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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 active drag (MAD pull). Swimming velocity and intra-abdominal pressure (IAP) were determined in all tests. Stroke indices during pull and swim and drag-swimming velocity relationship and maximum propulsive power during MAD pull were also determined. Swimming velocities during pull and swim while wearing an RS (1.59 ± 0.13 and 1.77 ± 0.09 m·s

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 hands and once aided by hand paddles on both hands. Each participant swam 10 times a distance of 16 m in each condition, for a total of 20 trials. To elucidate the relationship between propulsive forces and swimming velocity, each participant was instructed to swim each of the two sets of 10 trials at an arbitrarily different swimming velocity. During the trials, pressure sensors and underwater motion capture cameras were used together to analyze the pressure forces acting on the hand and hand kinematics, respectively. Six pressure sensors were attached to the right hand, and pressure forces acting on the right hand were estimated by multiplying the areas with the pressure differences between the palm and dorsal side of the hand. Acting directions of pressure forces were analyzed using a normal vector perpendicular to the hand or hand paddle, calculated from coordinates obtained using underwater motion capture analysis. As a result, there were no differences in propulsive forces and mechanical power to overcome water resistance (PD) with or without hand paddles at the same swimming velocities. However, the use of hand paddles decreased stroke rate and hand velocities, so mechanical power to push the water at the hand (PK) decreased. Using hand paddles thus increased Froude efficiency (ηF). These results suggest that training load decreases when swimmers swim at the same velocities while using hand paddles. This insight could prove useful for coaches and swimmers when using hand paddles for training to help ensure that they are used in accordance with their intended training purpose. If swimmers use hand paddles increasing propulsive force or PK, they should swim at a higher swimming velocity with hand paddles than without.

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 propulsive) force is particularly important in sprinters. To increase the velocity in races, swimmers increase their stroke frequency. However, experimental and simulation studies have revealed that there is a maximum frequency beyond which swimmers cannot further increase swimming velocity due to a change in the angle of attack of the hand that reduces its propulsive force. While the results of experimental and simulation studies are consistent regarding the effect of the arm actions on propulsion, the findings of investigations into the effect of the kicking motion are conflicting. Some studies have indicated a positive effect of kicking on propulsion at high swimming velocities while the others have yielded the opposite result. Therefore, this review contributes to knowledge of how the upper-limb propulsion can be optimised and indicates a need for further investigation to understand how the kicking action can be optimised in front crawl swimming.Abbreviations: C: Energy cost [kJ/m]; Ė: Metabolic power [W, kJ/s]; Fhand: Fluid resultant force exerted by the hand [N]; Ftotal: Total resultant force [N] (See Appendix A); Fnormal: The sum of the fluid forces acting on body segments toward directions perpendicular to the segmental long axis, which is proportional to the square of the segmental velocity. [N] (See Appendix A); Ftangent: The sum of the fluid forces acting on body segments along the direction parallel to the segmental long axis, which is proportional to the square of the segmental velocity. [N] (See Appendix A); Faddmass: The sum of the inertial force acting on the body segments due to the acceleration of a mass of water [N] (See Appendix A); Fbuoyant: The sum of the buoyant forces acting on the body segments [N] (See Appendix A); D: Fluid resistive force acting on a swimmer's body (active drag) [N]; T: Thrust (propulsive) force acting in the swimming direction in reaction to the swimmer's actions [N]; Thand: Thrust force produced in reaction to the actions of the hand [N]; Tupper_limb: Thrust force produced in reaction to the actions of the upper limbs [N]; Tlower_limb: Thrust force produced in reaction to the actions of the lower limbs [N]; Mbody: Whole-body mass of the swimmer [kg]; SF: Stroke frequency (stroke number per second) [Hz]; SL: Stroke length (distance travelled per stroke) [m]; v: Instantaneous centre of mass velocity of the swimmer [m/s]; V-: Mean of the instantaneous centre of mass velocities in the swimming direction over the period of the stroke cycle [m/s]; a: Centre of mass acceleration of the swimmer [m/s2]; V-hand: Mean of the instantaneous magnitudes of hand velocity over a period of time [m/s]; Ẇtot: Total mechanical power [W]; Ẇext: External mechanical power [W]; Ẇd: Drag power (mechanical power needed to overcome drag) [W, Nm/s]; α: Angle of attack of the palm plane with respect to the velocity vector of the hand [deg]; ηo: Overall efficiency [%]; ηp: Propelling efficiency [%]; MAD-system: Measuring Active Drag system; MRT method: Measuring Residual Thrust method.

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 mental health states of student-athletes in Japan during the COVID-19 pandemic. In Study 1 conducted in April 2020, the participants were 402 male student-athletes, and examined the relationships among student-athlete’s identity and mental health. The results of correlational analyses indicated that there were significant negative correlations between degree of student-athlete’s identity and depression and sports helplessness. In Study 2 conducted in March 2021, the participants were 136 male student-athletes, and examined the relationship between perceived social support from teammates, student-athlete’s identity and mental health. The results indicated that there was significant correlation among social support, student athlete’s identity and mental health. These results suggested that mental health may be improved if student-athletes are strongly aware of their social identity, which is their social role, when unforeseen events such as the COVID-19 pandemic occur. In addition, social support provided by significant others such as teammates may contribute to the improvement of mental health.

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 the mental health states of student-athletes in Japan during the COVID-19 pandemic. In Study 1, conducted in April 2020, the participants were 402 male student-athletes and we examined the relationships among student-athletes’ identity and mental health. The results of correlational analyses indicated significant negative correlations between the degree of student-athletes’ identity and depression and sports helplessness. In Study 2, conducted in March 2021, the participants were 135 male student-athletes and examined the relationship between perceived social support from teammates, student-athletes’ identity, and mental health. The results indicated a significant correlation between social support, student athletes’ identity, and mental health.

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 F&eacute, d&eacute, ration Internationale de Natation (FINA) Swimming World Cup (age: 20.80 &plusmn, 1.39, five males and five females). Each participant went through two experiments (they were subjected to both the positive and negative ion environment and the control environment) within a four-week interval. The training task was a High-Intensity Interval Training (HIIT) routine for the swimmers. The subjective arousal state was measured using a Two-Dimensional Mood Scale (TDMS). In addition, biological emotional evaluations in the form of an electroencephalogram (EEG) were conducted to assess the arousal state of the elite swimmers. The examination of the change in the arousal level at rest and during training demonstrated that both subjective and objective arousal levels were significantly higher in the positive and negative ion environment than in the control environment. In addition, the average training performance scores were also significantly higher in the positive and negative ion environment than in the control environment. This study posits that the positive and negative ion environment has a positive effect on sports training.

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 effectiveness of MVs using both subjective and biological evaluations. The subjects were six elite Japanese collegiate swimmers participating in the FINA Swimming World Cup (age: 21.33 ± 0.51, four males and two females). We employed subjective and biological evaluations to examine these elite swimmers’ psychological motivation while watching an MV as part of their practice. We adopted subjective and self-report Psychological Condition Inventory (Yamazaki et al., 2008) to measure the athletes’ level of vigor while watching the MV. An electroencephalogram (EEG) was employed to evaluate the emotions of the swimmers. The emotional condition (vigor) was analysed by combining the extracted raw EEG data using a KANSEI module logger (Littlesoftware, 2018). A subjective evaluation showed that the score for vigor significantly improved after watching the MV (t = 2.33, p < 0.05), which was also indicated by the results of the biological evaluation (t = 5.69, p < 0.01). There was also a significant correlation between subjective and biological vigor after watching the MV (r = 0.77, p < 0.01). The results of this study, therefore, indicated that biological evaluation can be employed anew to verify the effectiveness of MVs.

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 experiment, the reliability of the estimated measurements was evaluated in a series of experiments using a robotic leg that can reproduce breaststroke-kicking motions. The resulting estimates correlated significantly with the fluid force acting on the foot model that was measured by a load cell (r = 0.62−0.92). In the second experiment, breaststroke-kicking motions of human swimmers were analyzed using the methodology tested in the first experiment. The estimated fluid forces showed significant correlation with the velocities of the human swimmers (r = 0.87). Furthermore, this methodology can monitor intra-cycle force fluctuations. We conclude that the present methodology can be used to evaluate breaststroke-kicking motions quantitatively, thereby assisting swimmers and their coaches in better understanding of breaststroke kicking.

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 effort trials (Slow, Normal, Fast). The trials were recorded by digital video cameras (60Hz) and we calculated coordinates of a right foot by using 3D-DLT method. Eight pressure sensors (200Hz) were attached on the right foot of swimmers and measured pressure distribution. Fluid forces acting on the foot were obtained by the way of multiplying measured pressure value and area of foot. As a result, fluid forces acting on the foot reflected the motion of foot. Furthermore, we found differences of influence by the change of effort each of subjects.