Optimizing simulation for lower limb motion during throwing in water polo

Abstract

The objective of this study was to clarify the optimized lower limb motion during throwing in water polo by the simulation. The flexion/extension angles of the hip joint around the ball release were optimized in order to maximize the ball velocity, which corresponded to the hand velocity at the ball release, under the constraint in terms of the hip joint torque and power. The following findings were obtained from the results of optimization: The ball velocity in the case of original joint torque and power limit was 20.8 m/s. The increase in velocity from that of the original motion was 7%. In the case of doubled joint torque and power limits, the increase reached 15%. The characteristic motion in the optimized cases was the kicking forward (flexing) of both lower limbs just before the ball release. The preceding extending motion that was needed to increase the flexing velocity was also found. The increase in the ball velocity in the optimized motions can be explained as the sum of two components. One is the velocity relative to the center of mass of the whole rigid body, and the other is the absolute movement of the rigid body itself. With respect to the relative velocity, the flexing rotation of the lower half of the body produces the counter-rotation of the upper half of the body because of the conservation law of angular momentum. This effect contributed 70% of the total increase in the ball velocity. With respect to the absolute velocity, the rotations around the longitudinal and lateral axes of the inertia were induced by the reaction of kicking the fluid forward. This effect contributed the remaining 30% of the total increase in the ball velocity.

Youth Water Polo Performance Determinants: The INEX Study

“…Water polo players move their bodies vertically out of the water to execute specific motor abilities such as the pass, shot and block or to prevent the opponent from doing these [20]. Thus, players' over-the-water surface body elevation is crucial for success of specific technical abilities and should be based on effective eggbeater technique [6,24]. It was reported in 12-year-old and 14-year-old water polo players' equal and inferior in-water vertical jump values (respectively; [2,18]) compared with our data, which can be explained by their superior anthropometric features, with physical performance influencing the results.…”

“…Studying the individual performance characteristics can show compensating phenomenon effects when assuming that they singly do not determine a player performance level but the combination among them does. Even if the number of studies focusing on water polo anthropometrics, general motor performance [3,4] and biomechanical [5,6] and physiological determinants [7,8] has increased over the last years, the players' initial development processes are complex and require deeper theoretical and practical knowledge. This will allow for improvement of the training process and, consequently, the game's fundamental structures [4,9,10].…”

Kinematic and kinetic parameters to identify water polo players’ eggbeater kick techniques

“…During eggbeater kicking, athletes continuously alternate circular movements of their lower-limbs to generate upward propulsive forces that elevate the body. The generation of propulsive forces by the eggbeater kick enables the water polo players to keep the upper body above the water during passing, shooting, blocking, and to resist an opponent's action during contact play (McCluskey et al, 2010;Nakashima, Minami & Takagi, 2015;Nakashima, Nakayama, Minami & Takagi, 2014;4 Platanou, 2004;Smith, 1998). Therefore, performing an effective eggbeater kick is important for all water polo players.…”

Estimating the hydrodynamic forces during eggbeater kicking by pressure distribution analysis

“…In other studies, Nakashima et al. (2014) and Nakashima et al. (2015) have investigated the hydrodynamic forces that are mainly generated by the lower limbs' motion (including eggbeater kicking) when a water polo player performs a shooting motion.…”