Journal of Science and Medicine in Sport 16 (2013) 438–443 Contents lists available at SciVerse ScienceDirect Journal of Science and Medicine in Sport journal homepage: www.elsevier.com/locate/jsams Original research A longitudinal evaluation of anthropometric and fitness characteristics in junior rugby league players considering playing position and selection level Kevin Till a,∗ , Stephen Cobley b , John O’Hara a , Chris Chapman c , Carlton Cooke a a Carnegie Research Institute, Leeds Metropolitan University, Leeds, West Yorkshire, United Kingdom b Faculty of Health Sciences, The University of Sydney, New South Wales, Australia c Rugby Football League, Red Hall, Leeds, United Kingdom article info Article history: Received 7 June 2012 Received in revised form 4 September 2012 Accepted 11 September 2012 Keywords: Talent identification Maturation Development Athlete selection Expert performance abstract Objectives: The current study provided a longitudinal evaluation of the anthropometric and fitness char- acteristics in junior rugby league players across three annual-age categories (i.e., under 13s, 14s and 15s) considering playing position and selection level. Design: Longitudinal design. Methods: Eighty-one junior rugby league players selected to a talent development programme were tracked over a two year period. Anthropometric (height, sitting height, body mass and sum of four skinfolds) and fitness (lower and upper body power, speed, change of direction speed and maximal aerobic power) characteristics were measured on three occasions (i.e., under 13s, 14s and 15s). Repeated measures multivariate analysis of variance (MANOVA) and multivariate analysis of covariance (MAN- COVA; controlling chronological and maturational age) analysed changes across annual-age categories in relation to playing position and selection level. Results: Findings identified significant improvements in anthropometric and fitness characteristics across annual-age categories (p < 0.001). MANOVA and MANCOVA analysis identified significant overall effects for playing position (p < 0.001) and selection level (p < 0.05) throughout the two year period. Interac- tions between playing position and time were identified for height, vertical jump and estimated ˙ V O 2 max (p < 0.05). Selection level by time interactions were identified for 20 m, 30 m and 60 m sprint (p < 0.05). Conclusions: This study demonstrates the improvement of anthropometric and fitness characteristics within junior representative rugby league players. Interactive effects for playing position and selection level by time highlight the variation in the development of characteristics that occur during adolescence. Tracking the progression of characteristics longitudinally during adolescence, instead of at one-off time points, may assist selection and/or performance assessments within rugby league and other youth sport contexts. © 2012 Sports Medicine Australia. Published by Elsevier Ltd. All rights reserved. 1. Introduction Talent identification and development are anecdotally perceived to be crucial in the pursuit of excellence, with many national governing bodies and professional clubs investing consid- erable resources to accelerate the development process of athletes at an early age. 1,2 Currently, research and practical applications of talent identification and development programmes predomi- nantly utilise a cross-sectional approach to predict future adult performance. 3 The one-off nature of such assessments during adolescence fails to consider the impact of growth and maturation and only considers performance at specific time points. Instead, ∗ Corresponding author. E-mail address: k.till@leedsmet.ac.uk (K. Till). it is recommended that participants should be monitored over a number of years to improve the accuracy of the understanding of the factors that contribute to expert performance. 4 Therefore, when differentiating between an athlete’s adolescent performance level and the potential for progression into adulthood, longitudinal studies are essential. 3 Longitudinal studies in wider youth sport contexts have exam- ined anthropometric and performance characteristics over time, 5 changes in characteristics over a playing season 6 and the relation- ships between maturation and performance. 7 However, studies using a longitudinal methodology within talent identification and development research are limited even though they have been rec- ommended for the past decade. 3,4 Only two recent studies 8,9 have examined talent identified samples from a longitudinal perspective by tracking performance changes between selected/non-selected 8 and elite/sub-elite 9 juniors over a two year period. Both studies 1440-2440/$ – see front matter © 2012 Sports Medicine Australia. Published by Elsevier Ltd. All rights reserved. http://dx.doi.org/10.1016/j.jsams.2012.09.002