The expected value of possession in professional rugby league match-play     

Thomas Kempton  Nicholas Kennedy  Aaron J. Coutts 《Journal of sports sciences》2016,34(7):645-650

This study estimated the expected point value for starting possessions in different field locations during rugby league match-play and calculated the mean expected points for each subsequent play during the possession. It also examined the origin of tries scored according to the method of gaining possession. Play-by-play data were taken from all 768 regular-season National Rugby League (NRL) matches during 2010–2013. A probabilistic model estimated the expected point outcome based on the net difference in points scored by a team in possession in a given situation. An iterative method was used to approximate the value of each situation based on actual scoring outcomes. Possessions commencing close to the opposition’s goal-line had the highest expected point equity, which decreased as the location of the possession moved towards the team’s own goal-line. Possessions following an opposition error, penalty or goal-line dropout had the highest likelihood of a try being scored on the set subsequent to their occurrence. In contrast, possessions that follow an opposition completed set or a restart were least likely to result in a try. The expected point values framework from our model has applications for informing playing strategy and assessing individual and team performance in professional rugby league.  相似文献   

Differences in pedalling technique between road cyclists of different competitive levels     

Juan García-López  Sergio Díez-Leal  Ana Ogueta-Alday  Josu Larrazabal  José A. Rodríguez-Marroyo 《Journal of sports sciences》2016,34(17):1619-1626

The purpose of this study was to compare the pedalling technique in road cyclists of different competitive levels. Eleven professional, thirteen elite and fourteen club cyclists were assessed at the beginning of their competition season. Cyclists’ anthropometric characteristics and bike measurements were recorded. Three sets of pedalling (200, 250 and 300 W) on a cycle ergometer that simulated their habitual cycling posture were performed at a constant cadence (~90 rpm), while kinetic and kinematic variables were registered. The results showed no differences on the main anthropometric variables and bike measurements. Professional cyclists obtained higher positive impulse proportion (1.5–3.3% and P < 0.05), mainly due to a lower resistive torque during the upstroke (15.4–28.7% and P < 0.05). They also showed a higher ankle range of movement (ROM, 1.1–4.0° and P < 0.05). Significant correlations (P < 0.05) were found between the cyclists’ body mass and the kinetic variables of pedalling: positive impulse proportion (r = ?0.59 to ?0.61), minimum (r = ?0.59 to ?0.63) and maximum torques (r = 0.35–0.47). In conclusion, professional cyclists had better pedalling technique than elite and club cyclists, because they opted for enhancing pulling force at the recovery phase to sustain the same power output. This technique depended on cycling experience and level of expertise.  相似文献   

Can textured insoles improve ankle proprioception and performance in dancers?     

Nili Steinberg  Gordon Waddington  Roger Adams  Janet Karin  Rezaul Begg  Oren Tirosh 《Journal of sports sciences》2016,34(15):1430-1437

With the aim of determining both the acute and the chronic effects of textured insoles on the ankle discrimination and performance ability of dancers, 60 ballet dancers from the Australian Ballet School, aged 14–19 years, were divided into three groups (two intervention groups and a control group), age- and level-matched. In the first 5 weeks (weeks 1 to 5), the first intervention group (GRP1) was asked to wear textured insoles in their ballet shoes and the second intervention group (GRP2) was not given textured insoles to wear. In the next 5 weeks (weeks 6 to 10), GRP2 was asked to wear the same type of textured insoles and GRP1 did not wear the textured insoles. The control group (CTRL) did not wear textured insoles during the whole 10 weeks. All participants were tested preintervention, after 5 weeks and after 10 weeks for ankle discrimination score (AUC scores). Dance performance was assessed by 5–7 dance teachers. Pre-to-post change in AUC scores was significantly greater for the groups wearing insoles than for the controls (P = .046) and the size of pre-to-post changes did not differ between the two intervention groups (P = .834). Significant correlation was found between ankle discrimination score and performance scores, using the textured insoles (r = .412; P = .024). In conclusion, the stimulation to the proprioceptive system arising from textured insoles worn for five weeks was sufficient to improve the proprioceptive ability and performance ability of ballet dancers.  相似文献   

Performance differences when using 26- and 29-inch-wheel bikes in Swiss National Team cross-country mountain bikers     

Thomas Steiner  Beat Müller  Thomas Maier  Jon Peter Wehrlin 《Journal of sports sciences》2016,34(15):1438-1444

The purpose of this study was to analyse the effect of bike type – the 26-inch-wheel bike (26“ bike) and the 29-inch-wheel bike (29“ bike) – on performance in elite mountain bikers. Ten Swiss National Team athletes (seven males, three females) completed six trials with individual start on a simulated cross-country course with 35 min of active recovery between trials (three trials on a 26“ bike and three trials on a 29“ bike, alternate order, randomised start-bike). The course consisted of two separate sections expected to favour either the 29“ bike (section A) or the 26“ bike (section B). For each trial performance, power output, cadence and heart rate were recorded and athletes’ experiences were documented. Mean overall performance (time: 304 ± 27 s vs. 311 ± 29 s; P < 0.01) and performance in sections A (P < 0.001) and B (P < 0.05) were better when using the 29“ bike. No significant differences were observed for power output, cadence or heart rate. Athletes rated the 29“ bike as better for performance in general, passing obstacles and traction. The 29“ bike supports superior performance for elite mountain bikers, even on sections supposed to favour the 26“ bike.  相似文献   

Neuromuscular and technical abilities related to age in water-polo players     

Fabio De Siati  Guillaume Laffaye  Giorgio Gatta  Antonio Dello Iacono  Johnny Padulo 《Journal of sports sciences》2016,34(15):1466-1472

Testing is one of the important tasks in any multi-step sport programme. In most ball games, coaches assess motor, physical and technical skills on a regular basis in early stages of talent identification in order to further athletes’ development. The purpose of the study was to investigate anthropometric variables and vertical jump heights as a free throw effectiveness predictor in water-polo players of different age groups. Two hundred and thirty-six young (10–18 years) male water-polo players partitioned into three age groups underwent anthropometric variables’ measures and squat- and countermovement-jump tests, and performed water-polo free throws. Anthropometric variables, vertical jump heights and throw speed – as a proxy for free throw effectiveness – resulted different over age groups. Particularly, throw speed changed from 9.28 to 13.70 m · s^?1 (+48%) from younger to older players. A multiple-regression model indicated that body height, squat-jump height and throw time together explain 52% of variance of throw speed. In conclusion, tall height, high lower limb power and throwing quickness appeared to be relevant determinants for effective free throws. Such indications can help coaches during talent identification and development processes, even by means of novel training strategies. Further research is needed over different maturity statuses.  相似文献   

Positional group significantly influences the offensive and defensive skill involvements of junior representative rugby league players during match play     

Kyle J. M. Bennett  Job Fransen  Brendan R. Scott  Colin E. Sanctuary  Tim J. Gabbett  Ben J. Dascombe 《Journal of sports sciences》2016,34(16):1542-1546

This study examined the skill involvements of three positional groups across a junior representative rugby league season. Data were collected from 45 rugby league players (mean ± SD; age = 16.5 ± 1.0 years) currently participating in the Harold Matthews and SG Ball Cup. Players were subdivided into hit-up forwards, adjustables and outside backs. The frequency (n · min^?1) of offensive, defensive and overall involvements was coded for each group using a notation system and a practical coach skill analysis tool. Multivariate analysis of variance (MANOVA) revealed a significant effect of playing position on skill involvements (F = 9.06; P < 0.001; ES = 0.41). Hit-up forwards performed a significantly greater frequency of offensive (0.31 ± 0.10), defensive (0.42 ± 0.15) and overall involvements (0.74 ± 0.19) when compared to adjustables (0.20 ± 0.08, 0.28 ± 0.08 and 0.52 ± 0.15, respectively) and outside backs (0.20 ± 0.12, 0.11 ± 0.07 and ± 0.31 ± 0.17, respectively). Further, adjustables performed a significantly greater number of defensive (0.28 ± 0.08) and overall involvements (0.52 ± 0.15) when compared to outside backs (0.11 ± 0.07 and 0.31 ± 0.17, respectively). The findings of this study suggest that it is important to consider a junior player’s positional group when analysing their skill involvements. Information gained from this study could assist in the design of specific training methodologies for junior rugby league players in high-level talent development programmes.  相似文献   

Do cognitive training strategies improve motor and positive psychological skills development in soccer players? Insights from a systematic review     

Maamer Slimani  Nicola Luigi Bragazzi  David Tod  Alexandre Dellal  Olivier Hue  Foued Cheour 《Journal of sports sciences》2016,34(24):2338-2349

ABSTRACT

Soccer players are required to have well-developed physical, technical and cognitive abilities. The present systematic review, adhering to Preferred Reporting Items for Systematic reviews and Meta-Analysis guidelines, examined the effects of cognitive training strategies on motor and positive psychological skills development in soccer performance and identified the potential moderators of the “cognitive training–soccer performance” relationship. Thirteen databases were systematically searched using keywords related to psychological or cognitive training in soccer players. The review is based on 18 studies, employing 584 soccer players aged 7–39 years. Cognitive strategies, particularly imagery, appear to improve sports performance in soccer players. Regarding imagery, the combination of two different types of cognitive imagery training (i.e., cognitive general and cognitive specific) has a positive influence on soccer performance during training, whereas motivational imagery (i.e., motivational general-arousal, motivational general-mastery and motivational specific) enhance competition performance. Younger soccer players employ cognitive general and cognitive specific imagery techniques to a greater extent than older soccer players. Combined cognitive training strategies were more beneficial than a single cognitive strategy relative to motor skills enhancement in elite (particularly midfielders) and amateur (i.e., when practising complex and specific soccer skills in precompetitive period) soccer players. In conclusion, it appears that there are differences in cognitive/psychological training interventions, and their efficacy, according to whether they are directed towards training or competition, and the age, standard and playing position of the players.  相似文献   

Development of perceived competence,tactical skills,motivation, technical skills,and speed and agility in young soccer players     

Hannele Forsman  Arto Gråstén  Minna Blomqvist  Keith Davids  Jarmo Liukkonen  Niilo Konttinen 《Journal of sports sciences》2016,34(14):1311-1318

ABSTRACT

The objective of this 1-year, longitudinal study was to examine the development of perceived competence, tactical skills, motivation, technical skills, and speed and agility characteristics of young Finnish soccer players. We also examined associations between latent growth models of perceived competence and other recorded variables. Participants were 288 competitive male soccer players ranging from 12 to 14 years (12.7 ± 0.6) from 16 soccer clubs. Players completed the self-assessments of perceived competence, tactical skills, and motivation, and participated in technical, and speed and agility tests. Results of this study showed that players’ levels of perceived competence, tactical skills, motivation, technical skills, and speed and agility characteristics remained relatively high and stable across the period of 1 year. Positive relationships were found between these levels and changes in perceived competence and motivation, and levels of perceived competence and speed and agility characteristics. Together these results illustrate the multi-dimensional nature of talent development processes in soccer. Moreover, it seems crucial in coaching to support the development of perceived competence and motivation in young soccer players and that it might be even more important in later maturing players.  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   

Position-specific performance indicators that discriminate between successful and unsuccessful teams in elite women’s indoor field hockey: implications for coaching     

Don Vinson  Derek M. Peters 《Journal of sports sciences》2016,34(4):311-320

The aim of this investigation was to establish median performance profiles for the six playing positions in elite women’s indoor hockey and then identify whether these position-specific profiles could discriminate between qualifying (top four), mid-table and relegated teams in the 2011–2012 England Hockey premier league. Successful passing in relegated teams was significantly lower (P < 0.008) than in mid-table and qualifying teams in four of the five outfield positions. Furthermore, the right backs of qualifying teams demonstrated significantly fewer (P < 0.008) unsuccessful passes (x? = 15.5 ± CLs 15.0 and 10.0, respectively) and interceptions (x? = 4.0 ± CLs 4.0 and 3.0, respectively) than relegated teams (x? = 19.5 ± CLs 21.0 and 17.0; x? = 7.5 ± CLs 8.0 and 6.0, respectively). Finally, the right forwards of relegated teams demonstrated significantly fewer (P < 0.008) successful interceptions (x? = 4.0 ± CLs 5.0 and 4.0, respectively) than qualifying teams (x? = 5.0 ± CLs 6.0 and 3.0, respectively) and significantly more (P < 0.008) unsuccessful interceptions (x? = 5.5 ± CLs 6.0 and 4.0, respectively) than mid-table teams (x? = 3.0 ± CLs 3.0 and 2.0, respectively). Based on these findings, coaches should adapt tactical strategies and personnel deployment accordingly to enhance the likelihood of preparing a qualifying team. Research should build from these data to examine dribbling, pressing and patterns of play when outletting.  相似文献