Age Group Classification in USA Swimming
Total Page:16
File Type:pdf, Size:1020Kb
USA SWIMMING AGE CLASSIFICATION: ARE CURRENT COMPETITIVE AGE-GROUPS APPROPRIATE? by Kosuke Kojima Submitted to the faculty of the University Graduate School in partial fulfillment of the requirements for the degree Master of Scienece in the Department of Kinesiology Indiana University April, 2010 Accepted by the Graduate Faculty, Indiana University, in partial fulfillment of the requirements for the degree of Master’s of Science. Master’s Thesis Committees _________________________________________________ Joel M. Stager, Ph.D. _________________________________________________ Paul L. Jamison, Ph.D. ________________________________________________ David M. Koceja, Ph.D. _________________________________________________ Jeanne D. Johnston, Ph.D. ii ABSTRACT Matching youth sports participants in order to make competition fair and safe is an important goal of sports federations. USA Swimming has established 4 unisex age-groups based on chronological age (CA): 10 years & under, 11-12 years, 13-14 years, and 15 years & over. Due to considerable differences in growth and maturational status among adolescents within any given CA (Baxter-Jones, 1995; Malina & Beunen, 1996), combining swimmers of different ages into groups may not ensure fair competition. Because younger aged or late-maturing swimmers within an age-group are physically behind their same age-group older or precocious peers, the current age-grouping system may discourage them to continue competitive swimming. In addition, there is no historical rationale for the current USA Swimming age classification. The purposes of the study were to evaluate the current age classification enforced by USA Swimming and to provide an analytical rationale in support of the current or alternative age-groupings. Swim times of the top 100 U.S. women and men swimmers for each age (5 to 20 years) and a group of 21 years and over (a total of 17 separate age-groups for each sex) were acquired through the website of USA Swimming for 2005, 2006, and 2007. Data for each age were pooled over the past three years (2005-2007) and averaged for seven swim events (50-, 100-, and 200-yard freestyle, 100-yard backstroke, breaststroke, and butterfly, and 200-yard individual medley). A 17 × 2 × 7 (age × sex × event) ANOVA with Tukey’s post-hoc test was used to analyze the differences in swim time among ages and to propose alternative age-groups. The study found significant age-related differences in swim performance between each CA up to 15 years old in women and 17 years old in men for most events. Because there were differences in swim performance within the current defined age-groups, stratifying swimmers based on a single age may be a better way for ensuring fairness and equality in competition. The age-related differences in swim time occur later in men when compared with women. This may be due to sex-difference in timing of growth and maturity. The differences between sexes become greater with age but no significant sex-difference was found in 7 years and under age categories. Thus, based upon swim performance, there is no rationale for swimmers under the age of eight to compete in separate unisex categories. iii TABLE OF CONTENTS Page LIST OF TABLES……………………………………………………………………………… vi LIST OF FIGURES…………………………………………………………………………….. viii Chapter 1. INTRODUCTION………………………………………………………………… 1 Statement of the Problem…………………………………………………………. 1 Purpose of the Study………………………………………………………………. 2 Significance of the Study………………………………………………………….. 2 Delimitations………………………………………………………………………. 5 Limitations………………………………………………………………………… 5 Assumptions……………………………………………………………………….. 5 Hypotheses………………………………………………………………………… 6 Definitions of Terms………………………………………………………………. 7 2. REVIEW OF THE RELATED LITERATURE…………………………………... 10 Classification Systems in Youth Sports………………………………………….... 10 a) Skeletal Maturity…………………………………………………………. 11 b) Sexual Maturity…………………………………………………………… 13 c) Somatic Maturity…………………………………………………………. 14 d) Dental Maturity…………………………………………………………… 15 e) Neuromuscular Maturity (Motor Development)…………………………. 16 f) Overview…………………………………………………………………. 17 Variation within Maturity Indicators Relative to CA……………………………... 17 Classification Systems in Swimming……………………………………………... 22 a) Australia………………………………………………………………….. 22 b) Britain…………………………………………………………………….. 22 c) Canada……………………………………………………………………. 23 d) China……………………………………………………………………… 23 e) Germany…………………………………………………………………... 24 f) Japan………………………………………………………………………. 24 g) New Zealand……………………………………………………………… 25 h) Spain………………………………………………………………………. 25 i) Taiwan (Chinese Taipei)………………………………………………….. 26 j) The United States…………………………………………………………. 26 Preliminary Results………………………………………………………………… 29 History of Age-Group Swimming in the U.S……………………………………… 32 iv Summary…………………………………………………………………………… 33 3. METHODOLOGY………………………………………………………………… 35 Arrangements for Conducting the Study…………………………………………... 35 Selection of Variables and Gathering Data………………………………………... 35 Data Analysis………………………………………………………………………. 39 4. ANALYSIS AND DISCUSSION OF DATA……………………………………… 40 Age-Related Difference in Swim Performance……………………………………. 41 Sex-Differences in Swim Performance……………………………………………. 44 Alternative Age-Groupings………………………………………………………... 47 Discussion of Findings…………………………………………………………….. 49 Age-related differences in swim performance…………………………………….. 49 Hypothesis 1…………………………………………………………………... 49 Hypothesis 2…………………………………………………………………... 51 Hypothesis 3…………………………………………………………………... 53 Hypothesis 4…………………………………………………………………... 55 Sex-differences in swim performance………………………………………........... 56 Hypothesis 5…………………………………………………………………... 60 Hypothesis 6…………………………………………………………………... 61 Alternative age-groupings and its conception…………………………………….. 62 5. SUMMARY, FINDINGS, CONCLUSIONS, IMPLEMENTATIONS AND RECOMMENDATIONS…………………………………………………………. 65 Summary…………………………………………………………………………... 65 Findings…………………………………………………………………………… 65 Conclusions……………………………………………………………………….. 66 Implementations…………………………………………………………………... 67 Recommendations for Further Study……………………………………………... 67 REFERENCES……………………………………………………………………. 69 APPENDIX A: HUMAN SUBJECTS CONSENT FORMS………………………….. 83 v LIST OF TABLES Page Table 1. Variation in chronological age (CA) and skeletal age (SA) in a sample of children observed annually from six to eight years of age.……………………………………………………………….. 18 Table 2. Range of chronological age (CA) within each stage of genital maturation in a sample of boys ………………………………………………………………………………………………………… . 19 Table 3. Comparison of differences in height and weight within chronological age (CA) groups with those within somatic maturity stages (N = 401, 194 boys and 207 girls)……………………………………. 20 Table 4. Commonly used indicators for assessing biological maturity……………………………….. 21 Table 5. Relationships between chronological age (CA) and skeletal age (SA) at the time of reaching certain maturational events during adolescence……………………………………………………….. 21 Table 6. Age-group classification in representative swimming countries (federations)………………. 28 Table 7. Renewal rate of year-around athlete memberships of USA Swimming in 2007…………….. 32 Table 8. The average time of the top 100 U.S. swimmers for 16 age categories* in 100-yard freestyle from 2003 to 2007……………………………………………………………………………………... 36 Table 9. Year-differences (2005, 2006, and 2007) in the average swim time of the top 100 U.S. women and men swimmers (ages 6 to 20 years and a group of 21 years and over) for seven events…………. 37 Table 10. Age-groups and sample size used in the study……………………………………………… 38 Table 11. The average times of the top 100 U.S. women swimmers for 15 age categories in 7 events (mean ± S.D)…………………………………………………………………………………………… 42 Table 12. The average times of the top 100 U.S. men swimmers for 15 age categories in 7 events (mean ± S.D)…………………………………………………………………………………………………….. 42 Table 13. Summary of standard deviations of swim times of the top 100 swimmers across ages……. 43 vi Table 14. Summary of significance (p values) of the sex-differences in swim times……………….... 47 Table 15. Homogenous subsets of age categories ……………………………………………............. 48 Table 16. Potential alternative age-groups obtained from the study………………………………….. 48 Table 17. Relative improvement (%) of swim time across age………………………………………... 53 Table 18. The numbers of swimmers with USA Swimming membership in two representative swimming states for 2008 season………………………………………………………………………………….. 62 Table 19 A and B. Alternative age classification………………………………………………………. 64 vii LIST OF FIGURES Page Figure 1 A-D. The percentage of girl (A & B) and boy (C & D) swimmers in each CA category at the Indiana Age-group Championships (2008, March)……………………………………………………. 31 Figure 2 A and B. Comparison of the average time (± S.E.) in 100-yard freestyle among the past five years in women (A) and men (B) swimmers in the U.S……………………………………………….. 37 Figure 3 A and B. Year-differences (2005, 2006, and 2007) in the average swim time of the top 100 U.S. women and men swimmers (ages 6 to 20 years and a group of 21 years and over) for seven events…. 38 Figure 4. Standard deviations of the average times of the top 100 swimmers across ages……………. 43 Figure 5. The differences in swim time (the average of all events) between two adjacent ages and the progression across all age categories…………………………………………………………………… 44 Figure 6. Comparison of the average time of 16 age categories in women with that in men for 7 evetns …………………………………………………………………………………………………………. 45 Figure 7. Progression in swim performance in women