Detecting the impact point location is useful to explain the causal relationship between kicking motion and ball behavior. However, the three-dimensional measurement of impact point in kicking motion is rarely reported. We aimed to clarify differences in the three-dimensional impact point location among straight, curve, and knuckle kicks in soccer, and relationship between their trajectories and ball rotation. The optical three-dimensional motion capture system was used to record kick motion. Impact point location was detected using a virtual surface models of foot and ball. Face vectors of foot surface and swing vectors of impact point when the kick impact occurs were calculated. Coordinate values of impact points on the foot were lateral=-26.8±4.6 mm, horizontal=155.0±5.1 mm, vertical=50.6±1.7 mm; lateral=-37.1±2.2 mm, horizontal=151.3±13.0 mm, vertical=46.8±3.9 mm; lateral=-35.3±6.7 mm, horizontal=143.3±11.0 mm, vertical=50.0±2.5 mm in straight, curve, and knuckle kicks, respectively.

This paper describes what rugby sevens is and how to enjoy rugby sevens.

This paper summarizes how to contribute rugby sevens as a researcher.

Some snap shots during the drop kick were shown. The angle of the ball's longitudinal axis with respect to the ground changes during the free fall and bouncing. Finally, the result of inverse dynamics during the kick for goal was shown.

In order to observe the swing motion on the table tennis, the authors developed a table tennis racket sensor using a triple axes accelerometer and newly developed gyro sensors which are attached at the grip end of the racket. We called this, IoTTT, IoT on Table Tennis. The measurement and data transmission are controlled by Bluetooth BLE 4.2 from the tablet computer. Using this racket sensor, we obtained the service motion in the table tennis swing. Since, of variety of swing motion, the service is the only the swing which can be controlled by the athletes without any of disturbance factors, we conducted our experiment on the service motion. Then, the trajectory and the orientation of the racket in the service motion were calculated and visualized. We proposed that obtained data can be used for the evidence-based training using such as the quantification of the repeatability of motions, the differences between skilled athletes or the fake motion, etc.

Competitive swimming is a very complicated phenomenon from the viewpoint of physics. Most parts of a swimmer's body am underwater while some parts are above the water. A swimmer is performing three-dimensional motion with many degrees-of-freedom and the flow is high Reynolds number turbulent flow. Therefore, it is a very challenging task to be investigated from the mechanical viewpoint. In other words, there are many issues remained unsolved. In this article, several research works by the author's group are introduced. Overview of computational fluid dynamics studies are reviewed. As an example of experimental studies, a research work on the flow visualization by the author's research group is introduced. As the example of visualization of fluid forces acting on a swimmer, research works of the simulation model by the authors are described. Finally, future directions of this research area are stated with expectations.

In biomechanics research on ski jumping, a series of movements are analyzed by classifying them into six phases: approach, take-off, early flight, stable flight, landing preparation and landing. It is a well-known fact that movement from the take-off to the flight is important for improving performance. In actual competition, the athlete's downhill and flight speed reaches about 90 km/h, so aerodynamics dominates the competition performance. As many previous studies have shown, there is no doubt that aerodynamic forces acting on ski jumpers and skis have a significant effect on competitive performance. In studies aimed at improving athletic ability, there are many reports from the viewpoint of aerodynamics and biomechanics, and visualization of the obtained knowledge and information is required. This paper introduces recent research trends and measurement techniques. Then, the outline of the utilization of this visualized information in the training and competition field is described.