Stability of within-sport specialisation in competitive adolescent sub-elite swimmers

The study aimed to assess the stability of stroke selection during adolescence and the determination of within-sport specialisation. All swimmers (448 males, 14.1±1.6 y and 518 females, 13.9±1.6 y) who competed in an annual international schools championship from 2006 to 2013 were analysed. Kruskal-Wallis tests identified the significant differences between paired stroke combinations and the relative frequency of each pair was determined from Cohen's Kappa tests. The percentage of swimmers selecting the same event in two of three paired age categories (13-14, 15-16, 17-18 y) was calculated for each sex separately (n=78). Stability of stroke selections were determined using Cohen's Kappa tests. The most preferred combination of events selected was 50 and 100 m freestyle for males (33.9±5.8%) and females (36.9±6.5%). The least preferred combination was 100 m breaststroke with 100 m butterfly for males (2.7±1.7%), and 200 m freestyle with 100 m breaststroke for females (1.9±1.4%). Males were less stable than females in electing to swim the same events from when first competing until their final competition. Breaststroke was the only stroke where early specialisation was observed. Young swimmers appear to be drawn towards particular stroke combinations over distance specialisation and males choices stabilise later compared with females.