Cinemática do nado crawl : efeitos da pernada em diferentes intensidades de nado

Objetivos: identificar as mudanças no padrão biomecânico do nado crawl com e sem o auxílio da pernada. Métodos: participaram 23 nadadores (as) experientes no treinamento em natação. Os participantes realizaram 12 repetições de 25 m: seis em nado crawl completo (NC) e seis em nado crawl apenas com braçadas (AB), ambas as séries em seis intensidades diferentes. Foram aferidas: (1) velocidade média de nado (VN) pelo quociente entre 10 m e o tempo em s para percorrer estes 10 m centrais de cada 25 m, e (2) frequência média de ciclo de braçadas (FC) pelo quociente entre três ciclos de braçadas, realizados dentro dos 10 m centrais, e o tempo para realizá-los (s). Após, pelo quociente entre VN e FC, obteve-se (3) a distância média percorrida por ciclo de braçadas (DC). Utilizou-se ANOVA fatorial entre as condições (NC e AB) e as seis intensidades, e cálculo de tamanho de efeito entre as diferentes intensidades e condições. Resultados: de modo geral, a pernada foi capaz de incrementar a DC e a VN, em média, 15 e 12%, respectivamente. Não houve alteração estatística na FC. Como esperado, a intensidade de nado alterou, de modo estatístico e sistemático, a DC (reduzindo), a FC (aumentando) e VN (aumentando).Purpose: To identify the changes in the biomechanical pattern of the front crawl stroke with and without the leg kick. Methods: 23 swimmers with experience in swimming training performed twelve 25 m trials: six swimming the front crawl (FCS) and six swimming with the arms only (SAO), both series at six speeds. Kinematics parameters were measured: (1) the average swimming speed (V), by the quotient between 10 m and the time in seconds to swim through the central 10 m of each 25 m, and (2) stroke rate (SR), by the quotient between three stroke cycles, performed within the central 10 m and the time to perform them. After, by the quotient between V and SF, the (3) stroke length (SL) was obtained. Factorial ANOVA (swimming conditions - FCS and SAO and the 6 speeds) was applied. Effect size were calculated. Results: The leg kick was able to increase SL and V on average of 15 and 12% respectively. There was no statistical change in SR. As expected, the swimming speed modified, statistically and systematically, the SL (reducing), the SR (increasing) and the V (increasing)

Análise longitudinal do desempenho, da antropometria e da cinemática do nado de jovens atletas de 8 a 12 anos de idade

A natação é um dos esportes mais praticados em idades precoces, o que evidencia a necessidade de estudos para compreender o desenvolvimento atlético nos anos iniciais e os efeitos da maturação no desempenho. Para verificar possíveis modificações no desempenho a partir de variáveis cinemáticas de nado e crescimento biológico, são necessários dados longitudinais. Buscando encontrar resultados que auxiliem treinadores a elaborar planejamentos específicos para nadadores entre 8 e 12 anos de idade visando o desenvolvimento a longo prazo, três estudos foram desenvolvidos: (i) “Off-season: three-weeks of training cessation does not affect the performance of 12 years old and under age-group swimmers”, cujo objetivo foi investigar possíveis efeitos do destreino no desempenho e cinemática de nadadores entre 8 e 12 anos após 3 semanas de férias, a partir do teste de 200 m nado crawl, controlando estatura e envergadura; (ii) “200-m front crawl performance over a training season in 12 y and under age-group swimmers: growth and technique changes”, cujo objetivo foi analisar e quantificar as mudanças na técnica, antropometria e maturação e estimar suas contribuições no desempenho dos 200 m nado crawl durante uma temporada de treinamentos; (iii) “Evolution of young swimmers’ breast and butterfly strokes technique over a training season: a network analysis”, cujo objetivo foi analisar a cinemática de nado dos nados peito e borboleta de jovens nadadores no início e no final de uma temporada de treinamentos, além de controlar o crescimento e maturação, por meio de análise de redes. Os principais resultados dos estudos foram: (i) três semanas de cessação de treinamento não são suficientes para perda de performance nos 200 m nado crawl de jovens nadadores provavelmente pré púberes; (ii) a técnica apresenta o papel principal no desenvolvimento dos 200 m nado crawl ao longo de uma temporada de treinamentos de nadadores entre 8 e 12 anos de idade; (iii) técnica de nado e maturação são variáveis determinantes para o desenvolvimento dos nados peito e borboleta em jovens nadadores ao longo de uma temporada. Esta dissertação permitiu: (i) entender, de modo mais aprofundado as respostas dos parâmetros cinemáticos de nado e o crescimento de jovens nadadores em testes do nado crawl e dos nados simultâneos; (ii) identificar o trabalho da técnica de nado como primordial para o desenvolvimento de nadadores entre 8 e 12 anos de idade; e (iii) elaborar uma rede de relações que permite compreender a complexidade do desenvolvimento dos nados peito e borboleta em crianças.Swimming is one of the most practiced sports at early ages, which highlights the need for studies to understand the athletic development, including the effects of maturation on performance. To verify possible changes in performance from kinematic variables and biological growth, longitudinal data are required. Seeking to find results that help coaches to develop specific planning for swimmers between 8 and 12 years old looking forward to long-term development, three studies were performed: (i) “Off-season: three-weeks of training cessation does not affect the performance of 12 years old and under age-group swimmers”, whose objective was to investigate possible effects of detraining on the performance and kinematics of 8-12 years old swimmers after 3 weeks of vacation, from the 200-m crawl test, controlling stature and arm span; (ii) “200-m front crawl performance over a training season in 12 y and under age-group swimmers: growth and technique changes”, whose objective was to analyze and quantify changes in technique, anthropometrics and maturation, and estimate their contributions to performance in the 200-m crawl during a training season; (iii) “Evolution of young swimmers’ breast and butterfly strokes technique over a training season: a network analysis”, whose objective was to analyze the kinematics of breast and butterfly strokes in young swimmers in the beginning and in the end of a training season, in addition to controlling growth and maturation, through network analysis. The main results of the studies were: (i) three weeks of training cessation are not enough for loss in the 200-m crawl performance of young swimmers, probably prepubertal; (ii) technique plays the main role in the development of 200-m crawl over a training season of 8-12 years old swimmers; (iii) swimming technique and maturation are determining variables for the development of breastroke and butterfly stroke in young swimmers over a season. This dissertation allowed: (i) to undertand, in a deeper way, the responses of the kinematic parameters of swimming and growth of young swimmers in front crawl and simultaneous strokes tests; (ii) identify the development of swimming technique as essential for the 8-12 years old swimmers’ development; and (iii) to develop a network of relationships that allows us to understand the complexity of the breast and butterfly strokes development in children

The impact of a swimming training season on anthropometrics, maturation, and kinematics in 12-year-old and under age-group swimmers: a network analysis

Understanding fluctuations and associations between swimming performance-related variables provide strategic insights into a swimmer’s preparation program. Through network analysis, we verified the relationships between anthropometrics, maturation, and kinematics changes (1) in 25-m breaststroke (BREAST) and butterfly (FLY) swimming performance, before and after a 47-week swimming training season. Twenty age-group swimmers (n =11 girls: 10.0 ± 1.3 years and n = 9 boys: 10.5 ± 0.9 years) performed a 25-m all-out swim test (T25) in BREAST and FLY techniques, before and after 47 weeks. Three measures of centrality, transformed into a z-score, were generated: betweenness, closeness, and strength. Data were compared (t-test) and effect sizes were identified with Hedges’ g. Large effect sizes were observed for swimming performance improvements in BREAST (32.0 ± 7.5 to 24.5 ± 3.8 s; g = 1.26; 1 = −21.9 %) and FLY (30.3 ± 7.0 to 21.8 ± 3.6 s; g = 1.52; 1 = −26.5 %). Small to moderate effect sizes were observed for anthropometric changes. Moderate effect size was observed for maturity offset changes (−2.0 ± 0.9 to −1.3 ± 1.0; g = 0.73; 1 = 50.9 ± 281 %). Changes in maturity offset, stroke rate (SR), and stroke length for both BREAST and FLY swimming speeds were highlighted by the weight matrix. For betweenness, closeness, and strength, changes in arm span (AS) (BREAST) and stroke length (FLY) were remarkable. The dynamic process of athletic development and the perception of complexity of fluctuations and associations between performance-related variables were underpinned, particularly for simultaneous swimming techniques in age-group swimmers

Effects of exercise modalities on decreased blood pressure in patients with hypertension

This study aimed to evaluate the acute effects of aerobic and resistance exercises on blood pressure and endothelial blood markers. We also correlated post-exercise blood pressure response with baseline cardiovascular parameters in middle-aged patients with hypertension. This cross-sectional study randomized 54 volunteers into the aerobic exercise group (AG, n = 27; 45.6 ± 7.7 years) or dynamic resistance exercise group (RG, n = 27; 45.8 ± 8.4 years). Blood marker evaluation, cardiopulmonary exercise tests, resting blood pressure monitoring, ambulatory blood pressure monitoring (ABPM), flow-mediated dilatation monitoring, and body composition evaluation were carried out. Exercise sessions were performed to evaluate post-exercise hypotension (PEH) and endothelial marker responses, in addition to post-exercise ABPM (ABPMex). This study is an arm of the study which was approved by the local ethics committee (No. 69373217.3.0000.5347) in accordance with the Helsinki Declaration and was registered at ClinicalTrials. gov (NCT03282942). The AG performed walking/running at 60% of the reserve heart rate, while the RG performed 10 exercises with two sets of 15–20 repetitions. The mean 24 h ABPM and ABPMex values showed no significant statistical differences. Systolic and diastolic blood pressure hypotension after aerobic and dynamic resistance were −10.59 ± 5.24/−6. 15 ± 6.41 mmHg and −5.56 ± 7.61/−6.20 ± 8.25 mmHg, respectively. For an up-to-7 h assessment of resting pressure, there was a positive effect in the aerobic group. The concentrations of nitrites/nitrates (NOx) and endothelin-1 (ET-1) did not change during hypotension. Moreover, PEH and ABPMex were significantly correlated with baseline health variables. Thus, when middle-aged patients with hypertension perform aerobic or resistance exercise, the NOx/ET1 pathway does not provide the best explanation for PEH. Finally, we found associations between baseline cardiovascular variables and endothelial vasoconstrictors with PEH

Pedagogia da natação : evolução e relação do indivíduo com o meio aquático

Nas aulas de iniciação a natação, as crianças têm um breve período de adaptação ao meio aquático e logo são submetidas a uma sequência pedagógica que prioriza o ensino técnico dos quatro nados competitivos: crawl, costas, peito e golfinho. Considerando a necessidade de diversidade de experiências corporais aquáticas para o completo desenvolvimento motor aquático, o presente estudo teve como objetivo mapear a metodologia de ensino da natação na iniciação ao esporte em instituições de Porto Alegre, identificando se os professores trabalham visando ou não a relação e o domínio do indivíduo com o meio aquático. Esta pesquisa se caracteriza como qualitativa-quantitativa, descritiva e propositiva, ao passo que propõe concepção metodológica da natação para além do ensino dos quatro estilos. Ao longo deste estudo foram citadas e analisadas as atividades propostas pelos professores observados. Das 36 aulas observadas dos oito professores, 33 continham atividades de técnica de nado, em um total de 86 exercícios somados e realizadas 134 vezes. Conclui-se que há a necessidade de se repensar a pedagogia da natação, pois a predominância no cenário atual das instituições é o ensino técnico dos quatro estilos competitivos, antes mesmo do indivíduo se tornar independente e demonstrar domínio do meio aquático.In swimming initiation classes, the children have a brief period of adaptation to the aquatic environment and soon they are submitted to a pedagogical sequence, which prioritizes the technical teaching of the four competitive swimmingstrokes: front-crawl, backstroke, breastroke and butterfly. Considering the need for a diversity of aquatic corporal experiences for complete aquatic motor development, the present study had the objective of mapping the teaching methodology of swimming in the initiation to the sport in institutions of Porto Alegre, identifying if the teachers work with or without the relation and the domain of the individual with the aquatic environment. This research is characterized as qualitative-quantitative, descriptive and propositional, while it proposes a methodological conception of swimming in addition to teaching the four strokes. Throughout this study, the activities proposed by the observed teachers were mentioned and analyzed. Of the 36 classes observed from the eight teachers, 33 contained swimming technique activities, in 86 exercises added and performed 134 times. It is concluded that there is a need to rethink the pedagogy of swimming, because the predominance in the current scenario of the institutions is the technical teaching of the four competitive styles, before the individual becomes independent and demonstrate mastery of the aquatic environment