Kevin Till

The Long-Term Athlete Development model: Physiological evidence and application

Abstract Within the UK, the “Long Term Athlete Development” (LTAD) model has been proposed by a variety of national governing bodies to offer a first step to considering the approach to talent development. The model, which is primarily a physiological perspective, presents an advancement of understanding of developing athletic potential alongside biological growth. It focuses on training to optimize performance longitudinally, and considers sensitive developmental periods known as “windows of opportunity”. However, it appears that there are a number of problems with this theoretical model that are not necessarily transparent to coaches. Principally, the model is only one-dimensional, there is a lack of empirical evidence upon which the model is based, and interpretations of the model are restricted because the data on which it is based rely on questionable assumptions and erroneous methodologies. Fundamentally, this is a generic model rather than an individualized plan for athletes. It is crucial that the LTAD model is seen as a “work in progress” and the challenge, particularly for paediatric exercise scientists, is to question, test, and revise the model. It is unlikely that this can be accomplished using classical experimental research methodology but this should not deter practitioners from acquiring valid and reliable evidence.

The prevalence, influential factors and mechanisms of relative age effects in UK Rugby League.

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 effects of postactivation potentiation on sprint and jump performance of male academy soccer players.

Till, KA and Cooke, C. The effects of postactivation potentiation on sprint and jump performance of male academy soccer players. J Strength Cond Res 23(7): 1960-1967, 2009-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, randomized, and counterbalanced design. In addition to a control warm up, subjects performed deadlift (5 repetitions at 5 repetitions maximum), tuck jump (5 repetitions), and isometric MVC knee extensions (3 repetitions for 3 s) as PAP treatments in an otherwise identical warm up protocol. After each treatment, the subjects underwent 3 10 m and 20 m sprints 4, 5, and 6 minutes post-warm up and 3 vertical jumps (VJ) at 7, 8, and 9 minutes post-warm up. Repeated measures analysis of variance showed no significant differences in the first 10 m (p = 0.258) and 20 m (p = 0.253) sprint and VJ (p = 0.703) performance and the average 10 m (p = 0.215), 20 m (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 after dynamic and isometric MVCs compared with 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 to evaluate the potential for performance enhancement.

Using anthropometric and performance characteristics to predict selection in junior UK Rugby League players

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.

A longitudinal evaluation of anthropometric and fitness characteristics in junior rugby league players considering playing position and selection level

OBJECTIVES The current study provided a longitudinal evaluation of the anthropometric and fitness characteristics 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 (MANCOVA; 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. Interactions between playing position and time were identified for height, vertical jump and estimated V˙O2max (p<0.05). Selection level by time interactions were identified for 20m, 30m and 60m 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.

Considering maturation status and relative age in the longitudinal evaluation of 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 Leagues 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 multivariate analysis of variance 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 cm, late = 10.3 cm), medicine ball throw and 60‐m sprint (early = −0.46 s, late = −0.85 s) the most throughout the 2‐year period. Early (de)selection policies currently applied in talent identification and development programs 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.

Retrospective analysis of anthropometric and fitness characteristics associated with long-term career progression in Rugby League

OBJECTIVES The current study retrospectively investigated the differences in anthropometric and fitness characteristics of junior rugby league players selected onto a talent identification and development (TID) programme between long-term career progression levels (i.e., amateur, academy, professional). DESIGN Retrospective design. METHODS Former junior rugby league players (N=580) selected to a TID programme were grouped according to their career progression level. Anthropometric (height, sitting height, body mass and sum of four skinfolds), maturational and fitness (power, speed, change of direction speed and estimated V̇O2max) assessments were conducted at 13-15 years. Multivariate analysis of covariance (MANCOVA) analyzed differences between career progression levels controlling for chronological age. RESULTS 57.1% and 12.1% of players selected to the TID programme progressed to academy and professional levels in rugby league, respectively. Sum of four skinfolds (η(2)=0.03), vertical jump (η(2)=0.02), 10 m (η(2)=0.02), 20 m (η(2)=0.02), 30 m (η(2)=0.02), and 60 m (η(2)=0.03) speed, agility 505 left (η(2)=0.06), agility 505 right (η(2)=0.05) and estimated V̇O2max (η(2)=0.03) were superior within junior players who progressed to professional compared to amateur levels. No significant differences were identified between future academy and professional players for any measure. CONCLUSIONS Findings suggest that lower sum of four skinfolds and advanced fitness characteristics within junior (13-15 years) rugby league players may partially contribute to long-term career progression. Therefore, TID programmes within rugby league should aim to assess and develop body composition and fitness characteristics, especially change of direction speed. However, TID programmes should also consider technical, tactical and psycho-social characteristics of junior rugby league players that may be important for long-term career progression.

Anthropometric and physical characteristics of english academy rugby league players.

Abstract Till, K, Tester, E, Jones, B, Emmonds, S, Fahey, J, and Cooke, C. Anthropometric and physical characteristics of English academy rugby league players. J Strength Cond Res 28(2): 319–327, 2014—The purpose of the present 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 were 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, 10- and 20-m sprint, estimated V[Combining Dot Above]O2max via the yo-yo intermittent recovery test level 1, absolute 1 repetition maximum [1RM], and relative squat, bench press, and prone row) measures. Univariate analysis of variance demonstrated significant (p ⩽ 0.05) increases in height, body mass, vertical jump, absolute, and relative strength measures across the 5 annual-age categories (e.g., body mass: under 16s = 75.2 ± 11.1, under 20s = 88.9 ± 8.5 kg; vertical jump: under 16s = 45.7 ± 5.2, under 20s = 52.8 ± 5.4 cm; 1RM bench press: under 16s = 73.9 ± 13.2, under 20s = 114.3 ± 15.3 kg). 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 ± 9.7 kg) and physical (e.g., under 19s 20-m sprint: backs = 3.04 ± 0.08, forwards = 3.14 ± 0.12s; under 18s relative squat: backs = 1.65 ± 0.18, forwards = 1.51 ± 0.17 kg·kg−1) characteristics that were dependent 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.

Influences of gender and socioeconomic status on the motor proficiency of children in the UK.

As the development of movement skills are so crucial to a childs involvement in lifelong physical activity and sport, the purpose of this study was to assess the motor proficiency of children aged 4-7 years (range=4.3-7.2 years), whilst considering gender and socioeconomic status. 369 children (176 females, 193 males, aged=5.96 ± 0.57 years) were assessed for fine motor precision, fine motor integration, manual dexterity, bilateral co-ordination, balance, speed and agility, upper-limb co-ordination and strength. The average standard score for all participants was 44.4 ± 8.9, classifying the participants towards the lower end of the average score. Multivariate analysis of covariance identified significant effects for gender (p<0.001) and socioeconomic status (p<0.001). Females outperformed males for fine motor skills and boys outperformed girls for catch and dribble gross motor skills. High socioeconomic status significantly outperformed middle and/or low socioeconomic status for total, fine and gross motor proficiency. Current motor proficiency of primary children aged 4-7 years in the UK is just below average with differences evident between gender and socioeconomic status. Teachers and sport coaches working with primary aged children should concentrate on the development of movement skills, whilst considering differences between genders and socioeconomic status.

Longitudinal development of anthropometric and physical characteristics within academy rugby league players

Abstract Till, K, Jones, B, Darrall-Jones, J, Emmonds, S, and Cooke, C. Longitudinal development of anthropometric and physical characteristics within academy rugby league players. J Strength Cond Res 29(6): 1713–1722, 2015—The purpose of this study was to evaluate the annual and long-term (i.e., 4 years) development of anthropometric and physical characteristics in academy (16–20 years) rugby league players. Players were assessed at the start of preseason over a 6-year period and were required to be assessed on consecutive years to be included in the study (Under 16–17, n = 35; Under 17–18, n = 44; Under 18–19, n = 35; Under 19–20, n = 16). A subset of 15 players were assessed for long-term changes over 4 years (Under 16–19). Anthropometric (height, body mass, sum of 4 skinfolds) and physical (10- and 20-m sprint, 10-m momentum, vertical jump, yo-yo intermittent recovery test level 1, 1 repetition maximum [1RM] squat, bench press, and prone row) assessments were collected. Paired t-tests and repeated measures analysis of variance demonstrated significant annual (e.g., body mass, U16 = 76.4 ± 8.4, U17 = 81.3 ± 8.3 kg; p < 0.001, d = 0.59) and long-term (e.g., vertical jump, Under 16 = 44.1 ± 3.8, Under 19 = 52.1 ± 5.3 cm; p < 0.001, d = 1.74) changes in anthropometric and physical characteristics. Greater percentage changes were identified between the Under 16–17 age categories compared with the other ages (e.g., 1RM squat, U16–17 = 22.5 ± 19.5 vs. U18–19 = 4.8 ± 6.4%). Findings demonstrate the annual and long-term development of anthropometric and physical characteristics in academy rugby league players establishing greater changes occur at younger ages upon the commencement of a structured training program within an academy. Coaches should understand the long-term development of physical characteristics and use longitudinal methods for monitoring and evaluating player performance and development.