In competitive swimming, records at major events such as Olympic Games, World and European Championships are still being broken. The swimming fraternity is always aiming to enhance swimmers' final time by improving their performance in key moments of the race. Video analysis of elite swimmers' performance is a major tool for swimmers, coaches and researchers (O'Donoghue, 2006). The information that is retrieved by such analysis help swimmers in understanding their handicaps, and hence how to improve. If in the past the performance enhancement was underpinned by improving mostly the swim stroke (i.e. clean swim - refers to the swim speed during an intermediate distance, without the interference of the wall push-off) (McGibbon et al., 2018; Menting et al., 2019), now the focus is shifting more towards the remaining phases of a race (start, turn and finish) (Morais et al., 2019).
Lately there has been an increasing interest by practitioners, analysts and researchers in the role played by the start, turns and finish (Peterson Silveira et al., 2018; Veiga and Roig, 2016). As the race distance becomes longer (i.e. from 50 m to 1500 m), different phases of the race have different partial contributions to the final race time. In short events (e.g. 100 m events), the start and turn account for nearly a third of the final race time (Morais et al., 2018). Contrarily, in long-distance events (e.g. 800 m and 1500 m races), the swimming pace (i.e. swim stroke) plays the major role (Lipinska et al., 2016; Morais et al., 2019). Among the swimming community the 200 m events are claimed to be too long for sprinters and too short for long-distance swimmers (Madge, 2014). Moreover, these 100 m-200 m events are the only Olympic events where the distance can be doubled in all swim strokes (i.e. all swim strokes are raced in the 100 m and 200 m distances). Therefore, it is important to provide insights into a comparison of the phases of the race (namely the start, turn and finish) in these events for both coaches and swimmers, as stroke specialists could compete in both distances.
The literature has reported that the clean swim phase was the best predictor of the final race time in 200 m events (Arellano et al., 1994; Thompson et al., 2000). Nonetheless, differences can be observed in the clean swim between short- and middle-distance events, such as the 100 m and 200 m, respectively. Sprinters (100 m) achieve a faster speed in comparison to their middle-distance counterparts (200 m) (Arellano et al., 1994; Jesus et al., 2011). However, it is yet unclear whether differences in average race speed are also due to variations or changes in the performance delivered in the start and turning phases (Simbana et al., 2018a). It is reported that swimmers racing the 100 m events reach the 15 m mark, and also break the water sooner in comparison to their 200 m counterparts (Jesus et al., 2011; Veiga et al., 2016).
In other studies, the 200 m events at major competitions were analyzed (Chengalur and Brown, 1992; Hellard et al., 2008; Skorsky et al., 2014). Such analyses included the start (Arellano et al., 1994; Jesus et al., 2011), and turn (Mason and Cossor, 2001; Veiga and Roig, 2016). Moreover, surface and underwater profiles in these segments of the race were also analyzed (Veiga and Roig, 2016; Veiga et al., 2016). Start and turn phases can be further broken down into subphases (surface and underwater). These subphases might explain the performance delivered in the start and turn. However, solid insights into other variables related to the start and turn subphases in elite swimmers are not found in the extant literature (e.g. Tor et al., 2015; Veiga and Roig, 2016). As far as our understanding goes, the literature remains unclear about the importance of underwater and/or surface profiles during the start and turn, which can ultimately affect the water entry and the water break (e.g. Veiga and Roig, 2016; Veiga et al., 2016). For instance, swimmers may choose to extend their underwater phase, and hence save energy for the swim stroke. Or to break the water sooner, leading to a faster start of the swim stroke (Vantorre et al., 2014). On top of that, very few studies have analyzed the finish, and how important it is for the final race time (Ikuta, 1998; Suito et al., 2015). Among coaches and swimmers there is the claim that finishing fast is paramount to delivering a good performance. Nevertheless, we failed to find solid evidence to back up such a claim. Overall, despite the start, turn and finish being understood in the swimming fraternity as important contributors to the performance, it might be suggested that more evidence on this matter could be of substantial importance.
Therefore, the main aim of this study was to characterize and compare a set of variables related to the start, turn and finish performance between the 100 m and 200 m events in the four swimming strokes by elite male and female swimmers. It was hypothesized that the start time, turn time and the finish present a significant race effect (i.e. significant differences between races).
The performances of all 128 finalists (64 males and 64 females) in the 100 m, and 200 m events (four swim strokes, 8 swimmers per event) at the 2018 long course meter LEN European Aquatics Championships held in Glasgow were analyzed. Mean performance of the males corresponded to 96.83%, and 95.84% in the 100 m and 200 m freestyle world records, respectively; 96.75%, and 95.88% in backstroke; 96.58%, and 98.31% in breaststroke, and; 96.78%, and 96.26% in butterfly. Mean performance of the females corresponded to 96.15%, and 96.04% in the 100 m and 200 m freestyle world records; 97.15%, and 96.14% in backstroke; 95.83%, and 96.32% in breaststroke; and 96.22%, and 95.12% in butterfly. All procedures were in accordance to the Helsinki Declaration regarding Human research.
The official race times (final race times, every 50 m split time and reaction time) were retrieved from the official competition website (www.europeanchampionships.com). The championships organization provided the video clips of all races in high-definition video f= 50 Hz). The set-up system delivered real-time multi-angle recordings using individual tracking from high-definition pan-tilt-zoom cameras (AXIS v5915, Lund, Sweden). Each swimmer was recorded by one camera (i.e. one camera per lane). Two other high-definition fixed cameras (AXIS q1635, Lund, Sweden) recorded both ends of the swimming pool, one enabling the analysis of the start and finish, and the other the turn(s). The start flashing light was synchronized with the official timer and were visible by all cameras. The start flashing light was used as reference to set the time-stamp on an in-house customized software for race analysis in competitive swimming. The distances used for the start and turn variables were calibrated based on the pool's marks (i.e. 5 m and 15 m marks in the swim lanes) (Morais et al., 2018; Morais et al., 2019). Each start, turn and finish performance were analyzed individually for each swimmer. Two expert evaluators performed all race analyses individually and separately. The agreement between both evaluators was verified with the Intra-Class Correlation Coefficient (ICC). This ranged between 0.989 and 0.999 (very high agreement).