21 Performance development of top-elite swimmers 2 Methods Ethical approval All procedures used in the study were approved by the Local Ethical Committee of the University Medical Center Groningen, University of Groningen, The Netherlands (201900334) in the spirit of the Helsinki Declaration with a waiver of the requirement for informed consent of the participants given the fact that the study involved the analysis of publicly available data. Data collection The swimmers we selected for this study were international male and female swimmers with performance data on the 100m freestyle long course event. Performance data was obtained from Swimrankings (Swimrankings, 2018), a recognized public data source which records swimming race results. Performance data was collected from 113 countries across different parts of the world including Africa, America, Asia, Australia and Europe. We collected all available 100m freestyle long course results from Swimrankings’ database, which initially resulted in 2,683,412 observations between 1993 and 2018. Data processing Performance data from the 1st of January 2008 till the 1st of January 2010 were excluded from analysis. During that time, swimmers were allowed to wear newly introduced fullbody polyurethane swimsuits which led to a major benefit of the swimmers’ drag force reduction (Tiozzo et al., 2009; Toussaint et al., 2002; Tomikawa & Nomura, 2009). From the 1st of January 2010 onwards, FINA banned these suits. Swim performances over 180seconds were excluded from analysis to ensure a representative dataset. A total of 2,383,616 observations was remained. Based on swim dates, performance data were classified in swimming seasons. Each swimming season officially starts on the first of September of a calendar year and ends on the 31st of August of the next calendar year (1st of September 2018 till 31st of August 2019 corresponds to swimming season 2018/2019). Swimmers were classified in age categories based on their age on the 31st of December of the swimming season (a girl who is 14 years old on the 31st of December 2018 would be classified in age category 14 year for swimming season 2018/2019). Therefore, all ages mentioned in the present study refer to the age category in which a swimmer participated during the swimming season and not the calendar age of the swimmer. For each swimmer, we selected one Season Best Time (SBT) per swimming season which we used for further analysis. A total of 1,131,963 observations was remained.
RkJQdWJsaXNoZXIy MTk4NDMw