Ball Carrier Research Articles

Risk factors for head injury events in professional rugby union: a video analysis of 464 head injury events to inform proposed injury prevention strategies

ObjectivesThe tackle is responsible for the majority of head injuries during rugby union. In order to address head injury risk, risk factors during the tackle must first be identified. This...

Video Analysis of Primary Shoulder Dislocations in Rugby Tackles.

Background:Characteristics of rugby tackles that lead to primary anterior shoulder dislocation remain unclear.Purpose:To clarify the characteristics of tackling that lead to shoulder dislocation and to assess the correlation between the mechanism of injury and morphological damage of the glenoid.Study Design:Case series; Level of evidence, 4.Methods:Eleven elite rugby players who sustained primary anterior shoulder dislocation due to one-on-one tackling between 2001 and 2014 were included. Using an assessment system, the tackler’s movement, posture, and shoulder and head position were evaluated in each phase of tackling. Based on 3-dimensional computed tomography, the glenoid of the affected shoulder was classified into 3 types: intact, erosion, and bone defect. Orientation of the glenoid defect and presence of Hill-Sachs lesion were also evaluated.Results:Eleven tackles that led to primary shoulder dislocation were divided into hand, arm, and shoulder tackle types based on the site at which the tackler contacted the ball carrier initially. In hand and arm tackles, the tackler’s shoulder joint was forcibly moved to horizontal abduction by the impact of his upper limb, which appeared to result from an inappropriate approach to the ball carrier. In shoulder tackles, the tackler’s head was lowered and was in front of the ball carrier at impact. There was no significant correlation between tackle types and the characteristics of bony lesions of the shoulder.Conclusion:Although the precise mechanism of primary anterior shoulder dislocation could not be estimated from this single-view analysis, failure of individual tackling leading to injury is not uniform and can be caused by 2 main factors: failure of approach followed by an extended arm position or inappropriate posture of the tackler at impact, such as a lowered head in front of the opponent. These findings indicate that injury mechanisms should be assessed for each type of tackle, as it is unknown whether external force to the glenoid is different in each mechanism during shoulder dislocation.

The effect of technique on tackle gainline success outcomes in elite level rugby union

Tackling is a major component of rugby union and effective attacking and defensive play are essential for game outcomes. In this study, a number of pre-contact, contact and post-contact tackle characteristics that had an influence on tackle gainline success for the ball carrier and tackler were identified using match video evidence from European Rugby Champions Cup games. A total of 122 front-on tackles and 111 side-on tackles were analysed. For each ball carrier and tackler characteristic, the Odds Ratio and 95% Confidence Interval were calculated based on a gainline success outcome. A Chi-Square and Phi and Cramer’s V calculation was also conducted. A Chi-Square test then identified any statistically significant differences (p < 0.05) for proficiency characteristics between playing position. For both the ball carrier and tackler, tackle characteristics that were indicative of strong and powerful tackle technique such as ‘explosiveness on contact’ and ‘leg drive on contact’ were effective for achieving the desired gainline outcome. Playing position had an influence on only two proficiency characteristics that were statistically significant for gainline success: ‘fending into contact’ for ball carriers and ‘straight back, centre of gravity forward of support base’ for tacklers.

How Do Soccer Players Adjust Their Activity in Team Coordination? An Enactive Phenomenological Analysis.

This study examined how individual team members adjust their activity to the needs for collective behavior. To do so, we used an enactive phenomenological approach and explored how soccer players' lived experiences were linked to the active regulation of team coordination during eight offensive transition situations. These situations were defined by the shift from defensive to offensive play following a change in ball possession. We collected phenomenological data, which were processed in four steps. First, we reconstructed the diachronic and synchronic dynamics of the players' lived experiences across these situations in order to identify the units of their activity. Second, we connected each player's units of activity side-by-side in chronological order in order to identify the collective units. Each connection was viewed as a collective regulation mode corresponding to which and how individual units were linked at a given moment. Third, we clustered each collective unit using the related objectives within three modes of regulation—local (L), global (G), and mixed (M). Fourth, we compared the occurrences of these modes in relation to the observable key moments in the situations in order to identify typical patterns. The results indicated four patterns of collective regulation modes. Two distinct patterns were identified without ball possession: reorganize the play formation (G and M) and adapt to the actions of putting pressure on the ball carrier (M). Once the ball was recovered, two additional patterns emerged: be available to get the ball out of the recovery zone (L) and shoot for the goal (L and M). These results suggest that team coordination is a fluctuating phenomenon that can be described through the more or less predictable chaining between these patterns. They also highlight that team coordination is supported by several modes of regulation, including our proposal of a new mode of interpersonal regulation. We conclude that future research should investigate the effect of training on the enaction of this mode in competition.

Tackle technique and body position of the tackler and ball carrier significantly influences head injury risk in rugby union

ObjectiveInterventions to reduce head injury range from law changes to technique training and education. The effective targeting of such interventions requires that the mechanism of injury be well understood. This study describes the events contributing to head injuries in Rugby Union.DesignAn observational study with a cohort comprised of six professional Rugby Union competitions. Every Head Injury Assessment (HIA) reported during a three-year period was documented and described according to 15 descriptive criteria.Outcome measuresDescriptive criteria, and combinations thereof, including preceding and inciting event, tackle type, speed, direction and technique-related variables. The incidence of head injury was calculated per 1,000 events for each variableMain results611 HIAs were performed in 1,516 matches. 464 HIAs occurred after tackles (1.94 HIAs/1000 tackles). Active shoulder tackles, front-on tackles and high speed tackles have the greatest incidence of head injuries. For any tackle type and tackler position, the lowest incidence of HIAs occurs when the ball carrier is bent at the waist (1.2 HIAs/1000 tackles vs 2.4 and 9.8 HIAs/1000 tackles for upright and falling positions, respectively). For any ball carrier position, the greatest risk of head injury exists when the tackler is upright (2.7 HIAs/1000 tackles vs 1.9 and 1.2 HIAs/1000 tackles for bent at waist and diving, respectively).ConclusionsTechnique components of the tackle, related primarily to the body position adopted by the tackler and ball carrier, significantly influence head injury risk. Interventions may be targeted at improving these variables to reduce head injury incidence in the sport.Competing interestsThe primary author is employed in a scientific and research role by World Rugby (Pty) Ltd, who also funded the research study.

Response of performance and bacterial community to oligotrophic stress in biofilm systems for raw water pretreatment.

Understanding the dynamics of performance and bacterial community of biofilm under oligotrophic stress is necessary for the process optimization and risk management in biofilm systems for raw water pretreatment. In this study, biofilm obtained from a pilot-scale biofilm reactor was inoculated into a pilot-scale experimental tank for the treatment of oligotrophic raw water. Results showed that the removal of NH4+-N was impaired in biofilm systems when influent NH4+-N was less than 0.35mg L-1 or NH4+-N loading rate of less than 7.51mg L-1 day-1. The dominant bacteria detected in biofilm of different carrier were obvious distinct from phylum to genus level under oligotrophic stress. The dominant bacteria in elastic stereo media carrier changed from Proteobacteria (51.1%) to Firmicutes (32.7%), while Proteobacteria was always dominant in suspended ball carrier after long-term operation under oligotrophic conditions. Oligotrophic stress largely decreased the functional bacteria for the removal of nitrogen and organics including many genera in Proteobacteria and Nitrospirae, but increased several genera with spore forming organisms or potential bacterial pathogens in ESM carrier mainly including Bacillus, Mycobacterium, Pseudomonas, etc.

Quantifying synergies in two-versus-one situations in team sports: An example from Rugby Union.

Collective behaviors in team sports result in players forming interpersonal synergies that contribute to performance goals. Because of the huge amount of variables that continuously constrain players' behavior during a game, the way that these synergies are formed remain unclear. Our aim was to quantify interpersonal synergies in the team sport of Rugby Union. For that purpose we used the Uncontrolled Manifold Hypothesis (UCM) to identify interpersonal synergies that are formed between ball carrier and support player in two-versus-one situations in Rugby Union. The inter-player angle close to the moment of the pass was used as a performance variable and players running lines velocities as task-relevant elements. Interpersonal synergies (UCM values above 1) were found in 19 out of 55 trials under analysis, which means that on 34% of the trials, the players' running line velocities contribute to stabilizing the inter-player angle close the moment of the pass. The strength of the synergy fluctuates over time indicating the existence of a location effect during attack phases in Rugby Union. UCM analysis shows considerable promise as a performance analysis tool in team sports to discriminate between skilled sub-groups of players.

DECISION-MAKING AND TECHNIQUE: EVIDENCE FOR INCREASED HEAD INJURY RISK DURING TACKLING IN RUGBY UNION

BackgroundThe tackle is the most injurious game event in Rugby Union. We recently found that tackles account for 76% of head injury events in professional rugby. Specific analysis of the...

VIDEO ANALYSIS OF CONTACT TECHNIQUE DURING HEAD COLLISIONS IN RUGBY UNION

BackgroundRugby union is characterised by frequent and dynamic collisions. Players typically aim to avoid direct contact to the head due to its potential for serious head injury. However, head collisions...

TACKLE DIRECTION AND DOMINANT SIDE AFFECT UPPER BODY LOADING DURING RUGBY TACKLES

BackgroundApproximately 25% of Rugby Union injuries occur to players executing a tackle and they mostly involve upper-body regions.ObjectiveTo investigate how upper-body biomechanical loading changes depending on the tackle characteristics, such...

A DOWNWARD HEAD POSTURE LEADS TO HIGHER CERVICAL SPINE LOADING DURING HEAD-FIRST IMPACTS IN SIMULATED RUGBY TACKLES

BackgroundA rugby tackle is an open and unpredictable event, which can lead to intentional or unintentional head-first impacts rather than the preferred ‘shoulder first’ technique.ObjectiveTo identify the effect of head-neck...

Mechanisms of ACL injury in professional rugby union: a systematic video analysis of 36 cases

BackgroundThe mechanisms of ACL injury in rugby are not well defined.AimTo describe the mechanisms of ACL injury in male professional rugby players using systematic video analysis.Methods36 cases from games played...

Behavior prediction of ball carriers in basketball match video

This paper proposes a new method of behavior prediction of ball carriers in the basket-ball match video. Due to the low resolution of the head images, the fast motion of sportsmen and the clustered background in the video, this paper proposes the adoption of a covariance descriptor to fuse multiple visual features of the head region, which can be represented as Riemannian Manifolds. Then map the covariance descriptor to the tangent space and complete the head pose classification through the trained multiclass Logitboosts directly in this space for determination of the vision field. According to the distribution of all the sportsmen with-in the range of vision of the ball carrier, this paper predicts his behaviors of shooting, passing and dribbling through sportsmen information based on artificial potential field(APF). At last, this paper testifies the effectiveness of the proposed method by testing on the basketball match videos.

Mechanisms and Factors Associated With Tackle-Related Injuries in South African Youth Rugby Union Players

Background: The majority of injuries in rugby union occur during tackle events. The mechanisms and causes of these injuries are well established in senior rugby union. Purpose: To use information from an injury database and assess video footage of tackle-related injuries in youth rugby union matches to identify environmental factors and mechanisms that are potentially confounding to these injuries. Study Design: Descriptive epidemiological study. Methods: Injury surveillance was conducted at the under-18 Craven Week rugby tournament. Tackle-related injury information was used to identify injury events in match video footage (role-matched noninjury tackle events were identified for the cohort of injured players). Events were coded using match situational variables (precontact, contact, and postcontact). Relative risk ratio (RRR; ratio of probability of an injury or noninjury outcome occurring when a characteristic was observed) was reported by use of logistic regression. Results: In comparison with the first quarter, injury risk was greater in the third (RRR = 9.75 [95% CI, 1.71-55.64]; P = .010) and fourth quarters (RRR = 6.97 [95% CI, 1.09-44.57]; P = .040) for ball carriers and in the fourth quarter (RRR = 9.63 [95% CI, 1.94-47.79]; P = .006) for tacklers. Ball carriers were less likely to be injured when they were aware of impending contact (RRR = 0.14 [95% CI, 0.03-0.66]; P = .012) or when they executed a moderate fend (hand-off) (RRR = 0.22 [95% CI, 0.06-0.84]; P = .026). Tacklers were less likely to be injured when performing shoulder tackles (same side as leading leg) in comparison to an arm-only tackle (RRR = 0.02 [95% CI, 0.001-0.79]; P = .037). Ball carriers (RRR = 0.09 [95% CI, 0.01-0.89]; P = .040) and tacklers (RRR = 0.02 [95% CI, 0.001-0.32]; P =.006) were less likely to be injured when initial contact was made with the tackler’s shoulder/arm instead of his head/neck. Conclusion: The relative risk of tackle-related injury was higher toward the end of matches. Incorrect technique may contribute to increased injury risk. Implementing recovery strategies between matches, training safe and effective techniques, and improving levels of conditioning may counter the negative effects of fatigue. These findings may assist stakeholders in youth rugby to formulate injury prevention strategies and may improve the preparation of field-side medical staff for managing tackle-related injuries at these or similar tournaments.

Incidence and Factors Associated With Concussion Injuries at the 2011 to 2014 South African Rugby Union Youth Week Tournaments.

To determine the concussion incidence and to identify factors associated with concussion in South African youth rugby union players. Prospective cohort study. Injury surveillance was completed at the South African Rugby Union Youth Week tournaments (under-13, under-16, and under-18 age groups). South African youth rugby union players. A total of 7216 players participated in 531 matches between 2011 and 2014. None. Concussion incidence was calculated per 1000 player-match-hours with 95% CIs. Poisson regression was used to calculate the incidence rate ratio (IRR) between factors (age, time period, playing position, and activity at the time of concussion) potentially associated with concussions. The concussion incidence was 6.8/1000 player-match-hours (95% CI, 5.5-8.1) across all age groups. Under-13s (IRR, 1.5; P = 0.09) and under-16s (IRR, 1.7; P = 0.03) had higher concussion incidence rates than the under-18 age group. The incidence was higher in the third (IRR, 2.1; P = 0.04) and fourth (IRR, 2.5; P = 0.01) quarters of matches compared with the first quarter. Sixty-two percent of concussions occurred in the tackle situation. The tackler had a 4-fold greater concussion rate (IRR, 4.3; P < 0.001) compared with the ball carrier. The hooker and loose forwards had higher incidence rates than several other player positions (P < 0.05). The reported concussion incidence falls within the broad range previously reported in youth rugby. The evidence highlighted in this study may contribute to targeted concussion prevention strategies and provide a baseline against which the effectiveness of future interventions can be measured.

Risks associated with significant head impact events in elite rugby union

Primary objectives: To conduct video and statistical analysis on Rugby Union play, focusing mainly on the tackle, to establish the player to player configurations for significant direct head impacts and non-direct head impacts.Research design: Quantitative, observational cohort study.Methods and procedures: Video analysis of 52 significant direct head impacts (31 Tackle, 10 Ruck, 7 Dive and 4 Ground) and 40 non-direct head impact tackles from 2014/15 International Rugby Union matches. Relative risk, 95% CI and p-values were calculated for a range of tackle variables.Main outcome and results: Upper body tackles and lower body tackles accounted for 37% (19) and 23% (12) of cases, respectively, with the tackler as the head impacted player for 97% (30) of cases. The majority (81%) of tackle-related significant direct head impacts occurred in the second half of the game, with 63% of upper body tackle significant direct head impacts occurring in the final quarter. Tackler head placement and high speed tackles had statistical significance for causing tackle related significant direct head impacts as well as foot planting and difference in tackler and ball carrier mass for upper body tackles and ball carrier change in direction for lower body tackles.Conclusion: Tackle variables that statistically increased the risk of significant direct head impact were identified, which can aid player protection strategies.

The Velocity of Ball-Carriers and Tacklers during Shoulder Tackles

The most frequently executed type of tackle in rugby is the shoulder tackle. A shoulder tackle occurs when the tackler uses either shoulder as the first point of contact with the ball carrier. The aim of this study was to compare the velocity of the ball-carrier and tackler engaged in shoulder tackles, and determine whether factors such as the number of passes from the previous phase, match period, quality of attack, match location and position of tackler had an effect on the mean and approaching velocities of the ball-carrier and tackler. The velocity of the ball-carrier and tackler during shoulder tackles (n=12) were determined using a 2D analysis tool. The tackles were also coded according to pass number, match period, quality of defence and attack, match status, defensive shape and movement, position of tackler and ball-carrier. The ball-carrier’s velocity (4.10±1.85m.s-1) when entering contact was significantly higher than the tackler’s velocity (5.19±3.22 m.s–1)(p<0.05). The ball-carrier’s velocity was significantly higher when entering contact further from the set piece (p<0.001), when playing away from home (p<0.001) and when ranked in the top three (p<0.001). The findings of this study provide insight into the complexities of the tackle in rugby.

Assessing Novices’ Game Performance in Rugby Union: The Rugby Attack Assessment Instrument (RAAI)

The application of Teaching Games for Understanding (TGfU) and Game Centered Approaches (GCA) in team sports initiation generated the need for assessing game performance. In this paper we introduce the Rugby Attack Assessment Instrument (RAAI), a tool to assess the actions of players in attack and their incidence in the generated game situations in rugby. The RAAI focuses the attention on the ball carrier during a 5 vs. 5 situation. The actions of players in possession of the ball are described and codified. A weight is allocated to each simple and combined action in relation to its tactical value. Thus, the codified actions provide a weighted Index of Performance, the team score of the RAAI. Validity and reliability were tested in two different studies. Results suggest that the RAAI is valid and reliable to assess ball carrier’s actions and their influence in attacking game situations of novice rugby union players.

The relationships between rugby players’ tackle training attitudes and behaviour and their match tackle attitudes and behaviour

BackgroundThe tackle event in rugby is a technical and physical contest between opposing players. A player's ability to tolerate and contest during a tackle is a prerequisite for safe participation...

Collision characteristics of shoulder charge tackles in elite rugby league

The study objective was to investigate the tackle and collision characteristics of shoulder charge tackles within elite rugby league match-play. Tackle characteristics and injury outcomes from video footage of 201 matches (30 National Rugby League rounds and finals series) were examined. Players were categorised into positional groups: hit-up forwards, adjustables and outside backs. Where possible, data from Global Positioning System (GPS) units worn by players were linked to video footage for analysis. Tackles were classified as shoulder charge or conventional tackle. Outcome measures included shoulder charge incidence, tackle characteristics and impacts (G-force) sustained during shoulder charge tackles. In 201 video files, 59 shoulder charges were identified from 123,211 tackles. Shoulder charge incidence was 0.05% of total tackles, with an average rate of 0.29 shoulder charges per game. However, shoulder charge incidence increased from 0.22 in rounds 1-26 to 1.88 in the final series. In the majority of shoulder charge tackles (P<0.001) players executed the tackle through transferring body mass over the front foot and driving the right shoulder in an upright and oblique approach to the ball carrier. Impact forces from GPS ranged from 6.5-13.4G and 7.9-12.3G for attackers and defenders, respectively. The physical demands of the tackle were within the highest classification of sustained impacts during match-play.