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.

The purpose of this investigation was to evaluate the postactivation potentiation (PAP) effects of both dynamic and isometric maximum voluntary contractions (MVCs) on sprint and jump performance and establish whether PAP methods could be used effectively in warm up protocols for soccer players. Twelve male soccer players performed 4 warm up protocols in a cross over, randomised and counterbalanced design. In addition to a control warm up, subjects performed dead lift (5 repetitions at 5RM), tuck jump (5 repetitions) and isometric MVC knee extensions (3 repetitions for 3 seconds)as PAP treatments in an otherwise identical warm up protocol. After each treatment the subjects underwent three 10m and 20m sprints 4, 5 and 6 minutes post warm up and three vertical jumps (VJ) at 7, 8 and 9 minutes post warm up. Repeated measures ANOVA showed no significant differences in the first 10m (p=0.258), 20m (p=0.253) sprint and VJ (p=0.703) performance and the average 10m (p=0.215), 20m (p=0.388) and VJ (p=0.529) performance between conditions. There were also no significant differences in performance responses between the strongest and weakest subjects but large variations in individual responses were found between the subjects. The findings suggest that there was no significant group PAP effect on sprint and jump performance following dynamic and isometric maximum voluntary contractions compared to a control warm up protocol. However the large variation in individual responses (-7.1% to +8.2%) suggests PAP should be considered on an individual basis. Factors such as method, volume, load, recovery and interindividual variability of PAP must be considered in the practical application of PAP and the rigorous research design of future studies Postactivation Potentiation, Sprint and Jump Performance 4 to evaluate the potential for performance enhancement.

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Background: Interventions designed to increase workplace physical activity may not automatically reduce high volumes of sitting, a behaviour independently linked to chronic diseases such as obesity and type II diabetes. This study compared the impact two different walking strategies had on step counts and reported sitting times.

In the short term at least, this weight-loss program was effective across a range of health outcomes. Ongoing research is examining the maintenance of these improvements. Future research should investigate whether benefits can be generalized across weight-loss camps and how the intervention can be adapted to nonresidential, term-time settings.

Complex training is the method of coupling heavy and light loads into an organized sequence with the aim of facilitating postactivation potentiation. Anecdotal evidence has supported the use of complex training sequences, but scientific studies investigating the effects of sequencing isometric loads with dynamic muscle actions have been limited. The purpose of this study was to examine the effects of a preconditioning sequence of maximal isometric knee extensions on performance standards in selected dynamic whole-body exercise. Fourteen track and field athletes (23 +/- 5.7 years; 71.53 +/- 6.93 kg; 172.6 +/- 5.8 cm) were randomly assessed in selected whole-body exercises (drop and countermovement jumps, 5-second cycle sprint, knee extension) following a sequence of maximal voluntary isometric contractions (MVC; 3 repetitions of 3 seconds or 3 repetitions of 5 seconds) or in the absence of prior loading (control). Electromyographic (EMG) assessments of muscle activity were also made during the knee extension assessment. Significant (p < or = 0.05) increases in jump height (5.03%), maximal force (4.94%), and acceleration impulse (9.49%) were observed in the drop jump following 3 repetitions of 3-second MVC only. Knee extension maximal torque was also significantly increased (6.12%) following the 3-second MVC. No significant changes in countermovement jump or cycle sprint measures were observed for any of the experimental conditions. Though adaptations were found, changes in EMG activity were not significantly different for any of the experimental conditions. These data indicate that performing a sequence of repeated maximal isometric knee extensions (3 repetitions of 3 seconds) prior to selected dynamic exercise (< or =0.25 seconds) may have favorable effects on performance beyond standards achieved without prior heavy loading.

The purpose of the current study was to evaluate the anthropometric and physical characteristics of English academy rugby league players by annual-age category (Under 16s -Under 20s) and between backs and forwards. Data was collected on 133 academy players over a 6 year period (resulting in a total of 257 assessments). Player assessments comprised of anthropometric (height, body mass, sum of 4 skinfolds) and physical (vertical jump, 10m and 20m sprint, estimated Independent t-tests identified significant (p<0.05) differences between backs and forwards for anthropometric (e.g., Under 16s body mass -Backs = 68.4 ± 8.6, Forwards = 80.9 ± 9.7kg) and physical (e.g., Under 19s 20m sprint -Backs = 3.04 ± 0.08, Forwards = 3.14 ± 0.12s; Under 18s relative squat -Backs = 1.65 ± 0.18, Forwards = 1.51 ± 0.17kg/kg) characteristics that were dependant on the age category and measure assessed. Findings highlight that anthropometric and physical characteristics develop across annual-age categories and between backs and forwards in academy rugby league players. These findings provide comparative data for such populations and support the need to monitor player development in junior rugby league players.

This study longitudinally evaluated whether maturation and relative age interact with time during adolescence to differentially affect the development of anthropometric and fitness characteristics in junior rugby league players. Anthropometric and fitness characteristics of 81 junior players selected into the UK Rugby Football League's talent identification and development process were assessed over three consecutive occasions (i.e., Under 13s, 14s, 15s). Players were grouped and compared in relation to maturational status (i.e., Early, Average, Late) and relative age quartile (i.e., Quartile 1). Repeated measures MANOVA identified significant (p<0.001) overall main effects for maturation group, relative age quartile and importantly a maturation group by time interaction. Findings showed that the Early maturing group had the greatest anthropometric characteristics and medicine ball throw across the three occasions. However, the Late maturing group increased their height (Early = 5.0, Late = 10.3 cm), medicine ball throw and 60m sprint (Early = -0.46, Late = -0.85 s) the most throughout the 2 year period. Early (de)selection policies currently applied in talent identification and development programmes are questionable when performance related variables are tracked longitudinally. During adolescence, maturation status alongside relative age should be considered and controlled for when assessing athlete potential for future progression.