Suggestions of exercising with a water-bag before batting: rubber-ball baseball The present study investigated the brief reports to suggest an exercise with a water-bag before batting in male collegiate rubber-ball baseball. The participants were ten players with more than ten years' experience in baseball competitions. In the exercise, after the participants performed ten repetitions of a twisting motion with a water-bag weighing 3 kg, they swung the bat as fast as they could. After their exercise, they described how they felt about using the water-bag and whether they thought it had influenced their swing velocity. Many of the participants reported a feeling of being twisted around by the water in the bag. They also felt some change in their lower trunk. After they exerted the exercise, they felt that their lower trunk rotated more smoothly and faster than their arms. It seemed to them that their batting swing became faster. All participants agreed that the water-bag exercise was more effective than ordinary exercise with a training bat. The participants’ impressions suggest that exercising with a water-bag before their batting may have positively influenced a batter's swing velocity.
Effects of dual-task exercises using Moto tiles on the functional fitness and cognitive function of older adults living in the community
The purpose of the present study was to examine effects on the physical and cognitive functions of older adults living in the community of a dual-task exercise that combines exercise and cognitive tasks using Moto tiles, that is, 10 interactive tiles with built-in LED lights that are said to improve the balance, strength, endurance, mobility, and agility of older adults. The participants, 21 older adults, completed the memory domain items of the basic checklist (KCL) of the Ministry of Health, Labour and Welfare and, on the basis of the results, were divided into two groups: 12 with no decline (Group 1) and 9 with decline (Group 2). The following functional fitness parameters were examined: 30-sec chair stand (CS30), functional reach (FR), timed up-and-go (TUG), and 20-sec march test cycle time (pace, right foot, left foot), and the coefficient of variation (CV) was calculated. Cognitive function was evaluated using a simple reaction task, a Go/No-go reaction time task, the Eriksen flanker task, and the color-word Stroop task. The participants did the exercises twice a week for 12 weeks at the local community center. A repeated measures ANOVA showed a time effect for the 30-second chair stand, functional reach, timed up-and-go, checklist total scores, and the memory and physical domain scores on the checklist. The coefficient of variation of the left leg walking cycle during the 20-sec march test decreased significantly. After exercise, the changes in checklist total scores and cognitive region scores were larger in Group 2 than in Group 1. However, no significant change was observed on any of the cognitive function tests. In the present study, the group-based dual-task exercise for these older adults was associated with some improvement in their functional fitness and living function, so these exercises seem to be useful as a community-based exercise. However, further studies are required on the effects of the exercises on cognitive function.
Propulsion force of swimmers’ hands and mechanical power in sprint training
The present study reports a quantitative evaluation of the mechanical power (Pk) of the propulsion force of the hands of swimmers when doing sprint training for swimming competitions. The participants were 5 male university swimmers. The swimmers did four kind of sprint training (a push-off trial, a float trial, an assist trial, and a resist trial), once each. During these trials, three-dimensional motion analyses were conducted including measurement of the distribution of pressure and motion capture. The swimming speed in the assist trials was significantly higher than in the other three trials, but the average propulsion force of the swimmers’ hands and their mechanical power were significantly lower. No significant differences were found in average propulsion force or mechanical power in the push-off trials, float trials, and resist trials, but significantly higher maximum propulsion force was found in the resist trials compared to the other trials. In conclusion, the present study enabled a quantitative evaluation of features of 4 methods of sprint training. It is suggested that, for effective training, swimmers and coaches should be more aware of the positive and negative aspects of each of these methods.
Preliminary study of effects of a video delay playback device and problems associated with implementation of the device with a wrestling team
The present study is a preliminary investigation with wrestling teams of an automatic video delay playback device, in order to obtain information prior to the introduction of the device in more open-skill events. Effects of the video delay playback device on the performance of the athletes and on the training environment, and problems with using it were examined from the viewpoint of the wrestlers, coaches, and trainers. The participants were 17 wrestlers, 4 coaches, and 3 trainers from a university wrestling club. When initially asked to describe problems that they had during wrestling practice, 13 of the wrestlers answered that there were occasions in which they were unable to understand why they had received a particular score. Next, the video delay playback device was used for two months and then evaluated by the participants. Of the 13 wrestlers who had answered that there had been occasions in which they were unable to understand why they had received a particular score, 11 reported that using the delay playback device had reduced the number of such occasions. Although some improvements were made in the device, it seems that by introducing the automatic video delay playback device into the wrestlers’ training, the number of occasions in which the athletes did not understand a score that they had received might decrease. The wrestlers’, coaches’, and trainers’ evaluations of the device were generally good, which suggests that it may be effective for skill acquisition and coaching.
A proposed method for softball players to judge how a team should best handle hit balls
The present study investigated a method for softball players as a group to judge how to handle a hit ball by focusing on spatiotemporal information and communications among the players. The participants were 10 female university softball players whose positions were pitcher, catcher, first base, second base, third base, and shortstop. The present study was conducted in an actual softball field in a condition in which there were no outs and a runner on first base. It was proposed that the batter would make a sacrifice bunt, and the participants were requested to judge which player, that is, the pitcher, the catcher, the first baseman, or the third baseman, should catch the ball, and which player (first base or second base) the ball should be thrown to. The participants’ decisions about which player was responsible for handling the ball depended on their prediction of the location that the ball had been hit to. If it were hit into an area that a specific player handled, that player then would declare her intention to catch and throw the ball. On the other hand, if it were hit into an area that more than one player handled, the player who would catch and throw the ball called out to the others that she would do so and, in addition, gave instructions to the other players. Furthermore, estimates of the time required to catch the ball and the speed of the runner were used to judge which base to throw the ball to. These results suggest that it may be important to identify the time required to catch balls in order to make correct judgments as to the optimum base to throw the ball to.
Athletic rehabilitation and recovery process of the lower limb of a 64-year-old female masters short-distance runner who had had knee surgery
The present report describes the results of athletic rehabilitation (AR) and a rebound jump (RJ) test for evaluating the effects of surgery to reconstruct the anterior cruciate ligament (ACL) of the left knee of a 64-year-old female masters short-distance runner. The report also evaluates the validity and key points of this attempt. The objective of the athletic rehabilitation was to enable the runner to regain the ability to execute extension-contraction cycles in her lower limb. The exercise program combined drop jumps and rebound jumps. A rebound jump test was conducted during the period between 157 and 308 days after the surgery. The recovery dynamics of performance variables were evaluated with a polynomial trend curve. When the runner did a left lower limb rebound jump, her ground contact time was extended because, when she landed, her knee could not support her weight, and her rebound jump power did not change. Then, taking into account the rebound jump test results and the participant’s comments, the load was increased gradually by fine tuning the content of the athletic rehabilitation. Starting 200 days after the operation, her ground contact time shortened; it stabilized after approximately 250 days. Around 250 days after the operation, her rebound jump power had recovered to a level that enabled her to participate in competitions. Furthermore, 260 days after the operation, she achieved full return to her previous condition and participated in an official 100-meter dash competition. Since then, she has continued to improve.
Coaching a gymnast in the Zou Li Min (on one arm, giant swing forward with 1/1 turn to el-grip and 1/1 turn) on the horizontal bard
The present report describes exercises and coaching techniques for the Zou Li Min performed on the horizontal bar in order to demonstrate effects of an exercise method devised by the first author. The participant was a university student gymnast who had not previously done a Zou Li Min. After practicing the new exercise method, the participant was able to perform a Zou Li Min. This suggests that practicing this exercise method might enable gymnasts to do the Zou Li Min.
Identifying knacks used for the breakdance in men’s floor exercises and a proposed training method
The purposes of the present study were to introduce a method of extracting the knacks used in variations of breakdancing, which is a men’s floor exercise in gymnastics, and, based on those knacks, to provide suggestions for training in this exercise. The analysis, based on Kaneko’s phenomenological movement theory, was an elimination method in which the structure of a knack is examined by determining whether a movement can be performed when a knack is intentionally not used. The knacks identified were verified through the author’s self assessment, with the assistance of another observer. The results suggested that maintaining a leg split while rotating was necessary when doing breakdance variations in order to generate an upper and lower body twist. In addition, 6 steps for learning breakdance variations are proposed.
Phenomenological kinematics study of knacks for the half-in half-out (tuck position) in trampoline
The half-in half-out (tuck position) in trampoline is a complicated movement that includes a half twist when going into a double somersault and another half twist before landing. However, very little technical information is available for players who have problems with this technique, and also very little research has been done on how to coach athletes in this movement. The purpose of the present study, done from the viewpoint of phenomenological theory of movement in sports, was to examine knacks in the half-in half-out that are crucial and hence should not be removed when coaching this movement. The analytical method was an elimination method in which the structure of a knack is examined by determining whether a movement can be performed when a knack is intentionally erased. Each of four knacks used by the first author in the half-twist phase of the first rotation of the half-in half-out was removed. Analysis of the results revealed the following:- At the time of taking off from the trampoline, the athlete pulls his/her right armpit toward the upper part of the left shoulder. - At the time of taking off from the trampoline, the athlete pulls his/her left shoulder diagonally backward and to the right by inverting the left shoulder blade. The discussion suggests training methods based on this clarified understanding of these knacks.
Effects of rapid bodyweight squat training on the rate of force development(RFD)
It has been reported that it takes more than 300 ms to exert maximum muscle strength. Since most movements in sports are performed in an extremely short time, it is important for athletes to exert power within 300 ms. Therefore, maximum muscle strength should be increased in order to improve sports performance. However, increasing the rate of force development (RFD) may be more important. It has been reported that the speed of training movements has a large effect on the rate of force development. The present study examined effects of bodyweight squats on the rate of force development. The participants, 6 track-and-field athletes who were members of a university track-and-field club, were instructed to do bodyweight squats as fast as possible 10 times × 3 sets, 3 times a week for 6 weeks. Their maximum isometric leg extension muscle strength, standing long jump, and rate of force development (0-100 ms: RFD100, 100-200 ms: RFD200, respectively) were measured before and after the 6-week bodyweight squat training. Statistically significant differences were found in RFD100 and RFD200 following the squat training. RFD100 improved from 9.5 ± 3.4 kN/s to 11.9± 4.6 kN/s, and RFD200 improved from 8.9±2.1 kN/s to 10.5±2.4 kN/s. These results suggest that the bodyweight squats done at maximum speed may have improved RFD100 and RFD200.