BIOMECHANICS AND ADAPTED PHYSICAL ACTIVITY

Several examples of biomechanical research work on Adapted Physical Activity are presented in this paper. In many cases, the same biomechanical analyses used in general sports activities can be applied to disability-based sports, as well. The methodology and the knowledge of biomechanics are expected to contribute to the development of competitive sports for the disabled, especially in the following aspects in the future: (1) to analyze certain sports skills and to advise athletes how to improve their skill levels (2) to develop and amend sports equipment and apparatus based on the motion analysis (3) to support competitors in training to improve their physical fitness levels (4) to advise and support for the functional classification of the athlete

MOTION ANALYSIS OF OVERHAND THROWING: PAST, PRESENT, AND FUTURE

Overhand throwing motion is often regarded as one of the basic motions along with walking, running, and jumping. Three-dimensional (3-D) image analysis of the kinematics and kinetics using of rigid body segment model of overhand throwing motion has been studied widely in recent years. In this paper biomechanical research on throwing is reviewed with a special focus of studies from Japan. Considering throwing is not an ontogenic but rather a phylogenic motion, more thorough and longitudinal studies on various aspects of skill development and training would be expected. The fact that the trunk, shoulder, and hand are difficult to model as a single rigid body has limited research depth. Studies linking advanced 3-D motion analysis and musculo-skeletal modeling are required if a better understanding of the biomechanics of overhand throwing motion are to result

EFFECT OF TRAINING FOR NEUROMUSCULAR CONTROL ON PERFORMANCE OF CHOICE REACTION SIDESTEP CUT

The purpose of this study was to identify the effect of neuromuscular control training on a performance of the sidestep cut with a choice reaction task. Three stages were set in this study. The first one was an experimental session before training (PRE). This was followed by an 8-week training period, and finally an experimental session (POST) after the completion of training. Mean foot contact time in the POST was significantly shorter than in the PRE. The average rectified value (ARV) ratio of electromyography (mean ARV value for 100 ms before foot contact divided by mean ARV value for 100 ms after foot contact) of the rectus femoris was significantly greater in the POST than in the PRE. These results suggest that the postural adjustments for sidestep cut were performed in a shorter time with the aid of neuromuscular control training

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

KINEMATICS AND KINETICS OF SWING LEG IN CURVED SPRINT RUNNING

The purpose of this study was to demonstrate kinematics and kinetics of left and right swing legs in curved sprint running. Nine male sprinters and decathletes participated in this study. Participants run 60m on the curved path and their motion was recorded by a motion capture system. The joint angle, angular velocity, moment and power of both swing legs were calculated. For the statistical test, a statistical parametric mapping was used. There were no kinematic and kinetic differences in the hip joint. However, asymmetries were found in the knee joint. Runners may just move swing legs same as straight running/sprinting

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

CHANGES OF BALL SPIN DURING FLIGHT OF KICKED SOCCER BALL

INTRODUCTION: Flight trajectories of balls are changed by the lift force, which closely relates to the direction and rate of the ball spin. It was reported that soccer balls decelerate 20-28% after 20m flight (Bray and Kerwin 2003), while there has been no study about the changes of the direction of the spin axis and the spin rate of soccer balls in flight. The purposes of this study were to investigate the changes of the direction of the spin axis and the spin rate of the soccer ball in the flight, and to obtain a basic knowledge about the flight of kicked soccer balls

EFFECT OF WINDOW LENGTH WHEN SMOOTHING WITH SINGULAR SPECTRUM ANALYSIS TECHNIQUE IN RUNNING DATA

The purpose of this study was to demonstrate the effect of window length on running kinematic data in comparison to data smoothed using a digital Butterworth low pass filter. The raw marker trajectories were smoothed using a digital Butterworth filter with an optimum cutoff frequency and using the SSA technique with window lengths of L = n/2, n/5, and n/10 (n = 220). Data smoothing using SSA parameters of L = n/10, r = 2 produced similar results to the Butterworth low pass filter with an optimal cutoff frequency of 13 Hz. In conclusion, a window length of L = n/10 is recommended for running kinematics research, while window lengths of L = n/2 should be avoided

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