Differences between the sexes in the three-dimensional angular rotations of the lumbo-pelvic-hip complex during treadmill running     

Schache AG  Blanch P  Rath D  Wrigley T  Bennell K 《Journal of sports sciences》2003,21(2):105-118

The aims of this experiment were to determine whether there are differences between the sexes in the three-dimensional angular rotations of the lumbo-pelvic-hip complex during running and, if such differences exist, to establish whether factors other than sex can explain the observed differences. A cohort of 44 non-injured runners (22 males, 22 females) who usually ran more than 20 km per week were voluntarily recruited. All trials were conducted on a treadmill at a running speed of 4.0 m x s(-1). Reflective markers were placed over specific anatomical landmarks of the thoraco-lumbar spine, pelvis and femur. Data were captured using a VICON motion analysis system. Females tended to display a greater peak-to-peak oscillation for most of the angular rotations. An offset was the main difference between the male and female group mean waveforms for pelvis anterior-posterior tilt. Forward stepwise regression analysis revealed that sex was the most common variable related to the amplitudes of the angular rotations. Given these results, sport scientists conducting future biomechanical studies using angular data to test hypotheses are advised to be extremely cautious about averaging across male and female participants.  相似文献   

Simultaneous measurement of back and front foot ground reaction forces during the same delivery stride of the fast-medium bowler     

Hurrion PD  Dyson R  Hale T 《Journal of sports sciences》2000,18(12):993-997

Six male cricket bowlers (mean +/- s(mean): age 23.5 +/- 1.3 years; height 1.83 +/- 0.04 m; body weight 826 +/- 20 N) performed their typical bowling action at a set of stumps positioned at standard pitch length (20.1 m). A specially designed force platform rig allowed the correct positioning of two force platforms to be achieved beneath an outdoor polyflex runway (0.017 m depth) for each player's delivery stride pattern. For the back foot, the peak vertical ground reaction force was 1.95 +/- 0.08 kN (2.37 +/- 0.14 BW) and the braking force was 0.77 +/- 0.12 kN (0.94 +/- 0.16 BW). For the front foot, the peak vertical force was 4.80 +/- 0.92 kN (5.75 +/- 0.98 BW) and the braking force was 2.93 +/- 0.56 kN (3.54 +/- 0.67 BW). The mean peak vertical loading rate for front foot contact was 205 +/- 52.8 kN x s(-1) (249 +/- 64 BW x s(-1)) with mean values ranging from 81 to 446 kN x s(-1) (98 to 540 BW x s(-1)). The range for back foot contact was much smaller, 25-70 kN x s(-1) (30-85 BW x s(-1)), with a mean of 41.7 +/- 7.10 kN x s(-1) (50.6 +/- 8.6 BW x s(-1)). Mean peak impact occurred 24 ms after touchdown for the back foot and 16 ms after touchdown for the front foot. At impact, mean peak loading rates were greater for the front foot at 246 kN x s(-1) (298 BW x s(-1)), with a range of 80-483 kN x s(-1) (98-534 BW x s(-1)), than for the back foot at 65 kN x s(-1) (79 BW x s(-1)), with a range of 40-84 kN x s(-1) (49-110 BW x s(-1)).  相似文献   

Psychological characteristics and talent identification in soccer     

Morris T 《Journal of sports sciences》2000,18(9):715-726

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Predictors and Outcomes of Early vs. Later English Language Proficiency Among English Language Learners     

Halle T  Hair E  Wandner L  McNamara M  Chien N 《Early childhood research quarterly》2012,27(1):1-20

The development of English language learners (ELLs) was explored from kindergarten through eighth grade within a nationally representative sample of first-time kindergartners (N = 19,890). Growth curve analyses indicated that, compared to native English speakers, ELLs were rated by teachers more favorably on approaches to learning, self control, and externalizing behaviors in kindergarten and generally continued to grow in a positive direction on these social/behavioral outcomes at a steeper rate compared to their native English-speaking peers, holding other factors constant. Differences in reading and math achievement between ELLs and native English speakers varied based on the grade at which English proficiency is attained. Specifically, ELLs who were proficient in English by kindergarten entry kept pace with native English speakers in both reading and math initially and over time; ELLs who were proficient by first grade had modest gaps in reading and math achievement compared to native English speakers that closed narrowly or persisted over time; and ELLs who were not proficient by first grade had the largest initial gaps in reading and math achievement compared to native speakers but the gap narrowed over time in reading and grew over time in math. Among those whose home language is not English, acquiring English proficiency by kindergarten entry was associated with better cognitive and behavioral outcomes through eighth grade compared to taking longer to achieve proficiency. Multinomial regression analyses indicated that child, family, and school characteristics predict achieving English proficiency by kindergarten entry compared to achieving proficiency later. Results are discussed in terms of policies and practices that can support ELL children's growth and development.  相似文献   

The use of physiological, anthropometric, and skill data to predict selection in a talent-identified junior volleyball squad     

Gabbett T  Georgieff B  Domrow N 《Journal of sports sciences》2007,25(12):1337-1344

The aim of this study was to determine whether physiological, anthropometric, and skill test results could discriminate between junior volleyball players of varying ability. Twenty-eight junior volleyball players competed for selection in a talent-identification volleyball programme. Participants underwent measurements of stature, standing reach stature, body mass, skinfold thickness, overhead medicine ball throw, vertical jump, spike jump, 5-m and 10-m speed, "T" test agility, maximal aerobic power, and passing, setting, serving, and spiking technique and accuracy. A discriminant analysis was conducted on the selected and non-selected groups to obtain a regression equation that could be used to predict selection in junior volleyball squads based on the dependent variables. Passing and serving technique were the only significant variables included in the discriminant analysis. Cross-validation results showed that 17 of 19 selected players (89.5%) and 5 of 9 non-selected players (55.6%) were correctly classified into selected and non-selected groups, respectively, providing an overall predictive accuracy of 78.6%. The results of this study demonstrate that selected skill test results (i.e. subjective coach evaluations of passing technique and serving technique), but not physiological and anthropometric data, discriminate between successful and unsuccessful talent-identified junior volleyball players. These results demonstrate the importance of developing passing and serving technique in talent-identified junior volleyball players.  相似文献   

人类资源开发组     

T. Odhiambo  海燕 《科学对社会的影响》1990,(3)

培训必须适合具体国家与地区的需要。培训的主要目标,是使国家能够:(1)解决诸如保障能源基础、管理环境、保护自然资源;以及(2)迅速提高成年人口的平均科学技术水平,使国家能够采用、开发并有效地应用新技术。经济与社会发展需要科学技术环境。必须从中等教育开始,培养创立与管理这种环境所需的意识与基本技能。国家在经常是大量的证书或文凭持有者身上投入巨额资金,而这些人的技能却不能用或  相似文献   

MISCELLANEOUS NOTES     

I T A  J D 《Bulletin of the Medical Library Association》1938,26(4):258-265

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安徽读者方辉来信     

小T 《英语自学》2004,(1)

指出自己在备战英语自考过程中存在的三个主要问题,询问该如何克服: 1.单词记不牢,今天记住了,过两天就忘了。答:小T认为,将单词独立于上下文之外来记忆,是不太可取的方法。尽管很多同学平时都愿意花时间查词典,但通常的做法都是查出中文释义便了事,这种机械的单词记忆方法往往吃力不讨好。因此,小T建议你结合课文背单词。也就是说,在熟读课文的基础上记忆文中出现的所有生词。这样一来,你不仅可以在上下文的帮助下记忆单词的释  相似文献   

Statistical modelling of knee valgus during a continuous jump test     

Nagano Y  Sakagami M  Ida H  Akai M  Fukubayashi T 《Sports biomechanics / International Society of Biomechanics in Sports》2008,7(3):342-350

Landing with the knee in a valgus position is recognized as a risk factor for anterior cruciate ligament (ACL) injury. Using linear and non-linear regression analyses, the purpose of this study was to examine the correlation between two-dimensional (2D) knee valgus and three-dimensional (3D) knee kinematics measured during a jump landing task. Twenty-eight female collegiate athletes participated. All participants were required to perform a continuous jump test. The average maximum angles of abduction and internal tibial rotation during landing were measured using the Point Cluster Technique. Average peak knee valgus angle was measured using a 2D approach. Linear and non-linear regression analyses between 2D valgus and 3D knee abduction, and between 2D valgus and 3D internal tibial rotation, were performed. The R2 value between 2D valgus and 3D knee abduction was significantly different from zero and had a moderate correlation for all models, whereas the R2 value between 2D valgus and 3D internal tibial rotation was not significantly different from zero. The 2D approach could be used to screen a specific group of individuals for risk of ACL injury; however, using frontal plane 2D analysis of valgus motion to evaluate internal tibial rotation is not advised.  相似文献   

韩国济州岛:潮汐召唤着海女     

T.D.Hollowell  乐在其中 《英语辅导》2007,(7)

荷兰水手亨德里克·哈梅尔曾出版他的日志,里面记载了1653年在斯佩威尔号游艇失事后,他和同伴在济州岛上被关押长达13年的经历。即使在当时,神奇的海女就已经吸引并迷住了那些西方人,他们听到她们奇异的叫声,把岛上古怪的女人称为美人鱼。  相似文献