Estimating the hydrodynamic forces during eggbeater kicking by pressure distribution analysis

Abstract

This study investigates the reliability and validity of the estimation of the hydrodynamic forces during eggbeater kicking (a water-treading technique) by pressure distribution analysis (PDA). Our PDA procedure is very similar to that used in a previous study concerning breaststroke kicking (Tsunokawa et al., 2015). In this method, the force estimation is limited to a particular part of the body. However, unlike previous analyses, the PDA method obtains dynamic fluid forces under unsteady flow conditions without requiring cumbersome motion analysis in water. Twelve participants completed the eggbeater kicking activity under four load conditions (0, 1, 2 and 3 weights), and the hydrodynamic forces acting on their right foot are detected by the pressure sensors. To confirm the reliability of our PDA using successive tests, five participants are additionally made to complete the activity under a no-load condition. Further, the PDA is validated in a linear regression analysis of the mean resultant force calculated using the PDA method versus the applied vertical load. The reliability evaluation yields a high degree of coincidence (r = 0.99) and a mean effort of 4.1%. In the validity test, the net vertical loads are significantly correlated with the estimated forces [coefficient of determination (r2 = 0.91–1.00)]. Therefore, the PDA method is a reliable and valid estimator of eggbeater kicking.

Effects of exceeding stroke frequency of maximal effort on hand kinematics and hand propulsive force in front crawl

“…However, it is difficult to accurately assess the propulsive force exerted by the upper limbs because the direct measurement of the hydrodynamic profile around the entire limbs has not been established. In recent years, a method has been developed to estimate the propulsive force by measuring the pressure distribution around the hand and foot directly using water-proof pressure sensors (Tsunokawa, Tsuno, Mankyu, Takagi, & Ogita, 2018;Tsunokawa, Nakashima, & Takagi, 2015;Kawai, Tsunokawa, & Takagi, 2018). Takagi and Wilson (1999) examined the validity of the hand propulsive force calculated by measuring the pressure distribution at the hand during sculling with various weight load on the swimmers.…”

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

“…Fluid forces were calculated by a previously reported method (Kawai et al, 2020;Kawai et al, 2018). The foot was divided into four segments (segment 1-4: around the first toe, third toe, fifth toe and heel, respectively), and a pair of pressure sensors were attached to the dorsal and plantar side of each segment (Figure 1[A]).…”

“…The force data obtained in unsteady conditions yield results closer to reality than those in quasi-steady conditions (Kudo, Sakurai, Miwa & Matsuda, 2017;Tsunokawa, Mankyu, Takagi & Ogita, 2019;Tsunokawa et al, 2018). Kawai et al (2018) conducted the incremental load test with weights to confirm the validity and reliability of the fluid force analysis during the eggbeater kick using the PDA method. As a result, a strong linear relation was found between the fluid force estimated by the PDA method and the net vertical load of the player (R 2 = 0.97 ± 0.02), and the reliability of the test-retest method was also high.…”

“…Ltd., Japan). To measure the pressure distribution around the feet, sixteen waterproof pressure sensors (PS-05KC, Kyowa Electronic Instruments Co. Ltd., Japan) were attached to the right and left foot (four each on the dorsal and plantar surfaces) Kawai et al, 2018). The data measured by the pressure sensors were recorded on a laptop computer with a sampling frequency of 100 Hz via a universal recorder (EDX-100A, Kyowa Electronic Instruments Co. Ltd., Japan).…”

“…Researchers have proposed a method for estimating the upward propulsive force using the inverse dynamics approach Oliveira, Saunders & Sanders, 2016). Moreover, in the latest studies, a method of estimating the propulsive force by pressure distribution analysis (PDA) has been applied to the eggbeater kick (Kawai, Tsunokawa, Sakaue & Takagi, 2020;Kawai, Tsunokawa & Takagi, 2018).…”