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1.
Koyama H Muraki Y Ae M 《Sports biomechanics / International Society of Biomechanics in Sports》2006,5(2):139-153
We investigated the immediate effects of the combined use of inclined and raised flat boards on the take-off motion of the long jump. Eight male long jumpers were videotaped with two high-speed video cameras (250 Hz) set perpendicular to the runway. The athletes jumped with three modified take-off boards: upward-inclined boards of two different inclinations (2.5 and 5.0 degrees), and a raised flat board (50 mm high). The jumpers performed pre- and post-jumps using their own techniques before and after use of the boards to test their effects. The post- jump revealed significantly less reduction in the horizontal velocity during the take-off than the pre-jump, and the effectiveness of converting the velocity from horizontal to vertical increased significantly in the post-jump. The post-jump demonstrated significantly less knee flexion of the take-off leg during take-off. The reduced knee flexion and slower extension velocity of the take-off leg in the second phase of the post-jump contributed to increasing the knee extension torque in the second phase and resulted in the increases in vertical ground reaction force and vertical velocity. These results suggest that the combined use of the inclined and raised flat boards induced immediate effective changes in the kinematics and kinetics of the take-off motion and represent appropriate training tools for take-off techniques of the long jump. 相似文献
2.
Toshiaki Miyamoto Hiroyuki Kamada Akira Tamaki Toshio Moritani 《European Journal of Sport Science》2016,16(8):1104-1110
The aim of this study was to investigate the effect of low-intensity exercise training using belt electrode skeletal muscle electrical stimulation on muscle strength and cardiorespiratory fitness in healthy subjects. Nineteen healthy subjects were allocated into control or intervention groups; in both groups the participants kept regular physical activity while the intervention group underwent 30 min B-SES training at 3–4 METs for four weeks. Knee extensor muscle strength and cardiorespiratory endurance during incremental exercise test were measured at baseline and after four weeks for all participants. The relative change of knee extensor muscle strength in the intervention group was significantly higher than control group (p?p?相似文献
3.
Shinichi Demura Shunsuke Yamaji Fumio Goshi Hidetsugu Kobayashi Susumu Sato Yoshinori Nagasawa 《Journal of sports sciences》2002,20(2):153-164
The aims of this study were to assess the reliability and validity of three methods of bioelectrical impedance analysis (based on induction between the hand and foot, between one foot and the other foot and between one hand and the other hand) and the skinfold method, and to construct prediction equations for total body density by examining cross-validity in young Japanese adult males. The participants were 50 Japanese males aged 18-27 years (height 1.72 +/- 0.06 m, body mass 64.9 +/- 9.0 kg; mean +/- s), each of whom was measured twice using each of the four methods. Relative body fat based on underwater weighing was used as the criterion for validity. To construct prediction equations for body density, we used multiple regression analysis, whereby all possible combinations were examined. The reliability of all three bioelectrical impedance methods was high (R = 0.999). Three new prediction equations were constructed for the hand-foot method, foot-foot method and skinfold method. The cross-validity of the equations was guaranteed. The relative body fat calculated using the new equations did not differ from that based on the underwater weighing method. 相似文献
4.
汉语“站立”义词的现状与历史 总被引：7，自引：0，他引：7
表示站立意义的词属于人类语言的基本词。本文描述汉语站立义词的现实分布和历时演变,并尝试对两者的关系作出解释。现代方言中表站立义的主导词有3个:站、立、徛。它们的分布特点是:站分布最广,大多数北方方言说站,此外还散见于非官话区的部分方言点;徛密集分布于东南部的吴语、徽语、赣语、湘语、客家话、广西平话、粤语、闽语地区;立则呈零散分布,散落在官话、晋语、吴语、赣语、湘语、湖南乡话和广西平话各区。这3个词在汉语史上的情况大致是:立从有文字记载的上古早期起一直是影响最大的通语词,直到明代以后才在大部分北方地区被站替换;徛(倚)用作站立义始见于战国,历史上可能作为一个方言词一直存在于南部广大地区;站始见于唐代,明代以后在广大的官话区逐渐取代立成为新的通语词。站很可能是所谓的长江型词,即兴起于江淮流域而后往北扩散。 相似文献
5.
Takahito Iga Hiroyuki Nunome Shinya Sano Nahoko Sato Yasuo Ikegami 《Sports biomechanics / International Society of Biomechanics in Sports》2018,17(4):477-493
To assess ball impact force during soccer kicking is important to quantify from both performance and chronic injury prevention perspectives. We aimed to verify the appropriateness of previous models used to estimate ball impact force and to propose an improved model to better capture the time history of ball impact force. A soccer ball was fired directly onto a force platform (10 kHz) at five realistic kicking ball velocities and ball behaviour was captured by a high-speed camera (5,000 Hz). The time history of ball impact force was estimated using three existing models and two new models. A new mathematical model that took into account a rapid change in ball surface area and heterogeneous ball deformation showed a distinctive advantage to estimate the peak forces and its occurrence times and to reproduce time history of ball impact forces more precisely, thereby reinforcing the possible mechanics of ‘footballer’s ankle’. Ball impact time was also systematically shortened when ball velocity increases in contrast to practical understanding for producing faster ball velocity, however, the aspect of ball contact time must be considered carefully from practical point of view. 相似文献
6.
Hiroyuki Nunome Yasuo IkegamI Rumi Kozakai Tommy Apriantono Shinya Sano 《Journal of sports sciences》2013,31(5):529-541
Abstract Detailed time-series of the resultant joint moments and segmental interactions during soccer instep kicking were compared between the preferred and non-preferred kicking leg. The kicking motions of both legs were captured for five highly skilled players using a three-dimensional cinematographic technique at 200 Hz. The resultant joint moment (muscle moment) and moment due to segmental interactions (interaction moment) were computed using a two-link kinetic chain model composed of the thigh and lower leg (including shank and foot). The mechanical functioning of the muscle and interaction moments during kicking were clearly illustrated. Significantly greater ball velocity (32.1 vs. 27.1 m · s?1), shank angular velocity (39.4 vs. 31.8 rad · s?1) and final foot velocity (22.7 vs. 19.6 m · s?1) were observed for the preferred leg. The preferred leg showed a significantly greater knee muscle moment (129.9 N · m) than the non-preferred leg (93.5 N · m), while no substantial differences were found for the interaction moment between the two legs (79.3 vs. 55.7 N · m). These results indicate that the highly skilled soccer players achieved a well-coordinated inter-segmental motion for both the preferred and non-preferred leg. The faster leg swing observed for the preferred leg was most likely the result of the larger muscle moment. 相似文献
7.
Yoshinori Nagasawa Shinichi Demura 《Measurement in physical education and exercise science》2013,17(4):283-292
This study examined age-group corresponding relationships of the controlled force exertion based on sinusoidal and quasi-random waveforms in 175 right-handed male adults aged 20 to 86 years. The subjects were divided into 3 groups based on age-level: 53 young (mean age 24.6, SD?=?3.3 years), 71 middle aged (mean age 44.3, SD?=?8.7 years), and 51 elderly (mean age 69.3, SD?=?6.4 years). The participants matched their submaximal grip strength by the dominant hand to changing demand values displayed as either a sinusoidal or a quasi-random waveform appearing on the display of a personal computer. The quasi-random waveform was changed in π with amplitude and in π/2 with frequency (peak and mean frequency were 0.1 Hz in both waveforms). The participants performed the controlled force exertion test three times with a 1-min interval (one trial was 40 sec) after one practice trial using the dominant hand. The measurement order was randomly assigned. The total of the differences between the demand value and grip exertion value for 25 sec were used as an evaluation parameter. The coefficient of variance was almost the same range in all age groups in both waveforms (CVSW ?=?30.8–35.6, CVRW ?=?26.3–37.7), but the elderly group showed the highest value in the quasi-random waveform. Significant correlations were found among the sinusoidal and quasi-random waveforms in the young, middle-aged, and elderly groups, but significant differences were not found in the correlations among each age group. The controlled force exertion evaluation based on the sinusoidal and quasi-random waveform displays has a moderate relationship, and this relationship does not show age-level differences. 相似文献
8.
Yoshinori Nagasawa Shinichi Demura 《Measurement in physical education and exercise science》2013,17(3):176-185
This study examined age group and individual differences in controlled force exertion by emulating sinusoidal and quasi-random waveforms in 222 right-handed female adults aged 20 to 86 years. The subjects matched their submaximal grip strength by the dominant hand to changing demand values displayed as either a sinusoidal or a quasi-random waveform appearing on the display of a personal computer. A total of the differences between the demanded value and grip exertion value for 25 seconds was used as an evaluation parameter. The measurements showed a tendency to increase across the age groups in both waveforms. Significant second-order curve regressions were identified, but there was no significant difference in the increase rates of both waveforms. Analysis of variance showed non-significant differences among means of both waveforms in all age groups, and the differences between means in groups of participants over 50 and 20- to 24-year-olds increased in both waveforms. Individual differences were almost the same in both waveforms. 相似文献
9.
Eating, drinking, locomotion, and rearing activities of rats, maintained under a 12:12-h dark:light cycle, were measured continuously over 24 h a day for 40 days in the KGbox-24. For 20 days, beginning on Day 11, the shocks were given through the grid floor of the box 1 h after the beginning of the dark phase (at 2100 h). The daily food and water intake decreased, and there was no further gain in body weight after the introduction of shocks. The 2100-h shocks had some associative effects: (1) Suppression of ingestion developed during the period of 2000–2100 h; (2) acceleration of general activity developed during the period of 2000–2012 h; (3) anticipatory suppression of eating developed toward the end of the light phase. The 2100-h shocks also had suppressive aftereffects upon eating and drinking, especially during the early stage of the 20-day shock phase. Compensatory drinking was observed during the light phase, but no such effect was found for eating. Some findings which are not usually obtained in short-session experiments remain to be explained. References to two timing systems are made. 相似文献
10.