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

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.     

Incorporating perceptual decision-making training into high-intensity interval training for Australian football umpires

Existing methods for developing decision–making skill for Australian football umpires separate the physical and perceptual aspects of their performance. This study aimed to determine the efficacy of incorporating video-based decision-making training during high-intensity interval training sessions, specific for Australian football umpires. 20 amateur Australian football umpires volunteered to participate in a randomised control trial. Participants completed an 8-week training intervention in a conditioning only (CON; n=7), combined video-based training and conditioning (COM; n=7), or separated conditioning and video-based training (SEP; n=6) group. Preliminary and post-testing involved a Yo-Yo Intermittent Recovery Test (Yo-YoIR1), and 10x300m run test with an Australian football specific video-based decision-making task. Overall, changes in decision-making accuracy following the intervention were unclear between groups. SEP was possibly beneficial compared to COM in Yo-YoIR1 performance, whereas CON was likely beneficial compared to COM in 10x300m sprint performance. There was no additional benefit to completing video-based training, whether combined with, or separate to physical training, suggesting that this was not an optimal training method. For video-based training to be an effective decision-making tool, detailed feedback should be incorporated into training. It is recommended that longer conditioning and video-based training interventions be implemented to determine training effectiveness.     

Activity profiles of the Australian female netball team players during international competition: Implications for training practice

Abstract

In elite sport, to remain competitive at the international level, it is critical to understand the game demands on players to ensure sport specific training programmes are designed for optimal athlete preparation and conditioning. In netball, recent research examining the activity patterns of players at the elite level is lacking, with only one study undertaken on this level of competition in the past 30 years. Therefore, the aim of this study was to provide coaches with up to date knowledge of player activity patterns as a basis for the design of optimal sport specific training programmes. The Australian female netball team were analysed using video footage of three international test matches. Player activity was categorised into five movement and eight game-based activities; and further classified as work or rest. Results suggest that differences in the current game exist when compared to the previous analysis. Positional differences were also found with regard to player activity confirming the need for an individualised component of training based on player position.     

Assessment of decision-making performance and in-game physical exertion of Australian football umpires

Abstract

The aim of this study is to investigate the effects of in-game physical exertion on decision-making performance of Australian football umpires. Fifteen Australian football umpires (M_age = 36, s = 13.5 years; M_{games umpired} = 235.2, s = 151.3) volunteered to participate in the study. During five competitive Australian football pre-season games, measures of in-game physical exertion (blood lactate levels, global positioning system [GPS]) and decision-making performance (video-based test) were obtained. There were no significant correlations between physical exertion in a particular quarter and decision-making performance in either the same quarter or any other quarter. Video-based decision-making performance was effected by time in game χ²(3) = 24.24, P = 0.001, with Quarter 4 performance significantly better than both Quarter 2 and Quarter 3. In-game physical exertion (blood lactate) significantly decreased over the course of the game χ²(3) = 11.58, P = 0.009. Results indicate no definable link between in-game physical exertion and decision-making performance. It is, however, presumed that decision-making performance may be affected by the time or context of the game. Future research is warranted to explore the relationship between physical exertion and decision-making performance to potentially inform Australian football umpire training programmes that replicate in-game physical and decision-making demands.     

再论草原资源价值

草原资源的严重衰竭，危及传统畜牧业的生存和生态安全。计划经济制度的失败是因为不让价格反映经济资源的价值，而市场经济制度的失灵，是因为不让价格反映自然资源的价值。因此，草原资源的价值实体、价值量的计量，是永续利用草原资源的理论前提。而经济低代价增长、资源总量和环境容量扩大增长和和人口零度增长三模式增长模式，则是草原牧区可持续发展的实践课题。     

Applying self-determination theory to understand the motivation for becoming a physical education teacher

This study explored the reasons people choose physical education teaching as a profession and investigated the relationship of these choices with motivation. Physical education pre-service teachers (n = 324) completed the Academic Motivation Scale (AMS) and a measure of reasons for choosing physical education teaching. Confident interpersonal service reasons were linked with intrinsic motivation; whereas sport and physical activity reasons were related to extrinsic motivation. Enrolling because teaching seemed easy was linked with amotivation. Motivation was similar for different course entry methods, however, females were more intrinsically motivated than males and third year students were lower in motivation than other year levels.     

Video-based training to improve perceptual-cognitive decision-making performance of Australian football umpires

Decision-making is a central component of the in-game performance of Australian football umpires; however, current umpire training focuses largely on physiological development with decision-making skills development conducted via explicit lecture-style meetings with limited practice devoted to making actual decisions. Therefore, this study investigated the efficacy of a video-based training programme, aimed to provide a greater amount of contextualised visual experiences without explicit instruction, to improve decision-making skills of umpires. Australian football umpires (n = 52) were recruited from metropolitan and regional Division 1 competitions. Participants were randomly assigned to an intervention or control group and classified according to previous umpire game experience (i.e., experienced; less experienced). The intervention group completed a 12-week video-based decision-making training programme, with decision-making performance assessed at pre-training, and 1-week retention and 3-week retention periods. The control group did not complete any video-based training. Results indicated a significant Group (intervention; Control) × Test interaction (F(1, 100) = 3.98; P = 0.02, partial ?² = 0.074), with follow-up pairwise comparisons indicating significant within-group differences over time for the intervention group. In addition, decision-making performance of the less experienced umpires in the intervention group significantly improved (F(2, 40) = 5.03, P = 0.01, partial ?² = 0.201). Thus, video-based training programmes may be a viable adjunct to current training programmes to hasten decision-making development, especially for less experienced umpires.     

Content of curriculum in physical education teacher education: expectations of undergraduate physical education students

This study explored the perceptions of university physical education students of the importance of physical education curriculum content areas and how those perceptions related to the reasons for course choice and motivation. Physical education degree students (n = 188) completed measures of their perceptions of physical education content areas, attractors to physical education, and motivation. Strong reasons for course choice were sport and physical activity-related. Instruction of movement skills, health education, games, motor development, and physical education identity were perceived as more important, whereas sports and socio-critical perspectives were perceived as less important. Perceived importance of all content areas was positively related to the choice of course for confident interpersonal service, sport and physical activity, and role model reasons, as well as to intrinsic and extrinsic motivation. Physical education programmes should consider what content is delivered and how to effectively integrate practical and theoretical content.