Dr Amy Brightmore

Recent reports indicate that bone strength is not proportional to body weight in obese populations. Elite rugby players have a similar body mass index (BMI) to obese individuals, but differ markedly with low body fat, high lean mass and frequent skeletal exposure to loading through weight-bearing exercise. The purpose of this study was to determine relationships between body weight, composition and bone strength in male rugby players characterised by high BMI and high lean mass. Fifty two elite male rugby players and 32 non-athletic, age-matched controls differing in BMI (30.2±3.2 v 24.1±2.1 kg.m-2; p=0.02) received one total body and one total hip DXA scan. Hip Structural Analysis of the proximal femur was used to determine bone mineral density (BMD) and cross-sectional bone geometry. Multiple linear regression was computed to identify independent variables associated with total hip and femoral neck BMD and HSA-derived bone geometry parameters. Analysis of covariance was used to explore differences between groups. Further comparisons between groups were performed after normalising parameters to body weight and to lean mass. There was a trend for a positive fat-bone relationship in rugby players, and a negative relationship in controls, although neither reached statistical significance. Correlations with lean mass were stronger for bone geometry (r2=0.408-0.520) than for BMD (r2=0.267-0.293).Relative to body weight, BMD was 6.7% lower in rugby players than controls (p<0.05). Rugby players were heavier than controls, with greater lean mass and BMD (p<0.01). Relative to lean mass, BMD was 10-14.3% lower in rugby players (p<0.001). All bone geometry measures except cross-sectional area, were proportional to body weight and lean mass. To conclude, BMD in elite rugby players was reduced in proportion to body weight and lean mass. However, their superior bone geometry suggests that overall bone strength may be adequate for loading demands. Fat-bone interactions in athletes engaged in high impact sports require further exploration.

The use of global positioning systems (GPS) technology within referees of any sport is limited. Therefore, the purpose of the current study was to evaluate the movement and physiological demands of professional rugby league referees using GPS tracking analysis. Time-motion analysis was undertaken on 8 referees using 5-Hz GPS devices and heart rate monitors throughout a series of Super League matches. 44 data sets were obtained with results identifying similar total distance covered between first and second half periods with a significant (P=0.004) reduction in the number of high velocity efforts performed between 5.51-7.0 m.s-1 (1st=21±8, 2nd=18±8). Mean distance covered from greatest to least distance, was 3 717±432 m, 3 009±402 m, 1 411±231 m, 395±133 m and 120±97 m for the following 5 absolute velocity classifications, respectively; 0.51-2.0 m.s-1; 2.1-4.0 m.s-1: 4.01-5.5 m.s-1; 5.51-7.0 m.s-1; <7.01 m.s-1. Heart rate was significantly (P<0.001) greater in the first (85.5±3.4% maxHR) compared to the second (82.9±3.8% maxHR) half. This highlights the intermittent nature of rugby league refereeing, consisting of low velocity activity interspersed with high velocity efforts and frequent changes of velocity. Training should incorporate interval training interspersing high velocity efforts of varying distances with low velocity activity while trying to achieve average heart rates of ~ 84% maxHR to replicate the physiological demands.

The purpose of this article is to provide a descriptive and reflective account of the multidisciplinary support (i.e., nutrition, physiology and psychology) provided to a 40-year-old male client entering the Marathon des Sables (MdS) for the first time. Reflections will be provided from client and practitioner perspectives. An initial assessment phase, consisting of intake interview (e.g., initial introductions and contracting), sport analysis and client needs analysis (e.g., nutritional requirements for training/racing; performance profiling and physiological testing), was conducted 16 weeks prior to the race to identify key priorities and inform support provision. Professional codes of ethics and conduct (e.g., British Association of Sport and Exercise Sciences [BASES], British Psychological Society [BPS] and Sport and Exercise Nutrition Register [SENR]) were consistently adhered to. Institutional ethical approval to use case study data for research purposes was obtained retrospectively. “Priority areas” (e.g., fitness and mental endurance) and “unknown aspects” (e.g., heat/hydration, nutrition and tent-mates) of race preparation and completion were initially identified. Based on this information, a programme of client-tailored support consisting of psychological skills training (e.g., goal-setting), dietary analysis (e.g., completion/evaluation of diet diaries) and physiological testing (e.g., heat chamber trials to monitor fluid balance and sodium loss during treadmill running) was provided. “Unknown aspects” became particularly salient for client and practitioners following a serious ankle injury sustained by the client within the first month of the support programme. Despite intentions to provide an interdisciplinary support programme, a predominantly multidisciplinary approach was adopted. Furthermore, in the face of limited time and availability, the support team employed a largely clientled consultancy approach (i.e., client empowered to take responsibility for decision-making and problemsolving). Client feedback (e.g., “cautious confidence” about hydration/nutrition, adapting overall race goal to “complete” rather than “compete” and being able to draw on previous experiences of dealing with unfamiliar scenarios) indicated that the consultancy approach was successful in facilitating client involvement in developing appropriate race strategies. Although the support team did not accompany the client to the race venue, remote support (i.e., online messages) was provided throughout the race. During a debrief interview conducted 3 days postrace, the client reflected on the sense of “reassurance” which the support programme had provided en route to achieving his adapted goal of race completion. This case study provides an account of the multidisciplinary support offered to an ultra-marathon debutant over a short yet turbulent timeframe. Reflections on the challenges, successes and learning experiences encountered during the support programme demonstrates that developing the ability to adapt to novel and unexpected circumstances represents an important challenge for both clients and practitioners alike.

The Marathon Des Sables (MdS) is a multistage ultra-endurance footrace across the Sahara Desert. Event organisation supplies rationed water (9 L · day–1) but entrants must provide and carry a minimum of 2000 kcals · day–1 selecting provisions best suited to personal needs, health, environmental conditions, weight and backpack preference. This case study account details pre-race nutritional planning and preparation of a 40-year-old, recreationally trained but occupationally sedentary male client. The purpose of collaboration was to develop nutritional strategies to support training, alongside an event food plan that adhered to race regulations and maximised energy delivery within a client-determined backpack food weight allowance of 5 kg. The client (body mass 83.7 kg) self-referred 16 weeks prior to the event. Following initial assessment and dietary analysis, a nutrition intervention was designed to sustain training. Total energy requirement (TER) was predicted using basal metabolic rate and a physical activity level of 1.7 (2934 kcal). Nutritional targets were set based on American College of Sports Medicine (ACSM) guidelines; carbohydrate (CHO) 6–7 g · kgBM–1 · day–1, protein 1.2–1.7 g · kgBM–1 · day–1, fat 20–25% TER. A tailored event food plan was formulated and trialled pre-race. Post-race debrief occurred 3 days following completion. Initial assessment identified the need to shift the balance of CHO (mean intake 305 g, target 502–586 g) and protein (mean intake 192 g, target 100– 117 g) contributions to TER to support training. With emphasis placed on recovery nutrition strategies, an augmented CHO intake was advised as training duration increased. The client was taught to self-manage through the use of simple CHO content of common food resources. In respect of the event plan, using the limits of his own knowledge and generic information provided on the race website, the client had set a minimum target daily energy intake equivalent to 3000 kcal · day–1 using a range of freeze-dried meals and snack foods and sought the practitioner’s expertise to optimise energy availability of race provisions resulting in a mean energy and macronutrient profile of 3082 kcal, 389 g CHO, 110 g protein, 132 g fat. Post-race debrief indicated the intervention provided reassurance through the process of negotiation and practitioner expertise in accommodating the client’s taste preferences to formulate an event plan that was “fine-tuned” to safeguard product durability in extreme heat offering sufficient variety ensuring palatability and consumption. With the growing popularity of ultra-endurance events and the associated time and financial commitments of participants, this case study highlights the success of individualised nutrition strategies to facilitate performance and build client confidence in race completion.

The Marathon des Sables consists of 5.5 marathons in 6 days, while competitors are required to carry all food and living provisions in temperatures exceeding 50°C. Competitors may undertake sports science support prior to the event, likely to focus on hydration strategies due to the extreme heat of the event and the association with dehydration and potential hypernatraemia or hyponatraemia. Despite this, no data exists to aid practitioners when supporting clients running the Marathon des Sables. The purpose of the support was to educate a 40-year-old recreationally trained male client on the effect of running speed and rucksack weight on fluid loss, Na+ loss and blood[Na+] change during exercise in the heat. The client completed five trials, manipulating running speed and rucksack weight: 6.0 km h-1 (0 and 10 kg), 10.0 km h-1 (0 and 10 kg) and 8.0 km h-1 (7.5 kg) in a heat chamber (40°C and 20% relative humidity) for 30 min on a motorised treadmill. Ad libitum water intake was permitted (measured via mass change of drinks bottles) and body mass (BM) was determined pre- and post-exercise. Sweat patches were worn during exercise and analysed for [Na+]. Blood[Na+] was also measured preand post-exercise. Fluid loss was calculated (BMpre (kg) – BMpost (kg) + fluid intake (kg)) and estimations of fluid loss at various ecologically valid running speed and rucksack weights were calculated. Na+ loss was calculated based on [Na+] and fluid loss. Institutional ethical approval to use case study data for research purposes was obtained retrospectively. Fluid loss was 0.54 L h-1 at 6.0 km h-1 (0.0 kg), 0.94 L h-1 at 6.0 km h-1 (10.0 kg), 1.22 L h-1 at 10.0 km h-1 (0.0 kg) and 2.12 L h-1 10.0 km h-1 (10.0 kg). There was a strong significant positive relationship between fluid loss and sweat[Na+] (r = 0.966, P = 0.034) and a strong negative relationship between fluid loss and ?blood[Na+] (r = -0.776, P = 0.269). Estimations of potential fluid and Na+ deficits at the end of the day, dependent on the duration of stage, running speed and rucksack weight, were presented to the client. The physiological responses during this support were normal: increase in FL versus increase in running speed and rucksack weight and an increase in sweat [Na+] versus an increase in fluid loss, due to a reduction in Na+ reabsorption in the sweat gland duct (Cage and Dobson, 1965, Journal of Clinical Investigation, 44, 1270–1276). Despite the known findings, the client reported that the support was sufficient to provide confidence in his hydration strategy and an increased awareness of pacing, thus completing the Marathon des Sables safely without developing debilitating dehydration, hypernatraemia or hyponatraemia. D1.

Research examining the factors influencing selection within talented junior Rugby League players is limited. The aims of this study were firstly to determine whether differences existed for anthropometric and performance characteristics between regional and national selection in high performance UK junior Rugby League players, and secondly to identify variables that discriminated between these selection levels. Regional representative (n=1172) selected junior players (aged 13-16 years) undertook an anthropometric and fitness testing battery with players split according to selection level (i.e., national, regional). MANCOVA analyses, with age and maturation controlled, identified national players as having lower sum of 4 skinfolds scores compared to regional players, and also performed significantly better on all physical tests. Stepwise discriminant analysis identified that estimated maximum oxygen uptake (VO2max), chronological age, body mass, 20 m sprint, height, sum of 4 skinfolds and sitting height discriminated between selection levels, accounting for 28.7% of the variance. This discriminant analysis corresponded to an overall predictive accuracy of 63.3% for all players. These results indicate that performance characteristics differed between selection levels in junior Rugby League players. However, the small magnitude of difference between selection levels suggests that physical qualities only partially explain higher representative selection. The monitoring and evaluation of such variables, alongside game related performance characteristics, provides greater knowledge and understanding about the processes and consequences of selection, training and performance in youth sport.

Purpose: To evaluate the movement and physiological demands of the Australasian National Rugby League (NRL) referees, officiating with a ‘two referee’ (i.e., ‘lead’ and ‘pocket’) system and to compare the demands of the lead referee and pocket referees. Methods: 10 Hz global positioning system devices were used to obtain 86 data sets (‘lead’, n=41; ‘pocket’, n=45) on 19 NRL referees. Total distance, relative distance covered and heart rate per half and across match-play was examined within and between referees using t-tests. Distance, time and number of movement 'efforts' were examined in six velocity classifications (i.e., standing <0.5; walking 0.51–2.0; jogging 2.01-4.0; running 4.01-5.5; high speed running 5.51-7.0; sprinting > 7.0 m.s-1) using ANOVA. Cohen's d effect sizes were reported. Results: There were no significant differences between the ‘lead’ and ‘pocket’ referee for any movement or physiological variable. There was an overall significant (large; very large) effect for distance (% distance) and time (% time) (P < 0.001) between each velocity classification for both the ‘lead’ and ‘pocket’ referee. Both roles covered the largest distance and number of efforts at velocities between 0.51–2.0 m.s-1 and 2.01-72 4.0 m.s-1, which were interspersed with efforts >5.51 m.s-1. Conclusions: Findings highlight the intermittent nature of rugby league refereeing, but show that there were no differences in the movement and physiological demands of the two refereeing roles. Findings are valuable for those responsible for the preparation, training and conditioning of NRL referees, and to ensure training prepares for and simulates match demands.

Two of the leading competitions in rugby league are the European Super League (SL) and Australasian National Rugby League (NRL); however, they adopt different officiating systems. The SL operates with one referee, whereas the NRL operates with two referees (NRL head and NRL pocket referees). There is currently no research comparing the movement demands of the referees using these two systems. This study evaluated the movement demands of SL referees and NRL head and pocket referees during rugby league match play using global positioning system (GPS) tracking. With institutional ethical approval, time–motion analysis was undertaken on 8 full-time SL referees and 19 NRL referees using portable 10 Hz GPS devices (MinimaxX; Catapult Sports, Australia) during the SL and NRL 2013 seasons. A total of 230 matches (SL, n = 144; NRL head, n = 41; NRL pocket, n = 45) were analysed using Sprint software (Catapult Innovations, Australia). A one-way ANOVA was conducted with a Bonferroni post hoc to assess the differences between referees in addition to Cohen’s d effect sizes. The SL referees (6900 ± 830 m) and NRL head referees (7253 ± 1164 m) covered similar distances during match play, whilst the NRL pocket referees covered significantly greater distance (7539 ± 930 m, P < 0.001, d = 0.73) than the SL referees. When movement was categorised into velocity classifications (Rampini et al., 2007, International Journal of Sports Medicine, 28, 228–235) SL referees performed a significantly greater number of high-intensity efforts (9.7 ± 7.4) between 5.51 and 7.00 m · s-1 compared to both the NRL head (6.5 ± 4.2; P = 0.015, d = 0.51) and NRL pocket referees (6.4 ± 4.2; P = 0.009, d = 0.56). SL referees produced a similar number of low-intensity efforts (2.01–4.00 m · s-1) to the NRL head (215.0 ± 34.0 vs. 223.2 ± 45.9) and pocket referees (228.4 ± 37.9). The SL referees covered significantly less distance (3310 ± 510 m) accelerating between 0.00 and 1.00 m · s-2 than the NRL head (3609 ± 692 m; P = 0.010, d = 0.49) and the NRL pocket referees (3770 ± 631 m; P < 0.001, d = 0.80). There was no difference between SL (248 ± 186 m), NRL head (253 ± 176 m) and NRL pocket (268 ± 180 m) referees for distance covered when accelerating at >1.00 m · s-2. A comparison of the one-referee (SL) system with the two-referee (NRL head) system shows no effect on the total distance covered, low-intensity efforts or distance covered when accelerating above 1.00 m · s-2, during match play. However, the SL referees are required to perform more high-intensity efforts and cover less distance accelerating between 0.00 and 1.00 m · s-2 than NRL referees. This preliminary data suggest that the different refereeing systems may influence the movement demands of the referees.

We investigated 3-compartment body composition across one competitive season in professional male rugby union players using dual-energy X-ray absorptiometry (GE iDXA). Thirty five players from one English Premiership team (forwards: n=20, age: 25.5±4.7 years; backs: n=15, age: 26.1±4.5 years) received one total body DXA scan at pre-season (August), mid-season (January) and end-season (May), enabling quantification of body mass, total and regional fat mass, lean mass, percentage tissue fat mass (%TFM) and bone mineral content (BMC). Both team and individual changes were evaluated, and for the latter, least significant change (LSC) was derived from precision data and applied as per International Society for Clinical Densitometry guidelines. Mean body mass remained stable throughout the season (p>0.05), but total fat mass and %TFM increased from pre to end-season, and mid to end-season (p<0.05). There were also statistically significant increases in total-body BMC across the season (P<0.05). In backs, there was a loss of lean mass between mid and end-season (P<0.01). Individual evaluation using LSC and Bland Altman analysis revealed a meaningful loss of lean mass in 17 players and a gain of fat mass in 21 players from pre to end-season. Twelve players exhibited no change. Strategies to improve the maintenance of pre-season lean/ fat ratios across the season for professional rugby union players might be beneficial to performance and health, and thus require exploration. We recommend that future studies include an individualised approach to DXA body composition monitoring and this can be achieved through application of derived LSC.

Rugby league referees have the responsibility of enforcing the laws of the game and can influence the outcome based on their decisions. Performance demands inherent in refereeing involve fitness and positioning, law knowledge and application, contextual judgement and game management (Weston et al., 2012, International Journal of Sports Medicine, 42, 615–617). No study to date has investigated the relationship between the physiological and movement demands of refereeing and penalty accuracy. To quantify penalty accuracy scores of rugby league referees and determine the relationship with total distance covered (TD), high intensity distance (HIT) and mean heart rate per half and 10-min period of a match. With institutional ethical approval, all 8 professional Super League referees participated in this study. During the 2012 season, 148 Super League matches were analysed using 10Hz GPS units (MinimaxV4; Catapult Sports, Australia) and 1-Hz heart rate monitors (Polar Electro, Kempele, Finland). Decision-making demands were quantified using Opta Stats (Leeds, UK), which were retrospectively reviewed by an expert referee review panel to determine the accuracy of decisions when awarding or not awarding a penalty. A dependant t-test was used to assess the differences between halves. Repeated measures ANOVA was conducted with a Bonferroni post hoc to assess the differences between 10-min match periods, in addition to Cohen’s d effect sizes. Pearson’s product correlation was used to determine relationships. Super League referees made the correct penalty decision on 74 ± 5% of occasions. Significantly more distance was covered (3586 ± 394 vs. 3514 ± 424 m, P = 0.009, d = 0.18), and a significantly greater heart rate (154 ± 9 vs. 149 ± 9 beats.min-1, P = 0.001, d = 0.56) was achieved in the first compared to the second half. There was no significant difference (P = 0.812) in penalty accuracy (75 ± 4 vs. 73 ± 6 %) or HIT (P = 0.081) between halves. When observed per half and 10 minute periods, there was no significant relationship between penalty accuracy scores and TD (r = –0.023, P = 0.645), HIT (r = 0.093, P = 0.18) or heart rate (r = 0.129, P = 0.135). Findings suggest that the physiological and movement demands of refereeing in rugby league are not significantly related to penalty accuracy scores per 40-min or 10-min period. While it has been observed that there was no significant relationship between TD, HIT or heart rate and accuracy, further research is required to investigate confounding variables (i.e. refereeing experience and fitness levels) that may further influence penalty accuracy. Given the small sample population of professional referees (n = 8), a case study approach to future research is recommended.

Research into the physiological and movement demands of Rugby League (RL) referees is limited, with only one study in the European Super League (SL). To date, no studies have considered decision-making in RL referees. The purpose of this study was to quantify penalty accuracy scores of RL referees and determine the relationship between penalty accuracy and total distance covered (TD), high-intensity running (HIR) and heart rate per 10-min period of match-play. Time motion analysis was undertaken on 8 referees over 148 European SL games during the 2012 season using 10Hz GPS analysis and heart rate monitors. The number and timing of penalties awarded was quantified using Opta Stats. Referees awarded the correct decision on 74 ± 5% of occasions. Lowest accuracy was observed in the last 10-minute period of the game (67 ± 13%), with a moderate drop (ES= 0.86) in accuracy observed between 60-70 minutes and 70-80 minutes. Despite this, there were only small correlations observed between HRmean, total distance, HIR efforts and penalty accuracy. Although a moderate correlation was observed between maximum velocity and accuracy. Despite only small correlations observed, it would be rash to assume that physiological and movement demands of refereeing have no influence on decision-making. More likely, other confounding variables influence referee decision-making accuracy, requiring further investigation. Findings can be used by referees and coaches to inform training protocols, ensuring training is specific to both cognitive and physical match demands.

The Vendée Globe is a solo round-the-world sailing race without stopovers or assistance, a physically demanding challenge for which appropriate nutrition should maintain energy balance and ensure optimum performance. This is an account of prerace nutritional preparation with a professional and experienced female racer and assessment of daily nutritional intake (NI) during the race using a multimethod approach. A daily energy intake (EI) of 15.1 MJ/day was recommended for the race and negotiated down by the racer to 12.7 MJ/day, with carbohydrate and fluid intake goals of 480 g/day and 3,020 ml/day, respectively. Throughout the 99-day voyage, daily NI was recorded using electronic food diaries and inventories piloted during training races. NI was assessed and a postrace interview and questionnaire were used to evaluate the intervention. Fat mass (FM) and fat-free mass (FFM) were assessed pre- (37 days) and postrace (11 days) using dual-energy X-ray absorptiometry, and body mass was measured before the racer stepped on the yacht and immediately postrace. Mean EI was 9.2 MJ/day (2.4-14.3 MJ/day), representing a negative energy balance of 3.5 MJ/day under the negotiated EI goal, evidenced by a 7.9-kg loss of body mass (FM -7.5 kg, FFM -0.4 kg) during the voyage, with consequent underconsumption of carbohydrate by ~130 g/day. According to the postrace yacht food inventory, self-reported EI was underreported by 7%. This intervention demonstrates the practicality of the NI approach and assessment, but the racer's nutrition strategy can be further improved to facilitate meeting more optimal NI goals for performance and health. It also shows that evaluation of NI is possible in this environment over prolonged periods, which can provide important information for optimizing nutritional strategies for ocean racing.

The purpose of this study was to investigate longitudinal body composition of professional rugby union players over one competitive season. Given the potential for variability in changes, and as the first to do so, we conducted individual analysis in addition to analysis of group means. Thirty-five professional rugby union players from one English Premiership team (forwards: n = 20, age: 25.5 ± 4.7 years; backs: n = 15, age: 26.1 ± 4.5 years) received one total-body dual-energy X-ray absorptiometry (DXA) scan at preseason (August), midseason (January) and endseason (May), enabling quantification of body mass, total and regional fat mass, lean mass, percentage tissue fat mass (%TFM) and bone mineral content (BMC). Individual analysis was conducted by applying least significant change (LSC), derived from our previously published precision data and in accordance with International Society for Clinical Densitometry (ISCD) guidelines. Mean body mass remained stable throughout the season (p > 0.05), but total fat mass and %TFM increased from pre to endseason, and mid to endseason (p < 0.05). There were also statistically significant increases in total-body BMC across the season (p < 0.05). In both groups, there was a loss of lean mass between mid and endseason (p < 0.018). Individual evaluation using LSC and Bland-Altman analysis revealed a meaningful loss of lean mass in 17 players and a gain of fat mass in 21 players from pre to endseason. Twelve players had no change and there were no differences by playing position. There were individual gains or no net changes in BMC across the season for 10 and 24 players, respectively. This study highlights the advantages of an individualised approach to DXA body composition monitoring and this can be achieved through application of derived LSC.

Purpose: This study compared the body size and three compartment body composition between academy and senior professional rugby league players using dual energy X-ray absorptiometry (DXA). Methods: Academy (age 18.1±1.1 years; n=34) and senior (age 26.2 ±4.6 years; n=63) rugby league players received one total-body DXA scan. Height, body mass and body fat percentage alongside total and regional fat mass, lean mass and bone mineral content (BMC) were compared. Independent t-tests with Cohen’s d effect sizes and multivariate analysis of covariance (MANCOVA), controlling for height and body mass, with partial eta squared (η2) effect sizes, were used to compare total and regional body composition. Results: Senior players were taller (183.2±5.8 vs. 179.2±5.7 cm; p=0.001; d=0.70) and heavier (96.5±9.3 vs. 86.5±9.0 kg; p<0.001; d=1.09) with lower body fat percentage (16.3±3.7 vs. 18.0±3.7 %; p=0.032; d=0.46) than academy players. MANCOVA identified significant overall main effects for total and regional body composition between academy and senior players. Senior players had lower total fat mass (p<0.001, η2=0.15), greater total lean mass (p<0.001, η2=0.14) and greater total BMC (p=0.001, η2=0.12) than academy players. For regional sites, academy players had significantly greater fat mass at the legs (p<0.001; η2=0.29) than senior players. Conclusions: The lower age, height, body mass and BMC of academy players suggest that these players are still developing musculoskeletal characteristics. Gradual increases in lean mass and BMC whilst controlling fat mass is an important consideration for practitioners working with academy rugby league players, especially within the lower body.

Body composition analysis using dual energy X-ray absorptiometry (DXA) is becoming increasingly popular in both clinical and sports science settings. Obesity, characterised by high fat mass (FM), is associated with larger precision errors, however, precision error for athletic groups with high levels of lean mass (LM) are unclear. Total (TB) and regional (limbs and trunk) body composition were determined from two consecutive total body scans (GE Lunar iDXA) with re-positioning in 45 elite male rugby league players (age: 21.8 ±5.4 years BMI: 27.8 ±2.5 kg.m-1). The root mean squared standard deviation (percentage co-efficient of variation) were TB bone mineral content (BMC): 24g (1.7%), TB LM: 321g (1.6%), and TB FM: 280g (2.3%). Regional precision values were superior for measurements of BMC: 4.7-16.3g (1.7-2.1%) and LM: 137-402g (2.0-2.4%), than for FM: 63-299g (3.1-4.1%). Precision error of DXA body composition measurements in elite male rugby players is higher than those reported elsewhere for normal adult populations and similar to those reported in those who are obese. It is advised that caution is applied when interpreting longitudinal DXA-derived body composition measurements in male rugby players and population-specific least significant change should be adopted.

Recent research has demonstrated that greater player body mass, lean mass (LM) and lower percentage body fat (%BF) are positively related to rugby league performance (e.g. Gabbett et al., 2011, Journal of Sports Sciences, 29, 1655–1664). Correspondingly, over recent years, there has been an increasing emphasis on player size and muscularity in the professional sport. However, to date, there has been no published data on the longitudinal changes in the body composition of senior professional rugby league players. Therefore, the purpose of this study was to investigate changes in three-compartment body composition over six years, in UK professional rugby league players using dual energy X-ray absorptiometry (DXA). Following institutional ethical approval, 12 professional rugby league players (baseline age: 25.0 ± 3.9 years, height: 183.4 ± 8.4 cm) from one European Super League club received total body DXA scans (Lunar iDXA, GE Healthcare) midseason in 2008 and 2014 when euhydrated (urine osmolality < 700 mOsmol · kg−1). The regions of interest on scan images were checked and manually adjusted where necessary by a qualified densitometrist according to DXA manufacturer guidelines. The primary outcomes were total body mass, %BF, total and regional fat mass (FM), LM and bone mineral content (BMC). A repeated measures multivariate analysis of variance (MANOVA), controlling for chronological age, examined differences between the two time points. Effect sizes were calculated. The repeated measures MANOVA found an overall significant effect for time (P = 0.048, = 0.99). Univariate analysis identified increases in total body mass (95.3 ± 12.2 vs. 98.5 ± 12.2 kg, P = 0.005, d = 0.26), total LM (77.2 ± 8.6 vs. 79.8 ± 9.6 kg, P = 0.006, d = 0.29) and leg LM (25.8 ± 2.8 vs. 27.6 ± 3.8 kg, P = 0.049, d = 0.54) across the six-year period. Increases were also found for total BMC (4324 ± 566 vs. 4575 ± 582 g, P < 0.001, d = 0.44) and BMC at the arms (P = 0.006, d = 0.36), legs (P = 0.001, d = 0.43) and trunk (P < 0.001, d = 0.45) regions over the six-year period. No changes were identified in %BF or FM across the six-year period. This study demonstrates that senior professional rugby league players competing in the European Super League over a six-year period have increased total body mass, which can be predominantly explained by a gain in LM of the lower body. Such findings may reflect the increasing physical demands of the professional game and a greater emphasis on lower body resistance training. These players had remained competitive in the professional sport for six years, which suggests that increasing LM and BMC may be beneficial to career longevity.

The use of global positioning systems (GPS) technology within referees of any sport is limited. Therefore, the purpose of the current study was to evaluate the movement and physiological demands of professional rugby league referees using GPS tracking analysis. Time-motion analysis was undertaken on 8 referees using 5-Hz GPS devices and heart rate monitors throughout a series of Super League matches. 44 data sets were obtained with results identifying similar total distance covered between first and second half periods with a significant (P=0.004) reduction in the number of high velocity efforts performed between 5.51-7.0 m.s-1 (1st=21±8, 2nd=18±8). Mean distance covered from greatest to least distance, was 3 717±432 m, 3 009±402 m, 1 411±231 m, 395±133 m and 120±97 m for the following 5 absolute velocity classifications, respectively; 0.51-2.0 m.s-1; 2.1-4.0 m.s-1: 4.01-5.5 m.s-1; 5.51-7.0 m.s-1; <7.01 m.s-1. Heart rate was significantly (P<0.001) greater in the first (85.5±3.4% maxHR) compared to the second (82.9±3.8% maxHR) half. This highlights the intermittent nature of rugby league refereeing, consisting of low velocity activity interspersed with high velocity efforts and frequent changes of velocity. Training should incorporate interval training interspersing high velocity efforts of varying distances with low velocity activity while trying to achieve average heart rates of ~ 84% maxHR to replicate the physiological demands.