Identification of key somatic features that are common and the ones that differ between swim strokes through allometric modeling

The aim of this study was to explore which key somatic features are common to four swim strokes and medley, and specifically to identify which characteristics benefit only specific strokes. Methods: The sample was composed of 130 swimmers (95 males aged 19.5 ± 2.9 years and 35 females aged 18.4 ± 2.8 years). A set of anthropometric variables was used to predict swimming speed in the four swimming strokes and medley. Results: A multiplicative model with allometric body size components was used to identify the demographic and anthropometric predictors of swimming speed. Trunk height and waist circumference were the only variables significantly different among swimming strokes (p < 0.05). Associations between swimming speed and arm length were similar in breaststroke and medley, and in freestyle, backstroke and butterfly (R2 = 60.9%). The model retained as swimming speed predictors the age2, upper body circumference, hand breadth, waist circumference, and subscapular skinfold thickness (these last two had negative associations). Conclusion: All these predictors were common to all four swim strokes and medley. Arm length was also retained as a significant predictor, but this one varied significantly between the four different swim strokes and medley. These findings highlight the importance of having a “V-shape” trunk, longer upper limbs, and large hands as predictors of swimming performanceNG and JM were supported by National Funds (FCT—Portuguese Foundation for Science and Technology) under the project UIDB/DTP/04045/2020.info:eu-repo/semantics/publishedVersio

The kinematic profile of ventral swimming start: sex diversity

It has been suggested that sex distinctions in physiology may affect the swimming performance of each sex differently. Yet, sex-based performance dependency has not been taken into consideration by most of the researchers evaluating swimming start. Therefore, the purpose of this research was to determine the effect of sex heterogeneity on the spatiotemporal characteristics of swimming start by investigating the determinants of its performance. A total of fifty-two international-level swimmers (thirty females and twenty-two males) performed three repetitions of the kick-start up to the 15-m mark. During trials, data were collected using video cameras and instrumented starting block. To search for evidence of differences between the two groups, the one-way ANOVA was conducted. Pearson’s correlation coefficients were calculated between measurements widely used to describe overall starting performance and selected kinematical variables of swimming start. A sex effect was exposed for temporal variables describing all swimming start phases (p ≤ 0.015). Male swimmers, by spending less time during the push-off from the starting block (p = 0.002; ηp2 = 0.18), reaching higher take-off velocity (p &lt; 0.001; ηp2 = 0.29), traveling longer distances during flight (p &lt; 0.001; ηp2 = 0.40), and swimming faster in the water phase (p &lt; 0.001; ηp2 = 0.40), took starting advantage over their female counterparts. Consequently, performance measures such as 5-m, 10-m, and 15-m start times indicated that male participants were faster than females (p &lt; 0.001; ηp2 ≥ 0.40). Only in the group of male swimmers a significant correlation between variables describing overall starting performance (5-m, 10-m, and 15-m times), and variables commonly highlighted as starting performance determining factors (block phase duration, take-off horizontal velocity, and flight distance) was found. The current study shows that the spatiotemporal variables of swimming start, the relation between them as well as overall starting performance, vary by sex. Consequently, the requirement of sex factor and its heterogeneity effect should be included not only in detailed characteristics of separate variables but also in all approaches undertaken. Those findings seem to play a crucial role mainly in swimming start evaluations in post-pubertal age groups of swimmers

ANALYSIS OF RELATIONSHIPS BETWEEN THE LEVEL OF ERRORS IN LEG AND MONOFIN MOVEMENT AND STROKE PARAMETERS IN MONOFIN SWIMMING

The aim of this study was to analyze the error structure in propulsive movements with regard to its influence on monofin swimming speed. The random cycles performed by six swimmers were filmed during a progressive test (900m). An objective method to estimate errors committed in the area of angular displacement of the feet and monofin segments was employed. The parameters were compared with a previously described model. Mutual dependences between the level of errors, stroke frequency, stroke length and amplitude in relation to swimming velocity were analyzed. The results showed that proper foot movements and the avoidance of errors, arising at the distal part of the fin, ensure the progression of swimming speed. The individual stroke parameters distribution which consists of optimally increasing stroke frequency to the maximal possible level that enables the stabilization of stroke length leads to the minimization of errors. Identification of key elements in the stroke structure based on the analysis of errors committed should aid in improving monofin swimming techniqu

Teaching communication for safety in selected water based recreational disciplines

This paper describes the concept of didactic communication and verifies the course of teaching selected disciplines of water based recreation, i.e. swimming (at the standard technique level), handling a sailing boat whilst undertaking simple manoeuvres, and the basics of diving. At the same time, research in the area of experiments conducted in the field of teaching methods of these disciplines was reviewed in terms of teaching effectiveness, as well as the health and safety of the participants, and ways of communicating while in, on and under the water. Communication between an instructor and a student in any environment which is different from the norm, is difficult owing to its specificity. Additionally, teaching skills on, in or under water requires strict observance of safety rules. Lack of student’s readiness to act in a different water environment, be that based on anxiety or fear, may interfere with or, even prevent didactic communication. Consequently, the effectiveness of teaching decreases. The aim of this work is to search for innovative forms of information transfer that will enable a permanent change in the student’s behaviour, especially when acting in a difficult environment – on the water, in the water and under the water. There are premises to believe that immediate verbal instruction and emphasising the metalinguistic function in it should improve the quality and effectiveness of the process of teaching activities in various water based environments

SEARCHING FOR CRITERIA IN EVALUATING THE MONOFIN SWIMMING TURN FROM THE PERSPECTIVE OF COACHING AND IMPROVING TECHNIQUE

This study aims to analysise the selected kinematic parameters of the monofin swimming turn. The high complexity of performing turns is hindered by the large surface of the monofin, which disturbs control and sense of the body in water. A lack of objective data available on monofin swimming turns has resulted in field research connected with the specification of parameters needed for the evaluation of the technique. Therefore, turns observed in elite swimmers contain underlying conclusions for objective criteria, ensuring the highest level of coaching and the improving of turns in young swimmers. Six, high level, male swimmers participated in the study. The subject of the analysis was the fastest turn, from one out of three trial turns made after swimming a distance of 25 m. Images of the turns were collected from two cameras located under water in accordance with the procedures of the previous analyses of freestyle turns. The images were digitized and analysed by the SIMI®- Movement Analysis System. The interdependency of the total turn time and the remaining recorded parameters, constituted the basis for analysis of the kinematic parameters of five turn phases. The interdependency was measured using r- Pearson's correlation coefficients. The novel character of the subject covered in this study, forced interpretation of the results on the basis of turn analyses in freestyle swimming. The results allow for the creation of a diagram outlinig area of search for an effective and efficient monofin swimming turn mechanism. The activities performed from the moment of wall contact until the commencement of stroking seem to be crucial for turn improvement. A strong belief has resulted that, the correct monofin swimming turn, is more than just a simple consequence of the fastest performance of all its components. The most important criteria in evaluating the quality of the monofin swimming turn are: striving for the optimal extension of wall contact time, push-off time and glide tim

Using adolescent interest in swimming to accomplish utilitarian goals of education

As drowning is a serious threat to life, aquatic education is a necessity. The aim of this study was to carry out a quantitative analysis of students’ expressions of interest to participate in swimming activities compared to interests in other forms of physical activity. A total of 1328 girls and boys aged 16–18 years participated in the research. Subjects were at three different levels in nine high schools in a city in Poland. When completing a standardised questionnaire, respondents indicated and ranked five activities in which they were most interested. Relationships between interests, gender and age were analysed. Swimming evoked the most interest in adolescents, which was higher in girls than in boys and more permanent and stable throughout the monitored period. Despite the lack of swimming pools in the schools and the institutional mentoring, adolescents declared interest in swimming in almost each of the examined schools. Motives accompanying these interests are spontaneous in nature. Their skills and behaviours (safety) reveal negligence of the educational system. Adolescents’ interest in aquatic education can be used to shape attitudes towards physical culture and implement the utilitarian goals of education.Keywords: Educational objectives; Adolescent development; Health behaviour; Swimming

Comparison of performance of various leg-kicking techniques in fin swimming in terms of achieving the different goals of underwater activities.

The aim of this study was to compare underwater fin swimming performance using dolphin, flutter and breaststroke kicks with and without diving gear. Performance was evaluated in terms of average swimming velocity. The parameters of spatiotemporal structure of the stroke reflecting to the swimming economy were employed. Conscious modifications in propulsion technique were considered here with the aim of controlling swimming performance. A total of ten professional scuba divers swam at maximal speed underwater for 50m using each of three techniques: dolphin, flutter, or breaststroke kicks. Swimmers' performance was compared between holding their breath and using breathing apparatus. Two cameras recorded their movements in sagittal and transverse planes. The average swimming velocity (vav), stroke length (SL), stroke rate (SR), index of variation of intracycle velocity (VIVIndex) and stroke index (SI) were estimated. Relative to the other techniques, the dolphin kick without a diving gear demonstrated the highest vav and low SI and VIVIndex values, which reflects the most advantageous economy of propulsion at given velocity. Given the lack of statistical differences, using the breaststroke kick and flutter kick when swimming with a diving gear seems to be comparable to dolphin-kick in terms of average velocity and parameters reflecting the economy of propulsion. Thus, a search for fin swimming techniques with the aim of achieving specific goals seemed reasonable. The results suggest, that performance achieved while using various fin swimming techniques was probably controlled by different strategies of leg movements. These strategies revealed differences in a spatiotemporal (SR-SL) structure of the stroke and they were closely associated in terms of the velocity variation decrease

Firms' Default - from Prediction Accuracy to Informational Capacity of Predictors

Research background: Bankruptcy literature is populated with scores of (econometric) models ranging from Altman's Z-score, Ohlson's O-score, Zmijewski's probit model to k-nearest neighbors, classification trees, support vector machines, mathematical programming, evolutionary algorithms or neural networks, all designed to predict financial distress with highest precision. Purpose of the article: We believe corporate default is too an important research topic to be identified with the prediction accuracy only. Despite the wealth of modelling effort, a unified theory of default is yet to be proposed. Due to the disagreement, both on the definition and hence the timing of default as well as on the measurement of prediction accuracy, the comparison (of predictive power) of various models can be seriously misleading. The purpose of the article is to argue for the shift in research focus from maximizing accuracy to the analysis of the information capacity of predictors. By doing this, we may yet come closer to understand default itself. Methodology/methods: We have critically appraised the bankruptcy research literature for its methodological variety and empirical findings. Default definitions, sampling procedures, in and out-of-sample testing and accuracy measurement have all been scrutinized. We believe the bankruptcy models currently used are, using the language of Feyerabend, incommensurable. Findings: Instead of what we call the population of models paradigm (the comparison of predictive power of different models) prevailing today, we propose the model of population paradigm, consisting in the estimation a single unified default forecasting platform for both listed and non-listed firms, and analyze the marginal contribution of the different information sources. In addition to classical corporate financial data, information on both firm's strategic position and its macroeconomic environment should be studied

Profil antropometryczny dorosłych pływaków z Polski na tle analogicznych danych pływaków z Norwegii

The purpose of the research is to compare the somatic parameters of people practicing swimming in different conditions of the geographical environment - in Poland and Norway. The research material was collected by performing anthropometric measurements in a 112 person group of professional swimmers living in Poland and group 21 swimmers from Norway. The mean of the age in the group of Poles was 19.97 years (SD=3.31) and in the group of Norwegians it was 17.11 years (SD=1.05). A series of anthropometric measurements was performed in both research groups. Statistical analyzes were made using the Statistica 13.1 (StatSoft, USA). In summary of the results of the conducted research, it must be emphasized that these indicate differences in the somatic structure of swimmers living and training in Poland and Norway.Celem badań jest porównanie parametrów somatycznych osób uprawiających pływanie w różnych warunkach środowiska geograficznego - w Polsce i w Norwegii. Materiał badawczy, zebrano wykonując pomiary antropometryczne w 112 osobowej grupie wyczynowo trenujących pływaków mieszkających w Polsce oraz w grupie 21 pływaków z Norwegii. Średnia wieku w grupie Polaków wyniosła 19,97 lat, (SD=3,31), a w grupie Norwegów 17,11 lat (SD=1,05). Seria pomiarów antropometrycznych została wykonana w obu grupach badawczych. Analiz statystycznych dokonano przy użyciu oprogramowania Statistica 13.1 (StatSoft, USA). Podsumowując wyniki przeprowadzonych badań, należy podkreślić, że wskazują one na występowanie różnic w budowie somatycznej pływaków zamieszkujących i trenujących w Polsce i w Norwegii