A retrospective longitudinal analysis of anthropometric and physical qualities that associate with adult career attainment in junior rugby league players

What Tests are Used to Assess the Physical Qualities of Male, Adolescent Rugby League Players? A Systematic Review of Testing Protocols and Reported Data Across Adolescent Age Groups

BACKGROUND

Understanding the physical qualities of male, adolescent rugby league players across age groups is essential for practitioners to manage long-term player development. However, there are many testing options available to assess these qualities, and differences in tests and testing protocols can profoundly influence the data obtained.

OBJECTIVES

The aims of this systematic review were to: (1) identify the most frequently used tests to assess key physical qualities in male, adolescent rugby league players (12-19 years of age); (2) examine the testing protocols adopted in studies using these tests; and (3) synthesise the available data from studies using the most frequently used tests according to age group.

METHODS

A systematic search of five databases was conducted. For inclusion, studies were required to: (1) be original research that contained original data published in a peer-reviewed journal; (2) report data specifically for male, adolescent rugby league players; (3) report the age for the recruited participants to be between 12 and 19 years; (4) report data for any anthropometric quality and one other physical quality and identify the test(s) used to assess these qualities; and (5) be published in English with full-text availability. Weighted means and standard deviations were calculated for each physical quality for each age group arranged in 1-year intervals (i.e., 12, 13, 14, 15, 16, 17 and 18 years) across studies.

RESULTS

37 studies were included in this systematic review. The most frequently used tests to assess anthropometric qualities were body mass, standing height, and sum of four skinfold sites. The most frequently used tests to assess other physical qualities were the 10-m sprint (linear speed), 505 Agility Test (change-of-direction speed), Multistage Fitness Test (aerobic capacity), bench press and back squat one-repetition maximum tests (muscular strength), and medicine ball throw (muscular power). Weighted means calculated across studies generally demonstrated improvements in player qualities across subsequent age groups, except for skinfold thickness and aerobic capacity. However, weighted means could not be calculated for the countermovement jump.

CONCLUSION

Our review identifies the most frequently used tests, but highlights variability in the testing protocols adopted. If these tests are used in future practice, we provide recommended protocols in accordance with industry standards for most tests. Finally, we provide age-specific references for frequently used tests that were implemented with consistent protocols. Clinical Trial Registration This study was conducted in accordance with the Preferred Reporting Items of Systematic Review and Meta-analysis guidelines and was registered with PROSPERO (ID: CRD42021267795).

Physical giftedness/talent: A systematic review of the literature on identification and development

In this study, a systematic review was undertaken of the international scholarly literature on the identification and development of giftedness/talent in the physical domain, to establish the scope of current knowledge in the area. To identify relevant research, a search that involved the creation of a search string and the manual examination of the titles and abstracts of potentially relevant research, was conducted using two databases-Web of Science Core Collection and SportDiscus-and six inclusion/exclusion criteria (i.e., relevance to identification or development of physical giftedness/talent, an empirical study, publication in a reputable academic peer-reviewed journal, publication from 2000 to 2021, an English language publication, and authorship by scholars based in any part of the world). The 101 journal articles that met the inclusion/exclusion criteria were analyzed for key details, including the year of publication, methodological approaches, participants, and major findings. The five broad themes that emerged from the findings of these articles related to conceptions of physical giftedness/talent, identification characteristics/criteria, factors associated with identification, identification methods, and talent development interventions. An outline and discussion of the key issues and trends in the research, along with some recommendations for future research, conclude the systematic review.

Statistical analysis considerations within longitudinal studies of physical qualities in youth athletes: A qualitative systematic methodological review

Background

The evaluation of physical qualities in talent identification and development systems is vital and commonplace in supporting youth athletes towards elite sport. However, the complex and dynamic development of physical qualities in addition to temporal challenges associated with the research design, such as unstructured data collection and missing data, requires appropriate statistical methods to be applied in research to optimise the understanding and knowledge of long-term physical development.

Aim

To collate and evaluate the application of methodological and statistical methods used in studies investigating the development of physical qualities within youth athletes.

Methods

Electronic databases were systematically searched form the earliest record to June 2021 and reference lists were hand searched in accordance with the PRISMA guidelines. Studies were included if they tested physical qualities over a minimum of 3 timepoints, were observational in nature and used youth sporting populations.

Results

Forty articles met the inclusion criteria. The statistical analysis methods applied were qualitatively assessed against the theoretical underpinnings (i.e. multidimensional development, non-linear change and between and within athlete change) and temporal challenges (i.e. time variant and invariant variables, missing data, treatment of time and repeated measures) encountered with longitudinal physical testing research. Multilevel models were implemented most frequently (50%) and the most appropriately used statistical analysis method when qualitatively compared against the longitudinal challenges. Independent groups ANOVA, MANOVA and X2 were also used, yet failed to address any of the challenges posed within longitudinal physical testing research.

Conclusions

This methodological review identified the statistical methods currently employed within longitudinal physical testing research and addressed the theoretical and temporal challenges faced in longitudinal physical testing research with varying success. The findings can be used to support the selection of statistical methods when evaluating the development of youth athletes through the consideration of the challenges presented.

Methodological Approaches to Talent Identification in Team Sports: A Narrative Review

Talent identification (TID) and talent development (TD) continue to receive significant investment from team sports organisations, highlighting their importance in attempting to identify potential elite athletes. Accompanying this continual pursuit to unearth future talent is an ever-increasing body of research aiming to provide solutions and strategies to optimise TID and TD processes. Therefore, the aim of this review is to provide a summary and critical synthesis of the methodological approaches applied to TID in team sports and present considerations for future TID research. Specifically, this review highlights three key areas for consideration: (1) the timespan of the research design; (2) the use of monodisciplinary or multidisciplinary variables; and (3) the fidelity of the methodological approaches to the assessment of talent. The review highlights the benefits of longitudinal, multidisciplinary, and ecologically valid research designs for TID within team sports.

Assessing the Ecological-Context Strengths of School-Based Talent Development Programs in Rugby League

Purpose: Adopting an ecological perspective, the study explored the context-strengths of three successful school-based TDEs in rugby league. Method: Utilizing a mixed methods approach, incorporating validated psychometric questionnaires (N = 118) and semi-structured interviews, various stakeholder perspectives (N = 30; i.e., current/past students and coaches) were triangulated and corroborated to identify TDE ecological strengths. Results: Compared to benchmark TDE data, and supplemented by descriptions of TDE features and processes, results confirmed strong coherence to "effective" factors in TDE literature. Collective "ecological strengths" included quantitative findings of a highly supportive culture, shared "person" and "athlete" desired outcomes, and a long-term focus; and qualitative features of high behavioral expectations, strong values of hard work, and the promotion of personal ownership in athlete development. Opportunities to enhance TDE effectiveness were also identified, with psychological skill development (e.g., self-reflection, coping) and balancing intra-rugby league pathway demands (i.e., competition/training loads) highlighted. Conclusion: Findings identify characteristics, components, and processes of school-TDE environments associated with successful athlete development in schools and beyond (i.e., transition into an athlete development pathway).

Coaches' Assessment of Players Physical Performance: Subjective and Objective Measures are needed when Profiling Players

This mixed methods study aimed to assess the agreement between coaches ranking of youth rugby league players compared against objective physical performance data and gather coaches' subjective descriptions of their players performance. Five hundred and eight male rugby league players (U16 n = 255, U18 n = 253) completed a fitness testing battery of anthropometric and physical performance measures. Subsequently, 22 rugby (n = 11) and strength and conditioning (S&C) coaches (n = 11) ranked each player's physical qualities using a 4-point Likert scale (1 - top 25%; 2-25-50%; 3-50-75%; and 4 - bottom 25%) and described their performance. U16 S&C coaches displayed fair agreement when assessing players body mass (39.3%, κ = 0.20). U18 rugby coaches demonstrated fair agreement for strength and size (42.5%, κ = 0.23) and body mass (48.7%, κ = 0.31) whilst both U18 rugby and S&C coaches showed fair agreement levels for endurance (39.8%, κ = 0.25, 44.3%, κ = 0.29), respectively. Three higher-order themes were identified from coaches' descriptions of players including physical, rugby and attitude characteristics when evaluating performance. Overall, coaches cannot accurately assess players physical performance against fitness testing data. Though, findings suggest coaches adopt a multidimensional approach when evaluating players performance. Practitioners within talent development systems should utilise both objective and subjective assessments when making decisions regarding players performance.Highlights Rugby and S&C coaches cannot accurately assess all aspects of players physical performance.The greatest assessment agreement was for body mass, strength and size, and endurance, while the poorest were for strength, acceleration, and maximum speed.Rugby and S&C coaches considered rugby, physical and attitude attributes when evaluating players.Findings highlight the complex nature of physical profiling. Subjective and objective measures are required to provide an accurate description of players physical performance.

Short and long-term differences in anthropometric characteristics and physical performance between male rugby players that became professional or remained amateur

Objective

The objective of this study was to investigate which anthropometric and physical performance variables characterised players that advanced to professional teams (professionals) and how these variables changed over time, compared to those that did not secure professional contracts (i.e. remained amateurs).

Methods

Differences in anthropometry, strength, speed, power and intermittent running ability in 83 male rugby players collected between 2015 and 2019 were determined using repeated measures analysis.

Results

When arriving for the first year of the program, forwards that went on to become professional players were older (0.4 ± 0.3 yr, mean ± 95% CI, p = 0.004), heavier (4.6 ± 2.5 kg, p < 0.001) and stronger (range 6.2-16.4%) than forwards that remained amateur. Professional forwards were also slower at sprinting (range -2.7-2.9%, p < 0.001) and had lower Yo-Yo IRT L1 (-10.8%, p = 0.03). When first arrived on the program, professional backs were taller (3.5 ± 1.8 cm, p < 0.001), heavier (4.6 ± 2.4 kg, p < 0.001) and faster over 20 m (-1.9 ± 1.7%, p = 0.03) and 30 m (-1.7 ± 1.6%, p = 0.04) compared to amateurs. Compared to amateurs, professionals had a smaller increase in body mass (-4.2 ± 2.0%, p < 0.001) and greater improvement in sprinting (3.7, 2.8, 2.8% over 10, 20 and 30-m, respectively) and Yo-Yo IRT L1 (14.7 ± 11.0%, p = 0.05) over 3 years training.

Conclusion

Characteristics that are likely to assist players in becoming professionals include being older, heavier, taller and stronger.

Performance and reference data in the jump squat at different relative loads in elite sprinters, rugby players, and soccer players

The aims of this study were to compare the outcomes and provide reference data for a set of barbell mechanical parameters collected via a linear velocity transducer in 126 male sprinters (n = 62), rugby players (n = 32), and soccer players (n = 32). Bar-velocity, bar-force, and bar-power outputs were assessed in the jump-squat exercise with jump-squat height determined from bar-peak velocity. The test started at a load of 40% of the athletes’ body mass (BM), and a load of 10% of BM was gradually added until a clear decrement in the bar power was observed. Comparisons of bar variables among the three sports were performed using a one-way analysis of variance. Relative measures of bar velocity, force, and power, and jump-squat height were significantly higher in sprinters than in rugby (difference ranging between 5 and 35%) and soccer (difference ranging between 5 and 60%) players across all loads (40–110% of BM). Rugby players exhibited higher absolute bar-power (mean difference = 22%) and bar-force (mean difference = 16%) values than soccer players, but these differences no longer existed when the data were adjusted for BM (mean difference = 2.5%). Sprinters optimized their bar-power production at significantly greater relative loads (%BM) than rugby (mean difference = 22%) and soccer players (mean difference = 25%); nonetheless, all groups generated their maximum bar-power outputs at similar bar velocities. For the first time, we provided reference values for the jump-squat exercise for three different bar-velocity measures (i.e., mean, mean propulsive, and peak velocity) for sprinters, rugby players, and soccer players, over a wide range of relative loads. Practitioners can use these reference values to monitor their athletes and compare them with top-level sprinters and team-sport players.

Variations in the constituent year effect in Junior World Championships in alpine skiing: A window into relative development effects?

While research on the effects of 'birth month' is usually referred to as relative age effects, the study of the effects of 'birth year' is described as the constituent year effect (CYE). In the present study we examined the impact of the CYE on participation in the Junior World Championship in alpine skiing. Based on previous research, we expected to find increasing numbers of participants the older the age-group, and that the CYE would be stronger in the speed events compared to the technical ones. The sample in the present study consisted of 1188 male skiers and 859 female skiers within the age range of 17 to 21 years at the time of competition. The results show that the number of male participants increased with increasing age, which can be described as a CYE. For female skiers, a CYE was found, but it dissipated two years earlier than for male skiers. The CYE varied with event and was more pronounced the higher the speed of the event. The findings thus suggest that a constituent year effect exists among skiers participating in the FIS Junior World Ski Championship in the alpine skiing championships, and that the effect varies with gender and event, rather unrelated to age. Thus, it seems that the effect may not be a relative age effect, but instead a relative development effect.

Anthropometric, physiological characteristics and rugby-specific game skills of schoolboy players of different age categories and playing standards

Background

Rugby is increasingly gaining popularity among school-aged male junior players in countries hardly known for dominating international rugby, such as Zimbabwe. Given rugby combativeness, participating adolescents should possess qualities or skills commensurate with the physical demands of the sport for effective participation. This study investigated the independent and interactive effects of age category and playing standard on anthropometric, physiological characteristics and rugby-specific game skills among Zimbabwean athletes.

Methods

Two hundred and eight elite, sub-elite and non-rugby players competing at Under 16 and Under 19 age categories were assessed using the School Clinical Rugby Measure (SCRuM) test battery. Participants underwent height, sitting height, mass, skinfolds, speed, agility, upper-and-lower muscular strength and power, prolonged high-intensity intermittent running ability, tackling, passing and catching assessments in a cross-sectional experimental design.

Results

Age categories had significant main effect on all SCRuM test items except sum of seven skinfolds (p = 0.45, η²p = 0.003). Playing standard had significant main effects for all variables except height (p = 0.40, η²p = 0.01) and sum of seven skinfolds (p = 0.11, η²p = 0.02). Specifically, upper-and-lower muscular strength and power, prolonged high-intensity intermittent running ability, tackling, passing and catching improved with increasing playing standards. However, two-way analysis of variance only demonstrated significant interactions between the effects of age category and playing standards for vertical jump height (VJ) test, 2-kg medicine ball chest throw (2-kg MBCT) test, Yo-Yo intermittent recovery test level 1 (Yo-Yo IRT L1), and tackling and catching tests. Yo-Yo IRT L1, VJ, tackling and catching tests demonstrated greater discriminative ability among Under 16 s, whereas the 2-kg MBCT test showed better ability in Under 19 s.

Conclusion

All SCRuM variables except skinfolds improved with age, highlighting relative sensitivity in differentiating older from younger athletes. However, the discriminative ability by playing standards for VJ, 2-kg MBCT, Yo-Yo IRT L1, tackling and catching ability tests was age-dependent. These findings informs on general attribute development in junior rugby players with age and on specific players attributes in need of monitoring for attainment of elite status at U16 or U19 level.

Field-Based Tests for the Assessment of Physical Fitness in Children and Adolescents Practicing Sport: A Systematic Review within the ESA Program

High levels of physical fitness (PF) can positively affect both health and cognitive function, thus monitoring its levels in youth can help increase health and quality of life in adult populations later on. This systematic review aims to identify PF field-based tests used in young European populations practicing sport to find tools that are adequate for the considered target involving a new battery within the Enriched Sport Activities (ESA) project. The Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) statement was followed. In the 83 identified articles, the main tests used were: vertical/horizontal jumps (for muscular strength/power); push-ups, running at maximum effort, sit-ups (for muscular strength/endurance); multistage non-intermittent and intermittent tests (for aerobic endurance); sit and reach (for flexibility); sprinting and agility T-tests (for speed and agility, respectively); 10 × 5 m shuttle run (SR) (for both speed and agility). Few studies assessed coordination, reaction time, power, and balance. Although the selected tests are widely used and validated, they do not determine all PF aspects and do not reflect sport-specific features. A final decision was made for the inclusion of the following tests: standing broad jump, seated medicine ball throw, 20 m SR test, 30 m sprint, Illinois test, and a new test, i.e., the crunning test, to assess different skill-related components at once. The use of this combination of tests allows for the assessment of all PF components and can help planning effective training programs and cultivate sporting talent.

Qualities or skills discriminating under 19 rugby players by playing standards: a comparative analysis of elite, sub-elite and non-rugby players using the SCRuM test battery

Objective

Although schoolboy rugby is growing in popularity and played at different competitive levels in Zimbabwe, the influence of playing standard on qualities or skills of older male adolescent rugby players is unknown. Utilising a cross-sectional design, this study determined anthropometric, physiological characteristics and rugby-specific game skills defining elite under 19 (U19) schoolboy rugby players. Following development and subsequent assessment of test–retest reliability of School Clinical Rugby Measure (SCRuM) test battery, this study compared performance outcomes of elite rugby players (n = 41), sub-elite rugby players (n = 46) and non-rugby athletes (n = 26) to identify qualities or skills discriminating (i) elite from sub-elite and non-rugby players, and concomitantly (ii) sub-elite from non-rugby players.

Results

40 m speed test (p < 0.001, ES = 1.78) and 2 kg Medicine Ball Chest Throw test (p < 0.001, ES = 1.69) significantly discriminated elite U19 from sub-elite and non-rugby players. These tests further differentiated sub-elite from non-rugby athletes. Additionally, 1RM back squat (p = 0.009, ES = 0.57), 1RM bench press (p = 0.005, ES = 0.61), repeated high-intensity exercise test (p < 0.001, ES = 0.88) and passing ability test (p < 0.001, ES = 0.99) discriminated elite from sub-elite counterparts. These findings highlight important attributes linked to elite U19 schoolboy rugby in Zimbabwe. However, no significant differences were observed for sum of seven skinfold (p = 0.28), tackling (p = 0.08) and catching ability (p = 0.05).

Height prediction in elite Italian rugby players: A prospective study

OBJECTIVES

We investigated the validity of the Mirwald equation as an estimate of height in a cohort of rugby players.

METHODS

This was a prospective study with agreement analysis of height assessments conducted in 39 male youth rugby players (mean age 15.1 ± 0.9 years). During the 2007/2008 season, 151 young athletes were selected by rugby coaches using subjective decisions based on current performance and future potential. The rugby players were measured by physician experts and their height was estimated using the Mirwald formula (MF). Only 39 athletes were finally selected because they reached an elite level, allowing actual adult height to be collected from the official team websites in June 2018. Method agreement was assessed by intraclass correlation coefficient, regression, and plotted by Bland and Altman analysis.

RESULTS

Twenty athletes played in the Italian National team and 19 in the First Italian Division (Eccellenza). Overall, they presented an early maturation and the MF was able to accurately estimate height. The MF underestimated height (187.4-189.1 cm) and showed a high association with actual adult players' height (r = 0.925, P < .001).

CONCLUSIONS

Our results demonstrate that the MF, whose estimation of stature is based on height, sitting height, body mass, and leg length is able to predict stature in rugby players.

Removing relative age effects from youth swimming: The development and testing of corrective adjustment procedures

OBJECTIVES

(1) Generate accurate estimates of the relationship between decimal age (i.e., chronological and relative) with swimming performance based on longitudinal data. (2) Determine whether corrective adjustment procedures can remove Relative Age Effects (RAEs) from junior/youth swimming.

DESIGN

Longitudinal and repeated years of cross-sectional performance data were examined.

METHODS

(1) Participants were 553 male 100m Freestyle swimmers (10-18 years) who participated in ≥five annual events between 1999-2017. Growth curve modelling quantified the relationship between age and swimming performance, permitting corrective adjustment calculations. (2) Participants were N=2141 male 100m Freestyle swimmers (13-16 years) who swam at state/national events in 2015-2017. Relative age distributions for 'All', 'Top 50%', '25%' and '10%' of swimming times were examined based on raw and correctively adjusted swim times. Chi-square, Cramer's V and Odds Ratios (OR) determined whether relative age (quartile) inequalities existed according to age-groups, selection level and correctively adjusted swim times.

RESULTS

Based on raw swim times, for 'All' swimmers RAEs was evident at 13 and 14 years-old and dissipated thereafter. But, RAE effect sizes substantially increased with selection level, with large-medium effects between 13-15 years-old (e.g., 15 years - Top 50% Q1v Q4 OR=2.28; Top 10%=6.02). However, when correctively adjusted swim times were examined, RAEs were predominantly absent across age-group and selection levels.

CONCLUSIONS

With accurate longitudinal reference data, corrective adjustment procedures effectively removed RAEs from 100m Freestyle swimming performance, suggesting the potential to improve swimming participation experience and performance evaluation.

Distinct trajectories of athlete development: A retrospective analysis of professional rugby league players

Contemporary models of athlete development (e.g., Development Model of Sport Participation) suggest attainment benefits from early age multi-sport "sampling" behaviour before progressive transition into "invested" single-sport involvement in teenage years compared to intensive early-age specialisation. However, specific examinations of these development patterns across a number of team sports and cultural contexts remains limited. This study involved a large sample of professional Australian Rugby League (RL) players (N = 224) who progressed along the RL system pathways. It defined two contrasting athlete development trajectories based upon initial entry into formal age group representative teams ("Early": U16, U18; "Later": U20+) to compare their developmental participation patterns using the National Rugby League Athlete Development Questionnaire (NRLADQ). Between-Within Analyses of Variance (BW-ANOVA)'s identified interaction effects as the 'Later' group reported lower volumes of deliberate practice from 10-20 years, RL-game involvement from 10-20 years, deliberate play from 5-12 years, and a later reduction in other sporting involvement. Group differences in RL-related deliberate practice and play were supported by qualitative descriptions of training at age-categories.

CONCLUSION

RL professional senior elite success level can be attained via early intensified specialised investment and accelerated youth success as well as by a rather decelerated, much less cost-intensive participation pattern.