The purpose of this study was to examine the trajectory of the Center of gravity and hitting hand motion, how the momentum and force transfer from the whole body to the ball. High level player (age 32 y; height 181 cm; mass 75 kg) volunteered in this study. After the player warm up he had five trials before recording. Six trials were captured using two synchronize camera (Basler 100 Hz). The best successful three trials were selected for 3D motion analysis using (Winanalyze v2.0). The force curve for Center of gravity and hitting hand had a same path but there is a little difference in the momentum curve at the impact instant. This study suggests that combining of balance and coordination exercises may help to maintain the Center of gravity force trajectory in the same path with the hitting hand which gives an advantage for success serve. The takeoff within minimum time helps to increase the velocity of the Center of gravity and doesn't loss a generated force from the body to the hitting hand.

The purpose of this study was to present a practical novel method to calculate the penalty kick accuracy in football. The mathematical advantage considered the ratio of the rectangle goal dimension (1:3) and equalized between horizontal axis as it longer 3 times than the vertical axis. Twelve male soccer players 16 (3) years)), height 174.7 (4.5) cm)), body mass 67.6 (5.5) kg)) volunteered to participate in this study. The players were asked to do penalty kicks where the ball is aimed at the farthest point from the centre of the target portion for shooting. The soccer goal was split into quarters at three different velocities (low, medium, and high) the calculation was conducted two times by height to width ratio (HWR) and the most common method radial error. Kinovea Software 0.8.27. were used for digitizing. The ICC demonstrated high reliability (r = .99) for digitization at the moment the ball crossed the goal line for the inter and intra-ratter reliability. There was a significant relationship between some kinematics variables of the ball and the accuracy outcome of the HWR method in the four sections of the goal (p < .05).

The purpose of the presented study is to determine the specific kinematical changes related to discus throw during each phase of performance and comparing it with the specific kinematical variables in each phase in the national champion with elite athletes. a biomechanical analysis was performed on the first place thrower (Omar el gazaly) at the national champion of Egypt 2011 (64.74 m), which is the 4th place during world cup champion 2006, and the first place in the African champion 2006, (PB 66.58m in 2007). All trails of the subject were recorded, but a kinematical analysis was established for the best three trails. Two video cameras (DCR-SR68 SONY) 60 FPS were focused on the circle, one camera took the thrower from the side of his throwing Arm (right handed) and the second one took his rear view related to the direction of throw. Both views covered a width of 5 m related to the center of the circle, and the analysis was performed by DARTFISH TEAM PRO 4 software program. The results show that, the delivery phase time of the subject was 0.18 sec during his best trail, which was 20 % of the total performance time, the discus resultant velocity was 25.4 m/s and the flight time was 0.08 sec during the three trails, and that was about 9-11 % of total performance time. the average angle of release in three trails was about (34.4˚). the height of release in the best trail was 1.76 m. the total performance time of three trails was 0.880 sec but his phases time characteristics were different.