Data_Sheet_1_Implications of the choice of distance-based measures in assessing and investigating tumble turn performance.docx

Although the tumble turn in swimming has been studied extensively, no consensus exists about which measure is best suited to capture its performance. The aim of this study was to better understand the implications of choosing a particular distance-based performance measure for assessing and investigating tumble turn performance in freestyle swimming. To this end, a large set of retrospective turn data consisting of 2,813 turns performed by 160 swimmers was analyzed statistically in three steps. First, a mixed-effects model was derived for the entire data set, which showed that both performance level and sex had clear effects on the distance-based performance measures and performance determining variables studied in the literature. Second, repeated measures correlations were calculated for the entire data set and four performance level- and sex-based subgroups to determine the level of association between the performance measures. This analysis revealed that the performance measures were strongly correlated (r > 0.84 and p < 0.05 for all possible pairs), largely independent of performance level and sex. This finding implies that the choice of performance measure is not very critical when one is interested solely in the overall performance. In the third and last step, mixed-effects models were derived for the performance measures of interest to establish the importance of different turn-related actions for each measure, again for both the entire data set and the four subgroups separately. The results of this analysis revealed that performance measures with short(er) distances are more sensitive to changes in the adaptation time and reflect the wall contact time better than performance measures with long(er) distances, which in contrast are more useful if the focus is on the approach speed prior to the turn. In this final analysis, various effects of performance level and sex were found on the technical execution of the tumble turn.

尽管游泳中的翻滚转身动作已被广泛研究，但对于何种度量标准最适合捕捉其性能，尚无共识。本研究旨在深入探究选择特定基于距离的性能度量标准对评估和调查自由泳中翻滚转身性能的内在含义。为此，对由160名游泳者完成的2,813次转身动作的庞大历史数据集进行了统计分析，分为三个步骤。首先，针对整个数据集推导出了一个混合效应模型，该模型表明，性能水平和性别对文献中研究的基于距离的性能度量标准和性能决定变量均有显著影响。其次，对整个数据集及其基于性能水平和性别的四个子组计算了重复测量相关系数，以确定性能度量标准之间的关联程度。此分析显示，性能度量标准之间具有强相关性（所有可能配对的相关系数r均大于0.84，p值均小于0.05），在很大程度上独立于性能水平和性别。这一发现表明，当关注整体性能时，性能度量标准的选择并非至关重要。在第三个也是最后一个步骤中，针对感兴趣的绩效度量标准推导出混合效应模型，以确定不同转身相关动作对每个度量标准的重要性，这同样适用于整个数据集和四个子组。该分析的结果表明，基于较短距离的绩效度量标准对适应时间的变化更为敏感，并能更好地反映墙壁接触时间，而基于较长距离的绩效度量标准则更适用于关注转身前的接近速度。在最终的分析中，发现了性能水平和性别对翻滚转身技术执行的多种影响。