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ABSTRACTAnterior cruciate ligament (ACL) injuries in badminton commonly occur during single-leg landing after an overhead stroke in the backhand-side court. This study compared differences in trunk acceleration and kinematic variables during single-leg landing in the forehand- and backhand-side courts after an overhead stroke. Eighteen female junior badminton players performed two singles games while wearing a tri-axial accelerometer. The moment that over 4g of resultant acceleration was generated was determined using synchronised video cameras. Trunk lateral inclination and hip abduction angles at the point of landing with over 4g of resultant acceleration were analysed. Mediolateral acceleration in the backhand-side court was greater than that in the opposite-side court (p < 0.001, ES = 0.840). Both trunk lateral angles were larger than those previously reported in injured participants and the hip abduction angle in the backhand-side court was larger than that in the forehand-side court (p < 0.001, ES = 2.357). The lateral and vertical acceleration in the backhand-side court showed moderate-to-strong correlations with the trunk and hip angles. The mediolateral physical demand and high-risk posture in the backhand-side court may be associated with a higher incidence of knee injuries during badminton games. 相似文献
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Yoshiharu Ichikawa 《媒体管理杂志》2016,18(2):117-136
Public service broadcasters (PSBs) around the world are restructuring their constituencies to meet the new challenges of increasing media diversification. New PSB management approaches include the diversification of transmission channels and development of contents. The optimum deployment of distribution channels and content genres, referred to as Portfolio Management, is now a major management priority and will provide the most efficient strategic allocation of management resources. In this article, we take NHK (Nippon Hoso Kyokai), Japan’s PSB, as a research target and analyze and evaluate its portfolio management. NHK has introduced the Value for Money (VFM) index through the measurement of WTP (Willingness to Pay), and has initiated channel-genre matrix management. This study aims to estimate the WTP of viewers’ reception fees from viewer surveys, and then distribute these WTP values to the channel-genre matrix. We then use Propensity Score Matching (PSM) to evaluate how NHK’s channel-genre matrix management is oriented toward public service value by dividing the sample population into high citizen orientation and low citizen orientation groups, and examining how the distributed WTP to genres differs between the two groups. 相似文献
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Yasuharu Nagano Shogo Sasaki Ayako Higashihara Hiroshi Ichikawa 《Sports biomechanics / International Society of Biomechanics in Sports》2020,19(3):342-352
AbstractThis study aimed to elucidate the movements requiring greater trunk accelerations and its frequencies during badminton games, and compare the acceleration components among such movements. Trunk acceleration was measured using a triaxial accelerometer during badminton games. The moments that generated >4 G resultant acceleration were extracted, and movements consistent with the extracted moments were identified. We calculated the extracted movement ratio and frequency and compared the resultant, mediolateral, vertical and anteroposterior accelerations between the top five extracted movements. There were 1,342 movements that generated >4 G [mean, 7.72 (95% confidence interval, 7.31–8.14) cases/min]. The top five movements were lunging during underhand strokes with the dominant hand side leg, landing after overhand strokes on the dominant and non-dominant hand side leg, and cutting from a split step using the dominant and non-dominant hand side leg. Landing on the dominant hand side leg had a greater resultant acceleration than the other movements and had the greatest impact during the badminton game. Lunging during underhand strokes on the dominant hand side leg had greater mediolateral acceleration than the other movements. These results reflected the properties of badminton. 相似文献
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Stroke phase discrimination in breaststroke swimming using a tri-axial acceleration sensor device 总被引：3，自引：1，他引：2
Yuji?OhgiEmail author Hiroshi?Ichikawa Masanobu?Homma Chikara?Miyaji 《Sports Engineering》2003,6(2):113-123
Our previous study has demonstrated that the swimmer’s wrist acceleration in the crawl stroke and the breaststroke had distinctive
characteristics between subjects (Ohgiet al. 2000). In addition, stroke phase discrimination could be achieved for the crawl stroke by using the swimmer’s wrist acceleration.
This study provides evidence that the swimmer’s tri-axial wrist acceleration could be used for stroke phase discrimination
in the breaststroke. Swimmers’ triaxial wrist accelerations were measured and their underwater stroke paths calculated. The
authors examined the characteristics of the wrist acceleration, such as a local maximum or minimum, with reference to the
swimmers’ stroke paths. As a result, it was suggested that the three phases of the breaststroke, the recovery, the insweep
and the outsweep, could be distinguished using thex-axis (ulnar-radial axis) and they-axis (distal-proximal axis) acceleration. This methodology allows us to identify which stroke phase would be changed in skill
training or over training, and the acceleration sensor device has the potential to become a precise stroke pedometer or stroke
monitoring tool in the near future. 相似文献
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Hirofumi Shimojo Rio Nara Yasuhiro Baba Hiroshi Ichikawa Yusuke Ikeda Yoshimitsu Shimoyama 《Journal of sports sciences》2013,31(20):2339-2346
ABSTRACTAnkle flexibility is critical to obtain a high swimming velocity in undulatory underwater swimming (UUS). The present study investigated the Froude (propelling) efficiency and three-dimensional (3D) kinematics of human UUS following the extrinsic restriction of the ankle by tape application. In Experiment 1, swimmers (9 male and 8 female college swimmers) performed UUS trials involving normal swimming (Normal) and swimming with tape application at the ankle (Tape). Kicking frequency was controlled in both settings. UUS kinematics were obtained with a two-dimensional motion analysis. Swimming velocity significantly decreased during swimming with tape application compared with that during normal swimming (Normal, 1.33 m·s?1; Tape, 1.26 m·s?1, p < 0.05). The Froude efficiency was not affected (Normal, 0.77; Tape, 0.76), and ankle plantar angle did not decrease during swimming (Normal, 159.02°; Tape, 160.38°). In Experiment 2, lower limb rotations of a male swimmer were analysed using 3D motion analysis under the same conditions as Experiment 1. An insufficient forefoot rotation was observed during downstroke kicks (the phase of the highest acceleration to forward direction). These findings suggest that UUS velocity is affected by the mobility of end effector. 相似文献
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Yusuke Ikeda Hiroshi Ichikawa Rio Nara Yasuhiro Baba Yoshimitsu Shimoyama 《Journal of sports sciences》2017,35(2):189-195
The purpose of this study was to determine the installation of the backstroke start device reduces 15-m time. Thirteen college swimmers participated in this study. The aerial start and underwater motions were recorded with two digital video cameras. The center of mass (CM) of the swimmer, angular displacements and velocities of the shoulder, hip and knee joints were calculated. As an indicator of performance, the 5- and 15-m times were measured. The 5- and 15-m times in the backstroke start device condition were significantly shorter than in the non-backstroke start device condition. The vertical velocities of the CM at hand-off and toe-off in the backstroke start device condition were significantly greater than in the non-backstroke start device condition, while there was no significant difference in the CM horizontal velocity at toe-off. As a result, the height of the great trochanter at entry of the fingertips, with the backstroke start device, was 15 cm higher than in the non-backstroke start device condition. In addition, the CM horizontal velocities at 5 m in the backstroke start device condition were significantly greater than those of the non-backstroke start device. Thus, the use of the backstroke start device may reduce the 15-m time by diminution of the entry area. 相似文献
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Yukiko Kawashiro Reiko Anahara Toshihiko Kohno Chisato Mori Yoshiharu Matsuno 《Anatomical sciences education》2009,2(6):273-279
At Chiba University, gross anatomy laboratory sessions (“laboratories”) are required for physical therapy students. Though most physical therapy schools require their students to participate in laboratories so that they will better understand the structure of the human body, few data exist on the value of these laboratories specifically for physical therapy students. We administered questionnaires to physical therapy undergraduate students both before and after they participated in laboratories. Questionnaire items focused on student attitudes toward the laboratories and on human life and dignity. Data from 83 students were analyzed, with the following results: (1) 74.7% of students had a positive attitude about attending laboratories before doing so; (2) with few exceptions, students' attitudes about upcoming laboratories grew more positive after experiencing the laboratory work (P < 0.001); (3) laboratories caused students to contemplate the topics of human life and dignity; and (4) 83.1% of students hoped to participate in laboratories at least four times. These results indicate that laboratories reinforce physical therapy students' positive attitudes about laboratory learning and promote student reflection on human life and dignity. This study provides support for the implementation of multiple laboratory sessions using cadavers into a uniform curriculum for physical therapy students in Japan. Anat Sci Educ 2: 273–279, 2009. © 2009 American Association of Anatomists. 相似文献
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The bender element testing features its in-plane directivity, which allows using bender elements to measure the shear wave velocities in a wider range of in-plane configurations besides the standard tip-to-tip alignment. This paper proposed a novel bender element testing technique for measuring the horizontal shear wave velocity of soils, where the bender elements are surface- mounted and the axes of the source and receiver elements are parallel to each other. The preliminary tests performed on model ground of silica sand showed that, by properly determining the travel distance and time of the shear waves, the surface-mounted bender elements can perform as accurately as the conventional ＂tip-to-tip＂ configuration. Potentially, the present system provides a promising nondestructive tool for characterizing geomaterials and site conditions both in laboratory and in the fields. 相似文献
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