Relative age effects (RAEs), reflecting observed inequalities in participation and attainment as a result of annual age‐grouping policies in youth sport, are common in most team sports. The aims of this study were to determine if and when RAEs become apparent in Rugby League, determine how influential variables (e.g., gender) lead and clarify whether player retention at junior representative levels can explain persistent RAEs. Player data were collected for the male and female community games ranging from Under 7s to Senior (N=15 060) levels, junior representative selections (i.e., Regional) and professional players (N=298). Chi‐square analyses found significant (P<0.05) uneven birth date distributions beginning at the earliest stages of the game and throughout into senior professionals. In junior representative selections, 47.0% of Regional and 55.7% of National representative players were born in Quartile 1, with RAE risk increasing with performance level. Gender and nationality were also found to moderate RAE risk. When tracking representative juniors, over 50% were retained for similar competition the following season. Findings clearly demonstrate that RAEs exist throughout Rugby League with early selection, performance level and retention processes, appearing to be key contributing factors responsible for RAE persistence.

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Background In this Position Statement, the International Society of Sports Nutrition (ISSN) provides an objective and critical review of the literature pertinent to nutritional considerations for training and racing in single-stage ultra-marathon. Recommendations for Training. i) Ultra-marathon runners should aim to meet the caloric demands of training by following an individualized and periodized strategy, comprising a varied, food-first approach; ii) Athletes should plan and implement their nutrition strategy with sufficient time to permit adaptations that enhance fat oxidative capacity; iii) The evidence overwhelmingly supports the inclusion of a moderate-to-high carbohydrate diet (i.e., ~ 60% of energy intake, 5–8 g·kg− 1·d− 1) to mitigate the negative effects of chronic, training-induced glycogen depletion; iv) Limiting carbohydrate intake before selected low-intensity sessions, and/or moderating daily carbohydrate intake, may enhance mitochondrial function and fat oxidative capacity. Nevertheless, this approach may compromise performance during high-intensity efforts; v) Protein intakes of ~ 1.6 g·kg− 1·d− 1 are necessary to maintain lean mass and support recovery from training, but amounts up to 2.5 g.kg− 1·d− 1 may be warranted during demanding training when calorie requirements are greater; Recommendations for Racing. vi) To attenuate caloric deficits, runners should aim to consume 150–400 Kcal·h− 1 (carbohydrate, 30–50 g·h− 1; protein, 5–10 g·h− 1) from a variety of calorie-dense foods. Consideration must be given to food palatability, individual tolerance, and the increased preference for savory foods in longer races; vii) Fluid volumes of 450–750 mL·h− 1 (~ 150–250 mL every 20 min) are recommended during racing. To minimize the likelihood of hyponatraemia, electrolytes (mainly sodium) may be needed in concentrations greater than that provided by most commercial products (i.e., > 575 mg·L− 1 sodium). Fluid and electrolyte requirements will be elevated when running in hot and/or humid conditions; viii) Evidence supports progressive gut-training and/or low-FODMAP diets (fermentable oligosaccharide, disaccharide, monosaccharide and polyol) to alleviate symptoms of gastrointestinal distress during racing; ix) The evidence in support of ketogenic diets and/or ketone esters to improve ultra-marathon performance is lacking, with further research warranted; x) Evidence supports the strategic use of caffeine to sustain performance in the latter stages of racing, particularly when sleep deprivation may compromise athlete safety.

This study investigated the acute changes in body composition that occur over the course of a competitive season in elite rugby league players. Twenty elite senior players from an English Super League rugby league team underwent a total-body dual-energy x-ray absorptiometry scan at three phases of a competitive season: preseason (February), mid-season (June) and post-season (September). Body mass, fat mass, lean mass, percentage body fat and bone mineral content were reported at each phase. Between the start and mid-point of the season, body mass, lean mass, fat mass and body fat percentage showed no significant change (p>0.05), however bone mineral content was significantly increased (+0.71%; 30.70 ± 38.00g; p<0.05). Between the mid-season and post-season phase, body mass and bone mineral content showed no significant change (p>0.05), however significant changes were observed in lean mass (-1.54%; 1.19 ± 1.43kg), fat mass (+4.09%; 0.57 ± 1.10kg) and body fat percentage (+4.98%; 0.78 ± 1.09%; p<0.05). The significant changes in body composition seen over the latter stages of the competitive season may have implications for performance capabilities at this important stage of competition. An increase in fat mass and decrease in lean mass may have a negative effect on the power/body mass ratio, and therefore may be a cause for concern for playing, coaching and medical staff.

Nitrate-rich beetroot juice (BRJ) increases plasma nitrite concentration, lowers the oxygen cost (V O2) of steady-state exercise and improves exercise performance in sedentary and moderately-trained, but rarely in well-trained individuals exercising at sea-level. BRJ supplementation may be more effective in a hypoxic environment, where the reduction of nitrite into nitric oxide (NO) is potentiated, such that well-trained and less well-trained individuals may derive a similar ergogenic effect.We conducted a randomised, counterbalanced, double-blind placebo controlled trial to determine the effects of BRJ on treadmill running performance in moderate normobaric hypoxia (equivalent to 2500 m altitude) in participants with a range of aerobic fitness levels. Twelve healthy males (V O2max ranging from 47.1 -76.8 ml·kg -1 ·min -1 ) ingested 138 ml concentrated BRJ (~ 15.2 mmol nitrate) or a nitrate-deplete placebo (PLA) (~ 0.2 mmol nitrate). Three hours later, participants completed steady-state moderate intensity running, and a 1500 m time-trial (TT) in a normobaric hypoxic chamber (FIO2 ~15 %). Plasma nitrite concentration was significantly greater following BRJ versus PLA 1 hour post supplementation, and remained higher in BRJ throughout the testing session (p < 0.01). Average V O2 was significantly lower (BRJ: 18.4 ± 2.0, PLA: 20.4 ± 12.6 ml·kg -1 ·min -1 ; p = 0.002), whilst arterial oxygen saturation (SaO2) was significantly greater (BRJ: 88.4 ± 2.7, PLA: 86.5 ± 3.3 %; p < 0.001) following BRJ. BRJ improved TT performance in all 12 participants by an average of 3.2 % (BRJ: 331.1 ± 45.3 vs. PL: 341.9 ± 46.1 s; p < 0.001). There was no apparent relationship between aerobic fitness and the improvement in performance following BRJ (r 2 = 0.05, p > 0.05). These findings suggests that a high nitrate dose in the form of a BRJ supplement may improve running performance in individuals with a range of aerobic fitness levels conducting moderate and high-intensity exercise in a normobaric hypoxic environment.

This study evaluated the influence of annual-age category, relative age, playing position, anthropometry and fitness on the career attainment outcomes of junior rugby league players originally selected to a talent identification and development (TID) programme. Junior rugby league players (N=580) were grouped retrospectively according to their career attainment level (i.e., amateur, academy and professional). Anthropometric (height, sitting height, body mass, sum of four skinfolds), maturational (age at peak height velocity) and fitness (power, speed, change of direction speed, estimated 2max 4

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