A topography of free kicks in soccer     

Daniel Link  Otto Kolbinger  Hendrik Weber  Michael Stöckl 《Journal of sports sciences》2016,34(24):2312-2320

ABSTRACT

This study investigates the spatial relationship of performance variables for soccer free kicks. In order to suggest ways in which players might optimise their performance, we collected data from free kicks (<35 m to goal line) of two German Bundesliga seasons (2013/14, 2014/15) (n = 1624). In the analysis, we applied the ISO-map approach using colour gradients to visualise the mean values of a variable on a 2D-map of the pitch. Additionally, variograms were used to describe the degree of spatial dependence of the free kick variables. Results show that DENSITY, TYPE OF PLAY, PLAYERS IN WALL, DISTANCE TO WALL and RULE VIOLATION were strongly spatially dependent. Centrality and proximity to the goal increased the variables PLAYERS IN WALL, RULE VIOLATIONS and INTERRUPTION TIME, and the ratio of goals scored increased from 5.9% (central far) to 10.9% (central near). In 70.9% of the shots, players preferred a switched laterality, which did not result in a higher success rate. Furthermore, there was no statistical advantage for the defensive team when DISTANCE TO WALL was below 9.15 m or when there was a RULE VIOLATION. Crosses had a success rate (i.e., first controlled ball contact after the cross) of 20.8%. Played with natural laterality, they were 5% more successful than with switched laterality. Crosses from the right side outside the penalty box were 10% more successful than from the left side. Therefore, it might be worthwhile practising the defence of balls coming from this side.  相似文献   

Sprint and jump performances do not determine the promotion to professional elite soccer in Spain, 1994–2012     

Raul Martinez-Santos  Daniel Castillo 《Journal of sports sciences》2016,34(24):2279-2285

ABSTRACT

The aims of this study are (a) to describe the evolution of neuromuscular performance over an 18 year period within a Spanish elite reserve team; (b) to check if there were any relation between the playing position and sprint and jump performances and (c) to look into the alleged impact of this factor on the top playing level attained by the soccer players. We considered the physical tests (5 m and 15 m sprint times and countermovement jump (CMJ) height) made by 235 players enrolled in the reserve team of the Club from 1994 to 2012 and the highest competitive-level they achieved: Spanish first (n = 39) and second divisions (n = 36) and semi-professional (n = 160). Furthermore, the players were classified according to their playing positions. The main findings were a very-likely/most-likely lower neuromuscular performance (ES = 0.48–0.68, small to moderate) in the last six-season term (2006–2012) than in the first term (1994–2000); possibly/very-likely lower performances in sprinting and CMJ (ES = 0.22–0.55, small) by central defenders (CDs) and midfielders than by other playing positions; very-likely better performances in sprinting and jumping by first and second divisions central defenders than by semi-professional central defenders (ES = 0.90–1.02, moderate). Sprint and jump performances are not a relevant physical parameter to promote to the top level of soccer in Spain except for one in six of the playing positions: CDs.  相似文献   

Physiological profile of a professional boxer preparing for Title Bout: A case study     

Israel Halperin  Steven Hughes  Dale W Chapman 《Journal of sports sciences》2016,34(20):1949-1956

This study aimed to (1) profile a professional boxer (23 years and 80 kg) with boxing-specific, muscle function, aerobic capacity and body composition tests, and (2) quantify how these measures varied during an 8-week preparation phase leading to, and post a state-Title Bout fought in the 76.2-kg class. A series of boxing-specific and muscle function tests were completed on 11 occasions: 9 prior and twice after the bout, each separated by approximately 2 weeks. The boxing test included 36 maximal punches (9 of each: lead and rear straights, lead and rear hooks) to a punching integrator measuring forces and velocity. Muscle function tests included countermovement jump, drop-jumps, isometric mid-thigh pull and isometric bench-press. Body composition was assessed using skin-fold measurements on three occasions and one dual energy X-ray absorptiometry scan. Aerobic capacity was assessed using 2 VO₂ max tests. Leading up to the bout, performance decreased in isometric mid-thigh pull (8%), isometric bench-press (5%), countermovement jump (15%) and impact forces in 3 of 4 punches (4%–7%). Whereas measures of dynamic and isometric muscle function remained depressed or unchanged post competition, punching forces (6%–15%) and aerobic power (6%) increased. Data suggest the athlete may have super-compensated following rest as fatigue dissipated and further adaptation occurred.  相似文献   

The effects of physical contact type on the internal and external demands during a rugby league match simulation protocol     

Jonathan P. Norris  Jamie Highton  Stephen F. Hughes  Craig Twist 《Journal of sports sciences》2016,34(19):1859-1866

The aim of this study was to investigate how the type of contact influences physiological, perceptual and locomotive load during a simulated rugby league match. Eleven male university rugby league players performed two trials of the rugby league movement simulation protocol for interchange forwards with a traditional soft tackle bag and a weighted tackle sled to replicate contact demands. The interchange forward-specific simulation was chosen given the contact frequency is higher for this group of players compared to whole match players. Locomotive rate, sprint speed, tackle intensity, heart rate (HR) and rating of perceived exertion were analysed during the first and second bouts that replicated two ~23 min on-field passages. Countermovement jump (CMJ) was measured before and immediately after each trial. More time was spent in heart rate zone between 91 and 100% HR_peak during the first (effect size ± 90% confidence interval: 0.44 ± 0.49) and second bouts (0.44 ± 0.43), and larger (0.6 ± 0.69) decrements in CMJ performance were observed during the sled trial (5.9, s = 4.9%) compared to the bag trial (2.6, s = 5.4%). Changing the type of contact during the match simulation subtly altered both the internal and external loads on participants. Using a standard tackle bag results in faster sprint speed to contact, but lower overall high-intensity running. Conversely, a heavier tackle object increases the internal load and results in greater lower limb neuromuscular fatigue as reflected by the decrease in CMJ performance.  相似文献   

Accelerometer data requirements for reliable estimation of habitual physical activity and sedentary time of children during the early years - a worked example following a stepped approach     

Daniel D. Bingham  Silvia Costa  Stacy A. Clemes  Ash C. Routen  Helen J. Moore  Sally E. Barber 《Journal of sports sciences》2016,34(20):2005-2010

This study presents a worked example of a stepped process to reliably estimate the habitual physical activity and sedentary time of a sample of young children. A total of 299 children (2.9 ± 0.6 years) were recruited. Outcome variables were daily minutes of total physical activity, sedentary time, moderate to vigorous physical activity and proportional values of each variable. In total, 282 (94%) provided 3 h of accelerometer data on ≥1 day and were included in a 6-step process: Step-1: determine minimum wear-time; Step-2: process 7-day-data; Step-3: determine the inclusion of a weekend day; Step-4: examine day-to-day variability; Step-5: calculate single day intraclass correlation (ICC) (2,1); Step-6: calculate number of days required to reach reliability. Following the process the results were, Step-1: 6 h was estimated as minimum wear-time of a standard day. Step-2: 98 (32%) children had ≥6 h wear on 7 days. Step-3: no differences were found between weekdays and weekend days (P ≥ 0.05). Step-4: no differences were found between day-to-day variability (P ≥ 0.05). Step-5: single day ICC’s (2,1) ranged from 0.48 (total physical activity and sedentary time) to 0.53 (proportion of moderate to vigorous physical activity). Step-6: to reach reliability (ICC = 0.7), 3 days were required for all outcomes. In conclusion following a 7 day wear protocol, ≥6 h on any 3 days was found to have acceptable reliability. The stepped-process offers researchers a method to derive sample-specific wear-time criterion.  相似文献   

Ankle and knee kinetics between strike patterns at common training speeds in competitive male runners     

Daniel Kuhman  Daniel Melcher 《European Journal of Sport Science》2016,16(4):433-440

The purpose of this study was to investigate the interaction of foot strike and common speeds on sagittal plane ankle and knee joint kinetics in competitive rear foot strike (RFS) runners when running with a RFS pattern and an imposed forefoot strike (FFS) pattern. Sixteen competitive habitual male RFS runners ran at two different speeds (i.e. 8 and 6?min?mile^?1) using their habitual RFS and an imposed FFS pattern. A repeated measures analysis of variance was used to assess a potential interaction between strike pattern and speed for selected ground reaction force (GRF) variables and, sagittal plane ankle and knee kinematic and kinetic variables. No foot strike and speed interaction was observed for any of the kinetic variables. Habitual RFS yielded a greater loading rate of the vertical GRF, peak ankle dorsiflexor moment, peak knee extensor moment, peak knee eccentric extensor power, peak dorsiflexion and sagittal plane knee range of motion compared to imposed FFS. Imposed FFS yielded greater maximum vertical GRF, peak ankle plantarflexor moment, peak ankle eccentric plantarflexor power and sagittal plane ankle ROM compared to habitual RFS. Consistent with previous literature, imposed FFS in habitual RFS reduces eccentric knee extensor and ankle dorsiflexor involvement but produce greater eccentric ankle plantarflexor action compared to RFS. These acute differences between strike patterns were independent of running speeds equivalent to typical easy and hard training runs in competitive male runners. Current findings along with previous literature suggest differences in lower extremity kinetics between habitual RFS and imposed FFS running are consistent among a variety of runner populations.  相似文献   

Inaugural Essay     

Daniel W. Noonan 《Journal Of Archival Organization》2016,13(1-2):82-86

New to the Journal of Archival Organization, the “Technology matters in archives” column examines how technology affects archives and archivists. This inaugural column explains the nature of the column and sets the stage for topics and issues that it will address. It examines the meaning of the term technology. Further, the column explores the notion of technological dependence-- not just dependence on digital or electronic systems--as a lens in which to examine the archival enterprise in grappling with twenty-first century issues. Concluding with the suggestion that technology can be considered from three categorical points of view: soft (philosophical approaches and practices), medium (codified processes, guidelines and standards) and hard technology (hardware and software).  相似文献   

Using Google Forms to track library space usage     

Beth Daniel Lindsay 《Journal Of Access Services》2016,13(3):159-165

This article is a response to the excellent “Using Mobile Technology to Observe Student Study Behaviors and Track Library Space Usage” by Susan Thompson. Thompson reviews the literature regarding user counts on mobile devices and describes the California State University San Marcos (CSUSM) Library's evaluation of SUMA, Counter+, and CloudOn. After trialing these mobile technologies, CSUSM selected CloudOn. At New York University Abu Dhabi, we use Google Forms to conduct user counts on an iPad and Google Sheets to evaluate these data. We find that Google Forms are easy to set up, modify as necessary, and present the data in easy-to-manipulate spreadsheets.  相似文献   

Classroom observation systems in context: A case for the validation of observation systems     

Liu  Shuangshuang  Bell  Courtney A.  Jones  Nathan D.  McCaffrey  Daniel F. 《Educational Assessment, Evaluation and Accountability》2019,31(1):61-95

Educational Assessment, Evaluation and Accountability - Researchers and practitioners sometimes presume that using a previously “validated” instrument will produce “valid”...  相似文献   

Meta-ethnography of autoethnographies: a worked example of the method using educational studies     

Sherick Hughes  George Noblit 《Ethnography and Education》2017,12(2):211-227

ABSTRACT

Despite questions about autoethnography in the ethnography and education research family, autoethnography is published in selective peer-reviewed journals in education and in the social and health sciences. Even critics of autoethnographic studies note their ‘rising acceptance in the past 15 years’ [Delamont, S. 2009. “The Only Honest Thing: Autoethnography, Reflexivity and Small Crises in Fieldwork.” Ethnography and Education 4 (1): 51–63]. However, there has been less effort towards qualitative meta-synthesis to learn what other insights might be gained from collections of studies. With the advent of meta-autoethnography [Ellis, C. 2009. Revision: Autoethnographic Reflections of Life and Work. Walnut Creek, CA: Left Coast Press], each author can find a way to synthesise her/his own autoethnographic works, however, synthesising autoethnographies of different authors has received no attention. This article examines a critical, systematic approach to the meta-ethnography of autoethnographies and offers a worked example of the method using educational studies.  相似文献