Longitudinal intra and inter-individual variability in young swimmers performance and determinant factors

The aim of study was to follow-up the intra-individual and inter-individual stability of talented swimmers’ performance and its anthropometrics, kinematics, hydrodynamics and efficiency during two competitive seasons. Thirty talented swimmers (14 boys: 12.33 ± 0.65 years; and 16 girls: 11.15 ± 0.55 years) were followed-up. Performance (100-m freestyle), anthropometrics (body mass, height, arm span, chest perimeter, trunk transverse surface area, hand and foot surface area), kinematics (stroke frequency, stroke length, swimming velocity and speed fluctuation), efficiency (propelling efficiency and stroke index) and hydrodynamics (active drag and coefficient of active drag) were evaluated. Performance showed a significant improvement and moderate-very high stability between first and final evaluation moment. Anthropometric variables also presented a significant increase and moderate-very high stability between the first and final moment. As for kinematics, efficiency and hydrodynamics an increase between first and final moment was observed but with a low-very high stability. Overall, for performance and all its determinants a high intra and inter-individual variability was observed. Each swimmer had his/her own path during the two competitive seasons. As main conclusion: talented swimmers’ performance improved (moderate-very high stability), as well as its determinants (overall a moderate stability was observed). For all variables, it was also showed a single response by each swimmer, where different paths occurred during the two competitive seasons