Tackle and impact detection in elite Australian football using wearable microsensor technology     

Paul B. Gastin  Owen C. Mclean  Ray V.P. Breed  Michael Spittle 《Journal of sports sciences》2013,31(10):947-953

Abstract

The effectiveness of a wearable microsensor device (MinimaxX^TM S4, Catapult Innovations, Melbourne, VIC, Australia) to automatically detect tackles and impact events in elite Australian football (AF) was assessed during four matches. Video observation was used as the criterion measure. A total of 352 tackles were observed, with 78% correctly detected as tackles by the manufacturer’s software. Tackles against (i.e. tackled by an opponent) were more accurately detected than tackles made (90% v 66%). Of the 77 tackles that were not detected at all, the majority (74%) were categorised as low-intensity. In contrast, a total of 1510 “tackle” events were detected, with only 18% of these verified as tackles. A further 57% were from contested ball situations involving player contact. The remaining 25% were in general play where no contact was evident; these were significantly lower in peak Player Load? than those involving player contact (P < 0.01). The tackle detection algorithm, developed primarily for rugby, was not suitable for tackle detection in AF. The underlying sensor data may have the potential to detect a range of events within contact sports such as AF, yet to do so is a complex task and requires sophisticated sport and event-specific algorithms.  相似文献   

Information recall of younger and older skilled athletes: The role of display complexity,attentional resources and visual exposure duration     

Gershon Tenenbaum  Noa Levy‐Kolker  Michael Bar‐Eli  Robert Weinberg 《Journal of sports sciences》2013,31(6):529-534

This study was concerned with the interactive role of experience of athletic skill with other relevant environmental variables (display complexity, attentional resources, exposure time of stimuli) on perception (recall) of structured handball game situations. Nineteen experienced (older) and 19 less experienced (younger) handball players were assigned randomly either to ball‐bouncing (diverted attention) or to calm seated (focused attention) conditions. In each of the two conditions, the subjects were exposed to a total of 36 slides containing 2–3, 5–6 and 8–10 players. Eighteen slides were exposed for 0.5 s and 18 for 1.0 s. All the slides contained structured defence and offence situations. Recall scores were subjected to repeated‐measures ANOVA using attention condition and age as between‐subject factors and task complexity and exposure duration as within‐subject factors. The results showed that the recall of less experienced players deteriorated more than the recall of more experienced players following exposure to complex displays (≥ 8 players) while engaging in a secondary task (bouncing). The findings suggest that research paradigms should be applied in the field of sport which share both ecological validity and a potential to discover the cognitive substrates underlying experience and age in skilled motor performance.  相似文献   

The Effects of Three Styles of Teaching on the Psychomotor Performance And Social Skill Development of Fifth Grade Children     

Michael Goldberger  Philip Gerney  James Chamberlain 《Research quarterly for exercise and sport》2013,84(2):116-124

Abstract

The effects of Mosston's teaching styles B, C and E were examined in terms of motor skill acquisition and social skill development of fifth grade children. Ninety-six children, randomly selected and randomly assigned to one of three treatment groups, were taught a hockey accuracy task. Motor performance data were collected prior to, midway through, and following training; they were analyzed within groups, to determine if learning was evident, and across groups, to examine the relative effectiveness of these three styles of teaching. Social behavior patterns observed during learner-to-learner interaction were also examined during a second task in which pairs of learners were asked to “help” each other learn the task. A 3 × 3 analysis of variance with repeated measures revealed that (1) all three groups learned the task and (2) they learned comparably well. It was concluded that these three styles of teaching are all effective in facilitating learning of this type of motor task. Style C, an arrangement in whcih learners work in pairs, one performing the task while being provided with formative feedback by the other, was found not only to produce comparable learning, but to significantly enhance social skill development on those behaviors associated with giving feedback and receiving it from a peer.  相似文献   

Response to a Cold Pressor Test during Physical Training     

Ernest D. Michael Jr.  Arthur Gallon  Adran Adams 《Research quarterly for exercise and sport》2013,84(3):382-388

Abstract

Members of the 1958–59 varsity basketball team at Santa Barbara and a control group of physical education majors not in training were tested each three weeks during a 17-week season of basketball competition on their response to a step test and to a cold pressor test. The results indicated that significant step test recovery pulse rate changes were made by the basketball players after three weeks of training. Maximum changes were found to occur after 17 weeks of training. The diastolic pressure response to the cold pressor test increased significantly (7 mmHg.) after six weeks of training and this was maintained for 17 weeks. The results indicated that a possible increased sensitivity or tone of the peripheral vessels resulted from physical training.  相似文献   

Factor Structure and Measurement Invariance of a 10-Item Decisional Balance Scale: Longitudinal and Subgroup Examination Within an Adult Diabetic Sample     

Michael A. Pickering  Ronald C. Plotnikoff 《Measurement in physical education and exercise science》2013,17(4):206-226

This study explores the longitudinal and subgroup measurement properties of a 10-item, physical activity decisional balance scale, previously published by Plotnikoff, Blanchard, Hotz, and Rhodes (2001 Plotnikoff, R. C., Blanchard, C., Hotz, S. B. and Rhodes, R. 2001. Validation of the decisional balance scales in the exercise domain from the Transtheoretical Model: A longitudinal test. Measurement in Physical Education and Exercise Science, 5: 191–206. [Taylor & Francis Online] , [Google Scholar]), within a diabetic sample of Canadian adults. Results indicated that a three-factor measurement model consistently improved model fit compared to the previously published two-factor model. Evidence of configural, metric, and scalar measurement invariance across time and among subgroups suggests that the 10-item decisional balance scale is appropriate for investigating associative relationships with other constructs and for comparing group means of the pros and cons subscales among a variety of diabetic population subgroups.  相似文献   

eHPE: a history of the future     

Michael Gard 《Sport, Education and Society》2013,18(6):827-845

A grand convergence looms. It seems at least plausible that health and physical education may soon be lived by students in ways that are radically different from the past and sharply at odds with the imaginings of its founders and generations of academic aficionados. Perhaps in some respects, the differences will be superficial and less important than the continuities. Nonetheless, I draw connections between some recent futurist literature, developments in social theory and trends in health education, physical education and school-based health intervention—fields that I collectively call ‘HPE’—in order to imagine their digital futures. I contend that there is much for these fields to consider as developments in digital technology, the commercialisation of education, the spread of surveillance culture and medicalisation reshape how people think about HPE and its reason for being. But rather than an apocalyptic warning, this is an invitation to others to engage with some important questions that, although already urgent, have gone largely unnoticed. For example, what kind of thing will eHPE be if/when it exists primarily to generate profits and monitor and measure the minutiae of everyday life? At the very least, my argument here is that if it is not already the case, questions of pedagogical process and effectiveness may soon struggle for relevance in HPE's digital future.  相似文献   

Techniques and considerations for determining isoinertial upper‐body power     

Michael J. Falvo  Brian K. Schilling  Lawrence W. Weiss 《Sports biomechanics / International Society of Biomechanics in Sports》2013,12(2):293-311

Power is an integral aspect of many sports. Although power output of the lower body is often measured during jumping and cycling movements, much less is known about power as pertains to the upper body musculature. Recently, isoinertial methods ‐ with constant gravitational load ‐ of power testing have become common, but little is known of the reliability and criterion validity of these tests as they pertain to sport performance. In addition, the varied methodology makes a lucid model more evasive. The aims of this review are to examine the various methods of assessing upper body power, to establish its role in predicting athletic performance, and to assess the body of literature that has assessed power output of the upper extremities by isoinertial methods. To our knowledge, only two studies on isoinertial upper‐body power have shown a direct correlation to sporting ability (Baker, 2001; Baker et al., 2001); therefore, many unanswered questions exist as to the efficacy of these tests as predictors of athletic ability or as a method to track athletes’ training over time. From this review we hope to allow the sport coach to assess the overall utility of these tests in terms of availability, safety and external validity.  相似文献   

Optimization of the felge on parallel bars     

Michael J. Hiley  Roger Wangler  Gheorghe Predescu 《Sports biomechanics / International Society of Biomechanics in Sports》2013,12(1):39-51

The felge, or undersomersault, on parallel bars has become an important skill in men's artistic gymnastics as it forms the basis of many complex variations. To receive no deductions from the judges, the felge must be performed without demonstrating the use of strength to achieve the final handstand position. Two male gymnasts each performed nine trials of the felge from handstand to handstand while data were recorded using an automatic motion capture system. The highest and lowest scoring trials of each gymnast, as determined by four international judges, were chosen for further analysis. The technique used by each gymnast was optimized using a computer simulation model so that the final handstand position could be achieved with straight arms. Two separate optimizations found different techniques identified in the coaching literature that are used by gymnasts. Optimum simulations resulted in improved performances through a combination of increased vertical velocity and height of the mass centre at release. Although the optimum technique found close to the gymnasts' own technique was more demanding in terms of the strength required, it offered the potential for more consistent performance and future developments in skill complexity.  相似文献   

Relative shank to thigh length is associated with different mechanisms of power production during elite male ergometer rowing     

Andrew J. Greene  Michael H. Dickson  Floren Colloud  Richard M. Smith 《Sports biomechanics / International Society of Biomechanics in Sports》2013,12(4):302-317

The effect of anthropometric differences in shank to thigh length ratio upon timing and magnitude of joint power production during the drive phase of the rowing stroke was investigated in 14 elite male rowers. Rowers were tested on the RowPerfect ergometer which was instrumented at the handle and foot stretcher to measure force generation, and a nine segment inverse dynamics model used to calculate the rower's joint and overall power production. Rowers were divided into two groups according to relative shank thigh ratio. Time to half lumbar power generation was significantly earlier in shorter shank rowers (p = 0.028) compared to longer shank rowers, who showed no lumbar power generation during the same period of the drive phase. Rowers with a relatively shorter shank demonstrated earlier lumbar power generation during the drive phase resulting from restricted rotation of the pelvic segment requiring increased lumbar extension in these rowers. Earlier lumbar power generation and extension did not appear to directly affect performance measures of the short shank group, and so can be attributed to a technical adaptation developed to maximise rowing performance.  相似文献   

Major League Baseball and the Dominican Republic: What is in the best interest of the players?     

Adrien Bouchet  Michael Troilo  Jon Welty Peachey 《Sport Management Review》2013,16(2):236-250

This case is about Major League Baseball and the Dominican Republic. We explore how Major League Baseball has used this Caribbean island as an inexpensive labor market and the social problems of the situation. Specifically, we examine Corporate Social Responsibility, the leadership of Sandy Alderson, ethics and the various stakeholders involved. We also look into possible reform alternatives while addressing the central question: What is in the best interest of the players?  相似文献