## 4 Discussion
### Differences in Adapting the Technique Depending on the Distance  
The Dv, DSR, DSL, and DSI indicators were proposed in order to highlight the differences in swimming technique depending on the length of the competition. So far, it has been established that competitors participating in sprint races swim at higher v, SR, SI, and lower SL values than during middle- and long-distance events [9; 12]. In this study, it was also decided to investigate the differences in adjusting the technique to the distance between faster and slower swimmers. The Dv describing the size of the differences in velocity achieved for the 50 and 100 m distances in the FS and SS groups demonstrated similar values. Despite this similarity, the strategies employed to adapt the technique in the 50 and 100 m races differed. The subjects from the FS group modified their technique to a greater extent, which was reflected in the change in DSR and DSL values. In the SS group, the differences in these indicators for both distances were small. At the same time, in the FS group, the SI was higher in the 50 m than in the 100 m race, while in the group of slower swimmers, the SI values were higher for the longer distance. This may indicate that the differences in techniques between faster and slower swimmers are more pronounced during the performance of difficult tasks (swimming at or near maximal speed) than for easier efforts (e.g., moderate intensity). The differences are justified in the system-theoretical model of human motor behaviour [35]. Analysis of the aforementioned disproportions cannot be made without taking the differences in the sports level of the respondents into account. As already mentioned, for both the 50 and 100 m distances, the velocity of the subjects from the FS group was clearly higher than among the SS. This means that the FS subjects had to overcome significantly higher resistance values than the SS swimmers during the race, and this was possible owing to a significant increase in propelling force [34]. Its rise, in turn, can be achieved by increasing SR [36]. Therefore, it seems that the FS conformed to the 50 m distance requirements better than the SS. A significant modification of the technique depending on the distance covered in the FS subjects was the smaller SL in the 50 m freestyle competition (by 0.2 m). In the SS group, the SL value at this distance was slightly lower than at 100 m. It should be emphasized, however, that in the case of the 100 m freestyle, the differences between the groups were large (about 10%), while for the shorter distance, this difference was small (below 2%). At the same time, at 50 m, the decrease in SL for the group of faster swimmerswas compensated by a significant increase in SR. It seems that a different mechanism was used by the SS, slightly increasing the SR while maintaining a more stable SL. This allowed them to increase the speed for the 50 m distance compared with 100 m by approximately 0.22 m/s (in the FS group, by 0.25 m/s). The research results clearly confirm the earlier report by [PERSON] et al. [13], in which it was stated that the swimmers demonstrating a higher sports level of sports dispose of a wider range of tactical and technical solutions, which are selected according to the requirements of a given competition. Moreover, in the case of better swimmers, the change in technique does not affect movement efficacy, as evidenced by the slight difference in the SI over the shorter and longer distances. Among less skilled swimmers, lower values were achieved for this variable over shorter distances, which indicates a lower ability to adapt the technique to more difficult conditions of the task (the need to achieve maximal speed). Finally, certain limitations of this study should be emphasized. The main subject of the work was determining characteristics of the full stroke swimming technique; however, the results obtained for the 50 and 100 m freestyle were also influenced by the quality of the execution of starts and turns.