Impact of energetic-anthropometric features on 50-m and 100-m freestyle kinematic indices in young male swimmers

The determinants of the sports results of young and adult swimmers differ, especially in sprint races (50–100 m). Their identification can be used to assess the athlete’s potential and to set appropriate requirements. The aim was to distinguish energy-anthropometric profiles (clusters) among young athletes and to characterize their kinematic indices in freestyle sprint races (50–100 m). Kinematic variables from both distances were compared in each cluster. Methods: Anthropometric indices and mechanical power of the upper limbs (arm-cranking) were determined in 43 subjects (boys, aged 12–13 years), which were used for cluster analysis. For the 50- and 100-m races the following were determined: velocity (v), stroke rate (SR), stroke length (SL) and stroke index (SI). Comparative analysis was performed between clusters and between distances. Results: The following clusters were distinguished: Large (LSP), Medium (MSP) and Small Size and Power (SSP), which differed due to anthropometric and power indices. Intergroup differences (LSP, MSP and SSP, respectively) were revealed in v50 (1.65, 1.55, 1.49 m/s), v100 (1.52, 1.41, 1.34 m/s), SL100 (1.92, 1.77, 1.72 m), SI50 (2.92, 2.65, 2.54 m/s2), SI100 (2.91, 2.51, 2.31 m/s2). In all clusters differences were revealed between v50 and v100 and SR50 and SR100. Differences in SL50 and SL100 were noticed in LSP and MSP, while in SI50 and SI100 in MSP and SSP. Conclusions: The evaluation of the technique should consider the energy-anthropometric profile of the athlete. The swimming technique need to be modified depending on the distance – also in races perceived as sprints.