual coaching scene. The results of this study are mentioned below. 1. The waist changes its motion from advance to rotating 0.1 sec before the foot lands on the ground, and the right trochanter major speeds up by slowing down the left trochanter major while the waist rotates sharply. 2. It is possible to speed up the waist angular velocity by fixing the joints of the knee and the legs when the foot is landing

サッカーのインステップキックにおけるボール速度と支持脚との関係とその基本的役割

The purpose of this study is to investigate the relation between the joint angle and horizontal velocity of the supporting leg and the velocity of the ball by an instep kick as powerful as possible. Subjects were 3 male students who were skilled members of the college soccer club and 3 male non-skilled persons. In this study, the velocity of the ball, foot, greater trochanters and knee and angle of the knee were analyzed three-dimensionally (3-D). The results were as follows : (1) A significant correlation (r=0.903) was found between the velocity of the ball and the velocity of the foot. (2) Skilled persons kicked the ball using good waist rotation. This rotation is a factor which increases the velocity of the ball. (3) Skilled persons fixed the supporting leg, the angle of the knee was about 150 degrees and the velocity of the knee was lower than in non-skilled persons

発育期の野球投手におけるボールスピンの特徴

It has been reported that the spin axis of a pitched baseball differs between adult pitchers and youth pitchers (Tezuka and Himeno 2001). However, that information was based on visual observation, and has not been determined quantitatively. The purpose of this study was to investigate the ball spin orientation and spin rate of youth pitchers compared with those for adult pitchers. In addition, the development of the throwing motion and factors in the determination of spin rate were discussed. Fourteen youth baseball pitchers (13.9±1.2 years) and nine collegiate baseball pitchers (20.1± 0.8 years) were selected as subjects. All of them were classified as over-hand style pitchers. The baseball was filmed immediately after the ball release using a high-speed video camera (250 Hz). The direction of spin axis and the spin rate were calculated using positional changes of drawn marks on the ball surface. The direction of the spin axis was defined by two angles, θ(azimuth) and φ(elevation). The angle between spin axis and pitching direction (α) was also obtained (Jinji and Sakurai 2006). Mean values of the angles of the spin axis showed no significant differences between youth pitchers and collegiate pitchers. As for variations within each trial, however, youth pitchers were significantly more inconsistent than collegiate pitchers. Although youth pitchers have acquired similar pitching motion to adults on average, their motion was often unstable with large variations. There was a significant difference in the mean values of spin rate between the youth pitchers and collegiate pitchers (p<0.001). Moreover, the spin rate correlated significantly with the initial ball velocity (p<0.001). Pitchers with a higher initial velocity achieved a notably higher spin rate. It was concluded that a pitching motion that increased the ball velocity consequently increased spin rate

愛知県内少年野球チームの肩関節および肘関節のメディカルチェック

The purposes of this study are to clarify when and which characteristics that have been supposed to be the cause of "baseball shoulders" such as instability, subacromial impingement and SLAP lesions observed in adults develop them. We had medical check of forty juvenile baseball players (av.12.3 years). They belong to the same baseball club in Aichi prefecture. One senior sports doctor measured range of motion and examine tenderness points, sings and laxities of the bilateral shoulder and elbow joints. External rotation of the first position of the dominant side was significantly greater than that of the non-dominant side. External rotation of the third position of the dominant side was significantly greater than that of the non-dominant side and internal rotation of the third position of the dominant side was significantly less than that of the non-dominant side. There ware little pathological signs in shoulder and elbow joints of these juvenile baseball players. One player showed positive anterior load and shift test of the shoulder of dominant side and six showed those of non-dominant side. Seven players showed positive posterior load and shift test of the shoulders of dominant side and fifteen showed those of non-dominant side. Five players showed positive sulcus signs of the shoulders of dominant side and eight showed those of non-dominant side. The nine players who had positive sulcus signs on either dominant or non-dominant side had significantly less internal rotation of the third position than the other players. Whereas the eighteen players who had positive posterior laxity on either dominant or non-dominant side didn\u27t have significantly less internal rotation of the third position than the other players. Positive sulcus sign suggests inferior laxity. This means inferior laxity has different role on developing posterior tightness of the throwing shoulder from posterior laxity

Accuracy and Error Trends of Commercially Available Bat Swing Sensors in Baseball

In baseball, the swing speed and swing angle of the bat just before ball impact are important to increase the speed and horizontal distance of a batted ball. This study investigated the accuracies and error trends of four commercially available bat sensors to measure these parameters. The hitting motions of seven healthy participants were measured simultaneously using the bat sensors and an optical motion capture system, and the swing speeds and swing angles were compared. The swing speed was measured with high accuracy, as indicated by the high intraclass correlation coefficient (ICC) between the bat sensor and the motion capture system measurements (mean ICC = 0.78). However, the ICC for the swing angle was lower (mean ICC = 0.58) than that of the swing speed for all but one bat sensor, indicating low accuracy. Moreover, in the high swing speed range, the accuracy of the swing speed tended to decrease for three bat sensors, but the trend of the swing angle was different among bat sensors. Significant systematic biases or proportional errors were found for all bat sensors, indicating the possibility of error correction. The sensor used in this study can help to evaluate the differences between players with different competition levels and hitting motions. Coaches need to be cautious in taking measurements of players with high swing speeds and in assessing slight changes within an individual