著者

Hiroki Nakata Akito Miura Michiko Yoshie Takatoshi Higuchi Kazutoshi Kudo

出版者

The Japanese Society of Physical Fitness and Sports Medicine

雑誌

The Journal of Physical Fitness and Sports Medicine (ISSN:21868131)

巻号頁・発行日

vol.3, no.4, pp.457-466, 2014-09-25 (Released:2014-10-02)

参考文献数

16

被引用文献数

4 4

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We investigated differences in trunk rotation patterns during baseball batting in eight skilled (collegiate level) players and nine unskilled novices using high-speed video cameras. The maximum angle during the backswing, angle at bat-ball impact, and angular displacement during the forward swing were analyzed for data on upper torso, pelvis, and torso-pelvis interaction (trunk twist) angles. We also noted movement variability in these angles over 10 trials, which was calculated as the standard deviation. The timing of the maximum angle during the backswing and variability was also analyzed. Statistical analysis revealed that angular displacements in the upper torso, pelvis, and torso-pelvis interaction were significantly larger in skilled players than in unskilled novices (p < 0.001, p < 0.001, and p < 0.05, respectively). The timing of the maximum pelvis angle during the backswing was significantly later in skilled players than in unskilled novices (p < 0.05). Movement variability in angular displacement during the forward swing and timing during the backswing were significantly greater in unskilled novices than skilled players. Although many previous studies reported the importance of angular velocity in trunk rotation during baseball batting, our results indicate that angular displacement and movement variability during trunk rotation are also key components for understanding the proficiency of skilled baseball players and unskilled novices.

著者

Nobuaki Mizuguchi Hiroki Nakata Yusuke Uchida Kazuyuki Kanosue

出版者

The Japanese Society of Physical Fitness and Sports Medicine

雑誌

The Journal of Physical Fitness and Sports Medicine (ISSN:21868131)

巻号頁・発行日

vol.1, no.1, pp.103-111, 2012-05-25 (Released:2012-08-22)

参考文献数

112

被引用文献数

37 75

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In the present review, how to measure motor imagery ability, brain activity during motor imagery, the benefits of motor imagery practice, and the influence of sensory inputs on motor imagery, are summarized. First, the classification of motor imagery is explained. Many methods have been utilized to evaluate motor imagery ability. For example, questionnaires, mental chronometry, and mental rotation tasks have been used in the psychological approach. Brain activity has been measured utilizing transcranial magnetic stimulation (TMS), functional magnetic resonance imaging (fMRI), positron emission tomography (PET), and electroencephalography (EEG). Some brain regions are activated motor execution in both and motor imagery, including the supplementary motor area (SMA), the premotor cortex (PM) and the parietal cortex. Although motor imagery is done without movement or muscle contraction, sensory input from the periphery interacts with motor imagery. Brain activation during imagery of an action, as assessed by TMS, is stronger when sensory inputs resemble those present during the actual execution of the action. Many studies have provided evidence of the effects of motor imagery practice on basic motor skills and sport performance. Most elite athletes (70-90%) report that they use motor imagery to improve performance, and professional players, as compared to amateurs, utilize imagery practice more often. Many studies have confirmed that motor imagery practice can also be useful not only in sports, but also for improving performance in patient rehabilitation programs.

著者

Mana Ogawa Satoko Hoshino Motoko Fujiwara Hiroki Nakata

出版者

The Japanese Society of Physical Fitness and Sports Medicine

雑誌

The Journal of Physical Fitness and Sports Medicine (ISSN:21868131)

巻号頁・発行日

vol.8, no.3, pp.127-136, 2019-05-25 (Released:2019-05-18)

参考文献数

23

被引用文献数

1 4

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We investigated the relationship between basketball free-throw accuracy and anthropometry, physical fitness tests, and performance variables among 16 collegiate female basketball players. Each participant performed 20 basketball free throws. Anthropometric measures were height and weight; physical fitness tests were sit-and-reach, back strength, and grip strengths; other basketball performance variables were the phases of the pre-shoot routine: (a) time taken, (b) minimum angle when taking the ball back, (c) angle at ball release, (d) angular displacement during the forward arm swing, and (e) angular velocity at ball release on the elbow, shoulder, hip, knee, and ankle. We analyzed the correlation between free-throw accuracy and data on anthropometry and physical fitness, the time period and variability of the pre-shot routine, and kinematic data. There were negative correlations between free-throw accuracy and mean pre-shot time, and variability of the pre-shot time, indicating that participants with a shorter and less variable pre-shot time showed a higher free-throw accuracy. Angular displacement of the shoulder during the forward swing and angular velocity of the knee at ball release showed positive correlations with free-throw accuracy. There was also a negative correlation between free-throw accuracy and variability of angular displacement during the forward swing at the elbow, indicating that participants with smaller variability of angular displacement of the elbow showed higher free-throw accuracy. Some performance variables, including routine duration, angular displacement of the shoulder and elbow, and angular velocity of the knee, were related to free-throw accuracy.

著者

Ryoko Yamagishi Tomohiko Wakayama Hiroki Nakata Kannika Adthapanyawanich Tewarat Kumchantuek Miyuki Yamamoto Shoichi Iseki

出版者

日本組織細胞化学会

雑誌

ACTA HISTOCHEMICA ET CYTOCHEMICA (ISSN:00445991)

巻号頁・発行日

vol.47, no.3, pp.95-102, 2014-06-30 (Released:2014-06-28)

参考文献数

28

被引用文献数

2 10

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In the major salivary glands of mice, acinar cells in the parotid gland (PG) are known to be the main site for the production of the digestive enzyme α-amylase, whereas α-amylase production in the submandibular gland (SMG) and sublingual gland (SLG), as well as the cell types responsible for α-amylase production, has been less firmly established. To clarify this issue, we examined the expression and localization of both the mRNA and protein of α-amylase in the major salivary glands of male and female mice by quantitative and histochemical methods. α-amylase mRNA levels were higher in the order of PG, SMG, and SLG. No sexual difference was observed in α-amylase mRNA levels in the PG and SLG, whereas α-amylase mRNA levels in the female SMG were approximately 30% those in the male SMG. Using in situ hybridization and immunohistochemistry, signals for α-amylase mRNA and protein were found to be strongly positive in acinar cells of the PG, serous demilune cells of the SLG, and granular convoluted tubule (GCT) cells of the male SMG, weakly positive in seromucous acinar cells of the male and female SMG, and negative in mucous acinar cells of the SLG. These results clarified that α-amylase is produced mainly by GCT cells and partly by acinar cells in the SMG, whereas it is produced exclusively by serous demilune cells in the SLG of mice.