Resultant equations for training load monitoring during a standard microcycle in sub-elite youth football: a principal components approach.

Applying data-reduction techniques to extract meaningful information from electronic performance and tracking systems (EPTS) has become a hot topic in football training load (TL) monitoring. The aim of this study was to reduce the dimensionality of the internal and external load measures, by a principal component approach, to describe and explain the resultant equations for TL monitoring during a standard in-season microcycle in sub-elite youth football. Additionally, it is intended to identify the most representative measure for each principal component. A principal component analysis (PCA) was conducted with a Monte Carlo parallel analysis and VariMax rotation to extract baseline characteristics, external TL, heart rate (HR)-based measures and perceived exertion. Training data were collected from sixty sub-elite young football players during a 6-week training period using 18 Hz global positioning system (GPS) with inertial sensors, 1 Hz short-range telemetry system, total quality recovery (TQR) and rating of perceived exertion (RPE). Five principal components accounted for 68.7% of the total variance explained in the training data. Resultant equations from PCA was subdivided into: (1) explosiveness, accelerations and impacts (27.4%); (2) high-speed running (16.2%); (3) HR-based measures (10.0%); (4) baseline characteristics (8.3%); and (5) average running velocity (6.7%). Considering the highest factor in each principal component, decelerations (PCA 1), sprint distance (PCA 2), average HR (PCA 3), chronological age (PCA 4) and maximal speed (PCA 5) are the conditional dimension to be considered in TL monitoring during a standard microcycle in sub-elite youth football players. Current research provides the first composite equations to extract the most representative components during a standard in-season microcycle in sub-elite youth football players. Futures research should expand the resultant equations within training days, by considering other well-being measures, technical-tactical skills and match-related contextual factors.

Integrating physical and tactical factors in football using positional data: a systematic review.

Background: Positional data have been used to capture physical and tactical factors in football, however current research is now looking to apply spatiotemporal parameters from an integrative perspective. Thus, the aim of this article was to systematically review the published articles that integrate physical and tactical variables in football using positional data. Methods and Materials: Following the Preferred Reporting Item for Systematic Reviews and Meta-analyses (PRISMA), a systematic search of relevant English-language articles was performed from earliest record to August 2021. The methodological quality of the studies was evaluated using the modified Downs and Black Quality Index (observational and cross-sectional studies) and the Physiotherapy Evidence Database (PEDro) scale (intervention studies). Results: The literature search returned 982 articles (WoS = 495; PubMed = 232 and SportDiscus = 255). After screening, 26 full-text articles met the inclusion criteria and data extraction was conducted. All studies considered the integration of physical and tactical variables in football using positional data (n = 26). Other dimensions were also reported, such as psychophysiological and technical factors, however the results of these approaches were not the focus of the analysis (n = 5). Quasi-experimental approaches considered training sets (n = 20) and match contexts (n = 6). One study analysed both training and play insights. Small sided-games (SSG) were the most common training task formats in the reviewed studies, with only three articles addressing medium-sided (MSG) (n = 1) and large-sided games (LSG) (n = 2), respectively. Conclusions: Among the current systematic review, the physical data can be integrated by player's movement speed. Positional datasets can be computed by spatial movement, complex indexes, playing areas, intra-team and inter-team dyads. Futures researches should consider applying positional data in women's football environments and explore the representativeness of the MSG and LSG.

Molecular and cellular basis of hyperassembly and protein aggregation driven by a rare pathogenic mutation in DDX3X.

Current studies estimate that 1-3% of females with unexplained intellectual disability (ID) present de novo splice site, nonsense, frameshift, or missense mutations in the DDX3X protein (DEAD-Box Helicase 3 X-Linked). However, the cellular and molecular mechanisms by which DDX3X mutations impair brain development are not fully comprehended. Here, we show that the ID-linked missense mutation L556S renders DDX3X prone to aggregation. By using a combination of biophysical assays and imaging approaches, we demonstrate that this mutant assembles solid-like condensates and amyloid-like fibrils. Although we observed greatly reduced expression of the mutant allele in a patient who exhibits skewed X inactivation, this appears to be enough to sequestrate healthy proteins into solid-like ectopic granules, compromising cell function. Therefore, our data suggest ID-linked DDX3X L556S mutation as a disorder arising from protein misfolding and aggregation.

Numerical simulations of a swimmer's head and cap wearing different types of goggles.

The aim of this study was to analyse the effect of swimming goggles on swimming hydrodynamics by numerical simulations. An elite swimmer volunteered for this research. The swimmer's head was scanned both without goggles, and while wearing 3 different types of goggles (Nikko, Ankor and Swedish). Numerical simulations were conducted at 2 m/s with the Fluent code. The condition without goggles showed the highest viscous drag (1.65 N), followed by the Ankor (1.64 N), Swedish (1.63 N) and Nikko (1.62 N) goggles, respectively. The highest pressure drag was found in the situation without goggles (11.34 N), followed by the Ankor (10.87 N), Nikko (10.78 N) and Swedish (10.20 N) goggles. The condition without goggles presented the highest total drag (12.99 N), followed by the Ankor (12.52 N), Nikko (12.40 N) and Swedish (11.83 N) goggles. Thus, Swedish goggles yields the best hydrodynamics, followed by the Nikko and Ankor goggles and lastly without goggles. Thus, goggles minimise the swimmer's drag comparing to not wearing any. The design of the goggles may impose varying drag forces and therefore it is advised to use goggles at least in competition.

Effect of seasonal variations on fatty acid composition and nutritional profiles of siluriformes fish species from the amazon basin.

Siluriformes is a highly diverse order of species that exhibit a wide array of morphologies, diets and life strategies. This study evaluated the effect of seasonal variations on the proximate composition, fatty acid composition and nutritional profiles of nine fish species of Siluriformes order from the Amazon Basin. The proximate composition varied throughout seasonal periods with larger differences in total lipid content. Hypophthalmus edentaus showed the largest variation (9.26-26.29%) between drought and flood periods, respectively. The fatty acid composition also varied throughout seasonal periods; the polyunsaturated fatty acid (PUFA) contents significantly (p < 0.05) increased for most of the studied species in the flood period and n-3 fatty acids represented 23% of this increase. Docosahexaenoic acid was the most abundant PUFA during the flood period and Pseudoplatystoma tigrinum (40.17 mg g-1) and Pseudoplatystoma fasciatum (39.93 mg g-1) showed the highest contents. Some species such as Ageneiosus inermis exceed the recommended daily intake of EPA + DHA. All the fish species presented favorable indices of nutritional quality for total lipids. The principal component analysis resulted in a two-principal component model that described 85.15% of the total data variance. It also highlighted that the nine fish species were affected by seasonal variations in their habitat, some to a greater extent than others. The results suggested that the consumption of those fish species contributed to human health.

The Effectiveness of a Dry-Land Shoulder Rotators Strength Training Program in Injury Prevention in Competitive Swimmers.

Competitive swimmers usually undergo large mileage of daily training, in which propulsive force is produced mainly by the upper limbs. Some studies claim that dry-land shoulder rotators injury prevention programs before the in-water swim practice are paramount. However, the effect of shoulder strengthening prior to water training is unclear. This study aimed to analyse the acute effects of training programs conducted on dry land with the goal of preventing shoulder rotators injuries. A group of young swimmers (N = 23) was recruited to participate in this research. The peak torques of shoulder internal and external rotators were assessed before and after the completion of the compensatory strength training program. The isokinetic assessment was performed using two different protocols: 3 repetitions at 60⍛/s and 20 repetitions at 180⍛/s. Except for a trivial reduction in strength after the training program, there were no other significant differences in any of the studied variables (shoulders rotators endurance, strength and muscle balance). All results showed trivial to small effect sizes. Our findings suggest that a compensatory strength training program does not have a significant acute effect on the strength, endurance and muscle balance of shoulder rotators in young swimmers.

Pilot evaluation of an interactive multimedia platform to provide nutrition education to Portuguese adolescents.

BACKGROUND: Obesity prevalence has been rising worldwide and currently is one of the most serious public health problems. Nutrition literacy is important to the development of healthier habits that could help prevent and stem obesity and overweight. The aim of this study was to evaluate the impact of using a multimedia web platform to provide nutrition education to Portuguese adolescents. METHODS: The intervention consisted in a two-week period in which students (n = 1291) had access to an interactive multimedia web platform with nutritional content, and designed for a self-paced learning experience. Students completed a knowledge questionnaire at baseline and immediately after the end of the intervention. RESULTS: The results obtained revealed that 85.8% of the students increased their nutrition knowledge. No gender differences were observed post-intervention. There were significant differences in the knowledge acquisition regarding age (P < 0.001). The baseline knowledge seemed to influence the learning process. CONCLUSIONS: Overall, the intervention had a positive impact. The preliminary results observed will be important for the improvement of the intervention, though they need to be confirmed by further research. Nevertheless, it is safe to say that technology-based assets can be important tools to incorporate and complement health-related interventions in schools.

Anaerobic Threshold Biophysical Characterisation of the Four Swimming Techniques.

The anaerobic threshold (AnT) seems to be not only a physiologic boundary but also a transition after which swimmers technique changes, modifying their biomechanical behaviour. We expanded the AnT concept to a biophysical construct in the four conventional swimming techniques. Seventy-two elite swimmers performed a 5×200 m incremental protocol in their preferred swimming technique (with a 0.05 m·s-1 increase and a 30 s interval between steps). A capillary blood samples were collected from the fingertip and stroke rate (SR) and length (SL) determined for the assessment of [La], SR and SL vs. velocity inflexion points (using the interception of a pair of linear and exponential regression curves). The [La] values at the AnT were 3.3±1.0, 3.9±1.1, 2.9±1 .34 and 4.5±1.4 mmol·l-1 (mean±SD) for front crawl, backstroke, breaststroke and butterfly, and its corresponding velocity correlated highly with those at SR and SL inflection points (r=0.91-0.99, p<0.001). The agreement analyses confirmed that AnT represents a biophysical boundary in the four competitive swimming techniques and can be determined individually using [La] and/or SR/SL. Blood lactate increase speed can help characterise swimmers' anaerobic behaviour after AnT and between competitive swimming techniques.

Behavioral, contextual and biological factors associated with obesity during adolescence: A systematic review.

INTRODUCTION/OBJECTIVE: Adolescence is a critical period for the development of obesity. Obesity arises from a complex interaction between several factors, which are not yet fully understood. Therefore, the purpose of this review was to identify and assess the peer-reviewed scientific literature on the behavioral, contextual and biological factors associated with obesity in adolescents. METHODS: PubMed and Scopus were systematically searched to identify prospective cohort studies concerning the relation between behavioral, contextual and biological factors and obesity in adolescents aged 10 to 18 years. RESULTS: 40 studies published between the year 2000 and 2018 were included. A positive consistent association between genetic factors and obesity during adolescence was found. Also, there is evidence to support the association between socioeconomic status and obesity. There was conflicting evidence for the contribution of dietary intake, physical activity, sedentary behavior, sleep, food store environment, school food environment. For the remaining factors no associations were found, or no conclusions could be drawn due to the limited number of studies identified. CONCLUSIONS: Further prospective studies that assess multiple obesity determinants simultaneously and use state-of-art measures are warranted to aid in the development of effective strategies and interventions to prevent obesity during adolescence.

Neuromuscular and motor patterns in breaststroke technique / Padrões motores e musculares na técnica de bruços

Abstract The aim of this study was to analyze the inter-temporal neuromuscular and motor patterns in breaststroke technique. Five national level male swimmers performed 200 m breaststroke at maximal effort. Electromyography data onbiceps brachii, deltoid anterior, pectoralis major and triceps brachiiwere analysed. The relative duration of active and non-active phase and the average rectified value for the neuromuscular patterns were recorded. The swim bouts were videotaped in sagittal plane with a pair of cameras and the Theme software 5.0 was used toanalyse the detected patterns in each swimmer. The neuromuscular pattern revealed that by the average rectified value the biceps brachiiand triceps brachiiwere increased at the end of the test for swimmers 1 and 5, while biceps brachii. deltoid anteriorand pectoralis majorwere increased for swimmers 2 and 4. Different motor patterns between cycles, and between swimmers were observed.We found similarities between the swimmers, adjusting their style to the technical model. The absence of a neuromuscular pattern for all swimmers could be related to different technical models used by each swimmer, as presented in the motor patterns. These findings suggested that each swimmers adapted their own motor and neuromuscular pattern in a unique and distinct way.

Resumo O objetivo deste estudo consistiu em analisar a relação entre os padrões neuromusculares e motores na técnica do nado de peito. Cinco nadadores masculinos de nível nacional realizaram 200 mnado peito na máxima intensidade.Foram registrados dados de Electromiografia do bicepsbrachii, deltoid anterior, pectoralis major etricepsbrachii. A duração relativa da fase ativa e não ativa e o valor médio retificado dos padrões neuromusculares foram analisados. Os percursos de nado foram gravados no plano sagital e analisados para detectar os padrões motores de cadanadador através do software THÉME software 5.0. Os padrões neuromusculares indicaram, por meio do valor médio retificado que a atividade dos músculos bíceps brachii e tríceps brachii aumentam no final do teste para o nadador 1 e 5, enquanto que o bíceps brachii. deltoid anterior. pectoralis major aumentam para o nadador 2 e 4. Diferentes padrões motores entre ciclos e entre nadadores foram observados, indicando que existem semelhanças entre eles, levando a um ajuste do estilo e modelo técnico de nado. A ausência de um padrão neuromuscular para todos os nadadores poderá estar relacionada com os diferentes modelos técnicos utilizados por cada nadador, como demonstrado nos padrões motores. Esses resultados sugerem que cada nadador adapta o seu padrão motor e muscular de uma forma única e distinta.

Neoadjuvant Trabectedin plus Radiotherapy in High-Grade Sarcoma of the Leg: A Case Report.

Here, we present the case of a 78-year-old male patient with undifferentiated spindle cell sarcoma on the posteromedial surface of the right leg who experienced a long-lasting progression-free survival. Due to an underlying cardiac disease, the patient was not suitable for anthracyclines. In September 2015, he received first-line chemotherapy with trabectedin (Yondelis®) at the approved dosage and regimen - concomitant with external radiotherapy (RT). After the first 9 cycles of trabectedin plus RT given in the neoadjuvant setting, the patient underwent surgical resection. At that stage, we observed a very good pathological response with 80% of necrotic area. The patient resumed the therapy with trabectedin; however, approximately 5 months later, we observed a new nodular heterogeneous lesion with ill-defined margins in the right leg and suggestive of tumor relapse. Subsequently an above-the-knee amputation was performed, and the patient resumed his trabectedin therapy with the same dosage and regimen. In January 2018, almost 2 1/2 years after the start of trabectedin treatment and 30+ cycles of trabectedin, the patient is locoregionally and distant metastatically disease-free. Currently, the treatment with trabectedin is maintained without any significant serious toxicity. Future clinical trials are needed to gain additional insights into the role of trabectedin maintenance therapy until disease progression in the neoadjuvant setting and to identify predictive and prognostic criteria for response to trabectedin in patients with advanced sarcoma.

High-resolution synchrotron-based X-ray microtomography as a tool to unveil the three-dimensional neuronal architecture of the brain.

The assessment of neuronal number, spatial organization and connectivity is fundamental for a complete understanding of brain function. However, the evaluation of the three-dimensional (3D) brain cytoarchitecture at cellular resolution persists as a great challenge in the field of neuroscience. In this context, X-ray microtomography has shown to be a valuable non-destructive tool for imaging a broad range of samples, from dense materials to soft biological specimens, arisen as a new method for deciphering the cytoarchitecture and connectivity of the brain. In this work we present a method for imaging whole neurons in the brain, combining synchrotron-based X-ray microtomography with the Golgi-Cox mercury-based impregnation protocol. In contrast to optical 3D techniques, the approach shown here does neither require tissue slicing or clearing, and allows the investigation of several cells within a 3D region of the brain.

On the nature of the solvated electron in ice Ih.

The water-solvated excess electron (EE) is a key chemical agent whose hallmark signature, its asymmetric optical absorption spectrum, continues to be a topic of debate. While nearly all investigation has focused on the liquid-water solvent, the fact that the crystalline-water solvated EE shows a very similar visible absorption pattern has remained largely unexplored. Here, we present spin-polarized density-functional theory calculations subject to periodic boundary conditions of the interplay between an EE and a number of intrinsic lattice defects in ice Ih. Our results show that the optical absorption signatures in the presence of three unsaturated hydrogen bonds (HB) are very similar to those observed experimentally. Its low-energy side can be attributed to transitions between the EE ground state and a single localized excited level, in a picture that is different from that for the liquid solvent, where this portion has been associated with hydrogen-like s → p excitations. The blue tail, on the other hand, relates to transitions between the EE ground state and delocalized excited states, which is in line with the bound-to-continuum transition interpretations for the EE in liquid water. Finally, we find that, depending on the number of dangling HBs participating in the EE trap, its charge density may spontaneously break the spin degeneracy through exchange interactions with the surrounding electrons, displaying the many-electron quantum nature of the EE problem in ice Ih.

The Functional Test for Agility Performance is a Reliable Quick Decision-Making Test for Skilled Water Polo Players.

The reliability of the Functional Test for Agility Performance has only been evaluated in water polo players in a small group of novice athletes. Thus, the aim of this study was to evaluate the reliability of the Functional Test for Agility Performance in skilled water polo players. Forty-two athletes (17.81 ± 3.24 years old) with a minimum of 5 years of competitive experience (7.05 ± 2.84 years) and playing at the national or international level were evaluated. The Functional Test for Agility Performance is characterized as a specific open decision-making test where a tested player moves as quickly as possible in accordance to a pass made by another player. The time spent in the test was measured by two experienced coaches. Descriptive statistics, repeated measures analysis of variance (ANOVA), 95% limit of agreement (LOA), intraclass correlation coefficient (ICC) and standard error of measurements (SEM) were used for data analysis. Athletes completed the Functional Test for Agility Performance in 4.15 0.47 s. The ICC value was 0.87 (95% IC = 0.80-0.92). The SEM varied between 0.24 and 0.38 s. The LOA was 1.20 s and the CV average considering each individual trial was 6%. The Functional Test for Agility Performance was shown to be a reliable quick decision-making test for skilled water polo players.

Stretching of BDT-gold molecular junctions: thiol or thiolate termination?

It is often assumed that the hydrogen atoms in the thiol groups of a benzene-1,4-dithiol dissociate when Au-benzene-1,4-dithiol-Au junctions are formed. We demonstrate, by stability and transport property calculations, that this assumption cannot be made. We show that the dissociative adsorption of methanethiol and benzene-1,4-dithiol molecules on a flat Au(111) surface is energetically unfavorable and that the activation barrier for this reaction is as high as 1 eV. For the molecule in the junction, our results show, for all electrode geometries studied, that the thiol junctions are energetically more stable than their thiolate counterparts. Due to the fact that density functional theory (DFT) within the local density approximation (LDA) underestimates the energy difference between the lowest unoccupied molecular orbital and the highest occupied molecular orbital by several electron-volts, and that it does not capture the renormalization of the energy levels due to the image charge effect, the conductance of the Au-benzene-1,4-dithiol-Au junctions is overestimated. After taking into account corrections due to image charge effects by means of constrained-DFT calculations and electrostatic classical models, we apply a scissor operator to correct the DFT energy level positions, and calculate the transport properties of the thiol and thiolate molecular junctions as a function of the electrode separation. For the thiol junctions, we show that the conductance decreases as the electrode separation increases, whereas the opposite trend is found for the thiolate junctions. Both behaviors have been observed in experiments, therefore pointing to the possible coexistence of both thiol and thiolate junctions. Moreover, the corrected conductance values, for both thiol and thiolate, are up to two orders of magnitude smaller than those calculated with DFT-LDA. This brings the theoretical results in quantitatively good agreement with experimental data.

The reliability of a functional agility test for water polo.

Few functional agility tests for water polo take into consideration its specific characteristics. The preliminary objective of this study was to evaluate the reliability of an agility test for water polo players. Fifteen players (16.3 ± 1.8 years old) with a minimum of two years of competitive experience were evaluated. A Functional Test for Agility Performance (FTAP) was designed to represent the context of this sport. Several trials were performed to familiarize the athlete with the movement. Two experienced coaches measured three repetitions of the FTAP. Descriptive statistics, repeated measures analysis of variance (ANOVA), 95% limit of agreement (LOA), intraclass correlation coefficient (ICC) and standard error of measurements (SEM) were used for data analysis. It was considered that certain criteria of reliability measures were met. There was no significant difference between the repetitions, which may be explained by an effect of the evaluator, the ability of the players or fatigue (p > 0.05). The ICC average from evaluators was high (0.88). The SEM varied between 0.13 s and 0.49 s. The CV average considering each individual was near 6-7%. These values depended on the condition of measurement. As the FTAP contains some characteristics that create a degree of unpredictability, the same athlete may reach different performance results, increasing variability. An adjustment in the sample, familiarization and careful selection of subjects help to improve this situation and enhance the reliability of the indicators.

The 3D CFD study of gliding swimmer on passive hydrodynamics drag

The aim of this study was to analyze the effect of depth on the hydrodynamic drag coefficient during the passive underwater gliding after the starts and turns. The swimmer hydrodynamics performance was studied by the application of computational fluid dynamics (CFD) method. The steady-state CFD simulations were performed by the application of k - omega turbulent model and volume of fluid method to obtain two-phase flow around a three-dimensional swimmer model when gliding near water surface and at different depths from the water surface. The simulations were conducted for four different swimming pool size, each with different depth, i.e., 1.0, 1.5, 2.0 and 3.0 m for three different velocities, i.e., 1.5, 2.0 and 2.5 m/s, with swimmer gliding at different depths with intervals of 0.25 m, each starting from the water surface, respectively. The numerical results of pressure drag and total coefficients at individual average race velocities were obtained. The results showed that the drag coefficient decreased as depth increased, with a trend toward reduced fluctuation after 0.5m depth from the water surface. The selection of the appropriate depth during the gliding phase should be a main concern of swimmers and coaches.

Relationship between origin of shot and occurrence of goals in competitive men's water polo matches / Relacao entre a origem do arremesso e a ocorrencia do gol em competicao no polo aquatico masculino

Although some similar studies exist in water polo, there are no reports showing a possible association between the occurrence of goals and the origin of shots. The objective of this study was to correlate the origin of shot and the occurrence of goals in an official men's water polo match. Nine teams that competed in seven final matches of the Third National Men's Water Polo League were evaluated. The games were recorded using a camera installed along the length of the pool. Pearson's chi-square test was used to correlate the categorical variables studied. The effect size was calculated by the ratio between the chance of occurrence of a center goal and the chance of occurrence of a goal scored from the lateral position. An α value < 0.05 was adopted in all cases. There was a significant association between the occurrence of goals and origin of shot, with X2 (2) = 14.89 and p = 0.001, i.e., the proportion of goals scored from the center position was higher than that of goals scored from the lateral position. A center shot was 2.70 times more likely to be converted to a goal by the attacker. It can be concluded that a center shot presented a higher chance to be converted to a goal. This finding might be explained by the inability of the technical-tactical defense to organize, permitting closer proximity of the attackers. The same situation does not seem to apply to high-level technical-tactical matches.

Apesar da realização de algumas pesquisas desta natureza no polo aquático, não foram encontrados estudos que mostrem a possível associação entre a ocorrência do gol com a origem da realização do arremesso. Este estudo objetivou relacionar a origem do arremesso e a ocorrência do gol em uma competição oficial de polo aquático masculino. Foram avaliadas nove equipes que disputaram os sete jogos da fase final da III Liga Nacional de Polo Aquático Masculino. Os jogos foram gravados, utilizando-se uma filmadora localizada no sentido do comprimento do campo de jogo. Utilizou-se o Teste Qui-quadrado de Pearson com o objetivo de correlacionar as variáveis categóricas observadas. O tamanho do efeito foi calculado por meio da razão entre a chance do gol ocorrer pela região central, pela chance do gol ocorrer pelas laterais. Em todos os casos, considerou-se α < 0,05. Houve uma associação significativa entre a origem do arremesso e a ocorrência do gol, com X2 (2) = 14,89, (p = 0,001). Ou seja, a proporção de gols realizados pela região central da área de jogo foi maior do que aquela realizada pelas laterais. Um arremesso realizado pela região central teve 2,70 mais chances de ser convertido em gol a favor do atacante. Conclui-se que o arremesso realizado pela região central teve maior chance de ser convertido em gol. Isso pode dever-se a uma incapacidade técnico-tática da defesa se organizar e permitir maior proximidade dos atacantes. Este mesmo cenário parece não se repetir em jogos de maior qualidade técnico-tática.

Performance progression in Brazilian middle-distance runners from early training to peak performance: a pilot study / Evolução da performance de meio-fundistas Brasileiros da formação ao pico de rendimento: um estudo piloto

The aim of this study was to evaluate performance progression in Brazilian middle-distance runners based on the progression of their sports results from early training to peak performance. The sample consisted of the 10 best performance times (800 m and 1500 m) achieved by male runners aged 15 to 19 years in national rankings between 2001 and 2010. The 800-m performance times estimated with the models were 119.14±1.79 s at 15 years of age; 114.36±1.07 s at 16 years; 113.25±1.81 s at 17 years; 110.71±1.60 s at 18 years, and 109.73±1.17 s at 19 years. The prediction of 1500-m performance was 253.89±4.84 s at 15 years of age; 243.40±1.67 s at 16 years; 238.53±1.55 s at 17 years; 232.49±1.59 s at 18 years, and 230.48±2.28 s at 19 years. It is concluded that Brazilian male middle-distance runners achieve their best performance at 22.69±0.42 years of age in the 800-m event and at 22.29±0.34 years in the 1500-m event. These values are within the lower limit described in the literature as optimal age.

O objetivo deste estudo foi analisar a evolução da performance dos corredores de Meio-Fundo Brasileiros com base na progressão dos resultados desportivos obtidos no processo de formação e no pico de rendimento. A amostra constituiu-se dos dez melhores tempos dos rankings nacionais de 2001 a 2010, alcançados pelos corredores nas provas de MF, na faixa etária de 15 a 19 anos, do sexo masculino. Os resultados expressos pelo modelo matemático encontrado apresentam para os 800m aos 15 anos: 119,14±1,79s; 16 anos: 114,36±1,07s; 17 anos: 113,25±1,81s; 18 anos: 110,71±1,60s; 19 anos: 109,73±1,17s. Para os 1.500m constatou-se uma predição da performance aos 15 anos em: 253,89±4,84s; 16 anos: 243,40±1,67s; 17 anos: 238,53±1,55s; 18 anos: 232,49±1,59s; 19 anos: 230,48±2,28s. Conclui-se que a idade ótima de obtenção dos melhores resultados desportivos para os corredores de MF do sexo masculino, no Brasil, em provas de 800m, apresenta-se aos 22.69±0.42 anos e nas provas de 1.500m aos 22.29±0.34 anos. Estes valores situam-se no limite inferior do referido na literatura.

Computational fluid dynamics study of swimmer's hand velocity, orientation, and shape: contributions to hydrodynamics.

The aim of this paper is to determine the hydrodynamic characteristics of swimmer's scanned hand models for various combinations of both the angle of attack and the sweepback angle and shape and velocity of swimmer's hand, simulating separate underwater arm stroke phases of freestyle (front crawl) swimming. Four realistic 3D models of swimmer's hand corresponding to different combinations of separated/closed fingers positions were used to simulate different underwater front crawl phases. The fluid flow was simulated using FLUENT (ANSYS, PA, USA). Drag force and drag coefficient were calculated using (computational fluid dynamics) CFD in steady state. Results showed that the drag force and coefficient varied at the different flow velocities on all shapes of the hand and variation was observed for different hand positions corresponding to different stroke phases. The models of the hand with thumb adducted and abducted generated the highest drag forces and drag coefficients. The current study suggests that the realistic variation of both the orientation angles influenced higher values of drag, lift, and resultant coefficients and forces. To augment resultant force, which affects swimmer's propulsion, the swimmer should concentrate in effectively optimising achievable hand areas during crucial propulsive phases.