Cluster Stability as a New Method to Assess Changes in Performance and its Determinant Factors Over a Season in Young Swimmers

in International Journal of Sports Physiology and Performance
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To apply a new method to identify, classify, and follow up young swimmers based on their performance and its determinant factors over a season and analyze the swimmers’ stability over a competitive season with that method.


Fifteen boys and 18 girls (11.8 ± 0.7 y) part of a national talent-identification scheme were evaluated at 3 different moments of a competitive season. Performance (ie, official 100-m freestyle race time), arm span, chest perimeter, stroke length, swimming velocity, speed fluctuation, coefficient of active drag, propelling efficiency, and stroke index were selected as variables. Hierarchical and k-means cluster analysis were computed.


Data suggested a 3-cluster solution, splitting the swimmers according to their performance in all 3 moments. Cluster 1 was related to better performances (talented swimmers), cluster 2 to poor performances (nonproficient swimmers), and cluster 3 to average performance (proficient swimmers) in all moments. Stepwise discriminant analysis revealed that 100%, 94%, and 85% of original groups were correctly classified for the 1st, 2nd, and 3rd evaluation moments, respectively (0.11 ≤ Λ ≤ 0.80; 5.64 ≤ χ2 ≤ 63.40; 0.001 < P ≤ .68). Membership of clusters was moderately stable over the season (stability range 46.1–75% for the 2 clusters with most subjects).


Cluster stability is a feasible, comprehensive, and informative method to gain insight into changes in performance and its determinant factors in young swimmers. Talented swimmers were characterized by anthropometrics and kinematic features.

Morais is with the Dept of Sport Sciences, Polytechnic Institute of Braganca/CIDESD, Braganca, Portugal. Silva is with the Dept of Sport Sciences, Exercise and Health, University of Tras-os-Montes and Alto Douro/CIDESD, Vila Real, Portugal. Marinho is with the Dept of Sport Sciences, University of Beira Interior/CIDESD, Covilha, Portugal. Seifert is with CETAPS EA3832, Faculty of Sports Sciences, University of Rouen, Rouen, France. Barbosa is with the National Inst of Education, Nanyang Technological University, Singapore. Address author correspondence to Tiago Barbosa at