1. Birthdate, Relative Age and Athlete Development Joe Baker Lifespan Health & Performance Laboratory York University, Toronto, Canada

2. Date of Birth and Development “Whoever wishes to investigate medicine properly, should proceed thus: in the first place to consider the seasons of the year, and what effects each of them produces for they are not at all alike, but differ much from themselves in regard to their changes.” Hippocrates (400BC) Lifespan Health and Performance Laboratory

3. Date of Birth and Development Hippocrates (400BC) Season of Birth Research SOB related to: Schizophrenia/Bipolar Disorder Anorexia Nervosa/Bulimia Obesity Myopia Longevity Lifespan Health and Performance Laboratory

4. Season of birth effects relate to seasonal environments experienced during gestation which have the potential to significantly influence healthy development. Thought to be driven by biological processes. Lifespan Health and Performance Laboratory

5. Relative age effects relate to differences perceived to exist among individuals due to differences in their age compared to peers. Thought to be driven by socially-constructed processes. Lifespan Health and Performance Laboratory

6. Date of Birth and Development Relative Age refers to age compared to others in the same cohort or age group. September 2006October 2006November 2006December 2006 January 2007February 2007March 2007April 2007 May 2007June 2007July 2007August 2007

7. Relative Age Effects In education (Cobley et al., in press)

8. Relative Age Effects In education Attainment scores (Bell et al., 1997; Cobley et al., in press) Gifted and talented (Cobley et al., in press; Sharp, 1995; Thompson, 1971) Learning disabilities (Bookbinder, 1967; Cobley et al., in press; Wilson, 2000) Lifespan Health and Performance Laboratory

9. Relative Age Effects In sports

10. Relative Age Effects In sports Baker & Logan (2007) BJSM NHL Draftees (Canadian and American Data)

11. Relative Age Effects In sports Cote, MacDonald, Baker & Abernethy (2006) JSS MLB (American Data)

12. Relative Age Effects In sports Australian Data Abernethy & Farrow (2005) ISSP

13. Relative Age Effects In sports Germany (Handball data) Schorer, Cobley, Büsch, Bräutigam, & Baker (in prep.)

14. Relative Age Effects In sports Cote, MacDonald, Baker & Abernethy (2006) JSS NBA (American Data)

15. Relative Age Effects In sports Cote, MacDonald, Baker & Abernethy (2006) JSS PGA (American Data)

16. Relative Age Effects In sports Wattie, Baker, Cobley & Montelpare (2007) IJSP Women’s Hockey (Canadian data)

17. Relative Age Effects In sports Elite athlete status Gifted and talented (Cobley, Abraham & Baker, in press) Representative sport (Baker et al., under review) Lifespan Health and Performance Laboratory

18. Where do relative age effects come from? Historical examinations Lifespan Health and Performance Laboratory

19. RAE History: Canadian NHL Players Wattie, Baker, Cobley & Montelpare (2007) IJSP

20. RAE History: German Soccer Players Cobley, Schorer & Baker (2007) Under Review

21. Where do relative age effects come from? Historical examinations Causal hypotheses 1) Maturational Factors –Baker et al., under review Lifespan Health and Performance Laboratory

22. Where do relative age effects come from? Historical examinations Causal hypotheses 1) Maturational Factors 2) Psychological Factors –Positive appraisal from parents & coaches (Pygmalion Effect) –Relatively younger players dropout early (Barnsley & Thompson, 1988) Lifespan Health and Performance Laboratory

23. Where do relative age effects come from? Historical examinations Causal hypotheses 1) Maturational Factors 2) Psychological Factors 3) Experiential Factors –Cf. Vaeyens et al. (2005) and Baker et al. (under review) Lifespan Health and Performance Laboratory

24. Relative Age Implications Achievement and attainment in education and sport Overall physical activity participation –Dropout (Barnsley & Thompson 1988; Helsen et al., 1998) Impact on self-perceptions, self-appraisals and motivation –Self-esteem (Barnsley et al., 2004) –School Attendance (Carroll, 1992; Cobley et al., in press) Adolescent mortality –Youth Suicide (Thompson, Barnsley & Dyck, 1999)

25. Is it always an advantage to be relatively older? Relative age and injury

26. Wattie et al. Pediatrics, 2007

27. Is it always an advantage to be relatively older? Relative age and injury Relative age and draft order –Relatively younger athletes were more sought after in the NHL draft (Baker & Logan, 2007)

28. Solutions? Re-adjustment of age ranges Teacher/Coach Education –Cobley et al (2007) 1234 Attainment

29. Solutions? Re-adjustment of age ranges Teacher/Coach Education –Cobley et al (2007) 1234 Attainment

30. On-going Research –Relative age and PA/obesity? –Relative age in talent identification? –Relative age and psychological development? –Moderators of the relative age effect? –Causes/Solutions?