Contributions of the non-kicking-side arm to rugby place-kicking technique

To investigate non-kicking-side arm motion during rugby place kicking, five experienced male kickers performed trials under two conditions, both with an accuracy requirement but one with an additional maximal distance demand. Joint centre coordinates were obtained at 120 Hz during kicking trials and a three-dimensional model was created to enable the determination of segmental contributions to whole-body angular momentum. All kickers possessed minimal non-kicking-side arm angular momentum about the global medio-lateral axis. The more accurate kickers exhibited greater non-kicking-side arm angular momentum about the global antero-posterior axis. This augmented the whole-body antero-posterior angular momentum, and altered the whole-body lateral lean at ball contact. The accurate kickers also exhibited greater non-kicking-side arm angular momentum about the global longitudinal axis, which opposed the kicking leg longitudinal angular momentum and attenuated the whole-body longitudinal angular momentum. All participants increased the longitudinal angular momentum of the non-kicking-side arm in the additional distance demand condition, except for one participant whose accuracy decreased, suggesting that the longitudinal angular momentum of the non-kicking-side arm assists maintenance of accuracy in maximum distance kicking. Goal kickers should be encouraged to produce non-kicking-side arm rotations about both the antero-posterior and longitudinal axes, as these appear important for both the initial achievement of accuracy, and for maintaining accuracy during distance kicking.     

Lower extremity muscle function of front row rugby union scrummaging

A rugby scrum’s front row must act uniformly to transfer maximal horizontal force and improve performance. This study investigated the muscle activation patterns of lower extremity muscles in front row forwards during live and machine scrums at professional and amateur levels. Electromyography was collected bilaterally on vastus lateralis, rectus femoris and gastrocnemius muscles of 75 male rugby prop players during live and machine scrums. ANOVAs compared muscle reaction time, rate of change in muscle amplitude and muscle amplitude between groups and conditions. Cross-correlation analysis explored muscle synchronicity. There were significantly greater rates of change in each muscle amplitude in professional players than amateur players. Additionally, there was significantly quicker muscle reaction time in all muscles, and greater amplitude in vastus lateralis and gastrocnemius, during the live scrum vs. machine condition. The professional props produced more synchronised muscle activation than amateur players and all players produced more synchronised muscle activation against the scrum machine vs. live scrummage. The results indicate a higher skill proficiency and muscle synchronicity in professional players. While scrum machine training is ideally suited for functional muscle strengthening during practice, to truly simulate the requirements of the scrum, training should incorporate the live situation as much as possible.     

A descriptive study of step alignment and foot positioning relative to the tee by professional rugby union goal-kickers

This study describes foot positioning during the final two steps of the approach to the ball amongst professional rugby goal-kickers. A 3D optical motion capture system was used to test 15 goal-kickers performing 10 goal-kicks. The distance and direction of each step, as well as individual foot contact positions relative to the tee, were measured. The intra- and inter-subject variability was calculated as well as the correlation (Pearson) between the measurements and participant anthropometrics. Inter-subject variability for the final foot position was lowest (placed 0.03 ± 0.07 m behind and 0.33 ± 0.03 m lateral to the tee) and highest for the penultimate step distance (0.666 ± 0.149 m), performed at an angle of 36.1 ± 8.5° external to the final step. The final step length was 1.523 ± 0.124 m, executed at an external angle of 35.5 ± 7.4° to the target line. The intra-subject variability was very low; distances and angles for the 10 kicks varied per participant by 1.6–3.1 cm and 0.7–1.6°, respectively. The results show that even though the participants had variability in their run-up to the tee, final foot position next to the tee was very similar and consistent. Furthermore, the inter- and intra-subject variability could not be attributed to differences in anthropometry. These findings may be useful as normative reference data for coaching, although further work is required to understand the role of other factors such as approach speed and body alignment.     

Assessing rugby place kick performance from initial ball flight kinematics: development,validation and application of a new measure

The appropriate determination of performance outcome is critical when appraising a performer’s technique. Previous studies of rugby place kicking technique have typically assessed performance based on ball velocity, but this is not the sole requirement. Therefore, a mathematical model of rugby place kick ball flight was developed to yield a single measure more representative of true performance. The model, which requires only initial ball flight kinematics, was calibrated and validated using empirical place kick data, and found to predict ball position with a mean error of 4.0% after 22 m of ball flight. The model was then applied to the performances of 33 place kickers. The predicted maximum distance, a single performance measure which accounted for initial ball velocity magnitude and direction, and spin, was determined using the model and was compared against ball velocity magnitude. A moderate association in the rank-order of the kicks between these two measures (ρ = 0.52) revealed that the relative success of the kicks would be assessed differently with each measure. The developed model provides a representative measure of place kick performance that is understandable for coaches, and can be used to predict changes in performance outcome under different ball launch or environmental conditions.     

Pre-performance routine consistency: temporal analysis of goal kicking in the Rugby Union World Cup

Abstract

This study examined the consistency of pre-performance routines in international rugby union goal kickers on kicks of varying difficulty and under different amounts of situational pressure. Concentration times and physical preparation times were calculated from video recordings of the 572 place kicks taken during the 1999 Rugby Union World Cup. In contrast to the view that performers should seek consistent pre-performance routine times, the results revealed a strong positive relationship between kick difficulty and concentration time. Analysis of the effect of situational pressure, determined by the difference in score before the kick, revealed that players tended to have longer concentration times and shorter physical preparation times when the scores were close. There were no differences between the best and worst kickers in the tournament on routine time, consistency or rhythmicity. The view that increasing the temporal consistency of a routine will result in improved performance is challenged.     

橄榄球运动对骨密度的影响

目的：探讨橄榄球运动训练对男大学生跟骨骨密度（BMD）的影响及其意义。方法：采用Osteospace定量超声骨密度仪,对长期从事橄榄球专项训练的男大学生11名（运动组）,沈阳体育学院体育教育系的11名同龄男大学生（运动对照组）和沈阳体育学院非体育专业的10名学生（一般对照组）进行定量超声骨密度测试,测试部位为右脚跟骨。结果：运动组的BUA与运动对照组相比没有显著性差异（p=0．540）,与一般对照组相比具有非常显著性差异（p=0．004,p〈0．01）;运动组的STI与运动对照组相比无显著性差异（p=0．099）,与一般对照组相比差异显著（p=0．031,p〈0．05）;运动对照组的BUA、STI与一般对照组相比均无显著差异（p=0．135;p=0．997）。结论：橄榄球运动能提高骨密度,增加骨量;高力量性训练、高冲击性运动对骨密度具有良好的影响。     

A systematic review of education programmes to prevent concussion in rugby union

Background: There is a high incidence of concussion sustained by athletes participating in rugby union, many of which go unreported. A lack of sufficient knowledge about concussion injuries may explain athletes’ failure to report. Several rugby union-playing countries have developed injury education and prevention programmes to address this issue. Objective: The aim of the current review was to systematically assess the content and level of evidence on concussion education/prevention programmes in rugby union and to make recommendations for the quality, strength, and consistency of this evidence. Methods: We searched PubMed, PsycInfo, MEDLINE, SPORTDiscuss, Webofscience, and conducted a manual search for articles. Results: Ten articles were included for review. Of these, six focused on the BokSmart injury prevention programme in South Africa, two focused on the RugbySmart injury prevention programme in New Zealand, one was an analysis of prevention programmes, and one was a systematic review of rugby injury prevention strategies. Conclusions: Despite the initiative to develop concussion education and prevention programmes, there is little evidence to support the effectiveness of such programmes. There is evidence to support education of coaches and referees. In addition, there is scant evidence to suggest that education and rule changes may have the benefit of changing athlete behaviours resulting in a reduction in catastrophic injury.     

The match demands of international rugby sevens

The purpose of this study was to quantify the global match demands of international rugby sevens and to compare the match demands of forwards and backs, and between tournament rounds. To assess the match demands, global positioning system (GPS) and video analysis were collected from 27 international rugby sevens players from the same team across an entire International Rugby Board Sevens World Series season. Differences in running demands and match activities between forwards and backs were mostly trivial and small (ES = 0.05–0.84) while differences in running demands and match activities between Pool and Cup rounds were trivial (ES = 0.001–0.12). Cup round matches showed an increase in long-duration ball-in-play sequences (proportion ratio 0.46). These findings suggest international rugby sevens forwards and backs experience similar match demands while overall match demands remain consistent across tournament rounds.     

Flight dynamics of the screw kick in rugby

This paper describes the aerodynamic forces and the flight trajectory for the screw (spiral) kick in rugby. The screw kick is defined as that which causes the ball to spin on its longitudinal axis. The aerodynamic forces acting on a rugby ball spinning on its longitudinal axis were measured in a wind tunnel using a six-component strut type balance. It was found that the drag, the lift and the pitching moment depend on the angle of attack, while the side force (Magnus force) depends on both the spin rate and the angle of attack in the range where the wind speed lies between 15 and 30 m s^-1 and the spin rate is between 1 and 10 revolutions per second. Moreover, the flight trajectory was obtained by integrating the full nonlinear six degrees of freedom equations of motion on the basis of aerodynamic data. In a simulation, a ball spinning on its longitudinal axis tended to hook toward or away from the touchline even if the velocity and angular velocity vectors were parallel to the touchline. The direction of the hook depends on the direction of the angular velocity vector. The initial direction of the hook depends on the relationship between the flight path angle and the pitch angle as well as the direction of the angular velocity vector.     

Coaches’ perceptions of decision making in rugby union

ABSTRACT

Background: In team games situations, the ability to make fast and accurate decisions is crucial to performance. As such, effective decision making, characterised by the consistent and efficient ability to choose the right course of action at the right moment, is a key component of match performance in team sports such as rugby union. Previous research has identified pedagogical approaches to enhance decision making. However, there is dearth in research to investigate how coaches evaluate tactical decision making and subsequently develop context specific ‘on’ and ‘off-field’ coaching practices to improve it. Further, the value coaches place on decision making is under explored.

Purpose: The aim of this study was to explore coaches’ perceptions of decision making in rugby union. The specific objectives to meet this aim were to: (i) Explore coaches’ perceptions of the value and importance of decision making in rugby union; (ii) Identify coaches’ opinions of the key decision making moments in games and how to evaluate them; and (iii) Investigate coaches’ on and off field methods for improving players’ tactical and strategic decision making.

Participants: Purposive sampling was used to select five male coaches, whose ages ranged from 25 to 41 years, from a regional rugby union club in Wales to participate in the study. Coaching experience ranged from two years to 16 years.

Methods: The interpretative paradigm was used within the study with data collected through semi-structured interviews with academy rugby union coaches. This type of interview gathered rich, detailed and complex accounts of coaches’ opinions of players’ in-game decision making in rugby union in order to inform practice and theory. Inductive and deductive qualitative thematic analysis was used to analyse and interpret the data.

Findings: All five coaches agreed that decision making was a crucial part of the modern game of rugby union. There was some disagreement between them about the players’ autonomy to make their own decisions on the pitch and a general lack of clarity between ‘game plan’, ‘strategy’ and ‘tactics’ amongst the coaches. All the coaches agreed that the process of evaluation of players’ decision making should involve a joint discussion with the players. They also agreed that developing decision making was one of the hardest things to coach. Finally, they used a variety of ‘on’ and ‘off-field’ coaching methods to achieve this including video analysis, questioning and the use of games based scenarios.

Conclusion: This study acquired the coaches’ voice on players’ decision making in rugby union by exploring its perceived importance to them and how they evaluated and attempted to improve it. A clear attempt was made among the coaches to develop a ‘non-judgemental’ atmosphere in the evaluation and improvement of players’ decision making. Future research should consider the use of explicitation interviewing, where the interviewer (coach) aims to get the player into a state of evocation, to relive the key decision making moments in an attempt to improve it.     

我国优秀棒球投手投掷臂动作关节角度特征分析

借助三维录像系统,对我国5支棒球队中6名优秀投手进行比赛现场测试,运用运动生物力学原理与方法,对我国优秀棒球投手的投掷臂在投球过程中进行投球技术动作的测试与分析,试图揭示这一技术的运动学特征,并对受试者动作技术的合理性作出诊断与评价。     

The kinetics of rugby union scrummaging

Two rugby union forward packs of differing ability levels were examined during scrummaging against an instrumented scrum machine. By systematically moving the front‐row of the scrum along the scrum machine, kinetic data on each front‐row forward could be obtained under all test conditions. Each forward pack was tested under the following scrummaging combinations: front‐row only; front‐row plus second‐row; full scrum minus side‐row, and full scrum. Data obtained from each scrum included the three orthogonal components of force at engagement and the sustained force applied by each front‐row player. An estimate of sub‐unit contributions was made by subtracting the total forward force on all three front‐row players from the total for the complete scrum. Results indicated the primary role of the second‐row appeared to be application of forward force. The back‐row ('number eight') forward did not substantially contribute any additional forward force, and added only slightly to the lateral and vertical shear force experienced by the front‐row. The side‐row contributed an additional 20–27% to the forward force, but at the expense of increased vertical forces on all front‐row forwards. Results of this investigation are discussed in relation to rule modification, rule interpretation and coaching.     

基于SWOT分析法下中国橄榄球运动发展现状研究

运用SWOT分析法等对现阶段中国橄榄球运动的发展现状及其内部优势与不足、外部机遇与挑战进行分析研究。结果表明：橄榄球运动在我国大陆地区发展进程较慢,其主要原因包括该项目起步较晚、群众基础较差、硬件设施资源不足、运动文化冲突等因素,但该项目发展上升空间较大。     

Multi-optimisation of the screw kick in rugby by using a genetic algorithm

This paper describes the use of Pareto-optimal solutions for the screw kick in rugby. We attempted to optimise the initial conditions for a screw kick. The optimisation was carried out using an elitist non-dominated sorting genetic algorithm. Distance achieved in flight is considered as an objective function, as well as the lateral deviation between the ball and the touchline, or the flight time. Six initial conditions were defined as control parameters: the magnitude of the velocity vector, the flight path angle, the azimuth angle, the spin rate, the pitch angle and the yaw angle. The results are summarised as follows: it is impossible for both objective functions to be satisfied simultaneously, although the greatest distance achieved in flight and the smallest value of the lateral deviation between the ball and the touchline, or the least flight time, is the ideal situation. This kind of conflicting solution is called a ‘Pareto-optimal solution’. The optimal kick in Pareto-optimal solutions made by the leg nearest the touchline produces a greater flight distance than the optimal kick in Pareto-optimal solutions made using the leg furthest from the touchline. The initial pitch angle, which is the angle between the longitudinal axis of the ball and the horizontal plane, should be comparable to or slightly greater than the initial flight path angle in order to satisfy the Pareto-optimal solutions.     

Velocity and acceleration before contact in the tackle during rugby union matches

Abstract

The velocity and acceleration at which the ball-carrier or tackler enters the tackle may contribute to winning the contest and prevailing injury free. Velocity and acceleration have been quantified in controlled settings, whereas in match-play it has been subjectively described. The purpose of this study was to determine the velocity and acceleration of the ball-carrier and tackler before contact during match-play in three competitions (Super 14, Varsity Cup, and Under-19 Currie Cup). Using a two-dimensional scaled version of the field, the velocity and acceleration of the ball-carrier and tackler were measured at every 0.1 s to contact for 0.5 s. For front-on tackles, a significant difference (P < 0.05) between the ball-carrier (4.6 ± 1 m · s^–1) and tackler (7.1 ± 3.5 m · s^–1) was found at the 0.5 s time to contact interval in the Varsity Cup. For side-on tackles, differences between the two opposing players were found at 0.5 s (ball-carrier: 4.6 ± 1.7 m · s^–1; tackler: 3.1 ± 1.2 m · s^–1) and 0.4 s (ball-carrier: 6.3 ± 2.3 m · s^–1; tackler: 3.7 ± 1.6 m · s^–1) at Under-19 level. After 0.4 s, no significant differences (P > 0.05) were evident. Also, the ball-carrier's velocity over the 0.5 s was relatively stable compared with that of the tackler. Results suggest that tacklers adjust their velocity to reach a suitable relative velocity before making contact with the ball-carrier.     

The effect of ball carrying method on sprint speed in rugby union football players

Different methods of ball carrying can be used when a player runs with the ball in rugby union. We examined how three methods of ball carrying influenced sprinting speed: using both hands, under the left arm and under the right arm. These methods were compared with running without the ball. Our aim was to determine which method of ball carrying optimizes sprinting speed. Altogether, 48 rugby union players (age 21±2 years, height 1.83±0.1?m, body mass 85.3±12?kg, body fat 14?±?5%; mean±s) were recruited. The players performed twelve 30-m sprints in total (each player performed three trials under each of three methods of carrying the ball and sprinting without the ball). The design of the study was a form of Latin rectangle, balanced across the trial order for each of the methods and for pairwise combinations of the methods in blocks of four per trial. Each sprint consisted of a 10-m rolling start, followed by a 20-m timed section using electronic timing gates. Compared with sprinting 20?m without the ball (2.58±0.16?s), using both hands (2.62±0.16?s) led to a significantly slower time (P?<0.05). Sprinting 20?m with the ball under the left arm (2.61±0.15?s) or under the right arm (2.60± 0.17?s) was significantly quicker than when using ‘both hands’ (P?<0.05), and both these methods were significantly slower than when running without the ball (P?<0.05). Accordingly, running with the ball in both hands led to the greatest decrement in sprinting performance, although carrying the ball under one arm also reduced the players' sprinting ability. Our results indicate that to gain a speed advantage players should carry the ball under one arm.     

Influence of training and match intensity on injuries in rugby league

The aim of this study was to examine the influence of perceived intensity, duration and load of matches and training on the incidence of injury in rugby league players. The incidence of injury was prospectively studied in 79 semi-professional rugby league players during the 2001 season. All injuries sustained during matches and training sessions were recorded. Training sessions were conducted from December to September, with matches played from February to September. The intensity of individual training sessions and matches was estimated using a modified rating of perceived exertion scale. Training load was calculated by multiplying the training intensity by the duration of the training session. The match load was calculated by multiplying the match intensity by the time each player participated in the match. Training load increased from December (278.3 [95% confidence interval, CI 262.2 to 294.5] units) to February (385.5 [95% CI 362.4 to 408.5] units), followed by a decline until September (98.4 [95% CI 76.5 to 120.4] units). Match load increased from February (204.0 [95% CI 186.2 to 221.8] units) to September (356.8 [95% CI 302.5 to 411.1] units). More training injuries were sustained in the first half of the season (first vs second: 69.2% vs 30.8%, P?<0.001), whereas match injuries occurred more frequently in the latter stages of the season (53.6% vs 46.4%, P?<0.001). A significant relationship (P?<0.05) was observed between changes in training injury incidence and changes in training intensity (r?=?0.83), training duration (r?=?0.79) and training load (r?=?0.86). In addition, changes in the incidence of match injuries were significantly correlated (P?<0.05) with changes in match intensity (r?=?0.74), match duration (r?=?0.86) and match load (r?=?0.86). These findings suggest that as the intensity, duration and load of rugby league training sessions and matches is increased, the incidence of injury is also increased.     

The relative contribution of training intensity and duration to daily measures of training load in professional rugby league and union

ABSTRACT

This study examined the relative contribution of exercise duration and intensity to team-sport athlete’s training load. Male, professional rugby league (n = 10) and union (n = 22) players were monitored over 6- and 52-week training periods, respectively. Whole-session (load) and per-minute (intensity) metrics were monitored (league: session rating of perceived exertion training load [sRPE-TL], individualised training impulse, total distance, BodyLoad?; union: sRPE-TL, total distance, high-speed running distance, PlayerLoad?). Separate principal component analyses were conducted on the load and intensity measures to consolidate raw data into principal components (PC, k = 4). The first load PC captured 70% and 74% of the total variance in the rugby league and rugby union datasets, respectively. Multiple linear regression subsequently revealed that session duration explained 73% and 57% of the variance in first load PC, respectively, while the four intensity PCs explained an additional 24% and 34%, respectively. Across two professional rugby training programmes, the majority of the variability in training load measures was explained by session duration (~60–70%), while a smaller proportion was explained by session intensity (~30%). When modelling the training load, training intensity and duration should be disaggregated to better account for their between-session variability.     

Changes in acute biochemical markers of inflammatory and structural stress in rugby union

Rugby union is a sport governed by the impacts of high force and high frequency. Analysis of physiological markers following a game can provide an understanding of the physiological response of an individual and the time course changes in response to recovery.

Urine and saliva were collected from 11 elite amateur rugby players 24 h before, immediately after, and at 17, 25, 38, 62 and 86 h post-game. Myoglobin, salivary immunoglobulin A and cortisol were analysed by ELISA, whereas neopterin and total neopterin were analysed by high-performance liquid chromatography.

There was a significant post-game increase of all four markers. The increases were cortisol 4-fold, myoglobin 2.85-fold, neopterin 1.75-fold and total neopterin 2.3-fold when corrected with specific gravity. All significant changes occurred post-game only, with markers returning to and remaining at baseline within 17 h.

The intensity of the game caused significant changes in key physiological markers of stress. They provide an understanding of the stress experienced during a single game of rugby and the time course changes associated with player recovery. Neopterin provides a new marker of detecting an acute inflammatory response in physical exercise, while specific gravity should be considered for urine volume correction post-exercise.