First report of expansion of virulence in Puccinia striiformis f. sp. tritici to wheat resistance genes Yr10 and Yr24 in the Middle East.

Over the last decade, field assessments of the yellow rust differential lines for resistance genes Yr10 and Yr24 and race analysis in the Middle East have demonstrated efficient yellow rust control by Yr10 and Yr24 (=Yr26). Yellow rust samples collected during 2018-21 in Central West Asia & North and sub-Saharan Africa underwent race analysis at the Regional Cereal Rust Research Center in Izmir, Türkiye. The infected leaf segments were subjected to rehydration at 20°C for three hours. Subsequently, the leaf segments were rubbed on the first leaves of seedlings of susceptible cultivar Morocco. Inoculated seedlings were placed at 10°C in dark conditions with 95% humidity for 24 hrs, then moved to a growth chamber with a 16-hr light (220 µmolm-2s-1) cycle at 15°C and an eight-hour dark period at 12°C. Urediniospores were collected 15 days post-inoculation. A set of yellow rust differential lines including Morocco, Avocet 'S', Avocet 'R', Yr1/6* Avocet 'S', Kalyansona (Yr2), Vilmorin 23 (Yr3), Hybrid 46 (Yr4), Yr6/6* Avocet 'S', Yr7/6* Avocet 'S', Yr8/6* Avocet 'S', Yr9/6* Avocet 'S', Yr10/6* Avocet 'S', Moro (Yr10+), Yr17/6*Avocet 'S', Yr24/6* Avocet 'S', TP1295 (Yr25), Yr27/6* Avocet 'S', YrSp/6* Avocet 'S', Spalding Prolific (YrSP), Strubes Dickkopf (YrSD), Tres/6*Avocet'S', Cham 1, and Ambition was used in race analysis. A mixture of 2 mL Soltrol® and 0.5 mg fresh urediniospores was used to inoculate 10-day-old seedlings of the 23 differential varieties. Pre-inoculation, incubation, and post-inoculation conditions were the same as above. Seedling infection types (ITs) were recorded 15 days post-inoculation on a scale of 0 to 9 (McNeal et al. 1971), where ITs 0 to 6 are classified as low infection types (LITs= avirulent) and ITs 7 to 9 categorized as high infection types (HITs= virulent). HITs of 7 to 9 were observed for the first time on Yr10/6* Avocet 'S', Yr24/6* Avocet 'S', as well as on Moro (Yr10+) for 25 sample of the total 50 isolates from Lebanon and Türkiye in 2018. During the race analysis in 2019 to 2021, virulence for Yr10 and Yr24 was identified among tested samples from Egypt, Lebanon, Jordan, Syria, and Türkiye, indicating the expansion of virulence for Yr10 and Yr24 into new regions. HITs were observed for the durum wheat cultivar Cham 1 and wheat cultivar Ambition in all races. Virulence for YrA, Yr2, Yr6, Yr7, Yr8, Yr17, and 32 was common within the Yr10 and Yr24 virulent races, and virulence for YrSp and Yr27 were observed in low frequency. Molecular genotyping of 209 isolates, including the Yr10 virulent races, was performed using 19 microsatellite markers (Ali et al. 2017; Rodriguez-Algaba et al. 2017) and aligned with the Puccinia striiformis nomenclature system of the Global Rust Reference Center (GRRC). The results showed that 66 isolates were identical to the genotyping lineage "ME2018" identified in Egypt in 2018 by GRRC. This genetic lineage has now been designated as PstS17 (Hovmøller et al. 2023). The durum wheat cultivars have always been resistant to yellow rust in the Middle East. Seedling tests of 50 durum advanced lines from CIMMYT's International Durum Wheat Yield Nursery showed LITs in 45 accessions (90%) against an avirulent race for Yr10 and Yr24 (PstS2), but only 12% remained resistant while tested with a PstS17 (virulent for Yr10 and Yr24). This observation provides compelling evidence of the Yr10 and/or Yr24 presence within tested durum wheat germplasm. Continued monitoring of virulence and resistance of wheat germplasm to yellow rust is critical for successful breeding for rust resistance.

Profiling of elite male junior 50 m freestyle sprinters: Understanding the speed-time relationship.

The aim of this study was to (1) analyze and compare the race performance and stability between the fastest and slowest male swimmers during the 50 m freestyle event, and (2) to understand the speed-time relationship in this race. The performances (start, clean swim, and finish) of 86 swimmers (divided into two tiers: best and poorest performances) who competed in the 50 m freestyle event in the 2019 long course LEN European Junior Championships were analyzed. The swimming speed presented a significant difference between the groups (tier #1 vs tier #2) in all sections of the race, in which the start (S0-15 m: p < 0.001, d = 1.64) and finish sections (S45-50: p < 0.001, d = 1.63) showed the greatest differences. Significant variances over the race sections were noted for both groups in all variables, in which the swimming speed was the variable with the highest variance (tier #1: p < 0.001, η2  = 0.72; tier #2: p < 0.001, η2  = 0.82). Both groups exhibited a similar normative stability, with the fastest swimmers tending to be the best in all sections. The fit analysis produced a cubic speed-time relationship. Notwithstanding, junior swimmers who raced the 50 m freestyle can be considered to have an all-out pacing. This information is of paramount importance for coaches and swimmers to understand the intra-lap race performance in this short event.

Start Fast, Swim Faster, Turn Fastest: Section Analyses and Normative Data for Individual Medley.

The aims of the study were to provide benchmarks and normative data for 100 m, 200 m, and 400 m short-course individual medley (IM) races, investigate differences between the various swimming strokes and turns involved in IM, and quantify the effect and contribution of various race sections on swimming performance. All IM races (n = 320) at the 2019 European Short-Course Swimming Championships were video monitored and digitized with interrater reliability described by a mean intra-class correlation coefficient of 0.968. Normative data were provided for the eight finalists of each event (FINA points = 886 ± 37) and the eight slowest swimmers from each event (FINA points = 688 ± 53). Contribution and effects of race sections on swimming performance were investigated using stepwise regression analysis based on all races of each event. Regression analysis explained 97-100% of total variance in race time and revealed turn time (ß ≥ 0.53) as distinguishing factor in short-course IM races in addition to swim velocity (ß ≥ -0.28). Start time only affected 100 m (ß ≥ 0.14) and 200 m (ß ≥ 0.04) events. Fastest turn times were found for the butterfly/backstroke turn. Breaststroke showed slowest swim velocities and no difference between fastest and slowest 100 m IM swimmers. Therefore, breaststroke may provide largest potential for future development in IM race times. Correlation analyses revealed that distance per stroke (r ≥ -0.39, P < 0.05) rather than stroke rate (r ≤ -0.18, P > 0.05) is a performance indicator and may be used by coaches and performance analysts to evaluate stroke mechanics in male IM swimmers despite its more complex assessment. Performance analysts, coaches, and swimmers may use the present normative data to establish minimal and maximal requirements for European Championship participation and to create specific drills in practice.

Start and Turn Performances of Competitive Swimmers in Sprint Butterfly Swimming.

The purposes of this study were to establish relationships between selected underwater kinematics and the starting and turning performances and to quantify kinematic differences between these segments in sprint butterfly swimming. Fourteen male swimmers performed 50 m maximal butterfly swimming in a short course pre-calibrated pool. The entire race was filmed by a multi-camera system, which quantified the forward head displacement and velocity (vxhead ) throughout the race with a sampling frequency of 50 Hz. The time taken between 0-15 m (T0-15 ) and 25-35 m (T25-35 ) as well as 16 kinematic variables were acquired from the data provided by the system and manual video processing for further analysis. The mean underwater velocity (UW-vxmean ) was related to both T0-15 and T25-35 (r = -0.70 and -0.95, respectively; p < 0.01). UW-vxmean was positively correlated with vxhead during the first kick (r = 0.84, p < 0.001) in the start segment and with vxhead during the last kick in the turn segment (r = 0.68, p < 0.01), but other kinematic variables such as kick frequency, body angle, deceleration during kicks (Deckick ), and glide time were not related to UW-vxmean . Swimmers had larger vxhead at the beginning of the segment and during the first kick in the start than in turn segment (p < 0.001). However, vxhead during the last kick was similar due to the larger Deckick (p < 0.05) in the start than in turn segment. The underwater time was similar between the segments despite a longer underwater distance (p < 0.01) and a larger kick count and frequency (p < 0.01) in the start than turn segment. In conclusion, UW-vxmean is an important factor for start and turn performances, but swimmers select individual kinematic strategies to achieve a large UW-vxmean . Results also highlighted the importance of the different parts within the underwater segment in each segment.

Functional Role of Movement and Performance Variability: Adaptation of Front Crawl Swimmers to Competitive Swimming Constraints.

To study the variability in stroking parameters between and within laps and individuals during competitions, we compared and modeled the changes of speed, stroke rate, and stroke length in 32 top-level male and female swimmers over 4 laps (L1-L4) in 200-m freestyle events using video-derived 2-dimensional direct linear transformation. For the whole group, speed was greater in L1, with significant decreases across L2, L3, and L4 (1.80 ± 0.10 vs 1.73 ± 0.08; 1.69 ± 0.09; 1.66 ± 0.09  · s-1, P < .05). This variability was attributed to a decrease in stroke length (L2: 2.43 ± 0.19 vs L4: 2.20 ± 0.13 m, P < .05) and an increase in stroke rate (L2: 42.8 ± 2.6 vs L4: 45.4 ± 2.3 stroke · min-1, P < .05). The coefficient of variation and the biological coefficient of variation in speed were greater for male versus female (3.9 ± 0.7 vs 3.1 ± 0.7; 2.9 ± 1.0 vs 2.6 ± 0.7, P < .05) and higher in L1 versus L2 (3.9 ± 1.3 vs 3.1 ± 0.1; 2.9 ± 0.9 vs 2.3 ± 0.7, P < .05). Intra-lap speed values were best represented by a cubic (n = 38), then linear (n = 37) and quadratic model (n = 8). The cubic fit was more frequent for males (43.8%) than females (15.6%), suggesting greater capacity to generate higher acceleration after the turn. The various stroking parameters managements within lap suggest that each swimmer adapts his/her behavior to the race constraints.

[Simultaneous determination of insecticide in tea samples using QuEChERS-based clean up and ultra-fast liquid chromatography-tandem mass spectrometry].

OBJECTIVE: To develop a method for determination of imidacloprid, acetamiprid, chlorobenzamide and indoxacarb in tea samples using Qu ECh ERS-based pretreatment method and ultra-fast liquid chromatography-tandem mass spectrometry( UFLC-MS/MS). METHODS: Tea samples were firstly extracted by acetonitrile-water solution( 4∶ 1, V/V) by vortex and ultrasound, and then 1 g Na Cl and 4 g Mg SO4 were added into the mixture, following by vortex and centrifugation at 8500 r/min for 5 min. Finally the supernatant was purified by Mg SO4 and PSA power, and then the chromatographic separation process was performed on a Waters ACQUITY UPLC BEH C18 column( 2. 1 mm × 100 mm, 1. 7 µm) with a linear gradient elution procedure ofacetonitrile and 0. 1%( V/V) formic acid-5 mmol/L ammonium acetate in water as elution solvent. The multiple reaction monitoring( MRM) in positive mode was used for quantification by internal standard method. RESULTS: The four insecticides including imidacloprid, acetamiprid, chlorobenzamide, and indoxacarb showed good linearity in the range of 0. 20-50. 0 µg/L with coefficients( r) higher than 0. 9998. The limits of detection( LODs) varied from 0. 1 µg/kg to 0. 3 µg/kg. The recoveries of spiked tea samples in the range of 88. 4%-98. 8% at the three concentrations of 1. 0 µg/kg, 40. 0µg/kg and 80. 0 µg/kg, while the relative standard deviations( RSD) were all less than10%. CONCLUSION: The proposed method is simple, fast, sensitive and accuracy, and can be used for qualitative and quantitative analysis of imidacloprid, acetamiprid, chlorobenzamide, andindoxacarb in tea samples.

Race analysis in swimming: understanding the evolution of publications, citations and networks through a bibliometric review.

The aim of this study was to conduct a scoping and bibliometric review of swimming articles related to race analysis. The Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines were used to identify relevant studies. Articles on race analysis in swimming published between 1984 and December 31, 2023 were retrieved from the Web of Science database. 366 records were screened and a total of 74 articles were retained for analysis. Until 2012, there were some time intervals with no or few publications. From 2012, there was a clear upward trend in publications and citations. This theme was led by the United States of America, Australia, and Spain. Australia and Spain maintain their status as the countries with the most publications. The analysis of author collaborations revealed two clusters with Spanish authors, and the remaining clusters are composed of Portuguese, Swiss, and Australian authors. With this bibliometric review, it has been possible to understand the evolution of the articles published on race analysis in swimming, the countries and the authors that have contributed most to this topic over the years. The prediction model shows that the number of articles and citations on this topic will continue to increase over the next 10 years (until 2034).

Differences in Race Characteristics between World-Class Individual-Medley and Stroke-Specialist Swimmers.

The purpose of the present study was to investigate differences between world-class individual medley (IM) swimmers and stroke-specialists using race analyses. A total of eighty 200 m races (8 finalists × 2 sexes × 5 events) at the 2021 European long-course swimming championships were analysed. Eight digital video cameras recorded the races, and the video footage was manually analysed to obtain underwater distance, underwater time, and underwater speed, as well as clean-swimming speed, stroke rate, and distance per stroke. Each lap of the IM races was compared with the first, second, third, and fourth laps of butterfly, backstroke, breaststroke, and freestyle races, respectively. Differences between IM swimmers and specialists in each analysed variable were assessed using an independent-sample t-test, and the effects of sex and stroke on the differences were analysed using a two-way analysis of variance with relative values (IM swimmers' score relative to the mean specialists' score) as dependent variables. Breaststroke specialists showed faster clean-swimming speed and longer distance per stroke than IM swimmers for both males (clean-swimming speed: p = 0.011; distance per stroke: p = 0.023) and females (clean-swimming speed: p = 0.003; distance per stroke: p = 0.036). For backstroke and front crawl, specialists exhibited faster underwater speeds than IM swimmers (all p < 0.001). Females showed faster relative speeds during butterfly clean-swimming segments (p < 0.001) and breaststroke underwater segments than males (p = 0.028). IM swimmers should focus especially on breaststroke training, particularly aiming to improve their distance per stroke.

Are the 50 m Race Segments Changed From Heats to Finals at the 2021 European Swimming Championships?

This study explored in the 50 m races of the four swimming strokes the performance parameters and/or technical variables that determined the differences between swimmers who reach the finals and those who do not. A total of 322 performances retrieved from the 2021 Budapest European championships were the focus of this study. The results of the performances achieved during the finals compared to the heats showed that the best swimmers did not excel during the heats, as a significant progression of performance was observed in most of the strokes as the competition progressed. Specifically, combining men and women, the swimmers had in freestyle a mean coefficient of variation (CV) of ∼0.6%, with a mean range of performance improvement (∆%) of ∆ = ∼0.7%; in breaststroke a mean CV of ∼0.5% and ∆ = -0.2%; in backstroke a mean CV of ∼0.5% and ∆ = -0.6%, and; in butterfly a mean CV of ∼0.7% and ∆ = -0.9%. For all strokes, it was a reduction of the underwater phase with the aim of increasing its speed. However, this result was not always transferred to the final performance. In any case, most of the swimmers tried to make improvements from the start of the race up to 15 m. Furthermore, the swimmers generated an overall increase in stroke rate as the rounds progressed. However, a decrease in stroke length resulted and, this balance appeared to be of little benefit to performance.

A Study of Race Pacing in the Running Leg of the Japan University Triathlon Championship.

Choosing an appropriate pacing strategy is important for good triathlon performance. In the Japan Student Triathlon Championship held in 2020, the men's category was divided into two groups, which was a different racing style from the previous races that all athletes start at the same time. It is highly likely that the performance level will vary as grouping was performed according to the competence of each player. The aim of this study was to understand the relationship of the total time and time of each leg between the superior performance group and the inferior performance group, as well as the difference in pacing during running in participants of the 2020 Japan University Triathlon Championship Watarase Competition, which was held under unconventional conditions. We analyzed 153 male athletes (Group A: 77; Group B: 76) who completed the race. The total race time, leg time, and average speed in each leg and its variation coefficient were evaluated based on the official results of the competition and footage recorded during the race. The results showed that the total time and leg time for each leg were significantly shorter in Group A compared to those in Group B (p < 0.05). In both groups, the Lap 4 run was significantly slower than those of Laps 1-3 (p < 0.05), while there was no significant difference in the running speed to average speed ratio across all laps between the groups (p < 0.05). Thus, there was a difference in running speed between the groups, but no significant difference in pacing. The results of this study serve as basic data for examining superior pacing strategies, although further studies on a wide range of competition levels are necessary.

Turn Performance Variation in European Elite Short-Course Swimmers.

Turn performances are important success factors for short-course races, and more consistent turn times may distinguish between higher and lower-ranked swimmers. Therefore, this study aimed to determine coefficients of variation (CV) and performance progressions (∆%) of turn performances. The eight finalists and eight fastest swimmers from the heats that did not qualify for the semi-finals, i.e., from 17th to 24th place, of the 100, 200, 400, and 800 (females only)/1500 m (males only) freestyle events at the 2019 European Short Course Championships were included, resulting in a total of 64 male (finalists: age: 22.3 ± 2.6, FINA points: 914 ± 31 vs. heats: age: 21.5 ± 3.1, FINA points: 838 ± 74.9) and 64 female swimmers (finalists: age: 22.9 ± 4.8, FINA points: 904 ± 24.5 vs. heats: age: 20.1 ± 3.6, FINA points: 800 ± 48). A linear mixed model was used to compare inter- and intra-individual performance variation. Interactions between CVs, ∆%, and mean values were analyzed using a two-way analysis of variance (ANOVA). The results showed impaired turn performances as the races progressed. Finalists showed faster turn section times than the eight fastest non-qualified swimmers from the heats (p < 0.001). Additionally, turn section times were faster for short-, i.e., 100 and 200 m, than middle- and long-distance races, i.e., 400 to 1500 m races (p < 0.001). Regarding variation in turn performance, finalists showed lower CVs and ∆% for all turn section times (0.74% and 1.49%) compared to non-qualified swimmers (0.91% and 1.90%, respectively). Similarly, long-distance events, i.e., 800/1500 m, showed lower mean CVs and higher mean ∆% (0.69% and 1.93%) than short-distance, i.e., 100 m events (0.93% and 1.39%, respectively). Regarding turn sections, the largest CV and ∆% were found 5 m before wall contact (0.70% and 1.45%) with lower CV and more consistent turn section times 5 m after wall contact (0.42% and 0.54%). Non-qualified swimmers should aim to match the superior turn performances and faster times of finalists in all turn sections. Both finalists and non-qualified swimmers should pay particular attention to maintaining high velocities when approaching the wall as the race progresses.

Geographical Correlation and Genetic Diversity of Newly Emerged Races within the Ug99 Lineage of Stem Rust Pathogen, Puccinia graminis f. sp. tritici, in Different Wheat-Producing Areas.

Wheat stem rust caused by Puccinia graminis f. sp. tritici is one of the most destructive wheat diseases worldwide. Identifying stem rust races in general, Ug99 lineage particularly, and determining resistance genes are critical goals for disease assessment. Thirty wheat varieties and monogenic lines with major stem rust resistance genes (Sr) were examined here over the course of three succeeding seasons from 2020 to 2022. Fourteen stem rust races have been identified in ten African countries, as well as Central and West Asia and North Africa (CWANA) and ten European countries. The Ug99 group (Clade I) included four races (TTKSK, TTKST, TTKTK, and TTKTT) and was reported in five African countries (Egypt, Kenya, Rwanda, Tanzania, and Uganda) and Iran, but none of the European countries. On the other hand, none of the races in Clade III-B (TTRTF) and Clade IV-B (TKTTF and TTTTF) were found in Egypt. Furthermore, Egyptian races were clustered separately from races identified from other countries, and six races were found only in Egypt, including PKSTC, RKTTH, TKTTC, TTTSK, TCKTC, and TKTTH. Races from Kenya, Tanzania, Uganda, Rwanda, and Iran were all closely associated with one another, according to correlation analysis. However, most races identified from other investigated regions, including Eritrea, Spain, Ethiopia, Morocco, Italy, Poland, Kenya, Tanzania, and Uganda, were adversely linked with Egyptian races. The diagnostic 350 bp long PCR fragment linked with virulence to Sr31, Clement (Sr31), and Brigardier (Sr31) was used to identify the TTKSK (Ug99) race. The identification of the regional associations and genetic diversity of newly emerged races within the Ug99 lineage of P. graminis tritici in Africa, Asia, and Europe is one of the key goals of this study. It will help plant breeders to develop new resistant lines against the virulent races, especially TTKSK (Ug99) and TTTSK. This helps in ensuring global food security in the context of climate change.

The characteristics of the breaststroke pullout in elite swimming.

Since the rule change permitting the inclusion of one dolphin kick during the underwater breaststroke pullout phase following a swim start or turn, there has been an emergence of several different pullout techniques adopted by elite swimmers. The aim of this study was to characterize the underwater breaststroke pullout technique trends and to assess the effectiveness of each technique as utilized by elite male and female swimmers. The sample included 60 swimmers (n = 26 male, n = 34 female) competing across the 50, 100, and 200 m long-course breaststroke final races from the World Championships 2015, 2017, 2019 and Olympic Games 2016. An above-water camera was used to identify and measure the different phases of the underwater pullout techniques, which was found to be a highly accurate methodological approach (ICC = 0.97). From the 150 trials analyzed, three different pullout techniques were identified: the Fly-Kick First technique, the Combined technique and the Pull-Down First technique. Although the most common underwater pullout technique utilized by elite competitive breaststroke swimmers was the Combined technique (n = 71), followed by the Fly-Kick First technique (n = 65) and the Pull-Down First technique (n = 14), it was observed that technical selection deviates according to gender. This indicates that male and female swimmers should not be coached adhering to the same technical model. This study found no significant difference in terms of performance outcome with respect to each of these techniques, indicating that technique selection should be guided by one's individual preference. It was concluded that the results of this study will serve as an up-to-date resource for coaches and swimmers working with elite breaststroke swimmers and as a useful insight to current underwater pullout trends.

How Ice Rink Locations Affect Performance Time in Short-Track Speed Skating.

Purpose: To accurately provide evaluations on how match performance for elite skaters in short track speed skating developed, and whether geographical factors of ice rink locations should be considered apart from technical abilities. We created a dataset containing competition records from the 2013-14 to 2020-21 seasons (500 m event) on the official website. Methods: One-way ANOVA was applied to statistically analyze whether the best performance times exhibited significant differences in varied hosting cities. Performance-time matrix and multivariate regression model were further established to quantitatively explain how geographical factors (longitude, latitude, altitude, and barometric pressure) affected performance. Results: Our findings firstly confirmed that the fastest 500 m finishing times varied due to the hosting cities (P = 0.008) and showed that venue locations could boost or impair performance time with the maximum range of 3.6 s. Meanwhile, latitude (slightly over 46° when performance is maximized) was the most influential factor to account for the performance-time difference in different ice rink locations according to the multivariate regression model, though altitude (1,225 meters when performance is maximized) was also important. Conclusions: In this perspective, elite skaters should check the geographical factors of the venues before they participated in the upcoming competitions, assess the real strength of their rivals, and adopt flexible tactics during training sessions.

The Relationship Between Selected Load-Velocity Profile Parameters and 50 m Front Crawl Swimming Performance.

The purpose of the present study was to establish relationships between sprint front crawl performance and a swimming load-velocity profile. Fourteen male national-level swimmers performed 50 m front crawl and semi-tethered swimming with three progressive loads. The 50 m performance was recorded with a multi-camera system, with which two-dimensional head displacement and the beginning of each arm-stroke motion were quantified. Forward velocity (V50m), stroke length (SL) and frequency (SF) were quantified for each cycle, and the mean value of all cycles, excluding the first and last cycles, was used for the analysis. From the semi-tethered swimming test, the mean velocity during three stroke cycles in mid-pool was calculated and plotted as a function of the external load, and a linear regression line expressing the relationship between the load and velocity was established for each swimmer. The intercepts between the established line and the axes of the plot were defined as theoretical maximum velocity (V0) and load (L0). Large to very large correlations were observed between V50m and all variables derived from the load-velocity profiling; L0 (R = 0.632, p = 0.015), L0 normalized by body mass (R = 0.743, p = 0.002), V0 (R = 0.698, p = 0.006), and the slope (R = 0.541, p < 0.046). No significant relationships of SL and SL with V50m and the load-velocity variables were observed, suggesting that each swimmer has his own strategy to achieve the highest swimming velocity. The findings suggest that load-velocity profiling can be used to assess swimming-specific strength and velocity capabilities related to sprint front crawl performance.

World and European Rowing Medallists Pace With Smaller Variation Than Their Competitors.

Purpose: To establish the relation between pacing pattern and performance, within sex, and number of crew members, at the very highest performance level in World class rowing. Methods: Pacing profiles based on official 500 m split times in 106 A-finals with six contesting boat crews (n = 636 crews), in recent World (2017-2019) and European (2017-2021) championships, were analyzed. The coefficient of variation (CV) and sum of relative differences (SRD) of the split times, and normalized velocities in the four segments of the race, were compared between performance levels, that is, placement (1st-6th), and subgroups based on sex (female or male) and number of crew members (one, two, or four). Statistical tests and resulting p-values and effect sizes (Cohen's d) were used to assess differences between groups. Results: The pacing profiles of the medallists had smaller variation than those of the non-podium finishers (CV = 1.72% vs. CV = 2.00%; p = 4 × 10-7, d = 0.41). Compared to the non-podium finishers, the medallists had lower normalized velocities in the first and second segments of the race, slightly higher in the third segment and higher in the fourth segment. Female crews paced somewhat more evenly than male crews. No significant differences were found in the evenness of pacing profiles between singles, doubles/pairs and quads/fours. Analyses of SRD were overall consistent with analyses of CV. Conclusion: Medal winners in major rowing championships use a more even pacing strategy than their final competitors, which could imply that such a strategy is advantageous in rowing.

Champion Position Analysis in Short Track Speed Skating Competitions From 2007 to 2019.

Purpose: Short track speed skating is a racing sport with racing tactics are equally crucial to speed and technical skating skills. Therefore, to investigate the relationship between starting and finishing positions for elite skaters and subsequently, explore pacing patterns for champions are necessary. Methods: To investigate a pattern of effective tactical positioning strategy, Kendall's tau-b correlations between starting and finishing position were calculated, with 500 m races having the most positive correlation (0.347, P < 0.05). Results: Furthermore, starting position distributions of winners in each round, as well as the fluctuations in champion starting positions across rounds were analyzed. Our findings showed that skaters on the first track were inclined to win the rounds in 500, 1,000, and 1,500 m (28, 28, and 22%, respectively), and the differences between starting and finishing positions for champions were minimized in semi-finals. Meanwhile, the pacing patterns were gaining more fluctuations by the increase of race distances for champions, as the average standard deviation of lap rankings equaled 0.90, 1.15, and 2.21 for 500, 1,000, and 1,500 m races, respectively. Conclusion: In conclusion, elite skaters should adopt flexible tactics at the lowest cost of energy consumption. The overall variability of lap ranking in long-distance races were distinctly higher than it in short distance.

Key Factors Related to Short Course 100 m Breaststroke Performance.

BACKGROUND AND AIM: To identify kinematic variables related to short course 100 m breaststroke performance. METHODS: An automatic race analysis system was utilized to obtain start (0-15 m), turn (5 m before the wall until 10 m out), finish (95-100 m), and clean swimming (the rest of the race) segment times as well as cycle rate and cycle length during each swimming cycle from 15 male swimmers during a 100 m breaststroke race. A bivariate correlation and a partial correlation were employed to assess the relationship between each variable and swimming time. RESULTS: Turns were the largest time contributor to the finishing time (44.30 ± 0.58%), followed by clean swimming (38.93 ± 0.50%), start (11.39 ± 0.22%), and finish (5.36 ± 0.18%). The finishing time was correlated (p < 0.001) with start segment time (r = 0.979), clean swimming time (r = 0.940), and 10 m turn-out time (r = 0.829). The clean swimming time was associated with the finishing time, but cycle rate and cycle length were not. In both start and turns, the peak velocity (i.e., take-off and push-off velocity) and the transition velocity were related to the segment time (r ≤ -0.673, p ≤ 0.006). CONCLUSIONS: Breaststroke training should focus on: (I) 15 m start with generating high take-off velocity, (II) improving clean swimming velocity by finding an optimal balance between cycle length and rate, (III) 10 m turn-out with maintaining a strong wall push-off, and (IV) establishing a high transition velocity from underwater to surface swimming.

Pacing Behavior and Tactical Positioning in 500- and 1000-m Short-Track Speed Skating.

PURPOSE: To explore pacing behavior and tactical positioning during the shorter 500- and 1000-m short-track competitions. METHODS: Lap times and intermediate rankings of elite 500- and 1000-m short-track-skating competitors were collected over the 2012-13 season. First, lap times were analyzed using a MANOVA, and for each lap, differences between sex, race type, final ranking, and stage of competition were determined. Second, Kendall tau-b correlations were used to assess relationships between intermediate and final rankings. In addition, intermediate rankings of the winner of each race were examined. RESULTS: Top-placed athletes appeared faster than bottom-placed athletes in every lap in the 500-m, while in the 1000-m no differences were found until the final 4 laps (P < .05). Correlations between intermediate and final rankings were already high at the beginning stages of the 50-m (lap 1: r = .59) but not for the 1000-m (lap 1: r = .21). CONCLUSIONS: Although 500- and 1000-m short-track races are both relatively short, fundamental differences in pacing behavior and tactical positioning were found. A fast-start strategy seems to be optimal for 500-m races, while the crucial segment in 1000-m races seems to be from the 6th lap to the finish line (ie, after ± 650 m). These findings provide evidence to suggest that athletes balance between choosing an energetically optimal profile and the tactical and positional benefits that play a role when riding against an opponent, as well as contributing to developing novel insights in exploring athletic behavior when racing against opponents.