Biomechanical characterization of firefighters running under different rescue tasks.

The biomechanical characteristics of runs in firefighters with different rescue tasks are unclear. This study aimed to explore the biomechanical characteristics of firefighters running in different rescue tasks and provide theoretical and practical references for firefighter training and occupational injury prevention. Eighteen professional healthy male firefighters were randomly selected as participants and tested running on different rescue tasks: wearing firefighting protective clothing (FPC), FPC+carrying a gas can (20 kg, FPC+ C), and FPC+carrying a mannequin (60 kg, FPC+M). Eight Qualisys infrared cameras and an AMTI 3D force measurement platform were used for the participant's acquisition of lower limb kinematic/kinetic data. The results showed that gait velocity and stride length of the FPC+GC and FPC+ M rescue tasks were significantly decreased compared to the FPC rescue task, while the support time was significantly increased. Compared to the FPC rescue task, the FPC+GC rescue task showed significant decreases in vertical ground reaction force (vGRF), minimum ankle dorsiflexion angle, and the maximum ankle plantarflexion power. In contrast, the FPC+M rescue task demonstrated significant increases in ankle range of motion, maximum hip extension angle, minimum knee flexion angle, maximum ankle dorsiflexion angle, maximum hip extension moment, maximum knee flexion moment, maximum hip flexion power, and hip and knee stiffness while exhibiting significant decreases in minimum ankle dorsiflexion angle. Compared to the FPC+ GC rescue task, the FPC+M rescue task exhibited significant increases in the maximum hip extension angle, minimum knee flexion angle, maximum ankle dorsiflexion angle, maximum hip flexion moment, maximum hip extension moment, maximum knee flexion moment, maximum ankle plantarflexion moment, maximum hip flexion power, maximum ankle dorsiflexion power, hip stiffness, and vGRF. Conversely, it showed significant decreases in the maximum knee flexion power. In conclusion, compared to the FPC rescue task, the FPC+GC and FPC+M rescue tasks altered the firefighter's gait performance, as evidenced by decreased gait velocity and stride length and increased support time. FPC+M rescue task would increase firefighter's risk of hip and knee injuries. Therefore, we suggest firefighters increase their strength training of the trunk, hip, and knee joint muscles as part of their daily training programs under large weight load status (60 kg and above) to reduce injury risk during rescue tasks.

Physiological and biochemical changes in adolescents after high-intensity training / Alterações fisiológicas e bioquímicas no pós-treino de alta intensidade em adolescentes / Alteraciones fisiológicas y bioquímicas en el post-entrenamiento de alta intensidad en adolescentes

ABSTRACT Introduction Exercise intensity can approach an individual's maximum capacity rapidly. High-intensity exercise can improve aerobic capacity in obesity, overweight, heart disease, and diabetes. Knowledge of the physiological and biochemical changes in the post-workout period could provide safety indexes for a scientific basis. Objective To evaluate the immediate physiological and biochemical changes in adolescents submitted to high-intensity sports training. Methods The article selects several young athletes for research. They were randomly divided into two groups. Group A did high-intensity exercise, and group B did regular exercise. A statistical analysis of physiological and biochemical indicators of athletes before and after exercise is done. Results The vital capacity in the two groups was significantly different. However, no significant differences were found between the biochemical indicators collected before and after training. Conclusion High-intensity sport can improve cardiopulmonary function with low impact on biochemical indicators. These findings indicate high-intensity physical training can improve sports performance without compromising the health of adolescents. Evidence Level II; Therapeutic Studies - Outcome Research.

RESUMO Introdução A intensidade do exercício pode aproximar-se da capacidade máxima de um indivíduo rapidamente. Exercícios de alta intensidade podem melhorar a capacidade aeróbica em pessoas com obesidade, sobrepeso, doenças cardíacas e diabetes. O conhecimento das alterações fisiológicas e bioquímicas no pós-treino poderia fornecer índices de segurança para um embasamento científico. Objetivo Avaliar as alterações fisiológicas e bioquímicas imediatas nos adolescentes submetidos ao treino esportivo de alta intensidade. Métodos O artigo seleciona vários jovens atletas para pesquisa. Eles foram divididos aleatoriamente em dois grupos. O grupo A fez exercícios de alta intensidade e o grupo B fez exercícios normais. É feita uma análise estatística dos indicadores fisiológicos e bioquímicos dos atletas antes e depois do exercício. Resultados A capacidade vital nos dois grupos foi significativamente diferente. Porém, não foram encontradas diferenças significativas entre os indicadores bioquímicos coletados antes e depois dos treinos. Conclusão O esporte de alta intensidade pode melhorar a função cardiopulmonar com baixo impacto nos indicadores bioquímicos. Esse achado indica que o treinamento físico de alta intensidade pode melhorar o desempenho esportivo sem comprometer a saúde dos adolescentes. Nível de evidência II; Estudos Terapêuticos - Investigação de Resultados.

RESUMEN Introducción La intensidad del ejercicio puede acercarse rápidamente a la capacidad máxima de un individuo. El ejercicio de alta intensidad puede mejorar la capacidad aeróbica en personas con obesidad, sobrepeso, enfermedades cardíacas y diabetes. El conocimiento de las alteraciones fisiológicas y bioquímicas en el post-entrenamiento podría proporcionar índices de seguridad para una base científica. Objetivo Evaluar los cambios fisiológicos y bioquímicos inmediatos en adolescentes sometidos a un entrenamiento deportivo de alta intensidad. Métodos El artículo selecciona a varios jóvenes atletas para la investigación. Se dividieron aleatoriamente en dos grupos. El grupo A hizo ejercicio de alta intensidad y el grupo B hizo ejercicio normal. Se realizó un análisis estadístico de los indicadores fisiológicos y bioquímicos de los atletas antes y después del ejercicio. Resultados La capacidad vital en los dos grupos fue significativamente diferente. Sin embargo, no se encontraron diferencias significativas entre los indicadores bioquímicos recogidos antes y después del entrenamiento. Conclusión El deporte de alta intensidad puede mejorar la función cardiopulmonar con un bajo impacto en los indicadores bioquímicos. Este hallazgo indica que el entrenamiento físico de alta intensidad puede mejorar el rendimiento deportivo sin comprometer la salud de los adolescentes. Nivel de evidencia II; Estudios terapéuticos - Investigación de resultados.

Design of a Multimedia-Assisted Distance English Teaching System for College Students.

To address the problems of poor compatibility, weak load capacity, and time consumption of existing multimedia-assisted teaching systems, we propose and design a physics multimedia-assisted English teaching system based on a concept network. The architecture of the physics multimedia-assisted teaching system is constructed with the logical layer as the core, and the theoretical knowledge module, experiment module, and student practice module are designed, respectively. Based on the concept network, a large number of rules in the physics teaching system are attached to the concepts to form the concept network knowledge system and complete the design of the theoretical knowledge system. This paper explores the multimedia teaching of college English and points out the advantages and characteristics of this teaching mode and the problems to be paid attention to in the process of application. The design of the physics multimedia-assisted teaching system is completed by realizing students' practice and giving feedback on the practice results. The experimental results show that the system has good compatibility, strong load capacity, low time consumption, and practical application value.

[Regulating effect of N-acetyl-seryl-aspartyl-lysyl-proline on activation of c-jun N-terminal kinase pathway in rats with silicosis].

OBJECTIVE: To investigate the regulatory effect of N-acetyl-seryl-aspartyl-lysyl-proline (AcSDKP) on the activation of c-jun N-terminal kinase (JNK) signal transduction pathway and its role in silicotic fibrosis. METHODS: A rat model of silicosis was developed by intratracheal instillation. Sixty rats were randomly divided into 4-week control group (n = 10), 8-week control group (n = 10), 4-week silicosis model group (n = 10), 8-week silicosis model group (n = 10), AcSDKP treatment group (n = 10), and AcSDKP prevention group (n = 10). The content of hydroxyproline in lung tissue was measured using a p-dimethylaminoben-zaldehyde reagent; the expression levels of transforming growth factor (TGF)-beta 1 (TGF-ß1), phospho-JNK, JNK, and c-jun in lung tissue were measured by Western blot. The lung fibroblasts from neonatal rats were cultured, and the 4th generation of cells were used in the experiment; these cells were divided into control group, TGF-ß1 stimulation group, SP600125 intervention group, and AcSDKP intervention group. The distributions of phospho-JNK and c-jun in lung fibroblasts were observed by immunocytochemistry; the expression levels of type I collagen and type III collagen in lung fibroblasts were measured by Western blot. RESULTS: The expression levels of TGF-ß1, phospho-JNK, and c-jun and the content of hydroxyproline in the AcSDKP treatment group were 70.60%, 78.03%, 79.85%, and 71.28%, respectively, of those in the 4-week silicosis model group (P < 0.05) and 77.99%, 66.73%, 69.94%, and 64.82%, respectively, of those in the 8-week silicosis model group (P < 0.05); the expression levels of TGF-ß1, phospho-JNK, and c-jun and the content of hydroxyproline in the AcSDKP prevention group were 84.56%, 61.18%, 64.73%, and 74.96%, respectively, of those in the 8-week silicosis model group (P < 0.05). The expression levels of phospho-JNK and c-jun in the AcSDKP intervention group were 54.59% and 55.56%, respectively, of those in the TGF-ß1 stimulation group; the expression levels of type I collagen and type III collagen in the AcSDKP intervention group were 79.9% and 84.4%, respectively, of those in the TGF-ß1 stimulation group (P < 0.05). CONCLUSION: AcSDKP exerts anti-silicotic fibrosis effect probably by inhibiting the activation of JNK signal transduction pathway mediated by TGF-ß1 and the deposition of interstitial collagen.

[Effect of N-acetyl-seryl-aspartyl-lysyl-proline on regulation of expression of ras-raf-ERK1/2 signal transduction pathway in lung of rats with silicosis].

OBJECTIVE: to investigate the effect of N-acetyl-seryl-aspartyl-lysyl-proline (AcSDKP) on the expressions of c-Raf, ERK1/2 and TGF-ß1 in the lung of rats with silicosis, thus to investigate the regulating of AcSDKP on the Ras-Raf-ERK1/2 signal transduction pathway. METHODS: rats were instilled with silica through trachea as silicotic models and administered AcSDKP in the experiment. Rats were divided into 6 groups randomly, 10 rats in each group: Control 1 and 2 of silicotic model: each rat was intratracheally instilled with 1.0 ml normal sodium and was killed after 4 or 8 weeks; Silicotic model 1 and Silicotic model 2: each rat was intratracheally instilled with 1ml silica suspension and was killed after 4 or 8 weeks; Anti-fibrosis treatment of AcSDKP: after each rat was intratracheally instilled with 1ml silica suspension for 4 weeks, AcSDKP 800 microg × kg(-1) × d(-1) was administered into every rat and rats were killed at the eighth week; Preventing fibrosis treatment of AcSDKP: after AcSDKP 800 microg × kg(-1) × d(-1) was administered into every rat for 48 hours, each rat was intratracheally instilled with 1.0 ml silica suspension and rats were killed at the eighth week. The expression of c-Raf, phospho-c-Raf, ERK1/2, phospho-ERK1/2 and TGF-ß1 was measured by immunohistochemistry and western blot assay. RESULTS: compared with the corresponding control groups, the expressions of phospho-c-Raf, phospho-ERK1/2 and TGF-ß1 increased in the lung tissue of the silicotic models. Compared with the corresponding model groups, after administration AcSDKP, the expressions of phospho-c-Raf, phospho-ERK1/2 and TGF-ß1 in the lung tissue reduced obviously. In anti-fibrosis treatment of AcSDKP group, expressions of phospho-c-Raf, phospho-ERK1/2 and TGF-ß1 decreased to 52.25%, 51.72% and 67.74% compared with those of the silicotic model 1, and expressions of phospho-c-Raf, phospho-ERK1/2 and TGF-ß1 decreased to 49.37%, 55.76%, 65.63% compared with those of the silicotic model 2; In preventing fibrosis treatment of AcSDKP group, expressions of phospho-c-Raf, phospho-ERK1/2 and TGF-ß1 decreased to 54.64%, 55.76% and 78.91% compared with those of the silicotic model 2 (P < 0.05) while the expressions of c-Raf and ERK1/2 were not different significantly among each groups. CONCLUSION: AcSDKP possibly plays an important role in anti-silicotic fibrosis by blocking the TGF-ß-induced Ras-Raf-ERK1/2 signal transduction pathway.

New anti-fibrotic mechanisms of n-acetyl-seryl-aspartyl-lysyl-proline in silicon dioxide-induced silicosis.

AIMS: We previously reported that tetrapeptide N-acetyl-seryl-aspartyl-lysyl-proline (Ac-SDKP) inhibited pulmonary inflammation and fibrosis in SiO(2)-induced silicosis. This study aimed to explore the precise mechanism involved. MAIN METHODS: Rats were divided into 3 groups: 1) sham (saline), 2) silicosis+vehicle, and 3) silicosis+Ac-SDKP [800 microg/(kgd)]. SiO(2) particles or saline were administered by tracheal instillation and Ac-SDKP or vehicle (saline) via a mini-osmotic pump planted into the abdominal cavity 48 h before instillation. Animals were observed for 4 weeks. Silicotic nodule fraction (SNF) and macrophage infiltration (ED-1 positive cells) were measured by hematoxylin and eosin (H.E.) and immunohistochemical staining respectively. Collagen I and III, transforming growth factor-beta1 (TGF-beta1) proteins and monocyte chemotactic protein-1 (MCP-1) mRNA were detected by Western Blot (WB) and real-time RT-PCR respectively. In vitro, pulmonary fibroblasts were stimulated by TGF-beta1 (5 microg/ml) with or without Ac-SDKP. Phosphorylated c-Jun N-terminal Kinase (p-JNK) was detected by WB and p-JNK nuclear translocation by confocal analysis. KEY FINDINGS: SiO(2) significantly increased the SNF, collagen I and III proteins, TGF-beta1, MCP-1 mRNA and macrophage infiltration. All these pathological changes were inhibited by Ac-SDKP. TGF-beta1 resulted in fibroblast proliferation, increased expression of collagen I and III proteins, p-JNK and its subsequent nuclear translocation. Addition of Ac-SDKP markedly suppressed these changes. SIGNIFICANCE: These data indicate that the anti-fibrotic effect of Ac-SDKP in silicosis is mediated by inhibiting chronic inflammation, TGF-beta1 production, and TGF-beta1-induced pulmonary fibroblast proliferation and collagen synthesis.