Effects of swimming activity and feed restriction on antioxidant and digestive enzymes in juvenile rainbow trout: Implications for nutritional and exercise strategies in aquaculture.

BACKGROUND: In this study, we investigated the effects of swimming activity and feed restriction on digestion and antioxidant enzyme activities in juvenile rainbow trout (average body weight of 26.54 ± 0.36 g). METHODS: The stomach, liver and kidney tissues were obtained from four distinct groups: the static water group (fish were kept in static water and fed to satiation), the feeding restricted group (fish were kept in static water with a 25% feed restriction), the swimming exercised group (fish were forced to swimming at a flow rate of 1 Body Length per second (BL/s)) and the swimming exercised-feed restricted group (subjected to swimming exercise at a 1 BL/s flow rate along with a 25% feed restriction). We determined the levels of glutathione, lipid peroxidation and the activities of catalase, superoxide dismutase, glutathione peroxidase, glutathione reductase, glucose-6-phosphate dehydrogenase and lactate dehydrogenase, as well as the presence of reactive oxygen species in the tissues obtained from the fish. Additionally, the activities of pepsin, protease, lipase and arginase in these tissues were measured. RESULTS: Swimming activity and feed restriction showed different effects on the enzyme activities of the fish in the experimental groups. CONCLUSION: It can be concluded that proper nutrition and exercise positively influence the antioxidant system and enzyme activities in fish, reducing the formation of free radicals. This situation is likely to contribute to the fish's development.

Swimming Exercise Protocol and Care Methods for Pregnant Rats.

The developmental origins of health and disease concept highlights the impact of early environments on chronic non-communicable diseases like diabetes, cardiovascular disease, and cancer. Studies using animal models have investigated how maternal factors such as undernutrition, overnutrition, obesity, and exposure to chemicals or hypoxia affect fetal development and offspring health, leading to issues like low birth weight, high blood pressure, dyslipidemia, and insulin resistance. Given the increasing prevalence of overweight and obesity among reproductive-age women, effective interventions are critical. Maternal exercise during pregnancy has emerged as a key intervention, benefiting both mother and offspring and reducing the risk of disease. This study compares the differences of three exercise models on pregnant rats: voluntary wheel running, motorized treadmills, and swimming. Swimming is the most beneficial option due to its safe and controlled intensity levels. This protocol details the rat breeding methods, swimming training during pregnancy, and post-breeding nursing protocols. This model, suitable for various rat and mouse species, is useful for studying the benefits of maternal exercise on offspring health and intergenerational wellness.

Novel peptides from sea cucumber intestines hydrolyzed by neutral protease alleviate exercise-induced fatigue via upregulating the glutaminemediated Ca2+ /Calcineurin signaling pathway in mice.

Sea cucumber intestines are considered a valuable resource in the sea cucumber processing industry due to their balanced amino acid composition. Studies have reported that peptides rich in glutamate and branched-chain amino acids have anti-fatigue properties. However, the function of the sea cucumber intestine in reducing exercise-induced fatigue remains unclear. In this study, we enzymatically hydrolyzed low molecular weight peptides from sea cucumber intestines (SCIP) and administered SCIP orally to mice to examine its effects on exercise-induced fatigue using swimming and pole-climbing exhaustion experiments. The results revealed that supplementation with SCIP significantly prolonged the exhaustion time of swimming in mice, decreased blood lactate and urea nitrogen levels, and increased liver and muscle glycogen levels following a weight-loaded swimming test. Immunofluorescence analysis indicated a notable increase the proportion of slow-twitch muscle fiber and a significant decrease the proportion of fast-twitch muscle fiber following SCIP supplementation. Furthermore, SCIP upregulated mRNA expression levels of Ca2+ /Calcineurin upstream and downstream regulators, thereby contributing to the promotion of skeletal muscle fiber type conversion. This study presents the initial evidence establishing SCIP as a potential enhancer of skeletal muscle fatigue resistance, consequently providing a theoretical foundation for the valuable utilization of sea cucumber intestines.

Heart rate as an indicator of stress during the critical swimming speed test of farmed Atlantic salmon (Salmo salar L.).

A swim tunnel is to fish as a treadmill is to humans, and is a device used for indirect measuring of the metabolic rate. This study aims to explore the fish stress (if any) during the critical swimming test routines (fish handling, confinement, and swimming) using heart rate (fH , heartbeat per minute) bio-loggers in farmed Atlantic salmon (Salmo salar L.). In addition, the recovery dynamics of exercised fish using fH were explored for 48 h post swim tests. Continuous fH data were acquired following the surgical implantation and throughout the trials, such as during fish handling, swim tests (critical swimming speed, Ucrit ), and 48 h post swim tests. After 3 weeks of surgical recovery, fH stabilized at 46.20 ± 1.26 beats min-1 , equalizing a ~38% reduction in fH recorded post-surgical tachycardia (74.13 ± 1.44 beats min-1 ). Interestingly, fH was elevated by ~200% compared to baseline levels not only due to the Ucrit (92.04 ± 0.23 beats min-1 ) but also due to fish handling and confinement in the swim tunnel, which was 66% above the baseline levels (77.48 ± 0.34 beats min-1 ), suggesting fish stress. Moreover, significantly higher plasma cortisol levels (199.56 ± 77.17 ng mL-1 ) corresponding to a ~300% increase compared to baseline levels (47.92 ± 27.70 ng mL-1 ) were identified after Ucrit , predicting post-swim test stress (physiological exhaustion). These findings reinforce the importance of fish acclimation in the swim tunnel prior to the swimming tests. However, fH dropped over the course of the 48-h post-swim test, but remained comparatively higher than the basal levels, suggesting fish should be given at least 48 h to recover from handling stress for better fish welfare. This study further explored the influence of fish tagging on Ucrit , which resulted in reduced swimming capabilities of tagged fish (1.95 ± 0.37 body lengths s-1 ) compared to untagged fish (2.54 ± 0.42 body length s-1 ), although this was not significant (p = 0.06), and therefore future tagging studies are warranted.

Interaction of total dissolved gas supersaturation and suspended sediment on swimming performance of bighead carp (Hypopthalmichthys nobilis).

When dams discharge floodwaters, the river downstream often becomes supersaturated in total dissolved gases (TDG) and contains high volumes of suspended sediments (SS). Supersaturated TDG and high SS concentrations in water may affect fish physiologically in ways that manifest in swimming performance. Despite increasing awareness of the separate effects of TDG supersaturation and SS, knowledge about their synergistic effects remains unknown. To explore the interactive effects of TDG and SS on the swimming performance of bighead carp, the juveniles were exposed to 100, 110, 115, 120, 125, 130, 135, and 140% of TDG-supersaturated water with SS concentrations of 0, 50, 100, and 150 mg/L, respectively, and the critical swimming ability speed (Ucrit ) and burst swimming ability speed (Uburst ) were measured. The results indicated that the swimming ability (Ucrit and Uburst ) decreased when TDG levels and SS concentrations increased. TDG and SS did not interact significantly to decrease both Ucrit and Uburst . In contrast, exposure to TDG alone significantly decreased both Ucrit and Uburst , whereas exposure to SS alone decreased only Uburst . In addition, our results suggested that there was a negative linear relationship between TDG and fatigue time. Swimming ability can decline significantly due to high TDG levels (>130%). Therefore, high TDG levels (>130%) should be restricted during reservoir operation to prevent the stress caused by TDG.

Sensorimotor control of swimming Polypterus senegalus is preserved during sensory deprivation conditions across altered environments.

Control of locomotion involves the interplay of sensory signals and motor commands. Sensory information is essential for adjusting locomotion in response to environmental changes. A previous study using mathematical modelling of lamprey swimming has shown that, in the absence of sensory feedback, increasing fluid viscosity constrains swimming kinematics, limiting tail amplitude and body wavelength, resulting in decreased swimming speed. In contrast, previous experiments with Polypterus senegalus reported increased magnitude swimming kinematics (increased body curvature, body wave speed and frequency, and pectoral fin frequency) in high viscosity water suggesting that sensory information is used to adjust swimming form. It is not known what sensory systems are providing the necessary information to respond to these environmental changes. We tested the hypothesis that lateral line and visual input are responsible for the sensory-driven increase in swimming kinematics in response to experimentally increased fluid viscosity. The kinematics of five P. senegalus were recorded in two different viscosities of water while removing lateral line and visual sensory feedback. Unlike the mathematical model devoid of sensory feedback, P. senegalus with lateral line and/or visual senses removed did not reduce the magnitude of swimming kinematic variables, suggesting that additional sensory feedback mechanisms are present in these fish to help overcome increased fluid viscosity. Increases in swimming speed when both lateral line and visual sensory feedback were removed suggest that lateral line and visual information may be used to regulate swimming speed in P. senegalus, possibly using an internal model of predictions to adjust swimming form.

The relationship between anthropometric variables and swimming efficiency in early pubescent female front crawl swimmers / Relación entre las variables antropométricas y la eficiencia de natación en nadadoras de estilo crol en la pubertad temprana

SUMMARY: The aim of this study was twofold. The first aim was to examine the association of anthropometric measures on kinematic characteristic which represent stroke efficiency in young female front crawl swimmers. The second aim was to create a prediction model which could provide help to swimming coaches with the purpose of easier and better selection of female front crawl swimmers by measuring and following basic morphological characteristics. Eighty female competitive swimmers all members of the swimming Clubs in province of Vojvodina, Serbia (age 12.52 ± 08 years, years of training involvement 4.05 ± 1.2 and personal best times over 50 m front crawl 32.79 ± 0.86 s) performed 50 m front crawl race. The 50 m front crawl swimming efficiency expressed through stroke index significantly was related to body height (r = 0.44, p = 0.000), body mass (r = 0.402, p = 0.000), sitting height (r = 0.612, p = 0.000) arm spam (r = 0.576, p = 0.000), biacromial diameter (r = 0.470, p = 0.000), bicrestal diameter (r = 0.348, p = 0.001) and with chest circumference (r = 0.427, p = 0.000). Regression equation for stroke index prediction was defined by following variables: body mass, sitting height, arm span, chest circumference with 43.5% explained variance. Additionally by analyzing obtained model the higher the values of SH, ARSP, CHICR and the lower values of BM in a group of early pubescent female swimmers the higher 50 m front crawl efficiency values will be.

Este estudio tiene dos objetivos principales. El primer objetivo fue examinar la asociación de las medidas antropométricas con las características cinemáticas que representan la eficiencia de la brazada en nadadoras jóvenes estilo crol. El segundo objetivo era crear un modelo de predicción que pudiera ayudar a los entrenadores de natación con el propósito de seleccionar mejor y más fácilmente a las nadadoras crol midiendo y siguiendo las características morfológicas básicas. Ochenta nadadoras competitivas, todas miembros de los clubes de natación en la provincia de Vojvodina, Serbia (edad 12,52 ± 8 años, años de participación en el entrenamiento 4,05 ± 1,2 y mejores tiempos personales en 50 m estilo crol 32,79 ± 0,86 s) realizaron una carrera de 50 m estilo crol. La eficiencia de nado crol de 50 m expresada a través del índice de brazada se relacionó significativamente con la altura del cuerpo (r = 0,44, p = 0,000), la masa corporal (r = 0,402, p = 0,000), la altura sentado (r = 0,612, p = 0,000) y el brazo. spam (r = 0,576, p = 0,000), diámetro biacromial (r = 0,470, p = 0,000), diámetro bicrestal (r = 0,348, p = 0,001) y con perímetro torácico (r = 0,427, p = 0,000). La ecuación de regresión para la predicción del índice de brazada se definió mediante las siguientes variables: masa corporal, altura sentada, extensión de los miembros superiores, circunferencia del pecho con una varianza explicada del 43,5 %. Además, al analizar el modelo obtenido, cuanto más altos sean los valores de SH, ARSP, CHICR y los valores más bajos de BM en un grupo de nadadoras púberes tempranas, mayores serán los valores de eficiencia de crol de 50 m.

Impacts of core training on physical training in synchronized swimming / Impactos do treino do core sobre o treinamento físico de formação no nado sincronizado / Impacto del entrenamiento del core en la preparación física de formación en la natación sincronizada

ABSTRACT Introduction: Synchronized swimming is a sport of artistic expression, skill, and physical fitness. Explosive, high-intensity movements rely mainly on the athlete's good basal strength. Although China attaches great importance to the physical training of synchronized swimming athletes, there is no theoretical achievement in consolidating specific training. Objective: To analyze the impact of CORE strengthening on the physical training of synchronized swimming athletes. Methods: This article selects 30 synchronized swimmers as volunteers for the research. A basal metabolism test was used to verify the maximal oxygen consumption (VO2max), ventilatory anaerobic threshold (VT), and other indicators. The isokinetic force measurement system measured the athletes' maximum lumbar-abdominal muscle flexion/extension torque, explosive strength, fast muscle strength capacity, total work, and anti-fatigue capacity. Results: The synchronized limb training results of the swimming team were positively correlated with the stability of the CORE muscles. There is a positive relationship between 30 years old and maximal strength training and performance in athletes. Abdominal muscular endurance showed the highest correlation coefficient with synchronized swimming performance. Conclusion: Coaches should organize adequate strength training according to the growth and development characteristics of athletes and the characteristics of synchronized swimming movements. In this way, an excellent physical training effect can be achieved by CORE training. Level of evidence II; Therapeutic studies - investigation of treatment outcomes.

RESUMO Introdução: O nado sincronizado é um esporte de expressão artística, habilidade e aptidão física. Movimentos explosivos, de alta intensidade, dependem principalmente da boa força basal do atleta. Embora a China atribua grande importância ao treinamento físico de atletas do nado sincronizado, não há conquista teórica na consolidação de um treinamento específico. Objetivo: Analisar o impacto da aplicação do fortalecimento do core sobre o treinamento físico de atletas do nado sincronizado. Métodos: Este artigo seleciona 30 nadadores sincronizados como voluntários para a pesquisa. Um teste de metabolismo basal foi utilizado para verificar o consumo máximo de oxigênio (VO2max), o limiar anaeróbico ventilatório (VT) e outros indicadores. Utilizou-se o sistema de medição de força isocinética para medir o torque máximo de flexão/extensão muscular lombar-abdominal dos atletas, força explosiva, capacidade de força rápida muscular, trabalho total e capacidade anti-fadiga. Resultados: Os resultados de treinamento dos membros sincronizados da equipe de natação foram positivamente correlacionados com a estabilidade dos músculos do core. Há uma relação positiva entre os 30 anos de idade e o melhor desempenho no treinamento de força máxima em atletas. A resistência muscular abdominal apresentou o maior coeficiente de correlação com desempenho sincronizado de natação. Conclusão: Os treinadores devem organizar o treinamento de força adequado de acordo com as características de crescimento e desenvolvimento dos atletas e as características dos movimentos sincronizados de natação. Desta forma, um excelente efeito de treinamento físico pode ser alcançado pelo treino do core. Nível de evidência II; Estudos terapêuticos - investigação dos resultados do tratamento.

RESUMEN Introducción: La natación sincronizada es un deporte de expresión artística, de habilidad y de condición física. Los movimientos explosivos y de alta intensidad dependen principalmente de la buena fuerza basal del deportista. Aunque China atribuye una gran importancia a la preparación física de las atletas de natación sincronizada, no existe ningún logro teórico en la consolidación de un entrenamiento específico. Objetivo: Analizar el impacto de la aplicación del fortalecimiento del core en la preparación física de las atletas de natación sincronizada. Métodos: En este artículo se seleccionan 30 nadadores de sincronizados como voluntarios para la investigación. Se utilizó una prueba de metabolismo basal para verificar el consumo máximo de oxígeno (VO2max), el umbral anaeróbico ventilatorio (VT) y otros indicadores. Fue aplicado el sistema de medición de la fuerza isocinética para medir el par máximo de flexión/extensión de los músculos lumbares-abdominales de los atletas, la fuerza explosiva, la capacidad de fuerza muscular rápida, el trabajo total y la capacidad antifatiga. Resultados: Los resultados del entrenamiento de las extremidades sincronizadas del equipo de natación se correlacionaron positivamente con la estabilidad de los músculos del core. Existe una relación positiva entre los 30 años de edad y la fuerza máxima de entrenamiento y el rendimiento en los atletas. La resistencia muscular abdominal mostró el mayor coeficiente de correlación con el rendimiento de la natación sincronizada. Conclusión: Los entrenadores deben organizar un entrenamiento de fuerza adecuado en función de las características de crecimiento y desarrollo de los deportistas y de las características de los movimientos de la natación sincronizada. De este modo, se puede conseguir un excelente efecto de entrenamiento físico entrenando el core. Nivel de evidencia II; Estudios terapéuticos - investigación de los resultados del tratamiento.

Deep learning for analysis of changes in vital capacity and blood markers after swimming matches based on blended learning / Aprendizado profundo para análise das alterações da capacidade vital e marcadores sanguíneos após jogos de natação baseados no aprendizado combinado / Aprendizaje profundo para el análisis de los cambios en la capacidad vital y los marcadores sanguíneos después de los partidos de natación basados en el aprendizaje combinado

ABSTRACT Introduction Nowadays, more people are concerned with physical exercise and swimming competitions, as a major sporting event, have become a focus of attention. Such competitions require special attention to their athletes and the use of computational algorithms assists in this task. Objective To design and validate an algorithm to evaluate changes in vital capacity and blood markers of athletes after swimming matches based on combined learning. Methods The data integration algorithm was used to analyze changes in vital capacity and blood acid after combined learning swimming competition, followed by the construction of an information system model to calculate and process this algorithm. Results Comparative experiments show that the neural network algorithm can reduce the calculation time from the original initial time. In the latest tests carried out in about 10 seconds, this has greatly reduced the total calculation time. Conclusion According to the model requirements of the designed algorithm, practical help has been demonstrated by building a computational model. The algorithm can be optimized and selected according to the calculation model according to the reality of the application. Level of evidence II; Therapeutic studies - investigation of treatment outcomes.

RESUMO Introdução Atualmente, mais pessoas preocupam-se com o exercício físico e as competições de natação, como evento esportivo de destaque, tornou-se foco de atenção. Tais competições exigem atenção especial aos seus atletas e o uso de algoritmos computacionais auxiliam nessa tarefa. Objetivo Projetar e validar um algoritmo para avaliação das alterações da capacidade vital e marcadores sanguíneos dos atletas após os jogos de natação baseados no aprendizado combinado. Métodos O algoritmo de integração de dados foi usado para analisar as mudanças de capacidade vital e ácido sanguíneo após competição de natação de aprendizado combinado, seguido à construção de um modelo de sistema de informação para calcular e processar esse algoritmo. Resultados Experiências comparativas mostram que o algoritmo de rede neural pode reduzir o tempo de cálculo a partir do tempo inicial original. Nos últimos testes levados à cabo em cerca de 10 segundos, isto reduziu muito o tempo total de cálculo. Conclusão De acordo com os requisitos do modelo do algoritmo projetado, foi demonstrada a ajuda prática pela construção de um modelo computacional. O algoritmo pode ser otimizado e selecionado de acordo com o modelo de cálculo, segundo a realidade da aplicação. Nível de evidência II; Estudos terapêuticos - investigação dos resultados do tratamento.

RESUMEN Introducción Hoy en día, cada vez más personas se preocupan por el ejercicio físico y las competiciones de natación, como evento deportivo destacado, se han convertido en un foco de atención. Estas competiciones requieren una atención especial para sus atletas y el uso de algoritmos computacionales ayuda en esta tarea. Objetivo Diseñar y validar un algoritmo para evaluar los cambios en la capacidad vital y los marcadores sanguíneos de los atletas después de los partidos de natación basado en el aprendizaje combinado. Métodos Se utilizó el algoritmo de integración de datos para analizar los cambios de la capacidad vital y la acidez de la sangre tras la competición de natación de aprendizaje combinado, seguido de la construcción de un modelo de sistema de información para calcular y procesar este algoritmo. Resultados Los experimentos comparativos muestran que el algoritmo de la red neuronal puede reducir el tiempo de cálculo con respecto al tiempo inicial. En las últimas pruebas realizadas en unos 10 segundos, esto redujo en gran medida el tiempo total de cálculo. Conclusión De acuerdo con los requisitos del modelo del algoritmo diseñado, se ha demostrado la ayuda práctica mediante la construcción de un modelo computacional. El algoritmo puede optimizarse y seleccionarse según el modelo de cálculo en función de la realidad de la aplicación. Nivel de evidencia II; Estudios terapéuticos - investigación de los resultados del tratamiento.

Efeito da padronização dos critérios de observação e de avaliação da técnica da braça do nado crawl na confiabilidade inter e intra avaliadores / Effect of standardizing observation and rating criteria for the front crawl stroke technique on inter- and intra-rater reliability

RESUMO Esse estudo teve por objetivo avaliar o efeito da padronização dos critérios de observação e de avaliação da técnica da braçada do nado crawl na confiabilidade inter e intra avaliadores para uma proposta de lista de observação. Dois professores e dois treinadores de natação competitiva com formação acadêmica diferentes foram responsáveis por avaliar a técnica da braçada do nado crawl de 44 nadadores por meio de vídeo. Cada nadador realizou um percurso de 25m em velocidade confortável tendo seu deslocamento gravado nos planos lateral e frontal, ambos submersos e fora d'água, nos 10 m finais da piscina. No percurso de filmagem os nadadores não realizaram a respiração lateral. Somente o movimento realizado pelo braço direito foi foco de observação dos avaliadores e com base em uma lista de verificação. Após as filmagens os avaliadores participaram de três etapas: na primeira etapa houve uma intervenção para padronização dos critérios de observação e de avaliação. Na segunda etapa testou-se a concordância inter-avaliadores e, na terceira, a concordância intra-avaliador. Na segunda etapa do estudo a concordância variou de pequeno a baixa (k=0,08 e k=0,38). Na terceira etapa alguns avaliadores apresentaram concordância pobre e baixa (k=-0,13 e k=0,35), enquanto outros apresentaram concordância entre razoável e praticamente perfeita (k=0,64 e k=0,87). A partir dos resultados apresentados concluiu-se que a proposta de intervenção não surtiu o efeito desejado de padronização dos critérios de observação e avaliação entre os avaliadores.

ABSTRACT This study aimed to assess the effect of standardizing observation and rating criteria for the front crawl stroke technique on inter- and intra-rater reliability in order to propose an observation list. Two teachers and two competitive swimming coaches with different academic backgrounds were responsible for evaluating the front crawl stroke technique of 44 swimmers using video. Each swimmer completed a 25m course at a comfortable speed, having their displacement recorded in the lateral and frontal planes, both submerged and out of water, in the final 10 m of the pool. Throughout the recording, the swimmers did not breath laterally. Only the movement performed by the right arm was the raters' focus of observation and was based on a checklist. After the shooting, the raters participated in three stages: in the first stage, there was an intervention to standardize the observation and rating criteria; inter-rater agreement was tested in the second stage, while intra-rater agreement was obtained in the third. In the second stage of the study, the agreement ranged from small to low (k=0.08 and k=0.38). In the third stage, some raters showed poor and low agreement (k=-0.13 and k=0.35), while others showed agreement between reasonable and virtually perfect (k=0.64 and k=0.87). From the results presented, it was concluded that the intervention proposal did not have the desired effect of standardizing the observation and rating criteria among the raters.

Seawater Hydration Modulates IL-6 and Apelin Production during Triathlon Events: A Crossover Randomized Study.

A triathlon is an endurance event in which athletes need an efficient hydration strategy since hydration is restricted at different stages. However, it seems that seawater intake can be a suitable hydration alternative for this type of endurance event. Therefore, the aim of this study was to evaluate the efficacy of seawater hydration during a triathlon on cytokine production. Fifteen trained male triathletes (age = 38.8 ± 5.62 years old; BMI = 22.58 ± 2.51 kg/m2) randomly performed three triathlons, one of them consuming seawater (Totum SPORT, Laboratories Quinton International, S.L., Valencia, Spain), the other one consuming tap water ad libitum, and the last a physiologic saline solution as placebo. The triathlon consisted of an 800 m swim, a 90 km bike ride, and a 10 km run. Blood samples were taken at rest and after training, where markers of inflammation, hemoglobin, and hematocrit concentration were assessed. While the seawater was not ergogenic, it significantly increased the release of IL-6 and apelin post-exercise. However, no differences were found between the fractalkine, IL-15, EPO, osteonectin, myostatin, oncostatin, irisin, FSTL1, osteocrin, BDNF, and FGF-21 values over those of the placebo group. The present study demonstrates that hydration with seawater stimulates myokine production, which could lead to improved performance recovery after exercise.

Tail-stiffness optimization for a flexible robotic fish.

Undulation regulation in a robotic fish propelled by a passive flexible tail is more similar to that of a natural fish than with a rigid tail, owing to the smooth curvature of the flexible tail. Moreover, it has been observed that fish change the stiffness of their bodies to adapt to various swimming states. Inspired by this, a stiffness optimization scheme is explored for a novel elastic tail, which can improve the performance of the robotic fish. Spring steels are used as passive flexible joints of the fishtail; these can be easily expanded into multi-joint structures and the joint stiffness can be altered by changing the joint size. In this study, the Lagrangian dynamic method is employed to establish a dynamic model of the robotic fish in which passive flexible joints are simplified by a pseudo-rigid-body model. In addition, the hydrodynamics of the head and tail are analyzed using the simplified Morison equation and quasi-steady wing theory, respectively. Furthermore, to determine unknown hydrodynamic parameters in the dynamic model, a parameter identification method is applied. The results show that the identified simulation speeds fit the experimental speeds well within a wide range of stiffness values. Finally, to improve performance, the influence of joint stiffness and frequency on swimming speed is investigated based on the identified dynamic model. At each frequency, the optimal joint stiffness distribution is one that reduces the stiffness from the front to the rear. At the maximum driving frequency of 2.5 Hz, the optimal swimming speed is 0.3 body lengths per second, higher than that when rigid joints are used.

Characterization of locomotor phenotypes in zebrafish larvae requires testing under both light and dark conditions.

Despite growing knowledge, much remains unknown regarding how signaling within neural networks translate into specific behaviors. To pursue this quest, we need better understanding of the behavioral output under different experimental conditions. Zebrafish is a key model to study the relationship between network and behavior and illumination is a factor known to influence behavioral output. By only assessing behavior under dark or light conditions, one might miss behavioral phenotypes exclusive to the neglected illumination setting. Here, we identified locomotor behavior, using different rearing regimes and experimental illumination settings, to showcase the need to assess behavior under both light and dark conditions. Characterization of free-swimming zebrafish larvae, housed under continuous darkness or a day/night cycle, did not reveal behavioral differences; larvae were most active during light conditions. However, larvae housed under a day/night cycle moved a shorter distance, had lower maximum velocity and maximum acceleration during the startle response under light conditions. Next, we explored if we could assess behavior under both dark and light conditions by presenting these conditions in sequence, using the same batch of larvae. Our experiments yielded similar results as observed for naïve larvae: higher activity during light conditions, regardless of order of illumination (i.e. dark-light or light-dark). Finally, we conducted these sequenced illumination conditions in an experimental setting by characterizing behavioral phenotypes in larvae following neuromast ablation. Depending on the illumination during testing, the behavioral phenotype following ablation was characterized differently. In addition, the results indicate that the order in which the light and dark conditions are presented has to be considered, as habituation may occur. Our study adds to existing literature on illumination-related differences in zebrafish behavior and emphasize the need to explore behavioral phenotypes under both light and dark condition to maximize our understanding of how experimental permutations affect behavior.

Effects of moderate aerobic exercise, low-level laser therapy, or their combination on muscles pathology, oxidative stress and irisin levels in the mdx mouse model of Duchenne muscular dystrophy.

This study aimed to investigate how the combined use of low-level laser therapy (LLLT) and exercise, to reduce the possible side effects and/or increase the benefits of exercise, would affect oxidative stress, utrophin, irisin peptide, and skeletal, diaphragmatic, and cardiac muscle pathologies. In our study, 20 mdx mice were divided into four groups. Groups; sedentary and placebo LLLT (SC), sedentary and LLLT (SL), 30-min swimming exercise (Ex), and 30-min swimming exercise and LLLT (ExL). After 8 weeks of swimming exercise, muscle tests, biochemically; oxidative stress index (OSI), utrophin and irisin levels were measured. Skeletal, diaphragmatic and cardiac muscle histopathological scores, skeletal and cardiac muscle myocyte diameters were determined under the light and electron microscope. While only irisin levels were increased in group SL compared to SC, it was determined that OSI, heart muscle histopathological scores decreased and irisin levels increased in both exercise groups (p < 0.05). In addition, in the ExL group, an increase in rotarod and utrophin levels, and a decrease in muscle and diaphragm muscle histopathological scores were observed (p < 0.05). It was determined that the application of swimming exercise in the mdx mouse model increased the irisin level in the skeletal muscle, while reducing the OSI, degeneration in the heart muscle, inflammation and cardiopathy. When LLLT was applied in addition to exercise, muscle strength, skeletal muscle utrophin levels increased, and skeletal and diaphragmatic muscle degeneration and inflammation decreased. In addition, it was determined that only LLLT application increased the level of skeletal muscle irisin.

The effects of bee venom on liver and skeletal muscle in exhaustive swimming rats.

Oxidative damage and proinflammatory cytokines are involved in exhaustive exercise-induced fatigue. This study aimed to investigate the effects of bee venom, a natural toxin, on fatigue and tissue damage in rats that underwent forced swimming exercise. Rats were divided into four groups: control, swimming exercise (SE), bee venom (BV) and swimming exercise + bee venom (SE + BV). SE and SE + BV groups were subjected to forced swimming (load of 7% body weight) for 5 days. BV and SE + BV groups were injected with 1 mg/kg BV subcutaneously. Swimming time, blood lactate and TNF-α levels, MDA and GSH levels in liver and gastrocnemius muscle were evaluated. Swimming time was shorter in SE + BV group than SE group. There was no difference in lactate levels between SE and SE + BV groups. MDA and GSH levels were increased in SE, BV and SE + BV groups. TNF-α levels were increased in BV group compared to control and SE groups. Our study demonstrated that BV administration before exhaustive exercise in rats did not provide anti-fatigue effect. Additionally, BV did not show anti-inflammatory activity and had different effects on antioxidant capacity at tissue level. Further research might explore the effects of different doses and durations of BV on exhaustive exercise.

Effect of swimming exercise, insulin-associated or not, on inflammatory cytokines, apoptosis, and collagen in diabetic rat placentas.

Physical exercise is an important therapeutic agent for women with diabetes during gestation. However, its histophysiological consequences for the placenta remain unclear. In this study, we evaluated the expression of VEGF-A, IL1ß, TNFα, and type I collagen in the placentas of diabetic rats subjected to a swimming program. Thirty rats were divided into the following groups: CG, pregnant nondiabetic rats; CEG, nondiabetic pregnant rats subjected to swimming; DG, pregnant diabetic rats; DEG, pregnant diabetic rats subjected to swimming; DIG, pregnant diabetic rats treated with insulin; DIEG, pregnant diabetic rats treated with insulin and subjected to swimming. Diabetes was induced using streptozotocin [50 mg/kg intraperitoneally (i.p.)], and insulin was administered at a dose of 5 U/day i.p. (2 U at 10 am and 3 U at 7 pm) in the DIG group; in the DIEG group, insulin was administered at a dose of only 2 U/day at 7 pm. The rats were sacrificed on the 20th day of gestation. There was an increase in the expression of IL-1ß, TNF-α, VEGF-A, and type I collagen and a higher apoptotic index in the placentas of the DG and DEG groups, but there was a reduction in glycemia in the latter group. In the DIG and DIEG groups, the levels remained similar to those of the control; however, in these groups the reduction was more significant for all analyzed parameters. Therefore, in rats induced to diabetes during pregnancy, swimming, although reducing glycemic levels, did not prevent immunohistochemical changes in the placenta, suggesting the need for a multidisciplinary protocol associated with traditional pharmacological treatment.

Reproducibility of an endurance test for master swimmers

Abstract Aim: This study aimed to verify the reproducibility of an endurance test for master swimmers. Methods: Seventeen male swimmers, aged from 30 to 50 years (35.06 ± 5.36), weight (78.71 ± 13.06 kg), height (174.35 ± 0.07 cm), participated in this study. The participants underwent the Progressive Swim Test (PSwT), which corresponds to swimming progressively to exhaustion in a 25-meter pool, guided by the recording of sound signals indicating the swimming rhythm. We verified the following variables: heart rate before the test (BHR) and right after the end of the test (AHR), followed by the rate of perceived exertion (RPE) and a total of laps performed (SN - swimming number). For comparison between the three days of tests, the one-way repeated measures ANOVA with Tukey's Post-Hoc was performed. Relative reproducibility was performed by the r test and the intraclass correlation coefficient (ICC). Absolute reproducibility was determined using the coefficient of variation (CV) and the confidence interval (CI). Results: The results showed high reproducibility in (PSwT) in master swimmers in the analyzed variables of intergroup and intragroup with relative reproducibility of r > 0.60 and ICC > 0.70 and absolute reproducibility with CI 95% (lower −1.10 and upper 0.99) and CV < 10%. Most of the cases were within the limits of agreement of the Bland-Altman tests, all variables were considered a level of significance with (p <0.05). Conclusion: The Progressive Swim Test (PSwT) is a reproducible instrument in the assessment of endurance in master swimmers.

Exercise downregulates HIPK2 and HIPK2 inhibition protects against myocardial infarction.

BACKGROUND: Exercise can protect myocardial infarction (MI) and downregulate cardiac Homeodomain-Interacting Protein Kinase 2 (HIPK2). However, the role of HIPK2 in MI is unclear. METHODS: HIPK2-/- mice and miR-222-/- rats, HIPK2 inhibitor (PKI1H) and adeno-associated virus serotype 9 (AAV9) carrying miR-222 were applied in the study. Animals were subjected to running, swimming, acute MI or post-MI remodeling. HIPK2 inhibition and P53 activator were used in neonatal rat cardiomyocytes (NRCMs) and human embryonic stem cell-derived cardiomyocytes (hESC-CMs) subjected to oxygen glucose deprivation/reperfusion (OGD/R). Serum miR-222 levels were analyzed in healthy people and MI patients that were survival or readmitted to the hospital and/or died. FINDINGS: Cardiac HIPK2 protein levels were reduced by exercise while increased in MI. In vitro, HIPK2 suppression by lentiviral vectors or inhibitor prevented apoptosis induced by OGD/R in NRCMs and hESC-CMs. HIPK2 inhibitor-treated mice and HIPK2-/- mice reduced infarct size after acute MI, and preserved cardiac function in MI remodeling. Mechanistically, protective effect against apoptosis by HIPK2 suppression was reversed by P53 activators. Furthermore, increasing levels of miR-222, targeting HIPK2, protected post-MI cardiac dysfunction, whereas cardiac dysfunction post-MI was aggravated in miR-222-/- rats. Moreover, serum miR-222 levels were significantly reduced in MI patients, as well as in MI patients that were readmitted to the hospital and/or died compared to those not. INTERPRETATION: Exercise-induced HIPK2 suppression attenuates cardiomyocytes apoptosis and protects MI by decreasing P-P53. Inhibition of HIPK2 represents a potential novel therapeutic intervention for MI. FUNDING: This work was supported by the grants from National Key Research and Development Project (2018YFE0113500 to JJ Xiao), National Natural Science Foundation of China (82020108002, 81722008, and 81911540486 to JJ Xiao, 81400647 to MJ Xu, 81800265 to YJ Liang), Innovation Program of Shanghai Municipal Education Commission (2017-01-07-00-09-E00042 to JJ Xiao), the grant from Science and Technology Commission of Shanghai Municipality (18410722200 and 17010500100 to JJ Xiao), the "Dawn" Program of Shanghai Education Commission (19SG34 to JJ Xiao), Shanghai Sailing Program (21YF1413200 to QL Zhou). JS is supported by Horizon2020 ERC-2016-COG EVICARE (725229).

Swim training affects Akt signaling and ameliorates loss of skeletal muscle mass in a mouse model of amyotrophic lateral sclerosis.

We tested the hypothesis that swim training reverses the impairment of Akt/FOXO3a signaling, ameliorating muscle atrophy in ALS mice. Transgenic male mice B6SJL-Tg (SOD1G93A) 1Gur/J were used as the ALS model (n = 35), with wild-type B6SJL (WT) mice as controls (n = 7). ALS mice were analyzed before ALS onset, at ALS onset, and at terminal ALS. Levels of insulin/Akt signaling pathway proteins were determined, and the body and tibialis anterior muscle mass and plasma creatine kinase. Significantly increased levels of FOXO3a in ALS groups (from about 13 to 21-fold) compared to WT mice were observed. MuRF1 levels in the ONSET untrained group (12.0 ± 1.7 AU) were significantly higher than in WT mice (1.12 ± 0.2 AU) and in the BEFORE ALS group (3.7 ± 0.9 AU). This was associated with body mass and skeletal muscle mass reduction. Swim training significantly ameliorated the reduction of skeletal muscle mass in both TERMINAL groups (p < 0.001) and partially reversed changes in the levels of Akt signaling pathway proteins. These findings shed light on the swimming-induced attenuation of skeletal muscle atrophy in ALS with possible practical implications for anti-cachexia approaches.

Synergism effect of swimming exercise and genistein on the inflammation, oxidative stress, and VEGF expression in the retina of diabetic-ovariectomized rats.

AIMS: Retinal neovascularization is one of the visual disorders during the postmenopausal period or types two diabetes. Physical activities and also phytoestrogens with powerful antioxidant features have been widely considered to improve nervous system diseases. Therefore, this study investigated the effects of genistein, swimming exercise, and their co-treatment on retina angiogenesis, oxidative stress, and inflammation in diabetic-ovariectomized rats. MAIN METHODS: Wistar rats were randomly divided into six groups (n = 8 per group): sham, ovariectomized group (OVX), OVX + diabetes (OVX.D), OVX.D+ genistein (1 mg/kg, eight weeks; daily SC), OVX.D + exercise (eight weeks), and OVX.D+ genistein+exercise (eight weeks). At the end of 8 weeks, the retina was removed under anesthesia. The assessed effects of treatment were by measuring MiR-146a and miR-132 expression via RT-PCR, the protein levels of ERK, MMP-2, VEGF, and NF-κB via western blotting, inflammation, and oxidative stress markers levels via the Eliza. KEY FINDINGS: The results showed miR-132, miR-146b, and MMP-2, NF-κB, ERK, VEGF, TNF-α, IL-1ß proteins, and MDA factor in the OVX.D group were increased, but glutathione (GSH) was decreased in comparison with the sham and OVX groups. Both exercise and genistein treatment has reversed the disorder caused by diabetes. However, the combination of exercise and genistein was more effective than each treatment alone. SIGNIFICANCE: It can be concluded that the interaction of exercise and genistein on microRNAs and their target protein was affected in the inflammation, stress oxidative, and extracellular matrix metalloproteinase pathways, can leading to a decrease in impairment of retinal neovascularization of the ovariectomized diabetic rats.