Background: In football, annual age-group categorization leads to relative age effects (RAEs) in talent development. Given such trends, relative age may also associate with market values. This study analyzed the relationship between RAEs... more
Background: In football, annual age-group categorization leads to relative age effects (RAEs) in talent development. Given such trends, relative age may also associate with market values. This study analyzed the relationship between RAEs and market values of youth players. Methods: Age category, birthdate, and market values of 11,738 youth male football players were obtained from the “transfermarkt.de” database, which delivers a good proxy for real market values. RAEs were calculated using odds ratios (OR) with 95% confidence intervals (95%CI). Results: Significant RAEs were found across all age-groups (p < 0.05). The largest RAEs occurred in U18 players (Q1 [relatively older] v Q4 [relatively younger] OR = 3.1) ORs decreased with age category, i.e., U19 (2.7), U20 (2.6), U21 (2.4), U22 (2.2), and U23 (1.8). At U19s, Q1 players were associated with significantly higher market values than Q4 players. However, by U21, U22, and U23 RAEs were inversed, with correspondingly higher mar...
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Introduction: Elite soccer academies represent one of the most common forms of talent development programmes in the UK, yet they are increasingly being challenged regarding their ‘healthiness’ or ‘appropriateness’. The morality of... more
Introduction: Elite soccer academies represent one of the most common forms of talent development programmes in the UK, yet they are increasingly being challenged regarding their ‘healthiness’ or ‘appropriateness’. The morality of engaging young players in intensive, pressurised, performance focused environments, given that only few can “make it”, has been questioned. Instead, proponents argue that academies offer powerful contexts for positive development, readying players for life. As with any system, it makes sense to see academies as offering a context of impact possibilities; performance and personal, positive and negative, short- and long-term. This study aims to address the shortfall of holistic approaches in evaluating the impact of academy involvement. Methods: A mixed-methods approach was utilised to comprehensively and holistically evaluate the impact of one elite English youth soccer academy. Over one-year, longitudinal quantitative data on physical and psycho-social wel...
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Las pruebas de aptitud son una practica comun en los deportistas jovenes. Sin embargo, la interpretacion de sus datos se produce a menudo dentro de tablas cronologicas o categorias en funcion de la edad, lo que resulta genera... more
Las pruebas de aptitud son una practica comun en los deportistas jovenes. Sin embargo, la interpretacion de sus datos se produce a menudo dentro de tablas cronologicas o categorias en funcion de la edad, lo que resulta genera discrepancias en funcion del nivel de desarrollo de los deportistas. En su lugar, evaluar el rendimiento de aptitud con medias moviles puede ser mas apropiado. Este articulo presenta un metodo novedoso para analizar los datos de pruebas de aptitud en atletas juveniles usando puntuaciones z segun las medias moviles de las edades cronologicas y del estado de madurez. Esta tecnica de analisis permite la capacidad de interpretar la aptitud y desempeno de la juventud segun la edad y la maduracion, mejorando la exactitud de la interpretacion de los datos para la identificacion del talento, el desarrollo y la programacion de fuerza y acondicionamiento.
Relative age effects in sports participation highlight the presence of a significant social and developmental inequality. To assess its prevalence, patterning, and size, this study examined participation trends of youth (ages 7–21 years)... more
Relative age effects in sports participation highlight the presence of a significant social and developmental inequality. To assess its prevalence, patterning, and size, this study examined participation trends of youth (ages 7–21 years) Rugby League players registered to local community clubs across the North of England ( N = 23,943). Results showed that irrespective of relative age, participation growth occurred from U8 to U12s age categories. However, from U13 to U19s, participation became differentiated with the relatively younger showing earlier and progressively lowering participation proportions (e.g. Q4s – U13–U17 = 24–17%) and were up to 50% less likely to participate (i.e. Q4 vs. Q1 – U15–U16 OR = 0.48 and 0.50). Findings highlight the substantial earlier loss of participation for the relatively younger across youth ages. Player development systems containing inherent selection and differentiation during adolescence are presented as one key process affecting the decision t...
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Research Interests: Psychology and Football
The aim of this study was to examine the differences in the angular velocity profiles and key positional angles of multiple forward somersault dives from the 3m springboard. One internationally ranked male diver performed the forward 1½,... more
The aim of this study was to examine the differences in the angular velocity profiles and key positional angles of multiple forward somersault dives from the 3m springboard. One internationally ranked male diver performed the forward 1½, 2½, 3½ pike (P) dives while a second diver performed the 4½ tuck (T) dive. High speed video footage and inertial measurement units (IMU) were used to determine eight biomechanical variables. Results indicate that the diver performing the 4½T had a 177 deg/s increase in the angular velocity plateau and held onto his somersault position for 0.26s longer when compared to the 3½P. The forward 4½T takeoff angles were similar to those used in the 2½P and 3½P, but were slightly under rotated at entry. The IMUs proved to be a suitable analysis tool for springboard diving coaches wanting ‘quick turnaround’ performance analysis.
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Introduction Exercise has well-established benefits on depression and weight-management in normative populations. However, its effectiveness at postpartum phase remains uncertain. Objectives Determine the effectiveness of exercise or... more
Introduction Exercise has well-established benefits on depression and weight-management in normative populations. However, its effectiveness at postpartum phase remains uncertain. Objectives Determine the effectiveness of exercise or physical activity (PA) interventions on postnatal depression (PND) and weight-loss. Aims Identify exercise and PA modalities most effective in reducing PND symptoms and weight. Methods Systematic review of RCTs and experimental studies comparing exercise or PA modalities (e.g., flexibility versus resistance training) against control or alternative interventions (e.g. social support, diet). Data search included Cochrane Library (CENTRAL), MEDLINE, PsycINFO, EMBASE, CINAHL, Scopus and Science Citation Index. Results Of 8099 studies retrieved, six fulfilled inclusion criteria. Two implemented supervised exercise interventions, one using ‘Yoga & Pilates' (1×60 mins/session×12 weeks) and one using resistance (v flexibility) training focusing on major mus...
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Purpose: The study aimed to (1) accurately examine longitudinal relationships between maturity status and both technical skill indices and performance in Australian male (N = 64) age-group Front-crawl swimmers (10–15 y) and (2) determine... more
Purpose: The study aimed to (1) accurately examine longitudinal relationships between maturity status and both technical skill indices and performance in Australian male (N = 64) age-group Front-crawl swimmers (10–15 y) and (2) determine whether individual differences in maturation influenced relationships between technical skill level and swimming performance. Methods: A repeated-measures design was used to assess maturity status and performance on 200-m Front-crawl trial across 2 competition seasons (2018–2020). Assessments were made on 3 to 5 occasions (median = 3) separated by approximately 4 months. Average horizontal velocity and stroke frequency were used to calculate technical skill indices, specifically stroke index, and arm propelling efficiency. Relationships between variables were assessed using linear mixed models, identifying fixed, and random effect estimates. Results: Curvilinear trends best described significant longitudinal relationships between maturity status wit...
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The aim of this study was to determine if training age – rugby league training age, resistance training age and cardiovascular training age – was predictive of changes in physiological performance in developmental rugby league players.... more
The aim of this study was to determine if training age – rugby league training age, resistance training age and cardiovascular training age – was predictive of changes in physiological performance in developmental rugby league players. Developmental rugby league players from one elite club ( n = 147, mean age = 15.8 ± 1.1 years) playing at Under 16 and Under 18 representative levels were tracked longitudinally over two consecutive seasons. Estimated aerobic capacity, jump height, upper body strength endurance and change of direction were assessed. Mixed method random effect analysis determined relationships between training age domains and physiological change. Positive relationships were observed between rugby league training age and change in estimated V̇O2max ( β = 0.13, p = 0.018), and change in strength endurance ( β = 0.51, p = 0.033), and resistance training age and change in jump height ( β = 0.11, p = 0.007). A negative relationship was observed between rugby league trai...
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The pattern of propulsive force (measured at the pin), represented by force-time and force-angle graphs, typically differs among rowers. How the pattern differs according to competition level and gender has not been identified. Functional... more
The pattern of propulsive force (measured at the pin), represented by force-time and force-angle graphs, typically differs among rowers. How the pattern differs according to competition level and gender has not been identified. Functional data analysis (FDA) techniques were used on force-time and force-angle data to identify the main modes of variance in curves representing thirty eight rowers of different competition levels (domestic, underage international and open international) and different gender. Stepwise discriminant function analysis showed strong classification of rowers using force-time and force-angle graphs and strong classification of female rowers. Male rowers, Underage rowers and Open International rowers showed weaker classification. Despite this, FDA provided useful information for the assessment of rowing performance.
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Background: Within daily tasks (e.g., studying, driving), error in self-assessment of task capability can lead to significant implications and consequences including compromised task performance (e.g., exams) and risk of personal injury... more
Background: Within daily tasks (e.g., studying, driving), error in self-assessment of task capability can lead to significant implications and consequences including compromised task performance (e.g., exams) and risk of personal injury (e.g., accident). Objectives: This study sought to determine the overall capability to accurately align estimated and actual performance, identify the pervasiveness of estimation error (i.e., the Dunning-Kruger Effect - DKE), and identify moderating variables on self-assessment accuracy. Methods: A meta-analysis of systematically reviewed studies assessed estimation error in tasks, pooling correlations, mean differences and binary moderating variables. Results: Across studies, a small-moderate pooled correlation between estimated and actual performance (r = .32, CI = 0.29-0.35, p < .001) was identified. Further, the lowest quartile of performers consistently overestimated their performance (i.e., 37.44 percentile points; g = 2.17, CI = 1.74-2.60, ...
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Subtle age differences can lead to immediate participation and long-term attainment influences in sport; commonly known as Relative Age Effects (RAEs; Barnsley et al., 1985). The prevalence of the RAE remains relatively undetermined for... more
Subtle age differences can lead to immediate participation and long-term attainment influences in sport; commonly known as Relative Age Effects (RAEs; Barnsley et al., 1985). The prevalence of the RAE remains relatively undetermined for female sport contexts. Accordingly, the objective of this study was to examine female participation trends with respect to relative age in the published literature by evaluating the birth quartile distribution of athlete samples. Following PROSPERO (Reg. no. 42016053497) and PRISMA systematic search guidelines, 57 studies spanning 1984–2016 were identified and contained 308 independent samples across 25 sports. The overall prevalence and strength of the RAE across and within female sports contexts was determined, and moderator variables were assessed using odds ratio (OR; events vs. non-events) meta-analyses, applying an invariance random-effects model. The overall pooled estimate comparing the relatively oldest (Q1) v relatively youngest (Q4) sugges...
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The professionalisation of soccer academies has intensified, with youth players exposed to demanding performance focused environments in pursuit of a career in the professional game. Yet, academies are also under increasing pressure to... more
The professionalisation of soccer academies has intensified, with youth players exposed to demanding performance focused environments in pursuit of a career in the professional game. Yet, academies are also under increasing pressure to show that they develop players who can function in life beyond soccer. Therefore, this study explored the retrospective views of 13 ex-elite UK youth academy soccer players on whether their time within the academy provided developmental experiences that prepared them for life beyond soccer. We interviewed seven players who successfully progressed into professional contracts and six who did not. Players were recruited from two different academies to explore the developmental outcomes they associated with academy involvement and to unpick how those outcomes were achieved. Our findings showed that, promisingly, time in the academy provided both contracted and non-contracted players with transferable life skills as well as open educational and vocational ...
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The graphical presentation of the propulsive form applied by the oar to the pin, plotted against the oar horizontal angle, has been used as a diagnostic tool for rowing skill. How the pattern is related to variables such as level of... more
The graphical presentation of the propulsive form applied by the oar to the pin, plotted against the oar horizontal angle, has been used as a diagnostic tool for rowing skill. How the pattern is related to variables such as level of competitive has not been well identified. Bivariate functional principal components analysis (bfPCA) was used on form-angle data to identify the main modes of variation in curves representing twenty seven female rowers of two different competition levels (Australian Domestic and Australian International level), rowing at 32 strokes per minute in a single scull boat. Discriminant function analysis showed strong classification of rowers using force-angle graphs across both sides of the boat, with increased rate of force development identified as an important characteristic for international rowers. Additionally for the bow-side, spending less time in the first half of the drive phase was also identified as an important feature for international rowers. The...
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Cross-country eventing is one of the highest-risk sporting activities for serious injury outcomes. This study investigated relationships between fall characteristics and high-risk falls at jumps in cross-country eventing. A video analysis... more
Cross-country eventing is one of the highest-risk sporting activities for serious injury outcomes. This study investigated relationships between fall characteristics and high-risk falls at jumps in cross-country eventing. A video analysis protocol was systematically developed to analyse 87 video recordings of high-risk rider falls; defined as when the rider's head impacted the ground and/or where there was potential horse impact with the rider. Falls were classified according to competition type, jump type, horse-related and rider-related factors. At least one high-risk fall characteristic was observed in 45 of 87 examined falls. Multivariable best-subsets regression identified five independent variables explaining 38.4% of the variance in the number of high-risk falls. Increased likelihood of high-risk falls was associated with continuation of horse direction or speed upon rider ground impact, higher jump approach speed, changes in rider body posture upon landing, rider air jacket usage, and reduced rider fall time. The Eventing Fall Assessment Instrument (EFAI) video analysis protocol (attached as supplementary material) facilitated systematic examination of multiple characteristics associated with high-risk falls and identified likely influential characteristics. Based on EFAI and subsequent data-analyses, findings suggest optimised approach speed for correct striding and take-off; jump design to enable run-out; and rider training could help reduce the occurrence of high-risk falls. Air jacket usage and their design characteristics warrant further investigation.
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This study examined differences across skill levels in the kinematics of a complex, whole-body, asymmetrical, cyclical dance sequence, the 'Alternate Basic' in Cha-Cha-Cha, to determine whether observed differences were consistent... more
This study examined differences across skill levels in the kinematics of a complex, whole-body, asymmetrical, cyclical dance sequence, the 'Alternate Basic' in Cha-Cha-Cha, to determine whether observed differences were consistent with Bernstein's (1967) model of development of coordination. Bernstein proposed that with novel motor skills, beginners move their bodies rigidly and spastically, freezing kinematic degrees of freedom (DOF) to constrain the motor system. As the skill becomes practised, the DOF unfreeze and movements become more dynamic, allowing the integration of reactional elements (passive forces, moments, etc.) and organisation of more complex coordinative structures. Twenty-nine dancers - beginners (n = 10), intermediates (n = 10), experts (n = 9) - performed 12 cycles of the dance sequence (total duration ~60 s). Three-dimensional kinematic data from 36 joint angles were collected using a 14-camera infrared motion capture system. Most joints displayed increased amplitude and speed of movement, especially early in skill progression (beginner-intermediate stage), with no evidence of any decreases, showing that unfreezing occurred around the general movement pattern early. Speed of movement continued to increase later (intermediate-expert stage), as well as further unfreezing of the upper limbs. Changes to intra-limb couplings were limited, comprising some early reductions in coupling strength. Principal component analyses (PCA) showed that the structure of movement became more organised with increased skill. There was an early reduction in the number of coordinative structures, while later, movement was integrated more into the first coordinative structure. As predicted by Bernstein's coordination development model, therefore, the kinematic DOF unfroze as skill level progressed, leading to increased organisation of coordinative structures. The results of this study support the importance of a whole-body perspective in studies of coordination, with incorporation of kinetic variables in future research in order to examine the role that reactional elements play in motor skill development.
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Research Interests: Psychology and Medicine
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ABSTRACT This study examined the predictive ability of the medicine ball chest throw and vertical jump for muscular strength and power in adolescents. One hundred and ninety adolescents participated in this study. Participants performed... more
ABSTRACT This study examined the predictive ability of the medicine ball chest throw and vertical jump for muscular strength and power in adolescents. One hundred and ninety adolescents participated in this study. Participants performed trials of the medicine ball chest throw and vertical jump, with vertical jump peak power calculated via an estimation equation. One-repetition maximum and peak power for the chest press and leg press were assessed using pneumatic exercise machines. The medicine ball chest throw strongly correlated with chest press one-repetition maximum and peak power, while the vertical jump peak power strongly correlated with leg press one-repetition maximum and peak power. The predictive ability of medicine ball chest throw was better than vertical jump peak power for muscular strength and power when controlling for sex, age, height, weight, and maturation, and was not affected by involvement in sports. Results show good predictive ability of the medicine ball chest throw for muscular strength and power in adolescents, while predictable ability of vertical jump peak power is weakened when other factors are taken into account.
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BackgroundPhysical inactivity is one of the key global health challenges as it is associated with adverse effects related to ageing, weight control, physical function, longevity, and quality of life. Dancing is a form of physical activity... more
BackgroundPhysical inactivity is one of the key global health challenges as it is associated with adverse effects related to ageing, weight control, physical function, longevity, and quality of life. Dancing is a form of physical activity associated with health benefits across the lifespan, even at amateur levels of participation. However, it is unclear whether dance interventions are equally as effective as other forms of physical activity.ObjectiveThe aim was to systematically review the literature on the effectiveness of structured dance interventions, in comparison to structured exercise programmes, on physical health outcome measures.MethodsSeven databases were searched from earliest records to 4 August 2017. Studies investigating dance interventions lasting > 4 weeks that included physical health outcomes and had a structured exercise comparison group were included in the study. Screening and data extraction were performed by two reviewers, with all disagreements resolved b...
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This study explored the variability in angular velocity profiles across multiple somersault dives. Four international level divers performed 4-6 repeated dives of either 3½ somersaults with pike, or 4½ with tuck, from a 3 m springboard.... more
This study explored the variability in angular velocity profiles across multiple somersault dives. Four international level divers performed 4-6 repeated dives of either 3½ somersaults with pike, or 4½ with tuck, from a 3 m springboard. An inertial measurement unit (IMU) was attached to the lower back to record angular velocity during all trials. Each diver produced highly consistent patterns of dive time duration and angular velocity, with standard deviations less than 1% of the mean. No consistent pattern of correlation between velocity and duration of the held tuck/pike position was apparent, and no other evidence of mid-dive feedback control was evident from the present methodology. This may be the result of performing dives with a high degree of difficulty, providing little time for movement adjustments during 'kick out' to affect water-entry.
The recent IOC consensus statement1 on youth athletic development highlights how the careers of many youth athletes are often temporarily halted or derailed by overuse injuries, resulting from disproportionate training loads along with... more
The recent IOC consensus statement1 on youth athletic development highlights how the careers of many youth athletes are often temporarily halted or derailed by overuse injuries, resulting from disproportionate training loads along with insufficient rest and recovery. Training volume and intensity2 as well as excessive training doses predict specific injury types.3 Recently, the acute: chronic workload ratio has shown how inappropriate short-term increases in training load are associated with heightened injury risk.4 Further, chronic exposure to inappropriate training volume is associated with further deleterious outcomes.2 ,5 ,6 Empirical evidence exists suggesting that systematic regulation of training loads across the various stages of development occurs in some sport contexts. However, we suspect disparity and inconsistency in the quality of training load regulation across sport contexts and organisations. In some it may be inadequate, possibly lead by intuitive dogmatic approach...
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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'... more
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 relative 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. Their development was examined using the National Rugby League Athlete Development Questionnaire (NRLADQ). Two contrasting athlete development trajectories were identified based upon initial entry into formal age-group representative teams ("Early": U16, U18; "Later": U20+) and developmental participation patterns were compared. Between-Within Analyses of Variance (BW-ANOVA)'s...
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Objectives: To examine whether gender or side of the boat influenced shape characteristics of the force-angle profile in on-water single sculling. Design: Cross-sectional study design. Methods: Bivariate functional principal components... more
Objectives: To examine whether gender or side of the boat influenced shape characteristics of the force-angle profile in on-water single sculling. Design: Cross-sectional study design. Methods: Bivariate functional principal components analysis (bfPCA) was applied to force-angle data to identify the main modes of variance in curves of forty highly skilled male and female rowers (national and international level), rowing at 32 strokes per minute in a single scull boat. Results: Separate discriminant function analyses for each side of the boat showed strong classification of rowers for gender. Force application close to (or closely around) the perpendicular oar position was demonstrated to be different between genders. A mixed ANOVA exploring gender, boat side and their interaction revealed that bow and stroke side forces were also statistically different from each other independently of gender. A main effect, independent of side of the boat, was also present for gender and no interac...
The aim of this case study was to determine the practical application of 3D inertial measurement units and compare angular velocity profiles, key position angles and event timings for the backward 2½ somersaults with 1½ twists (5253B).... more
The aim of this case study was to determine the practical application of 3D inertial measurement units and compare angular velocity profiles, key position angles and event timings for the backward 2½ somersaults with 1½ twists (5253B). One male diver performed 11 trials of the 5253B while 3D inertial measurement units (IMU) and high speed video were used to measure kinematic variables. Peak angular velocity about the somersault and twist axes were 900±11deg/s and -1435±28.deg/s, with highly consistent patterns displayed for total flight time (<1%) and peak angular velocity (=2%). A comparison between the 5253B and the backward 2½ somersaults dive (205B) indicated significant kinematic differences at take-off, flight and entry. IMU provide a quick and practical analysis tool for coaches wanting to monitor their athlete’s daily performance.
OBJECTIVES To (1) examine the association between maturity timing and performance-based selection levels in (N=708) Australian male 100-m Freestyle swimmers (12-17 years); (2) identify the relationship between maturation status and 100-m... more
OBJECTIVES To (1) examine the association between maturity timing and performance-based selection levels in (N=708) Australian male 100-m Freestyle swimmers (12-17 years); (2) identify the relationship between maturation status and 100-m Freestyle performance; and (3) determine whether Maturation-based Corrective Adjustment Procedures (Mat-CAPs) could remove maturation-related differences in swimming performance. METHODS In Part 1, maturity timing category distributions ('Early', 'Early Normative', 'Late Normative' and 'Late') for 'All', 'Top 50%' and '25%' of raw swimming times were examined within and across age-groups. In Part 2, multiple regression analyses quantified the relationship between maturity offset (YPHV) and swimming performance. In Part 3, sample-based maturity timing category distributions were examined based on raw and correctively adjusted swim times for 12-17 year old age-groups. RESULTS Based on raw swim ti...
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Relative age effects (RAEs) occur when those who are relatively older for their age group are more likely to succeed. RAEs occur reliably in some educational and athletic contexts, yet the causal mechanisms remain unclear. Here we provide... more
Relative age effects (RAEs) occur when those who are relatively older for their age group are more likely to succeed. RAEs occur reliably in some educational and athletic contexts, yet the causal mechanisms remain unclear. Here we provide the first direct test of one mechanism, selection bias, which can be defined as evaluators granting fewer opportunities to relatively younger individuals than is warranted by their latent ability. Because RAEs are well-established in hockey, we analyzed National Hockey League (NHL) drafts from 1980 to 2006. Compared to those born in the first quarter (i.e., January–March), those born in the third and fourth quarters were drafted more than 40 slots later than their productivity warranted, and they were roughly twice as likely to reach career benchmarks, such as 400 games played or 200 points scored. This selection bias in drafting did not decrease over time, apparently continues to occur, and reduces the playing opportunities of relatively younger p...