Kinematic, arm-stroke efficiency, coordination, and energetic parameters of the 400-m front-crawl test: A meta-analysis.

Several studies have investigated biomechanical and energetic parameters in competitive swimming. Among these studies, it is possible to identify the 400-m front crawl as a useful test to assess these parameters. The present study provided a meta-analysis assessing representative variables for the kinematic, arm-stroke efficiency, coordination, and energetic parameters of the 400-m front crawl test. PubMed, Embase, Web of Science, and SPORTDiscus were the databases used to select the studies published between January 1970 and December 2022. Forty studies (n = 651 swimmers) were selected according to the eligibility and inclusion criteria. The variables chosen to represent each parameter were: clean swim speed (kinematics); index of coordination (coordination); arm-stroke efficiency (efficiency); and oxygen consumption (energetic). Swimming speed was moderate (1.34 m s-1) compared to the world's records performers. Thus, this speed contributed for the swimmers in remaining at high efficiency (35%), imposing a capture coordination model (index of coordination: -11%) with high oxygen consumption (58.8 ml·kg-1 min-1). High heterogeneity (>75%) was found among the outcome parameters in the studies. The different average speeds that represented the kinematic parameters seem to be the most responsible and influential in the arm-stroke efficiency, coordination, and energetic parameters for high 400-m freestyle (front crawl) performance. This meta-analysis can help researchers, coaches, and swimmers improving competitive performance, and developing further research in the sports sciences area, specifically in the swimming.

Manipulation of Stroke Rate in Swimming: Effects on Oxygen Uptake Kinetics.

The study aimed to assess the effect of different front crawl stroke rates (SRs) in the oxygen uptake (̇VO2) kinetics and ̇VO2 peak, the total time to exhaustion (TTE), and blood lactate concentration ([La]) at 95% of the 400-m front crawl test (T400) mean speed (S400). Twelve endurance swimmers performed a T400 and four trials at 95% of the S400: (i) free SR, (ii) fixed SR (100% of the average free SR trial), (iii) reduced SR (90% of the average free SR trial), and (iv) increased SR (110% of the average free SR trial). ̇VO2 was accessed continuously with breath-by-breath analysis. The results highlighted: (i) the time constant at increased SR (13.3±4.2 s) was lower than in the reduced SR condition (19.5±2.6 s); (ii) the amplitude of the primary phase of ̇VO2 kinetics in the fixed SR (44.0±5.8 ml·kg-1·min-1) was higher than in the increased SR condition (39.5±6.4 ml·kg-1·min-1); and (iii) TTE was lower in the fixed SR (396.1±189.7 s) than the increased SR condition (743.0±340.0 s). The results indicate that controlled SR could be considered a swimming training strategy, focusing on physiological parameters overload.

The 400-m Front Crawl Test: Energetic and 3D Kinematical Analyses.

The aim of the study was to verify the relative contributions of energetic and kinematic parameters to the performance in 400-m front crawl test. Fourteen middle-distance swimmers participated in the study. Oxygen consumption was measured directly and blood samples were collected to assay lactate concentration. Both oxygen consumption and lactate concentration were used to calculate the: (i) overall energy expenditure, (ii) anaerobic (alactic and lactic) and (iii) aerobic contributions. The mean centre of mass speed and intracycle velocity variation were determined through three-dimensional kinematic analysis. Mean completion time was 315.64±26.91s. Energetic contributions were as follows: 6.1±0.28% from alactic anaerobic metabolism, 5.9±0.63% from anaerobic lactic and 87.8±0.88% from aerobic. Mean intracycle velocity variation was 0.14±0.03. The results indicated that performance of 400-m test relies predominantly on aerobic power. Parameters such as lactate, mean speed, anaerobic lactic and alactic (kW) correlated with performance of 400-m test (p <0.05). Multiple linear regressions indicated that mean centre of mass speed and anaerobic alactic (kW) determined the 400-m test performance (R2=0.92). Even though the T400 is characterized by aerobic metabolism, the anaerobic alactic component cannot be negligible at this competition level.

Políticas públicas de mobilidade urbana e práticas corporais: repercussões do sistema de bicicletas compartilhadas / Public policies of urban mobility and physical exercises: repercussions of bike-sharing systems / Public policies sobre la movilidad urbana y ejercicio físico: los efectos del sistema de bicicletas compartidas

O estudo procurou analisar as percepções dos usuários quanto à implantação do projeto de bicicletas compartilhadas em Fortaleza, Ceará. Trata-se de uma pesquisa qualitativa em que foram entrevistados 11 usuários, sistematizada por meio da análise de conteúdo do tipo análise temática. Os resultados apontam que a bicicleta compartilhada tem se tornado um meio de deslocamento alternativo ao transporte público deficiente, mas que seu papel como instrumento de lazer prevalece; encontrou-se a percepção de que o uso da bicicleta de forma contínua traz benefício à saúde, bem como a sensação de segurança. Todavia, há concentração de estações em poucos pontos da cidade e dificuldades de acesso em horário de pico. Conclui-se que o projeto de bicicletas compartilhadas no cenário deste estudo não contempla as demandas a elas atribuídas de mobilidade urbana; entretanto, fomenta o desenvolvimento de práticas corporais.

The study sought to examine the perceptions of users regarding the implementation of bike-sharing systems in Fortaleza, Ceará. This qualitative study interviewed 11 users, and systematization of data through thematic analysis of content analysis. The results indicate that the bike-sharing systems has become an alternative means of transportation, but its role as a leisure instrument prevails; He met the perception that the use of continuously cycling brings health benefits and a sense of security. However, the project is in a few places in the city and with limited access at certain times. We conclude that the shared bicycle system does not address the needs of urban mobility; however, it enhances the development of physical exercise.

El estudio trató de examinar las percepciones de los usuarios en relación con la implementación de sistemas de bicicletas compartidas en Fortaleza, Ceará. Este estudio cualitativo entrevistó a 11 usuarios, y la sistematización de los datos a través del análisis temático de análisis de contenido. Los resultados indican Que los sistemas de bicicletas compartidas se ha convertido en un medio alternativo de transporte, pero su papel como instrumento de ocio prevalece; Se reunió con la percepción de que el uso de la bicicleta continuamente trae beneficios para la salud y una sensación de seguridad. Sin embargo, el proyecto se encuentra en unos pocos lugares en la ciudad y con acceso limitado a ciertas horas. Llegamos a la conclusión de que el sistema de bicicletas compartidas no se ocupa de las necesidades de movilidad urbana; Sin embargo, se potencia el desarrollo del ejercicio físico.