Positive youth development as a guiding framework in sport research: Is it time to plan for a transition?

Positive youth development is a popular guiding framework for studying the psychosocial development of youth. In sport research, for more than two decades, this framework has enhanced our understanding of the mechanisms involved in successful shifts from youth to adulthood. Nonetheless, scholars have recently taken a more critical stance on the positive youth development framework by elucidating some of its shortcomings. To help determine whether it may be warranted to plan for a transition from the positive youth development framework in sport research, a critical commentary is offered. The purpose of this commentary lies in situating three ontologically distinct arguments that depict the shortcomings of the positive youth development framework, namely the operationalization argument, the social justice argument, and the posthumanist argument. This paper is offered as an open invitation to instigate dialogue on what may come next for youth development in sport research and whether planning for a transition is warranted.

A cross-sectional study exploring the relationship between age, gender, and physical measures with adequacy in and predilection for physical activity.

BACKGROUND: Physical literacy is a complex construct influenced by a range of physical, behavioural, affective, and cognitive factors. Researchers are interested in relationships among these constituent factors. The purpose of this study was to investigate how age, gender, and physical competence components of physical literacy relate to a child's adequacy in and predilection for physical activity. METHODS: A sample of 8530 Canadian youth (50% girl) aged 8.0 to 12.9 years participated in the study. Participants completed the Canadian Assessment of Physical Literacy (CAPL) protocol, which assesses physical literacy in four domains: Physical Competence, Daily Behaviour, Motivation and Confidence, and Knowledge and Understanding. Stepwise multiple regression analyses were conducted to investigate the relationship between physical competence components of physical literacy (Progressive Aerobic Cardiovascular Endurance Run [PACER], Canadian Agility and Movement Skill Assessment [CAMSA], sit and reach, handgrip, plank, and body mass index) and children's perceived adequacy and predilection toward physical activity as measured by subscales from the Children's Self-Perceptions of Adequacy in and Predilection for Physical Activity scale (CSAPPA). RESULTS: The variable most strongly associated with adequacy and predilection was the PACER shuttle run score. The PACER accounted for 10.9% of the variance in adequacy and 9.9% of the variance in predilection. Participants' age was inversely related to adequacy (ß = - 0.374) and predilection (ß = - 0.621). The combination of other variables related to adequacy brought the total variance explained to 14.7%, while the model for predilection explained a total of 13.7%. CONCLUSIONS: Results indicate an association between cardiorespiratory fitness and measures of physical activity adequacy and predilection. These findings suggest that practitioners should consider the physiological and psychological makeup of the child, and ways to enhance adequacy and predilection among children with limited cardiorespiratory fitness, in order to create the best possible environment for all children to participate in physical activity.

Associations between teacher training and measures of physical literacy among Canadian 8- to 12-year-old students.

BACKGROUND: Quality physical education (PE) contributes to the development of physical literacy among children, yet little is known about how teacher training relates to this development. We assessed the association between teacher training, and the likelihood that children met recommended achievement levels for components of physical literacy as defined by the Canadian Assessment of Physical Literacy (CAPL). METHODS: Canadian children (n = 4189; M = 10.72 years, SD = 1.19) from six provinces completed the CAPL. Logistic regression was used to examine the relationship between teacher training (generalist/PE specialist), adjusting for children's age and gender, and physical competence protocols (sit and reach, handgrip, plank, Progressive Aerobic Cardiovascular Endurance Run [PACER], body mass index [BMI], waist circumference, Canadian Agility and Movement Skill Assessment [CAMSA]), the four CAPL domain scores, and the total CAPL score. RESULTS: Teacher training, in addition to children's age and gender, explained only a very small proportion of variance in each model (all R2 < 0.03). Children taught by a generalist were less likely to reach recommended levels of motivation and confidence (OR = 0.83, 95% CI, 0.72-0.95) or CAMSA scores (OR = 0.77, 95% CI, 0.67-0.90), even when accounting for a significant increase in CAMSA score with age (OR = 1.18, 95% CI, 1.12-1.26). All other associations between measures of components of physical literacy and teacher training were not significant. CONCLUSIONS: While teacher training is hypothesized to contribute to the development of physical literacy among elementary school students, the observed effects in this study were either small or null. Children taught by PE specialists were more likely than those taught by generalists to demonstrate recommended levels of motivation and confidence, and to have better movement skills, which are hypothesized to be critical prerequisites for the development of a healthy lifestyle. Further research with more robust designs is merited to understand the impact of teachers' training on the various components of physical literacy development.

Cardiorespiratory fitness is associated with physical literacy in a large sample of Canadian children aged 8 to 12 years.

BACKGROUND: The associations between cardiorespiratory fitness (CRF) and physical literacy in children are largely unknown. The aim of this study was to assess the relationships between CRF, measured using the 20-m shuttle run test (20mSRT), and components of physical literacy among Canadian children aged 8-12 years. METHODS: A total of 9393 (49.9% girls) children, with a mean (SD) age of 10.1 (±1.2) years, from a cross-sectional surveillance study were included for this analysis. The SRT was evaluated using a standardized 15 m or 20 m protocol. All 15 m SRTs were converted to 20mSRT values using a standardized formula. The four domains of physical literacy (Physical Competence, Daily Behaviour, Motivation and Confidence, and Knowledge and Understanding) were measured using the Canadian Assessment of Physical Literacy. Tertiles were identified for 20mSRT laps, representing low, medium, and high CRF for each age and gender group. Cohen's d was used to calculate the effect size between the low and high CRF groups. RESULTS: CRF was strongly and favourably associated with all components of physical literacy among school-aged Canadian children. The effect size between low and high CRF tertile groups was large for the Physical Competence domain (Cohen's d range: 1.11-1.94) across age and gender groups, followed by moderate to large effect sizes for Motivation and Confidence (Cohen's d range: 0.54-1.18), small to moderate effect sizes for Daily Behaviour (Cohen's d range: 0.25-0.81), and marginal to moderate effect sizes for Knowledge and Understanding (Cohen's d range: 0.08-0.70). CONCLUSIONS: This study identified strong favourable associations between CRF and physical literacy and its constituent components in children aged 8-12 years. Future research should investigate the sensitivity and specificity of the 20mSRT in screening those with low physical literacy levels.

Physical literacy levels of Canadian children aged 8-12 years: descriptive and normative results from the RBC Learn to Play-CAPL project.

BACKGROUND: The current physical literacy level of Canadian children is unknown. The Royal Bank of Canada (RBC) Learn to Play - Canadian Assessment of Physical Literacy (CAPL) project, which is anchored in the Canadian consensus statement definition of physical literacy, aimed to help establish the current physical literacy level of Canadian children. METHODS: The CAPL was used to assess the physical literacy (and component domains: Daily Behaviour, Physical Competence, Knowledge and Understanding, and Motivation and Confidence) of Canadian children aged 8-12 years. Data were collected from 11 sites across Canada, yielding a sample of 10,034 participants (5030 girls). Descriptive statistics by age and gender were calculated and percentile distributions of physical literacy scores, including each domain and individual measure, were derived. RESULTS: The mean age of participants was 10.1 ± 1.2 years. Total physical literacy scores (out of 100) were on average 63.1 ± 13.0 for boys and 62.2 ± 11.3 for girls. For boys and girls respectively, domain scores were 19.9 ± 4.7 and 19.3 ± 4.1 (out of 32) for Physical Competence; 18.6 ± 7.9 and 18.5 ± 7.4 (out of 32) for Daily Behaviour; 12.7 ± 2.8 and 12.2 ± 2.6 (out of 18) for Motivation and Confidence; and 11.8 ± 2.8 and 12.2 ± 2.6 (out of 18) for Knowledge and Understanding. Physical Competence measures were on average 28.1 ± 8.4 cm (sit-and-reach flexibility), 33.5 ± 9.4 kg (grip strength, right + left), 23.4 ± 14.1 laps (Progressive Aerobic Cardiovascular Endurance Run [PACER] shuttle run), 61.8 ± 43.8 s (isometric plank), 19.0 ± 3.8 kg/m2 (body mass index), 67.3 ± 10.8 cm (waist circumference), and 20.6 ± 3.9 out of 28 points for the Canadian Agility and Movement Skill Assessment (CAMSA), with scores for boys higher than girls and older children higher than younger children for grip strength, PACER, plank, and CAMSA score. Girls and younger children had better scores on the sit-and-reach flexibility than boys and older children. Daily pedometer step counts were higher in boys than girls (12,355 ± 4252 vs. 10,779 ± 3624), and decreased with age. CONCLUSIONS: These results provide the largest and most comprehensive assessment of physical literacy of Canadian children to date, providing a "state of the nation" baseline, and can be used to monitor changes and inform intervention strategies going forward.

The relationship between sedentary behaviour and physical literacy in Canadian children: a cross-sectional analysis from the RBC-CAPL Learn to Play study.

BACKGROUND: Physical literacy is the foundation of a physically active lifestyle. Sedentary behaviour displays deleterious associations with important health indicators in children. However, the association between sedentary behaviour and physical literacy is unknown. The purpose of this study was to identify the aspects of physical literacy that are associated with key modes of sedentary behaviour among Canadian children participating in the RBC-CAPL Learn to Play study. METHODS: A total of 8,307 children aged 8.0-12.9 years were included in the present analysis. Physical literacy was assessed using the Canadian Assessment of Physical Literacy, which measures four domains (Physical Competence, Daily Behaviour, Motivation and Confidence, Knowledge and Understanding). Screen-based sedentary behaviours (TV viewing, computer and video game use), non-screen sedentary behaviours (reading, doing homework, sitting and talking to friends, drawing, etc.) and total sedentary behaviour were assessed via self-report questionnaire. Linear regression models were used to determine significant (p<0.05) correlates of each mode of sedentary behaviour. RESULTS: In comparison to girls, boys reported more screen time (2.7±2.0 vs 2.2±1.8 hours/day, Cohen's d=0.29), and total sedentary behaviour (4.3±2.6 vs 3.9±2.4 hours/day, Cohen's d=0.19), but lower non-screen-based sedentary behaviour (1.6±1.3 vs 1.7±1.3 hours/day, Cohen's d=0.08) (all p< 0.05). Physical Competence (standardized ß's: -0.100 to -0.036, all p<0.05) and Motivation and Confidence (standardized ß's: -0.274 to -0.083, all p<0.05) were negatively associated with all modes of sedentary behaviour in fully adjusted models. Knowledge and Understanding was negatively associated with screen-based modes of sedentary behaviour (standardized ß's: -0.039 to -0.032, all p<0.05), and positively associated with non-screen sedentary behaviour (standardized ß: 0.098, p<0.05). Progressive Aerobic Cardiovascular Endurance Run score and log-transformed plank score were negatively associated with all screen-based modes of sedentary behaviour, while the Canadian Agility and Movement Skill Assessment score was negatively associated with all modes of sedentary behaviour other than TV viewing (all p<0.05). CONCLUSIONS: These results highlight differences in the ways that screen and non-screen sedentary behaviours relate to physical literacy. Public health interventions should continue to target screen-based sedentary behaviours, given their potentially harmful associations with important aspects of physical literacy.

The relationship between physical literacy scores and adherence to Canadian physical activity and sedentary behaviour guidelines.

BACKGROUND: Physical literacy is an emerging construct in children's health promotion, and may impact their lifelong physical activity habits. However, recent data reveal that only a small portion of Canadian children are regularly physically active and/or meet sedentary behaviour guidelines. To our knowledge, no study has investigated the association between physical literacy and movement behaviour guidelines. Therefore, the purpose of this study was to examine the relationship between physical literacy scores in Canadian children who meet or do not meet physical activity and sedentary behaviour guidelines. METHODS: Children (n = 2956; 56.6% girls) aged 8-12 years from 10 Canadian cities had their physical literacy levels measured using the Canadian Assessment of Physical Literacy, which consists of four domains (Physical Competence; Daily Behaviour; Knowledge and Understanding; and Motivation and Confidence) that are aggregated to provide a composite physical literacy score. Physical activity levels were measured by pedometers, and sedentary behaviour was assessed through self-report questionnaire. Analyses were conducted separately for each guideline, comparing participants meeting versus those not meeting the guidelines. Comparisons were performed using MANOVA and logistic regression to control for age, gender, and seasonality. RESULTS: Participants meeting physical activity guidelines or sedentary behaviour guidelines had higher physical literacy domain scores for Physical Competence and for Motivation and Confidence compared to those not meeting either guideline (both p < 0.0001). Participants had increased odds of meeting physical activity guidelines and sedentary behaviour guidelines if they met the minimum recommended level of the Physical Competence and Motivation and Confidence domains. Significant age (OR 0.9; 95% CI: 0.8, 0.9), gender (OR 0.4; 95% CI: 0.3, 0.5) and seasonality effects (OR 1.6; 95% CI: 1.2, 2.2 spring and OR 1.7; 95% CI: 1.2, 2.5 summer, reference winter) were seen for physical activity guidelines, and age (OR 0.8; 95% CI: 0.7, 0.8) and gender effects (OR 1.7; 95% CI: 1.4, 2.0) for sedentary behaviour guidelines. Knowledge and Understanding of physical activity principles was not related to guideline adherence in either model. CONCLUSIONS: These cross-sectional findings demonstrate important associations between physical literacy and guideline adherence for physical activity and sedentary behaviour. Future research should explore the causality of these associations.

Validation of PiezoRx Pedometer Derived Sedentary Time.

Although pedometers are valid tools for measuring physical activity, to date they have not been used to assess sedentary time. The primary purpose of this study was to determine if the PiezoRx pedometer is a valid and reliable measure of sedentary time compared to the hip-worn Actical accelerometer. A secondary purpose was to compare sedentary time derived via the Fitbit Flex with that of the Actical. Finally, a third purpose was to compare sedentary time derived from the above devices, with that of the ActivPAL inclinometer. Thirty-five participants ages 11-69 years (Mage= 23.3; 21 Female) wore five devices for up to one week: two PiezoRx pedometers, an Actical, an ActivPAL and a Fitbit Flex. Participants recorded daily wear-time of each device using a log sheet. The average sedentary time calculated from the PiezoRx (716±137.68 min/day) was not different from the Actical (694 ±136.11 min/day, p>0.05), although it was higher than the ActivPAL (475±171.52 min/day) and Fitbit Flex (530±149.94 min/day, all p<0.001). Sedentary time from all devices were significantly correlated with each other, with the strongest relationship seen between the Actical and PiezoRx (R2=0.93, p<0.001). In comparison to the ActivPAL, error in PiezoRx- (R2=0.96), Actical- (R2=0.96) and Fitbit Flex- (R2=0.34) determined sedentary time was strongly associated with standing time (all p<0.001). Sedentary time derived using the PiezoRx pedometer may be statistically equivalent to the Actical accelerometer, but not the ActivPAL inclinometer or Fitbit Flex.

Factors associated with using research evidence in national sport organisations.

The purpose of this study was to explore factors associated with the use of research evidence in Canadian National Sport Organisations (NSOs). Data were collected via individual semi-structured interviews with 21 representatives from Canadian NSOs. A qualitative description approach was used. Interviews were transcribed verbatim and subjected to an inductive-to-deductive thematic analysis. A research implementation framework (Rycroft-Malone, 2004) was used to organise inductively derived themes into the higher-order categories of evidence (use of evidence, disconnection between research and practice), context (lack of capacity, organisational structure), and facilitation (personal connections with researchers and sport scientists, formal meetings with stakeholders). Overall, NSO representatives did not have a clear understanding of evidence and lacked capacity to access and translate research. However, some context factors, along with internal and external facilitators, were in place and could be used to enhance research implementation.

Sit-Stand Desks To Reduce Workplace Sitting Time In Office Workers With Abdominal Obesity: A Randomized Controlled Trial.

BACKGROUND: Sit-stand desks reduce workplace sitting time among healthy office workers; however, their metabolic and behavioral impact in higher risk populations remains unknown. METHODS: 25 office workers with abdominal obesity were randomized to an intervention (sit-stand workstation) or control group (seated desk) for 12 weeks. Physical activity, sedentary behavior, and cardiometabolic risk factors were assessed before and after the intervention period in both groups. RESULTS: In comparison with the control group, which did not change, the intervention group experienced significant reductions in workday (344 ± 107 to 186 ± 101 min/day) and total (645 ± 140 to 528 ± 91 min/day) sitting time, as well as increases in workday standing time (154 ± 108 to 301 ± 101 min/day, P < .05). There were no changes in sitting or standing time outside of work hours, steps taken each day, or any marker of cardiometabolic risk in either group (all P > .05). CONCLUSION: Sit-stand desks were effective in reducing workplace sedentary behavior in an at-risk population, with no change in sedentary behavior or physical activity outside of work hours. However, these changes were not sufficient to improve markers of cardiometabolic risk in this population.

Identifying important factors for older adults' physical activity participation across individual/group, structured/unstructured contexts.

Most Canadian older adults do not meet physical activity recommendations. Researchers have investigated participation barriers and facilitators, with little consideration given to how specific factors influence activity participation for older adults. The purpose of this study was to identify unique factors that influence older adults' activity selection and to determine in which type of setting they are preferred. Using a two-phase methodology, identification of 25 factors affecting participation was followed by 45 older adults ranking the factors within four categories of activities: individual unstructured, group unstructured, individual structured, and group structured. Phase 1 analysis ranked each factor within each category. Further analysis found that there was a statistical difference between categories, indicating that older adults found different factors important, depending on the category of physical activity in question. This led to phase 2 analyses which identified three levels of factor groupings including the following factors: level A: fun, satisfaction, commitment, and energize; level B: safety, learning, awareness, internal motivation, and productive; and level C: meaningful contribution, intensity, and motivation. Additionally, some factors which were not identified in all categories were identified as unique to certain categories. These included creativity, hobbies, meaningful contribution, spiritual, competence, interaction casual, regularly scheduled, competition, self-efficacy physical, and team. This information can be used by individuals as well as program providers to nurture these factors within physical activity programs, which may lead to increased participation in this age cohort.

Understanding Sources of Knowledge for Coaches of Athletes with Intellectual Disabilities.

BACKGROUND: Recent research has investigated development of coaching knowledge; however, less research has investigated the development of coaches who coach athletes with intellectual disabilities. The purpose of this study was to understand how coaches of athletes with intellectual disabilities gain their knowledge. METHOD: Forty-five Special Olympics Canada coaches participated in structured telephone interviews investigating actual and ideal sources of coaching knowledge. Coaching knowledge was categorized across the dimensions of competition, organization and training. RESULTS: Coaches primarily learned by doing and by consulting with coaching peers. Information about ideal sources of coaching knowledge demonstrates that coaches would value structured coaching courses, learning from mentors and from administrative support, in addition to learning on their own and from peers. DISCUSSION: Results suggest that a broader approach to education should be incorporated into coaching athletes with intellectual disabilities. Recommendations for achieving such goals are provided.

A systematic review of standing and treadmill desks in the workplace.

OBJECTIVES: Standing and treadmill desks are intended to reduce the amount of time spent sitting in today's otherwise sedentary office. Proponents of these desks suggest that health benefits may be acquired as standing desk use discourages long periods of sitting, which has been identified as an independent health risk factor. Our objectives were thus to analyze the evidence for standing and treadmill desk use in relation to physiological (chronic disease prevention and management) and psychological (worker productivity, well-being) outcomes. METHODS: A computer-assisted systematic search of Medline, PubMed, PsycINFO, SPORTDiscus, CINAHL, CENTRAL, and EMBASE databases was employed to identify all relevant articles related to standing and treadmill desk use. RESULTS: Treadmill desks led to the greatest improvement in physiological outcomes including postprandial glucose, HDL cholesterol, and anthropometrics, while standing desk use was associated with few physiological changes. Standing and treadmill desks both showed mixed results for improving psychological well-being with little impact on work performance. DISCUSSION: Standing and treadmill desks show some utility for breaking up sitting time and potentially improving select components of health. At present; however, there exist substantial evidence gaps to comprehensively evaluate the utility of each type of desk to enhance health benefits by reducing sedentary time.

A qualitative investigation of exercising with MS and the impact on the spousal relationship.

BACKGROUND: Multiple Sclerosis is an autoimmune disease that affects more than 2.3 million people around the world. Symptoms are numerous and varied, often having a profound effect on activities of daily living. While for many years individuals with MS were told to avoid exercise for fear of worsening their symptoms, recent research has emphasized the multi-faceted benefits associated with regular physical activity. Given the strain that MS can put on family and interpersonal relationships, the intention of this study was to investigate the exercise experiences of individuals with MS and the extent to which these experiences affect, or are affected by, their spousal relationship. METHODS: In-depth qualitative interviews were conducted with 10 individuals, five with MS, along with each of their spouses, in order to gain a comprehensive understanding of living and exercising with the disease. An inductive approach was used to analyze the interview data. RESULTS: The results displayed the important physical, psychological, and social benefits of involvement in an exercise program. Spouses help to counteract barriers and facilitate exercise, and are well aware of the integral role they play in their partner's health and well-being. Spouses also valued the increased independence they gained, in the form of reduced care-giving responsibilities and enhanced social opportunities, as a result of the improved physical function of their partner. These findings contrast the severe strain on spousal relationships that is often reported in studies on people living with MS. CONCLUSIONS: Rather than an inexorable downward decline in physical ability that is common with MS, participants spoke of a positive reversal in physical function, which has had far-reaching implications for multiple aspects of their lives, including their psychological outlook, their sense of independence, overcoming isolation, and their relationship with their spouse, all of which are identified in the literature as notable aspects of life affected by the disease.

The influence of Driving Status on Transportation Challenges Experienced by Older Adults.

We explored the severity, number, and reasons for transportation challenges experienced by older adult drivers, nondrivers who live with a driver, and nondrivers who do not live with a driver. A random sample of 1,670 Atlantic Canadian community-dwelling older adults completed a mailed survey. Drivers comprised 80% of the participants. Just more than one fifth of participants experienced at least occasional transportation challenges. Two thirds of nondrivers who lived with a driver reported having no transportation challenges. Almost half of the nondrivers who did not live with a driver indicated never experiencing transportation challenges, and 84% of drivers had no transportation challenges. Nondrivers who did not live with a driver experienced greater frequency and severity of transportation challenges. This research contributes to our understanding of the characteristics of older adults with different driving statuses and their transportation challenges, which can contribute to providing appropriate transportation supports for older adults in the future.

Examination of birthplace and birthdate in World Junior ice hockey players.

The present study investigated birthdate (known as the Relative Age Effect; RAE) and birthplace as determinants of expertise in an international sample of elite ice hockey players. The sample included 566 World Junior (WJR) ice hockey players from four countries (Canada, n = 153; USA, n = 136; Sweden, n = 140; Finland, n = 137). Participants competed in the International Ice Hockey Federation World U20 Championship between 2001 and 2009. A series of Poisson regression models were conducted to examine the consistency of direct then interactive relationships between both birthdate and birthplace and WJR membership across the four countries (Canada, USA, Sweden, and Finland). Findings revealed a consistent RAE across the four countries for World Junior participation from 2000 to 2009. WJR players from the four countries were also less likely to be from major cities. In addition, there was no evidence in any of the four countries of an interaction between RAE and birthplace. Future research should explore the contextual and cultural factors that influence elite athlete development in smaller towns, cities and communities.

Birthplace effects on the development of female athletic talent.

This study examined the extent to which an athlete's place of birth can influence the likelihood of playing professional sport. Information regarding the birthplace of all American female athletes in the Ladies Professional Golf Association and Women's United Soccer Association was gathered from official league websites. Monte Carlo simulations were used to determine if the birthplace of these professional athletes differed in any systematic way from official census population distributions. Odds-ratios were determined for cities within specific population ranges to ascertain if the likelihood of playing professional sport was influenced in any systematic way by city size. The analyses revealed that female professional soccer players born in cities of less than 1,000,000 were over-represented, as were female professional golfers born in cities of less than 250,000. Results are consistent with those of male professional athletes in suggesting that areas of lower population provide conditions more conducive to the development of expertise than do larger city environments.

When "where" is more important than "when": birthplace and birthdate effects on the achievement of sporting expertise.

In this study, we assessed whether contextual factors related to where or when an athlete is born influence their likelihood of playing professional sport. The birthplace and birth month of all American players in the National Hockey League, National Basketball Association, Major League Baseball, and Professional Golfer's Association, and all Canadian players in the National Hockey League were collected from official websites. Monte Carlo simulations were used to verify if the birthplace of these professional athletes deviated in any systematic way from the official census population distribution, and chi-square analyses were conducted to determine whether the players' birth months were evenly distributed throughout the year. Results showed a birthplace bias towards smaller cities, with professional athletes being over-represented in cities of less than 500,000 and under-represented in cities of 500,000 and over. A birth month/relative age effect (in the form of a distinct bias towards elite athletes being relatively older than their peers) was found for hockey and baseball but not for basketball and golf. Comparative analyses suggested that contextual factors associated with place of birth contribute more influentially to the achievement of an elite level of sport performance than does relative age and that these factors are essentially independent in their influences on expertise development.