Kinematic analysis of proximal-to-distal and simultaneous motion sequencing of straight punches     

Philip Xaver Fuchs  Stefan Josef Lindinger  Hermann Schwameder 《Sports biomechanics / International Society of Biomechanics in Sports》2018,17(4):512-530

Consecutive proximal-to-distal sequencing of motion is considered to be integral for generating high velocity of distal segments in many sports. Simultaneous usage of proximal and distal segments as seen in martial arts is by far less well investigated. Therefore, the aim of the study was to characterise and differentiate the concepts of consecutive (CSM) and simultaneous (SSM) sequence of motion in straight reverse punches as practised in Practical Wing Chun. Four experienced martial artists succeeded an eligibility test for technical proficiency in both concepts and performed a total number of 20 straight punches per concept. Eight MX13 Vicon cameras (250 fps) and Visual3D were used for motion capture and analyses. Both motion concepts showed proximal-to-distal sequencing of maximal joint velocities but, in SSM, this was coupled with simultaneous initiation. Key characteristics were: high pelvis momentum and backswing of shoulder and elbow (CSM); and importance of shoulder involvement (SSM). Different ranges of motion, timing aspects and achieved maximal angular velocities distinguished both concepts, which led to differences (p < 0.05) in fist velocity at contact, execution time, distance and horizontal shift of the centre of mass. Proper application of both concepts depends on the environmental setting, situational requirements and individual fighting style.  相似文献   

Tips for K-12 educators for helping students communicate and create using visual motion media,photography, and technology     

Wolfgang Karl  Markus Leberecht  Michael Oberhuber 《TechTrends》2009,53(1):14-15

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Reproducibility of the maximum accumulated oxygen deficit and run time to exhaustion during short-distance running     

Mike Doherty  Paul M. Smith  Karl Schroder 《Journal of sports sciences》2013,31(5):331-338

The aim of this study was to determine the reproducibility of the maximal accumulated oxygen deficit and the associated exercise time to exhaustion during short-distance running. Fifteen well-trained males (mean - s : VO 2max = 58.0 - 4.6 ml.kg -1 .min -1 ) performed the maximum accumulated oxygen deficit test at an exercise intensity equivalent to 125% VO 2max . The test was repeated at the same time of day on three occasions within 3 weeks. There was no significant systematic bias between trials for either maximum accumulated oxygen deficit (mean - s : trial 1 = 69.0 - 13.1; trial 2 = 71.4 - 12.5; trial 3 = 70.4 - 15.0 ml O 2 Eq.kg -1 ; ANOVA, F = 0.70, P = 0.51) or exercise time to exhaustion (trial 1 = 194 - 31.1; trial 2 = 198 - 33.2; trial 3 = 201 - 36.8 s; F = 1.49, P = 0.24). In addition, other traditional measures of reliability were also favourable. These included intraclass correlation coefficients of 0.91 and 0.87, and sample coefficients of variation of 6.8% and 5.0%, for maximum accumulated oxygen deficit and exercise time to exhaustion respectively. However, the '95% limits of agreement' were 0 - 15.1 ml O 2 Eq (1.01 2 / 1 1.26 as a ratio) and 0 - 33.5 s (1.0 2 / 1 1.18 as a ratio) for maximum accumulated oxygen deficit and exercise time to exhaustion respectively. We estimate that the sample sizes required to detect a 10% change in exercise time to exhaustion and maximum accumulated oxygen deficit after a repeated measures experiment are 10 and 20 respectively. Unlike the results of previous maximum accumulated oxygen deficit studies, we conclude that it is not a reliable measure.  相似文献   

The effects of work – rest duration on intermittent exercise and subsequent performance     

Mike Price  Karl Halabi 《Journal of sports sciences》2013,31(8):835-842

This study examined the effects of different work?–?rest durations during 40?min intermittent treadmill exercise and subsequent running performance. Eight males (mean?±?s: age 24.3?±?2.0 years, body mass 79.4?±?7.0?kg, height 1.77?±?0.05?m) undertook intermittent exercise involving repeated sprints at 120% of the speed at which maximal oxygen uptake (v-[Vdot]O_2max) was attained with passive recovery between each one. The work?–?rest ratio was constant at 1:1.5 with trials involving short (6:9?s), medium (12:18?s) or long (24:36?s) work?–?rest durations. Each trial was followed by a performance run to volitional exhaustion at 150% v-[Vdot]O_2max. After 40?min, mean exercise intensity was greater during the long (68.4?±?9.3%) than the short work?–?rest trial (54.9?±?8.1% [Vdot]O_2max; P?<?0.05). Blood lactate concentration at 10?min was higher in the long and medium than in the short work?–?rest trial (6.1?±?0.8, 5.2?±?0.9, 4.5?±?1.3?mmol?·?l^?1, respectively; P?<?0.05). The respiratory exchange ratio was consistently higher during the long than during the medium and short work?–?rest trials (P <?0.05). Plasma glucose concentration was higher in the long and medium than in the short work?–?rest trial after 40?min of exercise (5.6?±?0.1, 6.6?±?0.2 and 5.3?±?0.5?mmol?·?l^?1, respectively; P?<?0.05). No differences were observed between trials for performance time (72.7?±?14.9, 63.2?±?13.2, 57.6?±?13.5?s for the short, medium and long work?–?rest trial, respectively; P = 0.17), although a relationship between performance time and 40?min plasma glucose was observed (P?<?0.05). The results show that 40?min of intermittent exercise involving long and medium work?–?rest durations elicits greater physiological strain and carbohydrate utilization than the same amount of intermittent exercise undertaken with a short work?–?rest duration.  相似文献   

Kinematic differences of elite and high-performance tennis players in the cross court and down the line forehand     

Johannes Landlinger  Stefan Josef Lindinger  Thomas Stöggl  Herbert Wagner  Erich Müller 《Sports biomechanics / International Society of Biomechanics in Sports》2013,12(4):280-295

This study identified and compared the full body kinematics of different skill levels in the forehand groundstroke when balls were hit cross court and down the line. Forty-three three-dimensional retro-reflective marker trajectories of six elite and seven high-performance players were recorded using an eight-camera 400 Hz, Vicon motion analysis system. The six highest horizontal velocity forehands with reliable kinematics of all participants were analysed for each specific situation (a total of 156 analysed shots). Significant differences (p < 0.01) and large effect sizes were observed between elite and high-performance players in linear velocity of the shoulder (2.0 vs. 1.2 m/s), angular velocity of the pelvis (295 vs. 168 °/s), and angular velocity of the upper trunk (453 vs. 292 °/s) at impact. The elite group showed a tendency towards higher racquet velocities at impact (p < 0.05). No significant differences were found in angular displacement of the racquet, hip alignment, or shoulder alignment at the completion of the backswing; nor did angular displacement vary significantly at impact. Irrespective of the group, different shoulder, hip, and racquet angles were found at impact, depending on the situation. The results should assist coaches when striving to improve their players' forehand.  相似文献   

Training transfer between card sorting and false belief understanding: helping children apply conflicting descriptions   总被引：2，自引：0，他引：2  

Kloo D  Perner J 《Child development》2003,74(6):1823-1839

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Too little or too much? Parafoveal preview benefits and parafoveal load costs in dyslexic adults     

Susana Silva  Luís Faísca  Susana Araújo  Luis Casaca  Loide Carvalho  Karl Magnus Petersson  Alexandra Reis 《Annals of dyslexia》2016,66(2):187-201

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The control of teacher education in the United States     

Karl W. Bigelow 《International Review of Education/Internationale Zeitschrift für Erziehungswissenschaft/Revue internationale l'éducation》1955,1(3):289-303

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Predicting course performance in freshman and sophomore physics courses: Women are more predictable than men     

Susan McCammon  Jeannie Golden  Karl L. Wuensch 《科学教学研究杂志》1988,25(6):501-510

This study investigated the extent to which thinking skills and mathematical competency would predict the course performance of freshman and sophomore science majors enrolled in physics courses. Multiple-regression equations revealed that algebra and critical thinking skills were the best overall predictors across several physics courses. Although arithmetic skills, math anxiety, and primary mental abilities scores also correlated with performance, they were redundant with the algebra and critical thinking. The most surprising finding of the study was the differential validity by sex; predictor variables were successful in predicting course performance for women but not for men.  相似文献   

The twofold character of comparative education: Cross-cultural comparison and externalization to world situations     

Jürgen Karl Schriewer 《Prospects》1989,19(3):389-406

Member of the Executive Committee of the Comparative Education Society in Europe. His research work focuses on the comparative social history of education. His publications include two books on France, Die französischen Universitäten 1945–1968 (1972) Schulreform und Bildungspolitik in Frankreich (1974), Geschichte der Pädagogik und systematische Erziehungswissenschaft(co-editor) (1976), and Theories and Methods in Comparative Education(1988). He has published numerous articles in scholarly reviews, especially in Zeitschrift für Pädagogik.  相似文献