Age-group Categorization in Competitive Swimming

Matching youth sports participants in order to make competition fair and safe is an important goal of sports federations. In competitive swimming, the most appropriate method for grouping children to assure fair competition has also been debated for decades with little progress being made. USA Swimming has established four unisex age-groups based on chronological age (CA): 10 years & under, 11-12 years, 13-14 years, and 15 years & over. FINA also combined multiple CAs into groups at the 2nd FINA World Youth Swimming Championships: ages 14-17 years for girls and ages 15-18 for boys.

However, 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 older or precocious peers in the age-group, the current multi-age-grouping system may discourage them to continue competitive swimming. In addition, there is no historical rationale for the current USA Swimming age classification. Thus, to provide an analytical rationale in support of the current or alternative age-groupings, we evaluated the current age classifications: 1) enforced by USA Swimming and 2) utilized at the 2nd FINA World Youth Swimming Championships.

1) We analyzed the top 100 US swim performances (times) for three years (2005, 2006, and 2007) for girls and boys in 15 age-groups (7 to 20 years and a singular group of 21 years and older for each age and sex) in seven competitive swim events in order to find differences in times between ages. Data showed that swim times differed significantly among each age up to age 14 in girls and age 16 in boys for all events. This 2-year lag was possibly related to differences between the sexes in timing of growth and maturation. We concluded that, until 2-years after the average age of the greatest growth rate in both sexes, stratifying swimmers by a single age is the best means to ensure competitive fairness and equality (girls until age 14 and boys until age 16 years, Table 1). However, we found that there is no rationale for swimmers under the age of 8 years to compete in separate unisex groups. Thus the following table proposes a possible alternative age-grouping:

Table 1. Alternative age-grouping paradigm proposed in this study (Kojima et al., 2012).Proposed age-group paradigm
G: group, 7&U: 7 years and under, 19&O: 19 years and over


2) With a similar analysis, we investigated the influence of the age-groupings on the swimmers qualifying for high level competition and finals (at the 2nd FINA World Youth Swimming Championships) and the influence of the age-groupings on ‘chance of participation’ in the Youth Championships and selection at the trials of each country. It was hypothesized that elite youth athletes are early-maturers but those who excel at youth competition are older children in each age-group, even at an international level competition. Our results illustrated a greater proportion of older participants and older finalists at the international event (Table 2). We concluded that most age-grouping systems, particularly those combining multiple ages into groups, unduly influence participation and bias competition outcomes. From these research findings, continued international discussion on this topic appears to be warranted.

Table 2. Mean relative frequency distributions (%) of the top 8 swimmers and the top 8 relay members over all events for the four age categories.FINA World Age Group Champs breakdown
IE, individual event
Significantly different from all other age categories (p < 0.05).
Significantly different from two youngest age categories (p < 0.05).
* Significantly different from the youngest age category (p < 0.05)


Age classification systems clearly influence participation and competition outcomes in competitive youth swimming. The number of swimmers qualifying for competitive events and then qualifying for the finals at state, national, and international-level events is significantly greater for swimmers who are the oldest in their age-groups. Grouping swimmers using a range of CAs is not the optimal way to encourage younger competitors. Stratifying swimmers by a single age is the best means to ensure competitive fairness and equality. With today’s computing power and software sophistication, novel strategies are available to group swimmers without affecting the meet timeline or expense. These new innovative strategies may act to enhance competition and encourage participation to further development and prosperity of age-group swimming.


Kojima, K. & Stager, J. M. (2010). Competitive systemization in age-group swimming: An evaluation of performances, maturational considerations, and international paradigms. In P. Kjendlie, R. Stallman, & J. Cabri (Eds.), Biomechanics and Medicine Swimming XI (pp. 267-269). Champaign: Human Kinetics.

Kojima, K., Jamison, P. L., & Stager, J. M. (2012). Multi-age-grouping paradigm for young swimmers. Journal of Sports Sciences, 30(3), 313-320.