Takaaki Tsunokawa

University of Tsukuba · Faculty of Health and Sport Sciences

Propulsive force is a determinant of swimming performance. Several methods have been proposed to estimate the propulsive force in human swimming; however, their practical use in coaching is limited. Herein, we propose a novel method for estimating the propulsive force generated by swimmers’ hands using an inertial measurement unit (IMU) and pressur...

PurposeThis study investigated the relationship between hand kinematics, hand hydrodynamic pressure distribution and hand propulsive force when swimming the front crawl with maximum effort.Methods Twenty-four male swimmers participated in the study, and the competition levels ranged from regional to national finals. The trials consisted of three 20...

The aim of this study was to review the literature on front crawl swimming biomechanics, focusing on propulsive and resistive forces at different swimming velocities. Recent studies show that the resistive force increases in proportion to the cube of the velocity, which implies that a proficient technique to miminise the resistive (and maximise the...

The purpose of the two studies was to investigate the relationships among student athletes’ identity and mental health during the COVID-19 pandemic. In addition, this study aimed to clarify the relationship between perceived social support from teammates and mental health in student-athletes. Two studies were conducted to investigate and clarify th...

The purpose of this study was to investigate the relationships among student athlete’s identity and mental health during the COVID-19 pandemic. In addition, this study aimed to clarify the relationship between perceived social support from teammates and mental health in student-athletes. Two studies were conducted to investigate to clarify the ment...

We investigated the effects of jammer-type racing swimsuits (RS) on swimming performance during arm-stroke-only (pull) and whole-body stroke (swim) in 25-m front-crawl with maximal effort. Twelve well-trained male collegiate swimmers wore RS and a conventional swimsuit (CS) and performed three tests: pull, swim, and pull using the system to measure...

This study aims at clarifying the factors responsible for the change in hand propulsive force when the stroke frequency was changed. Eight male swimmers performed five 20-m-front crawls. The first trial involved maximal effort, whereas the stroke frequency was controlled during the next four trials. The instructed stroke frequencies were 70%, 80%,...

The purpose of the present study was to evaluate the effectiveness of different step movement of relay starts with a back plate in competitive swimming. Twelve elite swimmers performed three different types of relay start and Kick Start. The start motions were recorded by six video cameras, and the 3D-DLT method was used to calculate the kinematic...

This study aimed to assess kinematic and kinetic changes in front crawl with various stroke frequency (SF) conditions to investigate why swimming velocity (SV) does not increase above a certain SF (SF max). Eight male swimmers performed 20 m front crawl four times. The first trial involved maximal effort, whereas SF was controlled during the next t...

The purpose of this study was to re-examination of the hand propulsive force (FP) during the entry and catch (EC) phase in a stroke of front crawl. The EC phase was defined as non-propulsive phase (Collet et al., 2000), which is until a hand starts moving backwards after it enters the water and moves forward. The other phases in the stroke was defi...

The purpose of this study was to characterise the unsteady propulsive force during eggbeater kicking by a fluid force estimation method based on pressure distribution analysis. The eggbeater kick was performed by six male water polo players. The participants’ eggbeater kicking motions were recorded by three cameras, and the kinematic foot variables...

Research Journal of Sports Performance

The purpose of this study is to examine the subjective and objective arousal of elite swimmers during physical training under a positive and negative ion environment. The participants were 10 elite Japanese collegiate swimmers participating in the Fédération Internationale de Natation (FINA) Swimming World Cup (age: 20.80 ± 1.39, five males and fiv...

[Introduction] Pressure measurement and underwater motion capture analysis has recently developed and is being applied to swimming research. Via simultaneous analysis using these techniques, fluid forces acting on the swimmer’s body can now be analysed. Therefore, through pressure measurement and underwater motion capture analysis, this study aime...

Through pressure measurement and underwater motion capture analysis, the aim of this study was to clarify how propulsive forces, Froude efficiency, and stroke parameters change with swimming velocity during front-crawl swimming. Eight male swimmers performed 2 trials, once using pressure measurement and underwater motion capture analysis and once u...

Through pressure measurement and underwater motion capture analysis, this study aimed to elucidate the effects of hand paddles on hand propulsive forces, mechanical power, and Froude efficiency in arm-stroke-only front-crawl swimming at various velocities. Eight male swimmers swam under two conditions in randomized order, once using only their hand...

Motivational videos (MVs) are used in Japan in many competitive sports, both professional and amateur. However, several researchers have stated that the effectiveness of MVs has not been scientifically verified, and only subjective evaluations have been conducted in previous studies (Yamazaki & Sugiyama, 2009). This study examined the psychological...

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 estima...

This study aimed to estimate hand propulsive force during the front crawl and to clarify its relationship with swimming velocity. Eight male swimmers performed 16-m front crawl ten times at various velocities. During trials, pressure measurement and underwater motion capture were used jointly to analyse hand kinematics and fluid forces. Six pressur...

Through pressure measurement, this study aimed to clarify the effects of hand paddle use on pressure and force generation around the hand during the front crawl. Eight male swimmers performed two trials of front crawl swimming with maximal effort, once using only their hands and once aided by hand paddles. During trials, pressure sensors and underwat...

The purpose of this study was to estimate fluid forces acting on a foot during eggbeater kicks of water polo players by the pressure-distribution-measuring method. Six male water polo players performed eggbeater kicks. Four pairs of pressure sensors were attached to the dominant foot to measure pressure distribution. Fluid-force vectors were calcul...

The purpose of this study was to verify the utility of the methodology using the pressure distribution analysis and motion capture system that can measure the pressure distribution, the fluid forces, and the hand kinematics. A male swimmer participated in the study, and imitated the front crawl stroke motion at standing position with changing the s...

The purpose of this study was to identify the characteristics of the pressure distribution around the foot during breaststroke kicking and the relationship between the fluid force and the pressure distribution by comparison among different swimmers. Eight male elite swimmers, whose specialties were breaststroke and individual medley, participated i...

The aims of this study were twofold: first, use a robotic leg to investigate the reliability of estimating fluid forces acting on the foot during breaststroke kicking and second, test the utility for actual human swimmer’s kicking. In this study, fluid forces were estimated from the measurement of pressure distribution around a foot. In the first e...

The purpose of this study was to identify the relationship between swimming performance and estimated ‰uid force by pressure distribution analysis of breaststroke kicking motion. Eleven elite male swimmers participated in the study, and provided written informed consent. Each subject performed the breaststroke kicking motion for 10 seconds without...

The purpose of this study was to develop a method to predict fluid forces acting on the foot and to clarify those characteristics during breaststroke kicking motion. Three male competitive swimmers whose specialties were breaststroke participated in this study. They performed breaststroke kicking motion without upper limb motion at three different...