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) 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.     

Repeated high-intensity exercise in professional rugby union

Abstract

The aim of the present study was to describe the frequency, duration, and nature of repeated high-intensity exercise in Super 14 rugby union. Time–motion analysis was used during seven competition matches over the 2008 and 2009 Super 14 seasons; five players from each of four positional groups (front row forwards, back row forwards, inside backs, and outside backs) were assessed (20 players in total). A repeated high-intensity exercise bout was considered to involve three or more sprints, and/or tackles and/or scrum/ruck/maul activities within 21 s during the same passage of play. The range of repeated high-intensity exercise bouts for each group in a match was as follows: 11–18 for front row forwards, 11–21 for back row forwards, 13–18 for inside backs, and 2–11 for outside backs. The durations of the most intense repeated high-intensity exercise bouts for each position ranged from 53 s to 165 s and the minimum recovery periods between repeated high-intensity exercise bouts ranged from 25 s for the back row forwards to 64 s for the front row forwards. The present results show that repeated high-intensity exercise bouts vary in duration and activities relative to position but all players in a game will average at least 10 changes in activity in the most demanding bouts and complete at least one tackle and two sprints. The most intense periods of activity are likely to last as long as 120 s and as little as 25 s recovery may separate consecutive repeated high-intensity exercise bouts. The present findings can be used by coaches to prepare their players for the most demanding passages of play likely to be experienced in elite rugby union.     

Technical determinants of tackle and ruck performance in International rugby union

The most frequently occurring contact events in rugby union are the tackle and ruck. The ability repeatedly to engage and win the tackle and ruck has been associated with team success. To win the tackle and ruck, players have to perform specific techniques. These techniques have not been studied at the highest level of rugby union. Therefore, the purpose of this study was to identify technical determinants of tackle and ruck performance at the highest level of rugby union. A total of 4479 tackle and 2914 ruck events were coded for the Six Nations and Championship competitions. Relative risk ratio (RR), the ratio of the probability of an outcome occurring when a characteristic was observed (versus the non-observed characteristic), was determined using multinomial logistic regression. Executing front-on tackles reduced the likelihood of offloads and tackle breaks in both competitions (Six Nations RR 3.0 Behind tackle, 95% confidence interval [95% CI]: 1.9–4.6, effect size [ES] = large, P < 0.001); Championship RR 2.9 Jersey tackle, 95% CI: 1.3–6.4, ES = moderate, P = 0.01). Fending during contact increased the chances of offloading and breaking the tackle in both competitions (Six Nations RR 4.5 Strong, 95% CI: 2.2–9.2, ES = large, P = P < 0.001; Championship RR 5.1 Moderate, 95% CI: 3.5–7.4, ES = large, P < 0.001). For the ruck, actively placing the ball increased the probability of maintaining possession (Six Nations RR 2.2, 95% CI: 1.1–4.3, ES = moderate, P = 0.03); Championship RR 4.0, 95% CI: 1.3–11.8, ES = large, P = 0.01). The techniques identified in this study should be incorporated and emphasised during training to prepare players for competition. Furthermore, these techniques need to be added to coaching manuals for the tackle and ruck.     

The development of position-specific performance indicators in professional rugby union

The aim of this study was to construct a valid and reliable methodology for the analysis of performance profiles of individual playing positions within rugby union. Twenty-two matches were sampled from the domestic season of a professional male rugby union team. Key performance indicators for individual positions were developed and notated using a computerized behavioural analysis system. Performance profiles of playing positions containing data from one or more individuals were then constructed to compare intra-positional differences. Significant differences (chi-square) were observed between individuals within all the tested playing positions for the principal performance indicators (passing, carrying and tackling for the forward positions, and passing, carrying, tackling and kicking for the backs). For example, the difference between the two outside-halves in the study (P?<?0.001) was illustrated by one of the players having a median of 6 successful carries for the season (95% confidence limits of 13 and 3), whereas the other had a median of 2 successful carries (95% confidence limits of 5 and 1). The findings suggest that while general positional performance profiles appear to exist, intra-positional differences may occur due to variations in an individual's style of play, the decision-making demands of the position and the effects of potential confounding variables. Multiple profiles may therefore be necessary for some playing positions to account for variation in factors such as playing conditions and the strength of the opposition.     

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.     

Differences in step characteristics and linear kinematics between rugby players and sprinters during initial sprint acceleration

The initial steps of a sprint are important in team sports, such as rugby, where there is an inherent requirement to maximally accelerate over short distances. Current understanding of sprint acceleration technique is primarily based on data from track and field sprinters, although whether this information is transferable to athletes such as rugby players is unclear, due to differing ecological constraints. Sagittal plane video data were collected (240?Hz) and manually digitised to calculate the kinematics of professional rugby forwards (n?=?15) and backs (n?=?15), and sprinters (n?=?18; 100?m personal best range?=?9.96–11.33?s) during the first three steps of three maximal sprint accelerations. Using a between-group research design, differences between groups were determined using magnitude-based inferences, and within-group relationships between technique variables and initial sprint acceleration performance were established using correlation. Substantial between-group differences were observed in multiple variables. Only one variable, toe-off distance, differed between groups (d?=??0.42 to ?2.62) and also demonstrated meaningful relationships with sprint performance within all three groups (r?=??0.44 to ?0.58), whereby a stance foot position more posterior relative to the centre of mass at toe-off was associated with better sprint performance. While toe-off distance appears to be an important technical feature for sprint acceleration performance in both sprinters and rugby players, caution should be applied to the direct transfer of other kinematic information from sprinters to inform the technical development of acceleration in team sports athletes.     

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 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.     

An objective method for depicting team performance in elite professional rugby union

Abstract

Using a two-study approach, we examined a methodology for objectively depicting team performance and form in a professional rugby union side. Study 1 developed standardized indicators to examine a team's performance in a single match relative to their previous matches over a domestic season via a performance report and form chart. This resulted in standardized performance indicators that provided instant and coherent feedback on the team's performance relative to previous standards. Study 2 then utilized this methodology to compare a match between two professional sides, played the following season, to assess the extent to which the performance by one team affected that of the other. Comparison of the two teams' performances, for the match they played against each other, identified a drop in relative performance (against previous standards) for both teams on the same performance indicators. This appeared to be due to the match being a close, hard-fought contest particularly in the tackle and around the gain-line. The findings of the two studies suggest an accurate and viable methodology for depicting team performance that is superior to the global measures previously adopted. Presenting teams' current standardized performances (i.e. form) on a single visual scale also has utility for coaches within an applied setting. Future research should further investigate the effect of one team's performance on another through both individual and team outcomes.     

Doping in sport: an analysis of sanctioned UK rugby union players between 2009 and 2015

To inform anti-doping policy and practice, it is important to understand the complexities of doping. The purpose of this study was to collate and systematically examine the reasoned decisions published by UK Anti-Doping for doping sanctions in rugby union in the UK since the introduction of the 2009 World Anti-Doping Code. Case files were content analysed to extract demographic information and details relating to the anti-doping rule violation (ADRV), including individuals’ explanations for how/why the ADRV occurred. Between 2009 and 2015, 49 rugby union players and one coach from across the UK were sanctioned. Over 50% of the cases involved players under the age of 25, competing at sub-elite levels. Reasons in defence of the ADRV focused on functional use and lifestyle factors rather than performance enhancement. An a priori assessment of the “need”, “risk” and “consequence” of using a substance was not commonplace; further strengthening calls for increasing the reach of anti-doping education. The findings also deconstruct the view that “doped” athletes are the same. Consequently, deepening understanding of the social and cultural conditions that encourage doping remains a priority.     

Tackler characteristics associated with tackle performance in rugby union

Abstract

Tackling is an important skill for performance in rugby, yet little has been reported on tackler characteristics and its relationship to performance in competition. The aim of this study was to identify tackler characteristics and its association with tackle performance in matches. Eighteen matches of the 2010 Super 14 were analysed, which amounted to 2092 coded tackles. Tackler characteristics such as head position – in motion, up and forward, type of tackle – shoulder tackler, arm tackle or ball-carrier fend – absent, moderate, strong and leg drive–absent, moderate, strong or shoulder usage were coded and associated with tackle outcomes. Relative risk ratio (RRR), the ratio of the probability of an outcome occurring when a characteristic was observed (versus the non-observed characteristic) was determined using multinomial logistic regression. Having the head in motion decreased the tackler's chances of a successful tackle (RRR 2.24, 95% CI 1.72–2.92, p < 0.001) relative to an up and forward head position. Ball-carriers using a fend significantly decreased the tackler's probability of success (moderate fend RRR 2.97, 95% CI 2.04–4.31, p < 0.001). Moderate leg drive (RRR 0.36, 95% CI 0.26–0.50, p < 0.001) by the tackler increased the likelihood of tackle success. Head up and forward, counter-acting the ball-carrier fend, shoulder tackles targeted at the ball-carrier mid-torso, using the arms to wrap or pull, and leg driving were key tackler characteristics associated with positive tackle outcome in matches. Based on these findings, it is recommended that these technical characteristics are emphasised and incorporated into training to effectively prepare tacklers for competition.     

Upper-body repeated-sprint training in hypoxia in international rugby union players

Abstract

This study investigated the effects of upper-body repeated-sprint training in hypoxia vs. in normoxia on world-level male rugby union players’ repeated-sprint ability (RSA) during an international competition period. Thirty-six players belonging to an international rugby union male national team performed over a 2-week period four sessions of double poling repeated-sprints (consisting of 3 × eight 10-s sprints with 20-s passive recovery) either in normobaric hypoxia (RSH, simulated altitude 3000 m, n?=?18) or in normoxia (RSN, 300 m; n?=?18). At pre- and post-training intervention, RSA was evaluated using a double-poling repeated-sprint test (6 × 10-s maximal sprint with 20-s passive recovery) performed in normoxia. Significant interaction effects (P?<?0.05) between condition and time were found for RSA-related parameters. Compared to Pre-, peak power significantly improved at post- in RSH (423?±?52 vs. 465?±?69 W, P?=?0.002, η²=0.12) but not in RSN (395?±?65 vs. 397?±?57 W). Averaged mean power was also significantly enhanced from pre- to post-intervention in RSH (351?±?41 vs. 388?±?53 W, P?<?0.001, η²=0.15), while it remained unchanged in RSN (327?±?49 vs. 327?±?43 W). No significant change in sprint decrement (P?=?0.151, η²?=?0.02) was observed in RSH (?17?±?2% vs. ?16?±?3%) nor RSN (?17?±?2% vs. ?18?±?4%). This study showed that only four upper-body RSH sessions were beneficial in enhancing repeated power production in international rugby union players. Although the improvement from RSA to game behaviour remains unclear, this finding appears of practical relevance since only a short preparation window is available prior to international games.     

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.     

Effective attacking strategies in rugby union

Abstract

Evasive change-of-direction manoeuvres (agility skills) are a fundamental ability in rugby union. In this study, we explored the attributes of agility skill execution as they relate to effective attacking strategies in rugby union. Seven Super 14 games were coded using variables that assessed team patterns and individual movement characteristics during attacking ball carries. The results indicated that tackle-breaks are a key determinant of try-scoring ability and team success in rugby union. The ability of the attacking ball carrier to receive the ball at high speed with at least two body lengths from the defence line against an isolated defender promoted tackle-breaks. Furthermore, the execution of a side-step evasive manoeuvre at a change of direction angle of 20–60° and a distance of one to two body lengths from the defence, and then straightening the running line following the initial direction change at an angle of 20–60°, was associated with tackle-breaks. This study provides critical insight regarding the attributes of agility skill execution that are associated with effective ball carries in rugby union.     

Load,stress, and recovery in adolescent rugby union players during a competitive season

Abstract

Despite increased professionalization of adolescent sport and improved articulation to elite adult participation, the impact of sports such as rugby union among adolescents is under-explored. This study describes psychological stress–recovery responses relative to training loads in 106 male adolescent rugby union players. The results showed that players with the highest training and physical activity volumes during the season demonstrated more favourable recovery–stress states than moderate- and low-volume groups. Stress and under-recovery did not increase with increases in weekly volume when assessed across a season. When assessed more acutely during intensive competition phases, stress and under-recovery increased with increases in participation demands. Despite better psychological stress and recovery profiles of more elite, higher-load players, not all participants demonstrated favourable capacities to deal with stress and recovery processes. Seven participants were in at least two of three categories of highest volume, highest stress, and poorest recovery. Even in the absence of a full understanding of the impact of high-volume, high-stress, poor-recovery participation among adolescent athletes, these markers may be precursors for more deleterious outcomes such as injury, performance decrements, and overtraining. Findings support the efficacy of serially monitoring young athletes.     

What they know and who they are telling: Concussion knowledge and disclosure behaviour in New Zealand adolescent rugby union players

ABSTRACT

The purpose of this study was to survey high school rugby players from a range of ethnic, geographic and socioeconomic backgrounds in New Zealand (NZ) to gain an understanding of concussion knowledge, awareness of NZ Rugby’s (NZR) guidelines and attitudes towards reporting behaviours. Male and female high school rugby players (n= 416) from across NZ were surveyed. The findings indicated that 69% of players had sustained a suspected concussion, and 31% had received a medical diagnosis of concussion. 63% of players indicated they were aware of NZR’s guidelines. Māori and Pasifika players were less likely to be aware of the guidelines compared to NZ European, Adjusted OR 0.5, p = 0.03. Guideline awareness was significantly higher for those from high decile schools when compared to low (Unadjusted OR 1.63, p = 0.04); however, when ethnicity and school locations were controlled for this became non-significant (Adjusted OR= 1.3, p=0.37). The coach was the key individual for the provision of concussion information and disclosure of symptoms for players. The findings of this study will inform the development and delivery of NZR’s community concussion initiative and how these examined factors influence a high school player’s concussion knowledge and reporting behaviour.     

Changes in player characteristics and match activities in Bledisloe Cup rugby union from 1972 to 2004

Abstract

To illustrate changes in elite rugby union match activities, we analysed coded videotape recordings of the first match in each Bledisloe Cup series played between Australia and New Zealand from 1972 to 2004. We also analysed the stature and body mass of players. Effects associated with professionalism, weather conditions, and time (expressed as change per decade) were estimated with a simple generalized linear model and standardized for interpretation of magnitude. The sample size permitted confident conclusions about effects that were of at least moderate magnitude (standardized mean difference >0.6). Increases in passes, tackles, rucks, tries, and ball-in-play time were associated with the advent of professionalism, whereas there were reductions in the numbers of lineouts, mauls, kicks in play, and in mean participation time per player. Noteworthy time trends were an increase in the number of rucks and a decrease in the number of scrums. Good weather conditions were associated with increases in tries and points scored and with reductions in the number of kicks in play and participation time per player. With the advent of professionalism, players have become heavier and backs have become taller. Overall, there have been major changes in international rugby match activities and player size over the past three decades. We believe law changes and developments in match analysis, equipment technology, and player training have contributed to the changes associated with the introduction of professionalism.     

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.     

Collision count in rugby union: A comparison of micro-technology and video analysis methods

The aim of our study was to determine if there is a role for manipulation of g force thresholds acquired via micro-technology for accurately detecting collisions in rugby union. In total, 36 players were recruited from an elite Guinness Pro12 rugby union team. Player movement profiles and collisions were acquired via individual global positioning system (GPS) micro-technology units. Players were assigned to a sub-category of positions in order to determine positional collision demands. The coding of collisions by micro-technology at g force thresholds between 2 and 5.5 g (0.5 g increments) was compared with collision coding by an expert video analyst using Bland–Altman assessments. The most appropriate g force threshold (smallest mean difference compared with video analyst coding) was lower for all forwards positions (2.5 g) than for all backs positions (3.5 g). The Bland–Altman 95% limits of agreement indicated that there may be a substantial over- or underestimation of collisions coded via GPS micro-technology when using expert video analyst coding as the reference comparator. The manipulation of the g force thresholds applied to data acquired by GPS micro-technology units based on incremental thresholds of 0.5 g does not provide a reliable tool for the accurate coding of collisions in rugby union. Future research should aim to investigate smaller g force threshold increments and determine the events that cause coding of false positives.