The aim of this study was to analyse the detraining process that occurs during a season break, and its influence on the performance, anthropometrics, and biomechanics of young swimmers. The sample included 54 young swimmers (22 boys: 12.79 ± 0.71 years; 32 girls: 11.78 ± 0.85 years). Performance for the 100 m freestyle and anthropometric and biomechanical variables were evaluated as main determinants. Performance impaired significantly for boys (2.17%) and girls (1.91%). All anthropometric variables increased between moments of assessment for boys and girls. Overall, the boys enhanced all biomechanical variables during the detraining period, and girls showed mixed results. For both sexes, the stroke index was the variable with the highest increase (boys: Δ = 16.16%; d = 0.89; p = 0.001; girls: Δ = 19.51%; d = 1.06; p = 0.002). Hierarchical linear modelling showed that the height retained the amount of impairment in the performance. One unit of increase in the height (cm) led to less 0.41 s impairment in the performance. Present data indicated that during an 11-weeks detraining period, young swimmers impaired their performance, but the determinant factors showed an impaired relationship. This increase in the determinant factors is mainly related to the increase in the swimmers' anthropometrics. Moreover, the increase in height was responsible for retaining the performance impairment.

The aim of this study was to: (1) verify differences between swimmers of the same competitive level in variables related to the start and finish (50 m and 100 m freestyle); (2) verify if starting and finish variables are responsible for faster race time, and which starting variables are responsible for the start performance in such events. For the 50 m and 100 m freestyle race at the junior European Championships 2019, 86 and 88 male swimmers were analysed, respectively. A set of starting and finishing variables were used for analysis. Both races (50 m: p < 0.001; 100 m: p < 0.001) presented a significant level effect for the final race time. The same trend was observed for the start and finish performances. For both races, hierarchical linear modelling retained the 15 m mark time and finish speed as predictors. The 50 m start retained the reaction time and underwater speed, and the 100 m start retained the reaction time and the water break distance. This indicates the underwater phase of the start is of substantial importance to improve the 15 m mark time. Coaches and swimmers are advised to enhance the start underwater phase, and finish segments to improve the swimmers' performance.

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The present study aimed to determine the intra-abdominal pressure during front crawl swimming at different velocities in competitive swimmers and to clarify the relationships between stroke indices and changes in intra-abdominal pressure. The subjects were 7 highly trained competitive collegiate male swimmers. Intra-abdominal pressure was measured during front crawl swimming at 1.0, 1.2 and 1.4 m · s(-1) and during the Valsalva maneuver. Intra-abdominal pressure was taken as the difference between minimum and maximum values, and the mean of 6 stable front crawl stroke cycles was used. Stroke rate and stroke length were also measured as stroke indices. There were significant differences in stroke rate among all velocities (P < 0.05). However, there was no significant difference in stroke length by velocity. Significant within-subject correlations between intra-abdominal pressure and stroke rate or stroke length (P < 0.01) were observed, although there were no significant correlations between intra-abdominal pressure and stroke indices when controlling for swimming velocity. These findings do not appear to support the effectiveness of trunk training performed by competitive swimmers aimed at increasing intra-abdominal pressure.

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