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The present study discusses the numerical simulation results of swimming similar to manta rays. The complex three-dimensional kinematics of manta rays were implemented to unravel the intricacies of its propulsion mechanisms by using the discrete vortex method (DVM). The DVM replaces the requirement for a structured grid across the computational domain with a collection of vortex elements. This method simplifies grid generation, especially for intricate geometries, resulting in time and effort savings in meshing complex shapes. By modeling the pectoral fins with discrete panels and utilizing vortex rings to represent circulation and wake, the study accurately computes the pressure distribution, circulation distribution, lift coefficient, and thrust coefficient of the manta ray. This study focuses on the modulation of aerodynamic performance by altering the span length and the length change ratio during the downstroke and upstroke motion ( S V ). The manta ray's three-dimensional vortex configurations comprise a combination of vortex rings, vortex contrails, and horseshoe vortices. Analysis of the three-dimensional vortex structure indicates the presence of multiple vortex rings and horseshoe vortex rings at higher S V values, while adequate formation of horseshoe vortices is not observed at lower S V values. In terms of propulsive performance, both lift and thrust increase with S V , while the propulsive efficiency demonstrates its peak at S V = 1.75. The analysis reveals that at higher S V values, the net thrust generated primarily originates from the tip of the fins. Moreover, the study illustrates a significant enhancement in propulsive efficiency, particularly in association with optimal Strouhal numbers ranging between 0.3 and 0.4. The key findings of this study may be used in efficient design of agile autonomous underwater vehicles for marine exploration and surveillance applications. [ABSTRACT FROM AUTHOR]

This note reports on eight observations of inverted swimming behavior by species of ceratioid whipnose anglerfishes in the genus Gigantactis, from the Caribbean, tropical east Atlantic, tropical western Indian Ocean, the north‐east and north‐west Pacific and south‐west Pacific. It covers four putative species and strongly suggests that this is the normal behavior for the genus. A possible reason is briefly discussed. In addition, a new depth record of 5866 m for the ceratioid anglerfish is recorded. [ABSTRACT FROM AUTHOR]

Objective: This study aimed to identify Key Performance Indicators (KPIs) for men's swimming strokes using Principal Component Analysis (PCA) and Multiple Regression Analysis to enhance training strategies and performance optimization. The analyses included all men's individual 100 m races of the 2019 European Short-Course Swimming Championships. Results: Duration from 5 m prior to wall contact (In5) emerged as a consistent KPI for all strokes. Free Swimming Speed (FSS) was identified as a KPI for 'continuous' strokes (Breaststroke and Butterfly), while duration from wall contact to 10 m after (Out10) was a crucial KPI for strokes with touch turns (Breaststroke and Butterfly). The regression model accurately predicted swim times, demonstrating strong agreement with actual performance. Bland and Altman analyses revealed negligible mean biases: Backstroke (0% bias, LOAs − 2.3% to + 2.3%), Breaststroke (0% bias, LOAs − 0.9% to + 0.9%), Butterfly (0% bias, LOAs − 1.2% to + 1.2%), and Freestyle (0% bias, LOAs − 3.1% to + 3.1%). This study emphasizes the importance of swift turning and maintaining consistent speed, offering valuable insights for coaches and athletes to optimize training and set performance goals. The regression model and predictor tool provide a data-driven approach to enhance swim training and competition across different strokes. [ABSTRACT FROM AUTHOR]

Based on a set of printed sources (reports, newspapers) and iconographic archives, this study aims to formalize, between 1896 and 1924, the historical determinants that weighed on the evolution of geography and the development of places intended for the organization of Olympic swimming events with regard to the identity characteristics of the swimmers admitted to participate. The metamorphosis of open water events (1896-1900), reserved for amateur or professional male swimmers, to competitions in the Olympic swimming pool (1924) for athletes of both sexes, was determined by ideological, political and economic choices conducted by the various bodies in charge of their organization. It shows that the spaces of Olympic swimming have been strongly normalized by dominant ideologies of gender, class and race. [ABSTRACT FROM AUTHOR]

Understanding the external load demands of basketball games is fundamental information for training planning and programming. However, there is a scarcity of information about external load during official games at high-level basketball. The purpose of this research was to investigate basketball game external load differences between two elite basketball teams involved in separate competitions. External load demands experienced by forty-six elite basketball players (from two teams) were analyzed using inertial devices during official basketball games. External load was expressed with calculated (PlayerLoad, PL, averaged and in different time epochs) and inertial movement analysis variables (acceleration, deceleration, change of direction and jump). The results showed that the Euroleague team had a higher peak PL in epochs of 30-s (p<.001) and 60-s (p=.02) with moderate and small effect sizes compared to the Eurocup team. The Eurocup team had a significantly higher number of low and moderate accelerations and changes of direction with effect sizes from 0.34 to 1.15. In conclusion, external load demands in basketball vary depending on the team and league therefore practitioners should consider the specific level and style of play when comprising a training plan. Furthermore, practitioners should rely on their own team's external load values for training load management, rather than attempting to adhere to standards established by external sources. [ABSTRACT FROM AUTHOR]

The article presents a framework for a Bioinformatics competition that focuses on 4 key aspects: structure, model, overview, and perspectives. Structure represents the organizational framework employed to coordinate the main tasks involved in the competition. Model showcases the competition design, which encompasses 3 phases. Overview presents our case study, the League of Brazilian Bioinformatics (LBB) 2nd Edition. Finally, the section on perspectives provides a brief discussion of the LBB 2nd Edition, along with insights and feedback from participants. LBB is a biannual team competition launched in 2019 to promote the ongoing training of human resources in Bioinformatics and Computational Biology in Brazil. LBB aims to stimulate ongoing training in Bioinformatics by encouraging participation in competitions, promoting the organization of future Bioinformatics competitions, and fostering the integration of the Bioinformatics and Computational Biology community in the country, as well as collaboration among participants. The LBB 2nd Edition was launched in 2021 and featured 251 competitors forming 91 teams. Knowledge competitions promote learning, collaboration, and innovation, which are crucial for advancing scientific knowledge and solving real-world problems. In summary, this article serves as a valuable resource for individuals and organizations interested in developing knowledge competitions, offering a model based on our experience with LBB to benefit all levels of Bioinformatics trainees. Author summary: There are various methods of learning, and one such approach involves a commonly used in the computing field, fostering competition, where communication, teamwork, group learning, and problem-solving play crucial roles. Similarly, in bioinformatics and computational biology, certain institutions or platforms promote learning through challenges. However, national-level competitions in these domains are relatively scarce. Here, we would like to present a framework for a Bioinformatics competition by showing structure, model, overview, and perspectives, using the League of Brazilian Bioinformatics (LBB) 2nd Edition as case study. LBB is the first bioinformatics competition in Latin America and aims to encompass the diverse multidisciplinary aspects of Bioinformatics and promote networking. In LBB, individuals not only have the opportunity to learn but also get to know one another. Further, to stimulate undergraduate training, we promoted teams with a mixture of different academic backgrounds. This approach promotes integration among participants and facilitates the exchange of information. To ensure that all participants have the opportunity to connect and form teams regardless of their background, we have created the MATCH, a script that allows individuals to be randomly paired with others, enabling them to get to know each other and create teams effectively. This approach fosters collaboration and creates a conducive environment for learning and problem-solving. [ABSTRACT FROM AUTHOR]

Hybrid figures serve as an important component of artistic swimming, however, no prior research has investigated objective indicators for predicting total scores in competition. This study aimed to identify significance of hybrid figure (HF) elements in predicting total scores in artistic swimming competitions and compare these variables between the Beijing team trials and international official competitions. Eight HF variables were measured in the videos from the international artistic swimming competitions, with calibration and measurement of the variables leg height index and leg angle deviation being performed by means of Kinovea. Multiple linear regression was conducted to predict the total scores based on these variables investigated for the international teams, which showed 5 significant predictors including movement frequency, leg height index, leg angle deviation, mean pattern duration, and rotation frequency. Wilcoxon signed-rank test was used to determine the differences in the variables between the Beijing team and the international teams (top 5), which showed significant difference on movement frequency, leg angle deviation, leg height index and total score. When designing hybrid figures choreography of team free routine in artistic swimming, coaches should prioritize appropriate movement frequency, pattern changes and rotations over excessively long durations. Overly complex HF choreography may lead to a decline on performance in artistic swimming competition. [ABSTRACT FROM AUTHOR]

Galeaspids are extinct jawless relatives of living jawed vertebrates whose contribution to understanding the evolutionary assembly of the gnathostome bodyplan has been limited by absence of postcranial remains. Here, we describe Foxaspis novemura gen. et sp. nov., based on complete articulated remains from a newly discovered Konservat-Lagerstätte in the Early Devonian (Pragian, ∼410 Ma) of Guangxi, South China. F. novemura had a broad, circular dorso-ventrally compressed headshield, slender trunk and strongly asymmetrical hypochordal tail fin comprised of nine ray-like scale-covered digitations. This tail morphology contrasts with the symmetrical hypochordal tail fin of Tujiaaspis vividus , evidencing disparity in galeaspid postcranial anatomy. Analysis of swimming speed reveals galeaspids as moderately fast swimmers, capable of achieving greater cruising swimming speeds than their more derived jawless and jawed relatives. Our analyses reject the hypothesis of a driven trend towards increasingly active food acquisition which has been invoked to characterize early vertebrate evolution. [ABSTRACT FROM AUTHOR]

This article analyzes North Atlantic Treaty Organization (NATO) – Russia dynamics in Eastern Europe, focusing on the competition for influence in Georgia and Montenegro with comparisons to Moldova and Ukraine. Whereas all four countries have expressed a desire to join NATO – and Russia has consistently communicated its disapproval – Moscow has pursued divergent means to curb NATO expansion and escalated with tit-for-tat strategies. We argue that whether Russia deployed military strategies, economic levers, political tactics or covert actions has varied according to its relative power projection capacity along with the responses of NATO and the target countries. Where power projection capacity is greater due to its contiguous geography (Georgia, Ukraine), Russia staged military interventions, and where it was weaker, in non-contiguous countries (Montenegro, Moldova), it resorted to non-military means. Russia may be uniformly opposed to NATO expansion, but its strategies to keep its neighbours out of NATO and in Russia's orbit are contingent upon its relative power. [ABSTRACT FROM AUTHOR]

Abstract: Just a few years ago, no one could imagine that ice swimming could evolve into a competitive sport. In the past, people swimming in ice-cold water were called madmen and, at best, were studied as scientific objects. Today regular competitions in ice swimming over different distances (ice mile, ice km, and shorter distances such as 50m, 100m, and 200m), and different disciplines are organized (freestyle, breaststroke, backstroke, butterfly). National championships, as well as continental and world championships, are also held, with new records set regularly. In this overview, we summarize the historical development of ice swimming up to a competitive sport and explore the risks in this nascent sports discipline. [ABSTRACT FROM AUTHOR]

Human papillomavirus (HPV) infection is the most common sexually transmitted disease worldwide and is associated with negative reproductive outcomes because of which it is recommended to postpone medically assisted reproduction (MAR). This raises major concerns for elder infertile couples. We showed that a hyaluronidase-based sperm washing (IALu) procedure blunted the HPV viral load in semen. Here, were report two cases of couples with long-term idiopathic infertility, ascribed to persistent semen HPV detection, finding a beneficial outcome from the use of IALu protocol applied to intra-uterine insemination (IUI). Case 1: A Caucasian couple (female aged 32, male aged 35), complained of having been attempting pregnancy for 4 years. HPV-DNA (genotypes 51 and 54) was detected on sperms. After a first unsuccessful IUI cycle attempt, using standard swim-up selection of spermatozoa, a second IUI cycle using the IALu procedure was associated with a pregnancy and a successful trimester of gestation. Case 2: A Caucasian couple (female aged 43, male aged 52) complained of having been attempting pregnancy for 3 years and showed the detection of HPV-DNA (genotype 66) on sperms. After a first unsuccessful standard IUI cycle attempt, two further IUI cycles using IALu procedure were pursued. The last cycle was associated with a pregnancy and a successful trimester of gestation. Although preliminary, the IALu procedure is a promising approach for straightforward fertility treatments in cases of recurrent HPV-DNA semen detection, avoiding critical latencies. [ABSTRACT FROM AUTHOR]

While the butterfly stroke has received considerable attention in sports science, the origin of the fastest master butterfly swimmers remains unknown. The present study investigated which geographical locations produce the top-performing master butterfly swimmers within their age groups and gender. A total of 26,512 master butterfly swimmers (11,288 women and 15,224 men) competed in 50 m, 100 m and 200 m races in World Masters Championships held between 1986 and 2019. From each swimmer, the year of competition, first name, last name, age group and distance were recorded. Descriptive data were presented using mean, standard deviation, maximum and minimum values, and/or confidence intervals. The top 10 race times for master butterfly swimming and gender were identified for descriptive purposes. Nationalities were then grouped into six categories: the top five nationalities with the most appearances in the top 10 fastest times in butterfly swimming by distance each year and one group consisting of all other nationalities. In the event of a tie, the nationality with the most participants overall was selected. Generalized linear models (GLMs) with a gamma probability distribution and log link function were used to assess the effect of age groups and gender on swimming time. In summary, Germany had the fastest women butterfly master swimmers across all distances, while the USA had the fastest men butterfly master swimmers for all distances. Men covered all distances faster than women and younger swimmers were quicker than older swimmers. The results of this study can be utilized to determine the countries that produce the most successful master butterfly swimmers, providing a foundation for further research to explore the factors that lead to their success. [ABSTRACT FROM AUTHOR]

The goal of this study was to define the individual model characteristics of lactic acid removal after 200m breaststroke competitive load in a female swimmer in relation to different pool lengths (25m vs. 50m). The second goal was methodological and referred to the presentation of newly applied metrological procedures for the Individual Lactate Recovery Profile modeling. Six races from the competitive season 2021/22 were selected, in which the athlete achieved the most valuable results in relation to the FINA score. To establish the metabolic response of the organism to the competition effort, the method of determining the level of lactate concentration in capillary blood (La in mmol/L) was used. Differences between the mean values of variables were established using ANOVA. The polynomial curve equation function was used to create a blood lactate concentration in a function of recovery time model (La-trecovery). The ANOVA showed that there was no statistically significant difference between the monitored variables and the pool length function (p=.097). The maximum achieved blood lactate concentration in the acute race recovery phase was 13.17 ± 2.81 and 12.08 ± 1.80 mmol/L and the given concentration initially occurred in the time of 240.0 ± 85.6 s and 169.3 ± 79.9 s in the 25 and 50m pool, respectively. In relation to the time of complete passive recovery required to establish acidosis at the level of 2 mmol/L (25 and 50m pool) occurred in 1191.7 ± 481.3 s and 1326.7 ± 405.1 s, while the full index of intensity of blood lactate clearance was 135.7 ± 60.7 s/mmol/L and 124.0 ± 60.7 s/mmol/L for 25m and 50m pool, respectively, although no statistically significant difference was found between the parameters of recovery in relation to pool length. The offered mathematical models enabled a practical individual approach to controlling the specific adaptation to training for achieving a higher competitive level performance. [ABSTRACT FROM AUTHOR]

Sport has long been considered a social phenomenon that addresses all people, being a right recognised at international and national levels. Initially, adapted sport was a means of medical recovery and a means of spending free time in a pleasant way alongside peers with and without disabilities. Subsequently, adapted sport has turned into a means of comparing the motor skills of contestants having the same medical problems during competitions specially organized for these athletes. In recent years, there has been an increase in the number of people with disabilities who play sports but also in the number of non-disabled people who, in one form or another, get involved in adapted sport. In the present study, we aim to highlight the progress achieved in learning and consolidating the swimming technique by an athlete with Down syndrome (aged 25) who has been practising swimming as a recreational activity for 1 year. Based on certain items, the swimming technique was assessed for the three styles known to the athlete, and the means used in the 18 training sessions conducted over 7 months aimed at achieving the goals established at the beginning of the study. Structured, participatory and systematic observation, documentation, mathematical statistics and graphical representation are the methods used to complete the case study. At the end of the study, we could conclude that the athlete has obviously progressed, which is revealed by the assessments carried out. However, the process of learning and improvement had to be continued for the athlete to succeed in swimming correctly and be able to participate in swimming competitions without being disqualified because of technical errors. [ABSTRACT FROM AUTHOR]

Simple Summary: Adolescent swimmers perform a lot of physical training with the aim of improving their performance in the sport. To achieve this goal, their diet must be adequate. In this scenario, studies have suggested that amino acids and acylcarnitines can improve the physical performance of athletes. However, we still do not have information as to whether the same occurs for adolescent swimmers. Thus, we compared amino acids and acylcarnitines present in the blood of adolescent swimmers of both sexes. We also correlated these substances with the performance of athletes. Our results showed that among amino acids and acylcarnitines, only tyrosine was lower in female adolescent swimmers when compared to male athletes. Additionally, significant associations between the female swimmers with tyrosine were observed. Future studies are necessary to understand this relationship, offering new possibilities for nutrition applied to the performance of adolescent swimmers. The main aim of this study was to compare the performance over different distances, the critical velocity (CV), and plasma acylcarnitines/amino acids of male and female adolescent swimmers. Moreover, we applied the complex network approach to identify which molecules are associated with athletes' performances. On the first day under a controlled environment, blood samples were collected after 12 h of overnight fasting. Performance trials (100, 200, 400, and 800-m) were randomly performed in the subsequent four days in a swimming pool, and CV was determined by linear distance versus time mathematical function. Metabolomic analyses were carried out on a triple quadrupole mass spectrometer performing electrospray ionization in the positive ionization mode. No difference was observed between the performance of male and female swimmers. Except for 200-m distance (p = 0.08), plasma tyrosine was positively and significantly associated with the female times during the trials (100-m, p = 0.04; 400-m, p = 0.04; 800-m, p = 0.02), and inversely associated with the CV (p = 0.02). The complex network approach showed that glycine (0.406), glutamine (0.400), arginine (0.335), free carnitine (0.355), tryptophan (0.289), and histidine (0.271) were the most influential nodes to reach tyrosine. These results revealed a thread that must be explored in further randomized/controlled designs, improving the knowledge surrounding nutrition and the performance of adolescent swimmers. [ABSTRACT FROM AUTHOR]

Magnetically actuated small-scale robots have great potential for numerous applications in remote, confined, or enclosed environments. Multiple small-scale robots enable cooperation and increase the operating efficiency. However, independent control of multiple magnetic small-scale robots is a great challenge, because the robots receive identical control inputs from the same external magnetic field. In this article, we propose a novel strategy of completely decoupled independent control of magnetically actuated flexible swimming millirobots. A flexible millirobot shows a crawling motion on a flat plane within an oscillating magnetic field. Millirobots with different magnetization directions have the same velocity response curve to the oscillating magnetic field but with a difference of phase. We designed and fabricated a group of up to four heterogeneous millirobots with identical geometries and different magnetization directions. According to their velocity response curves, an optimal direction of oscillating magnetic field is calculated to induce a desired velocity vector for the millirobot group, one of which is nonzero and the others are approximately zero. The strategy is verified by experiments of independent position control of up to four millirobots and independent path following control of up to three millirobots with small errors. We further expect that with this independent control strategy, the millirobots will be able to cooperate to finish complicated tasks. [ABSTRACT FROM AUTHOR]

This research is a way to solve a problem that has been presented for several years, on the selection of sports talent in the province of Santi Espíritus, not only in a single category but in the different categories of swimming at provincial and national level: the selection of talent is the most important indicator in swimming and in the different sports without it there would not be high results in competitions, however, despite its importance this is a little researched aspect in the sports sphere of swimming, so this work aims: Systematize the theoretical and methodological aspects of the selection of swimming talent with the intention, since this sport is paramount in the triathlon to go out in the first group of swimming in competitions and a good final result. Experiential Experiential, Historical-Logical and Synthesis Analysis methods were used in this research. This work is useful for swimmers and especially for coaches, both in swimming and triathlon, I know that they will be able to use this document as a working tool or as reference material. Thus, it was concluded that when a proper selection occurs, once the athletes captured for the national team can improve their results from the comparison with reality and that these athletes go to international events the results in swimming are far away and the career of these athletes is lousy, therefore, it is insisted on making a good selection of talents in swimming to be in the elite in the sport of triathlon. [ABSTRACT FROM AUTHOR]

Quantum entanglement brings high-speed and inherently privacy-preserving transmission for information communication in quantum networks. The qubit scarcity is an important issue that cannot be ignored in quantum networks due to the limited storage capacity of quantum devices, the short lifespan of qubits, and so on. In this article, we first formulate the qubit competition problem as the Cooperative-Qubit-Allocation-Problem (CQAP) by taking into account both the waiting time and the fidelity of end-to-end entanglement with the given transmission link set. We then model the CQAP as a Markov Decision Process (MDP) and adopt a Reinforcement Learning (RL) algorithm to self-adaptively and cooperatively allocate qubits among quantum repeaters. Further, we introduce an Active Learning (AL) algorithm to improve the efficiency of the RL algorithm by reducing its trial-error times. Simulation results demonstrate that our proposed algorithm outperforms the benchmark algorithms, with 23.5 ms reduction on the average waiting time and 19.2 improvement on the average path maturity degree, respectively. [ABSTRACT FROM AUTHOR]

Microswimmer and miniswimmer toward precision-targeted medicine have attracted extensive attention recently. We have developed an autonomous manipulation approach for magnetic-driven helical miniswimmer at low Reynolds number in the horizontal plane ($H$ -plane). Different from our previous work which just makes the barycenter of miniswimmer on the reference path as well as takes the swimming direction not into consideration in planar path following, our control policy in this article can make the miniswimmer to follow the reference path and, at the same time, its swimming direction is also along the reference path. A robust tracking method is employed to locate the helical miniswimmer in real time. Due to different external disturbances, an angle compensating model in the global coordinate frame is developed by radial basis function (RBF) networks trained by backpropagation algorithms, which is used to express the swimming model of the helical miniswimmer facing the gravity and lateral disturbances. A discrete-time optimal controller is formulated based on the linear-quadratic feedback control. Simulations and experiments are conducted to quantitatively validate the autonomous manipulation, and the results show the control performance with submillimeter accuracy in the $H$ -plane. Note to Practitioners: This article is motivated by the potential application of precision-targeted medicine using magnetic-driven microswimmer/miniswimmer. The formulated controller employs the error model in the horizontal plane to design the control law. Simulations and experiments validate the effectiveness of the proposed discrete-time optimal control scheme using magnetic-driven miniswimmers. [ABSTRACT FROM AUTHOR]

This study extends the research frontier of relay swim team selection. In particular, the extension is to select the optimum teams for a club competing at a masters competition. The model uses an integer optimisation routine to select several teams of different cumulative ages who fall into the age classification categories defined at masters level. Data analysed to demonstrate the method is based on the best times of masters competitors for a swimming club in South Africa. [ABSTRACT FROM AUTHOR]

Purpose: The aim of this study was to investigate the correlations of lower limb power and jump height in the SJ, CMJ, ACMJ and CJ30s tests with time, speed, force, power, and work done during dolphin kick. Methods: Seventeen female swimmers and seventeen male swimmers of an elite swimming sports school in Poland participated in the study. The parameters being recorded and used in the analysis were the jump height and lower limb power in jump tests. In the test of 25 meters of dolphin kick in swimming at maximum pace, the results used in the analysis were the mean values of time, velocity, power, force and work. Results were expressed as means ± standard deviations. Descriptive statistics of the groups were then compiled to finally perform Pearson correlation calculations. Results: The highest correlations occurred between lower limb power during jumps and swimming speed, especially for men in the ACMJ (r = 0.5468, p = 0.023) and SJ (r = 0.5411, r = 0.025) tests. Jump height was not as often and strongly correlated with swimming time and speed as lower limb power. An important observation is that no statistically significant correlations were found for power, force and work during dolphin kick with lower limb power and jump height. Conclusions: The present study showed strong correlations between the performance variables of swimmers on dry land and in water. The most important finding is that the power during all the jumps (ACMJ, SJ, CJ30s and CMJ) was strongly correlated with the time and speed of swimming using dolphin kick. [ABSTRACT FROM AUTHOR]

Swimming coaches provide regular timed and technical feedback to swimmers and guide them efficiently in training sessions. Due to the complexity of swimmers' performance, which is not visible in qualitative observation, quantitative and objective performance evaluation can better assist the coach in this regard. Inertial measurement units (IMUs) are used in swimming for objective performance evaluation. In this study, we propose a new performance evaluation feedback (SmartSwim) using IMU and investigate its effects on the swimmer's weekly progress. Measurements were conducted each week with 15 competitive swimmers for 10 weeks using a Sacrum IMU. The SmartSwim report included a comprehensive representation of performance based on goal metrics of each phase extracted from the IMU signals. The swimmers were divided into two groups: the experimental and control groups. The SmartSwim report for each swimmer in the experimental group was given to the coach, who used it to adjust the training accordingly. The results showed that the experimental group outperformed the control group when comparing each swimmer, each session and the whole sessions. At the level of each individual, more members of the experimental group showed significant downward trend of average lap time (Mann-Kendall trend test, 95% confidence level). While comparing the sessions, the experimental group showed significantly lower lap time than the control group from the sixth session onwards (p-value < 0.05 from t-test). Considering all sessions, the experimental group showed significantly higher progress, lower average lap time, and more consistent records (Mann-Whitney U test at 95% confidence level) than the control group. This study demonstrated that SmartSwim can assist coaching by quantitatively assessing swimmers' performance, leading to more efficient training. [ABSTRACT FROM AUTHOR]

Strict lockdown measures were introduced in response to the COVID-19 pandemic, which caused mass disruption to adolescent swimmers' daily routines. To measure how lockdown impacted nutritional practices in this cohort, three-day photograph food diaries were analysed at three time points: before (January), during (April), and after (September) the first UK lockdown. Thirteen swimmers (aged 15 ± 1 years) from a high-performance swimming club submitted satisfactory food diaries at all time points. During lockdown, lower amounts of energy (45.3 ± 9.8 vs. 31.1 ± 7.7 kcal∙kg BM∙day-1, p<0.001), carbohydrate (5.4 ± 1.2 vs. 3.5 ± 1.1 g∙kg BM∙day-1, p<0.001), protein (2.3 ± 0.4 vs. 1.7 ± 0.4 g∙kg BM∙day-1, p = 0.002), and fat (1.6 ± 0.4 vs. 1.1 ± 0.3 g∙kg BM∙day-1, p = 0.011) were reported. After lockdown, no nutritional differences were found in comparison compared to before lockdown (energy: 44.0 ± 12.1 kcal∙kg BM∙day-1; carbohydrate: 5.4 ± 1.4 g∙kg BM∙day-1; protein: 2.1 ± 0.6 g∙kg BM∙day-1; fat: 1.5 ± 0.6 g ∙kg BM∙day-1, all p>0.05), despite fewer training hours being completed (15.0 ± 1.4 vs. 19.1 ± 2.2 h∙week-1, p<0.001). These findings highlight the ability of adolescent swimmers to alter their nutrition based on their changing training circumstances when receiving sport nutrition support. However, some individuals displayed signs of suboptimal nutrition during lockdown that were not corrected once training resumed. This warrants future research to develop interactive education workshops that maintain focus and motivation towards optimal nutrition practices in isolated periods away from training. [ABSTRACT FROM AUTHOR]

Objective: To establish reference data on required competition age regarding performance levels for both sexes, all swimming strokes, and race distances and to determine the effect of competition age on swimming performance in the context of other common age metrics. In total, 36,687,573 race times of 588,938 swimmers (age 14.2 ± 6.3 years) were analyzed. FINA (Fédération Internationale de Natation) points were calculated to compare race times between swimming strokes and race distances. The sum of all years of race participation determined competition age. Results: Across all events, swimmers reach top-elite level, i.e. > 900 FINA points, after approximately 8 years of competition participation. Multiple-linear regression analysis explained up to 40% of variance in the performance level and competition age showed a stable effect on all race distances for both sexes (β = 0.19 to 0.33). Increased race distance from 50 to 1500 m, decreased effects of chronological age (β = 0.48 to − 0.13) and increased relative age effects (β = 0.02 to 0.11). Reference data from the present study should be used to establish guidelines and set realistic goals for years of competition participation required to reach certain performance levels. Future studies need to analyze effects of transitions between various swimming strokes and race distances on peak performance. [ABSTRACT FROM AUTHOR]

Purpose: The purpose of this study was to assess the influence of physiological and kinematic predictors on 400-m front crawl race in young male swimmers and to consider the interrelation between them. Methods: Nineteen male swimmers took part in this study (age: 13.5 ± 0.44 years, height: 168.6 ± 7.77 cm, body mass: 56.9 ± 10.57 kg). Measurements of physiological parameters were conducted using expired air analyzer (Start 2000 MES, Poland) during step-test in water flume. Kinematic indices were computed while analyzing video recording of 400-m front crawl race. To check for possible influence of biological age (BA) diversity in studied group, partial correlation with age control was computed. Results: Swimming to exhaustion in water flume defined as speed at maximum oxygen uptake and anaerobic threshold (VO2 max V & and VAT) occurred to be strongly positively correlated with 400-m race speed. Speed in surface swimming zones (Vsurface) was related to ability of kinematics adjustment and significantly correlated with stroke index (SI). Vsurface at the beginning and the end of the race, i.e., at 1st, 7th and 8th lap interplayed with stroke rate (SR) measured at corresponding laps. Conclusions: Our study showed that 400-m front crawl performance of young male swimmers is strongly dependent on swimming efficiency developed with aerobic conditioning. Significant role of proper pacing strategy was also identified, which indicates that race pace training should be implemented. [ABSTRACT FROM AUTHOR]

The nutritional intake of elite open water swimmers during competition is not well established, and therefore this case study aims to provide new insights by describing the feeding strategies adopted by an elite female swimmer (28 yrs; height; 1.71 m; body mass: 60 kg; body fat: 16.0%) in the FINA open water Grand Prix 2014.Seven events of varying distances (15-88 km) and durations (3-12 hrs) were included. In all events, except one, feeds were provided from support boats. Swimmer and support staff were instructed to track in detail all foods and beverages consumed during the events. Nutritional information was gathered from the packaging and dietary supplements labels and analyzed by nutrition software. Mean carbohydrate (CHO) and protein intake reached 83 ± 5 g-h-1 and 12 ± 8 g·h-1, respectively. Fat intake was neglected (~1 g·h-1). Mean in-race energy intake reached 394 ± 26 kcal·h-1. Dietary supplements in the form of sport beverages and gels, containing multitransportable CHO, provided 40 ± 4 and 49 ± 6% of all CHO energy, respectively. Caffeine (3.6 ± 1.8 mg·kg-1 per event) and sodium (423 ± 16 mg±h-1) were additionally supplemented in all events. It was established that continuous intake of high doses of CHO and sodium and moderate dose of caffeine were an essential part of the feeding strategy for elite-level high intensity ultra-endurance open-water swimming races. A well scheduled and well-prepared nutrition strategy is believed to have ensured optimal individual performance during Grand Prix events. [ABSTRACT FROM AUTHOR]

Mantis shrimp swim via metachronal rowing, a pattern in which the pleopods (swimming limbs) stroke sequentially, starting with the last pair and followed by anterior neighbors. A similar swimming pattern is used at various sizes, Reynolds numbers, and advance ratios by diverse organisms including ciliates, ctenophores, copepods, krill, and lobsters. Understanding this type of locomotion is important because it is widespread and may inspire the design of underwater vehicles where efficiency, robustness, and maneuverability are desired. However, detailed measurements of the flow around free-swimming, metachronally rowing organisms are scarce, especially for organisms swimming in a high Reynolds number regime (Re   ≥   104). In this study, we present time-resolved, planar PIV measurements of a swimming peacock mantis shrimp (Odontodactylus scyllarus). Simultaneous kinematics measurements of the animal, which had body and pleopod lengths of 114 and 20 mm, respectively, reveal mean swimming speeds of 0.2–1.9 m s−1 and pleopod beat frequencies of 3.6–13 Hz, corresponding to advance ratios of 0.75–1.84 and body-based Reynolds numbers of 23,000–217,000. Further, the animal's stroke is not purely metachronal, with a long phase lag between initiation of the first and fifth pleopod power strokes. Flow measurements in the sagittal plane show that each stroking pleopod pair creates a posteriorly moving tip vortex which evades destruction by the recovery strokes of other pleopod pairs. The vortex created by the anteriormost pleopod pair is the strongest and, owing to the animal's high advance ratio, is intercepted by the power stroke of the posteriormost pleopod pair. The vortex strength increases as a result of this interaction, which may increase swimming speed or efficiency. A relationship for vortex interception by the posterior pleopod is proposed that relates the phase lag between the interacting pleopods to the beat frequency, distance between those pleopods, and speed of the vortex relative to the animal. We describe this interaction with a novel parameter called the interpleopod vortex phase matching Strouhal number St IVPM which is equal to the phase lag between interacting pleopods. This new nondimensional parameter may be useful in predicting the conditions where a constructive interaction may occur in other species or in physical models. Finally, we relate the advance ratio to the Reynolds number ratio, the ratio between the body-based Reynolds number and the pleopod-based Reynolds number. The importance of these parameters in promoting the interpleopod vortex interactions identified here, in dynamically scaled experiments, and in wake signatures behind schooling metachronal swimmers is discussed. [ABSTRACT FROM AUTHOR]

Several active organisms in nature tend to reside as a community in viscous fluid media. We analyze the variation of the swimming characteristics of an active swimmer present in a dilute and disperse suspension, modeled as an effective Brinkman medium. This idealized representation of a collection of active swimmers allows one to distinguish the impact of the interior domain available to an individual swimmer as well as the contribution of its neighbors. Darcy's law along with an analytical solution enable the effective resistivity to be predicted as a function of the volume fraction, which is in close agreement with the well-known Carman–Kozeny equation. This facilitates the successive analysis of the propulsion speed, power dissipation, and swimming efficiency of the targeted swimmer—which are decisive in nutrient transport and uptake or reproduction in a collective environment—as a function of the volume fraction. A stress-jump condition is also imposed across a cell to indicate the mean effective force due to nearby swimmers. For suitable values of this stress-jump coefficient, the relative increase in migration velocity and swimming efficiency is noticeably higher at an optimum occupancy. To highlight the rheological characteristics, we have analyzed the effective viscosity of the active suspension, which varies distinctively from a random suspension and alludes to self-assembly. [ABSTRACT FROM AUTHOR]

The study aimed to investigate the effects of time-of-day, chronotype, and sex differences on the relationships between anxiety, depression, sleep quality, and swimming performance of normally diurnally active adolescent athletes. Thirty-three competitive swimmers, 20 boys (14.8 ± 1.60 y) and 13 girls (14.4 ± 1.51 y) from two different swimming centers participate in the study. They performed 50 m and 400 m front crawl trials twice, at 08:00 h and 18:00 h, with an interval of 48 h in a 50 m swimming pool. Chronotype, depression, anxiety levels, and sleep quality were accessed by questionnaires. No effect of time-of-day was observed in girls for the 50 and 400 m trials. The swimming performance of boys was similar in the 50 m trials independent of time-of-day, but in the 400 m trial the performance time was better in the evening compared to morning. The best evening performance was observed among N-types. Linear regression analysis of the data of all participants revealed a positive correlation between sleep quality and anxiety level (p =.016; R2 = 0.1769) and sleep quality and depression level (p =.006; R2 = 0.2192). There was no correlation between chronotype and sleep quality in either sex (p =.4044; R2 = 0.0232). We conclude that time-of-day can influence the performance of adolescent swimmers that differs with the distance of the trial and by sex. We also demonstrated the importance of sleep quality among adolescents swimmers as a factor that can influence anxiety and depression and thus consequently affect their performance. [ABSTRACT FROM AUTHOR]

Aim: The aim was to predict and understand variations in swimmer performance between individual and relay events, and develop a predictive model for the 4x200-m swimming freestyle relay event to help inform team selection and strategy. Data and methods: Race data for 716 relay finals (4 x 200-m freestyle) from 14 international competitions between 2010–2018 were analysed. Individual 200-m freestyle season best time for the same year was located for each swimmer. Linear regression and machine learning was applied to 4 x 200-m swimming freestyle relay events. Results: Compared to the individual event, the lowest ranked swimmer in the team (-0.62 s, CI = [−0.94, −0.30]) and American swimmers (−0.48 s [−0.89, −0.08]) typically swam faster 200-m times in relay events. Random forest models predicted gold, silver, bronze and non-medal with 100%, up to 41%, up to 63%, and 93% sensitivity, respectively. Discussion: Team finishing position was strongly associated with the differential time to the fastest team (mean decrease in Gini (MDG) when this variable was omitted = 31.3), world rankings of team members (average ranking MDG of 18.9), and the order of swimmers (MDG = 6.9). Differential times are based on the sum of individual swimmer's season's best times, and along with world rankings, reflect team strength. In contrast, the order of swimmers reflects strategy. This type of analysis could assist coaches and support staff in selecting swimmers and team orders for relay events to enhance the likelihood of success. [ABSTRACT FROM AUTHOR]

The timing of sodium bicarbonate (NaHCO3) supplementation has been suggested to be most optimal when coincided with a personal time that bicarbonate (HCO3–) or pH peaks in the blood following ingestion. However, the ergogenic mechanisms supporting this ingestion strategy are strongly contested. It is therefore plausible that NaHCO3 may be ergogenic by causing beneficial shifts in the strong ion difference (SID), though the time course of this blood acid base balance variable is yet to be investigated. Twelve highly trained, adolescent swimmers (age: 15.9 ± 1.0 years, body mass: 65.3 ± 9.6 kg) consumed their typical pre-competition nutrition 1–3 hours before ingesting 0.3 g∙kg BM-1 NaHCO3 in gelatine capsules. Capillary blood samples were then taken during seated rest on nine occasions (0, 60, 75, 90, 105, 120, 135, 150, 165 min post-ingestion) to identify the time course changes in HCO3–, pH, and the SID. No significant differences were found in the time to peak of each blood measure (HCO3–: 130 ± 35 min, pH: 120 ± 38 min, SID: 98 ± 37 min; p = 0.08); however, a large effect size was calculated between time to peak HCO3– and the SID (g = 0.88). Considering that a difference between time to peak blood HCO3– and the SID was identified in adolescents, future research should compare the ergogenic effects of these two individualized NaHCO3 ingestion strategies compared to a traditional, standardized approach. [ABSTRACT FROM AUTHOR]

Polygonatum kingianum Coll & Hemsl is an important Chinese medicine used for enhancing physical function and anti-fatigue, and polysaccharides (PKPs) are considered as the main bioactive components. However, the mechanisms through which PKPs exert their anti-fatigue effects are not fully understood. This study aimed more comprehensively to explore the anti-fatigue mechanisms of PKPs, focusing on metabolism, protein expression, and gut flora, by using exhaustive swimming experiments in mice. Results showed a significant increase in the exhaustive swimming time of the mice treated with PKPs, especially in the high-dose group (200 mg/kg/day). Further studies showed that PKPs remarkably improves several fatigue-related physiological indices. Additionally, 16S rRNA sequence analysis showed that PKPs increased antioxidant bacteria (e.g., g_norank_f_Muribaculaceae) and the production of short-chain fatty acids (SCFAs), while reducing the abundance of harmful bacteria (e.g., g_Escherichia-Shigella and g_Helicobacter). PKPs also mitigated oxidative stress through activating the NRF2/HO-1 signaling pathway, and promoted energy metabolism by upregulating the expression of AMPK/PGC-1α/TFAM signaling pathway proteins. This research may offer theoretical support for incorporating PKPs as a novel dietary supplement in functional foods targeting anti-fatigue properties. • Polygonatum kingianum Coll & Hemsl polysaccharides (PKPs) can relieve fatigue. • PKPs suppress oxidative stress and upregulate energy metabolism related proteins. • PKPs reduce the abundance of g_Escherichia-Shigella and g_Helicobacter. • PKPs increase levels of short chain fatty acids (SCFAs) in mice. [ABSTRACT FROM AUTHOR]

Polygonatum kingianum Coll & Hemsl is an important Chinese medicine used for enhancing physical function and anti-fatigue, and polysaccharides (PKPs) are considered as the main bioactive components. However, the mechanisms through which PKPs exert their anti-fatigue effects are not fully understood. This study aimed more comprehensively to explore the anti-fatigue mechanisms of PKPs, focusing on metabolism, protein expression, and gut flora, by using exhaustive swimming experiments in mice. Results showed a significant increase in the exhaustive swimming time of the mice treated with PKPs, especially in the high-dose group (200 mg/kg/day). Further studies showed that PKPs remarkably improves several fatigue-related physiological indices. Additionally, 16S rRNA sequence analysis showed that PKPs increased antioxidant bacteria (e.g., g_norank_f_Muribaculaceae) and the production of short-chain fatty acids (SCFAs), while reducing the abundance of harmful bacteria (e.g., g_Escherichia-Shigella and g_Helicobacter). PKPs also mitigated oxidative stress through activating the NRF2/HO-1 signaling pathway, and promoted energy metabolism by upregulating the expression of AMPK/PGC-1α/TFAM signaling pathway proteins. This research may offer theoretical support for incorporating PKPs as a novel dietary supplement in functional foods targeting anti-fatigue properties. • Polygonatum kingianum Coll & Hemsl polysaccharides (PKPs) can relieve fatigue. • PKPs suppress oxidative stress and upregulate energy metabolism related proteins. • PKPs reduce the abundance of g_Escherichia-Shigella and g_Helicobacter. • PKPs increase levels of short chain fatty acids (SCFAs) in mice. [ABSTRACT FROM AUTHOR]

Modern biotechnology and nanotechnology are conducive to the selection and training of athletes, promote the development of Sports Biological Science, and effectively improve athletes' sports ability. In this paper, the main study of modern biology and nanotechnology on the impact of competitive sports. In this paper, eight boys were randomly divided into two groups, one group wore the swimsuit made of nanofiber materials, the other group wore the swimsuit made of common clothing materials for three swimming competitions. The experiment found that in the first competition, the results of the Nano group were mostly higher than the ordinary swimsuit group. Only the No. 3 player in the Nano group scored 9.23 s, which was lower than the 8.99 s of the No. 3 player in the ordinary group. In the second competition, the performance of the Nano group is still higher than that of the ordinary group, except that the No. 2 player in the Nano group has a score of 10.22 s. In the third time, the four members of the frontier Nano group achieved higher scores than the ordinary group. The No. 3 player in the ordinary group had a large error in the results, which was not meaningful.According to the results of the three competitions, under the control of variable factors, the results of nano group are much better than those of ordinary group. The results show that nanotechnology and modern biotechnology can effectively reduce the unnecessary energy consumption of athletes in the competition, save the competition time, and bring new vitality to competitive sports. [ABSTRACT FROM AUTHOR]

Baikal sculpins are a unique group of fishes, including both externally and internally fertilizing species. Sperm traits, such as morphology and motility, are predicted to undergo adaptive changes due to species fertilization modes. However, studies exploring such traits in Baikal sculpins are lacking. Here, we conducted a field study and investigated sperm traits of three sculpins with external fertilization (Cottocomephorus grewingkii, Leocottus kesslerii and Paracottus knerii) and one sculpin with internal fertilization (Comephorus dybowskii). Sperm head morphology was spherical in both types of fertilizing species; however, the head cross‐sectional area of the sperm of the internal fertilizer was smaller than that of external fertilizers. This result implies that sperm head morphology might be adapted to swim in a viscous ovarian fluid. The internal fertilizer, C. dybowskii, had longer and faster‐swimming sperms with longer motility duration than the external fertilizers, perhaps due to different sperm competition levels. Sperms of the internal fertilizer were only motile in isotonic solutions, whereas sperms of the external fertilizers were motile in lake waters, suggesting that sperm motilities are specialized according to their external/internal environments. To our knowledge, this is the first study to demonstrate sperm traits of Baikal sculpins, which may have evolved adaptively along with changing fertilization modes. [ABSTRACT FROM AUTHOR]

The present study investigated whether a difference exists in reactive and proactive control for sport considered open or closed skills dominated. Sixteen young (11–12 years) athletes (eight soccer players and eight swimmers) were asked to be engaged into two games competitions that required either a reactive and a proactive type of control. By means of kinematic (i.e. movement time and duration) and dynamic analysis through the force platform (i.e. Anticipatory Postural Adjustments, APAs), we evaluated the level of ability and stability in reacting and anticipating actions. Results indicated that soccer players outperformed swimmers by showing higher stability and a smaller number of falls during the competition where proactive control was mainly required. Soccer players were able to reach that result by anticipating actions through well-modulated APAs. On the contrary, during the competition where reactive control was mainly required, performances were comparable between groups. Therefore, the development of specific action control is already established at 11–12 years of age and is enhanced by the training specificity. [ABSTRACT FROM AUTHOR]

Understanding the connection between physiology and kinematics of natural swimmers is of great importance to design efficient bio-inspired underwater vehicles. This study looks at high-fidelity three-dimensional numerical simulations for flows over an undulating American eel with prescribed anguilliform kinematics. Particularly, our work focuses on why natural anguilliform swimmers employ wavelengths shorter than their bodylengths while performing wavy kinematics. For this purpose, we vary the undulatory wavelength for a range of values generally observed in different aquatic animals at Strouhal numbers 0.30 and 0.40. We observe that our anguilliform swimmer is able to demonstrate more suitable hydrodynamic performance for wavelengths of 0.65 and 0.80. For longer wavelengths, the swimmer experiences large frictional drag, which deteriorates its performance. The wake topology was dominated by hairpin-like structures, which are closely linked with the underlying physics of anguilliform swimming found in nature. [ABSTRACT FROM AUTHOR]

El presente estudio examinó los niveles de residencia, el optimismo disposicional y las estrategias de afrontamiento como predictores de los niveles de estrés-recuperación y aspectos correlaciónales asociados. 91 nadadores, con edades comprendidas entre 13 y 29 años (M = 15.73; DT = 2.62), participaron en el estudio cumplimentando la siguiente batería de cuestionarios: la Escala de Residencia (RS), la Escala de Orientación hacia la vida-Revisado (LOT-R), el Cuestionario de Estrategias de Afrontamiento en Competición Deportiva (ISCCS) y el Cuestionario de Estrés-Recuperación para Deportistas (RESTQ-Sport). El objetivo principal del estudio fue realizar un modelo predictivo del estrés y de la recuperación en una muestra de nadadores de competición. El modelo de regresión ajustado reveló asociación positiva entre la residencia y el optimismo disposicional con la utilización de estrategias orientadas a la tarea. Elevados niveles de residencia y optimismo se relacionaron con menores niveles de estrés y mayores de recuperación, siendo el modelo invariante al sexo. Nuestros hallazgos reflejan que la residencia, el optimismo disposicional y las estrategias de afrontamiento son características psicológicas que influyen en el estado de forma del deportista. [ABSTRACT FROM AUTHOR]

Some scientific publications (e.g., Luo et al., 2015) mention that expensive Fastskin swimsuits have a special texture to lower hydrodynamic drag and give an advantage in swimming competitions. Our research attempted to investigate that claim. In particular, we measured the skin drag (part of the total passive drag) of different swimsuits using an experimental flume and an Acoustic Doppler Velocimeter (ADV). In the boundary layer, downstream velocity was measured at several distances from the swimsuit surface. The resulting plot of velocity versus distance was curve-fit with an exponential function that decays towards the free-flow velocity as distance increases. From the decay exponent, a metric of drag (proportional to the shear stress on the swimsuit surface) was derived to characterize the skin drag of the swimsuit. Finally, the metric was plotted against the prices of the swimsuits. The result indicates that a more expensive swimsuit does not necessarily give less skin drag than a less expensive swimsuit. We discovered that velocity readings from the ADV near the boundary is biased, and explain that the bias applies consistently to all the swimsuits we tested. Therefore, our conclusion is not affected by the bias. [ABSTRACT FROM AUTHOR]

Researchers sought to identify and analyze the actions of elite swimmers on a competition day that the athletes believed were critical to their success, and to understand the meaning the athletes assigned to each of these activities. The present study describes the competition-day routines of the elite swimmers by presenting the athletes' actions, meanings, segments, and preparations within a substantive grounded theory. To this end, five U.S. Olympic medal-winning male swimmers from the 2008 Beijing Summer Olympic Games participated in a three-stage data collection: an initial interview during a two-day training visit, a competition observation at an elite meet, and a follow-up interview via telephone. In addition, each participant's coach was interviewed. Utilizing constructivist grounded theory (Charmaz, 2006), a substantive theory of a competition-day routine for elite swimmers emerged. Results suggested that athletes understood all their actions during a competition day as one routine, and research of competitive routines should include boththe ostensive (i.e., plan) and performative (i.e., enactment) aspects of routines (Feldman & Pentland, 2003). [ABSTRACT FROM AUTHOR]

This study qualitatively examined the congruence between anticipated and experienced stressors and coping, and approaches to coping by elite adolescent swimmers across a competitive season. Eight swimmers were interviewed before and after 4 swim meets in a season. Data collection and analysis were guided by theories of stress and coping. Accuracy of anticipating stressors was low, and the stressors and coping strategies were variable across the season. Idiographic profiles were created for each athlete and grouped according to similar characteristics. Three groups included athletes who (a) generally perceived stressors as something to be avoided, (b) generally perceived stressors as problems to be solved, or (c) generally perceived swimming as fun and minimally stressful. These patterns appeared to be associated with anticipating stressors, highlighting the complex and dynamic nature of stress and coping among adolescent athletes. [ABSTRACT FROM AUTHOR]

While talent development and the contributing factors to success are hardly discussed among the experts in the field, the aim of the study was to investigate annual variation in competition performance (AVCP), number of races per year, and age, as potential success factors for international swimming competitions. Data from 40'277 long-course races, performed by all individual female starters (n = 253) at the 2018 European Swimming Championships (2018EC) for all 10 years prior to these championships, were analyzed. Relationships between 2018EC ranking and potential success factors, i.e., AVCP, number of races per year, and age, were determined using Pearson's correlation coefficient and multiple linear regression analysis. While AVCP was not related to ranking, higher ranked swimmers at the 2018EC swam more races during each of the ten years prior to the championships (P < 0.001). Additionally, older athletes were more successful (r = -0.42, P < 0.001). The regression model explained highly significant proportions (P < 0.001) and 43%, 34%, 35%, 49% of total variance in the 2018EC ranking for 50m, 100m, 200m, and 400m races, respectively. As number of races per year (β = -0.29 –-0.40) had a significant effect on ranking of 50-400m races, and age (β = -0.40 –-0.61) showed a significant effect on ranking over all race distances, number of races per year and age may serve as success factors for international swimming competitions. The larger number of races swum by higher ranked female swimmers may have aided long-term athlete development regarding technical, physiological, and mental skill acquisitions. As older athletes were more successful, female swimmers under the age of peak performance, who did not reach semi-finals or finals, may increase their chances of success in following championships with increased experience. [ABSTRACT FROM AUTHOR]

We studied the reproduction and population structure of a population of Achelous spinimanus in the region of Ubatuba, Brazil. We collected them monthly, in 2000, in eight sites of different depths (5 to 40 m). The size at the onset of sexual maturity was estimated by the carapace width and the population structure was analyzed based on the size frequency distribution. In total, we collected 402 individuals: 28 juveniles, 105 males and 269 females. In 2000, A. spinimanus reproduced continuously and had a single peak in September–October. This timing contrasts with what has been observed in other populations and may be a local strategy to decrease the interspecific competition with other swimming crabs. The individuals of A. spinimanus from Ubatuba in 2000 were smaller (16.8–93.5 mm) than those from Fortaleza Bay (near Ubatuba) in 1988–1989 (19.0–97.3 mm). We suggest that intense trawling pressure may have contributed to a reduction in the size of individuals. [ABSTRACT FROM AUTHOR]

The poem "The Tribes and Castes of Gujarat; Or what the Gazetteer of the Bombay Presidency does not say" by Gopika Jadeja.