Strength training methods for skiers / Métodos de treinamento de força para esquiadores / Métodos de entrenamiento de fuerza para esquiadores

ABSTRACT Introduction: The ski jumping sequence can be divided into four steps: support, take-off, flight, and landing. Each stage has specific tasks and functions and is closely related, with the completion of each stage depending on the previous one. Objective: Explore the effectiveness of special strength training methods for ski sportsmen. Methods: Using the method of scientific literature review, expert interview, experience, and mathematical statistics to perform the special strength training for Chinese ski athletes, comparing the changes in the jump speed and take-off of the big jumps before and after 16 weeks of strength training with a specially developed protocol. Results: There were significant differences in take-off speed and air height before and after the experiment (P<0.05). The athletes in the experimental group significantly differed in takeoff speed before and after participation in the experiment (P=0.01). Conclusion: The experimental results fully evidence that by improving the rapid contraction strength of flexor and extensor muscles of the trunk and hip joints, modern abdominal center strength training methods are more effective than traditional methods. Level of evidence II; Therapeutic studies - investigation of treatment outcomes.

RESUMO Introdução: A sequência de saltos de esqui pode ser dividida em quatro etapas: apoio, decolagem, voo e pouso. Cada etapa tem tarefas e funções específicas e está intimamente relacionada, sendo a conclusão de cada etapa dependente da etapa anterior. Objetivo: Explorar a eficácia dos métodos especiais de treinamento de força para esportistas em esqui. Métodos: Usando o método de análise científica literária, entrevista com especialistas, experiência e estatísticas matemáticas para realizar o treinamento de força especial para atletas chineses de esqui, comparando as mudanças na velocidade de salto e decolagem dos grandes saltos antes e depois de 16 semanas de treinamento de força com um protocolo especialmente desenvolvido. Resultados: Houve diferenças significativas na velocidade de decolagem e na altura aérea antes e depois do experimento (P<0,05). Os atletas do grupo experimental tiveram uma diferença muito significativa na velocidade de decolagem antes e depois da participação no experimento (P=0,01). Conclusão: Os resultados experimentais evidenciaram plenamente que ao melhorar a força de contração rápida dos músculos flexores e extensores das articulações do tronco e quadril, os métodos modernos de treinamento de força do centro abdominal são mais eficazes do que os métodos tradicionais de treinamento. Nível de evidência II; Estudos terapêuticos - investigação dos resultados do tratamento.

RESUMEN Introducción: La secuencia de salto de esquí puede dividirse en cuatro pasos: apoyo, despegue, vuelo y aterrizaje. Cada paso tiene tareas y funciones específicas y está estrechamente relacionado, siendo la conclusión de cada paso dependiente del anterior. Objetivo: Explorar la eficacia de los métodos especiales de entrenamiento de la fuerza para los deportistas de esquí. Métodos: Utilizando el método de revisión de la literatura científica, la entrevista a expertos, la experiencia y la estadística matemática para realizar el entrenamiento de fuerza especial para los atletas de esquí chinos, comparando los cambios en la velocidad de salto y el despegue de los grandes saltos antes y después de 16 semanas de entrenamiento de fuerza con un protocolo especialmente desarrollado. Resultados: Hubo diferencias significativas en la velocidad de despegue y la altura del aire antes y después del experimento (P<0,05). Los atletas del grupo experimental tuvieron una diferencia muy significativa en la velocidad de despegue antes y después de la participación en el experimento (P=0,01). Conclusión: Los resultados experimentales evidencian plenamente que, al mejorar la fuerza de contracción rápida de los músculos flexores y extensores de las articulaciones del tronco y la cadera, los métodos modernos de entrenamiento de la fuerza del núcleo abdominal son más eficaces que los métodos de entrenamiento tradicionales. Nivel de evidencia II; Estudios terapéuticos - investigación de los resultados del tratamiento.

Age at menarche and associated factors of female junior middle school students in Tianjin area / 中国学校卫生

Objective@#This study aims to investigate the menarcheal age of female junior middle school students in Tianjin and associated factors, providing suggestions for further development of adolescence education on physiological and mental health.@*Methods@#A total of 4 127 junior middle school girls in Tianjin area were selected by stratified random sampling method, and investigated by the method of physical examination and questionnaire survey, results were analyzed.@*Results@#There were 1 383 girls reported menarche. Mean age at menarche was(12.68±1.19) years old; One-way ANOVA showed that girls with higher family income, higher parental education had earlier menarcheal age(F=4.97, 9.52, 10.64, P<0.05). It showed that the tendency that obesity group and over-weight group was higher in the rate of menarche than that of normal group and marasmus group(F=4.20, P<0.05). However, different time on watching TV, computer or celephone and sleeping was found to be unrelated with age at menarche(P>0.05). Kruskal Wallis H test showed that girls whose mothers’ AAM was earlier had earlier menarcheal age(H=82.94, P<0.05). According to age, girls were divided into groups of 10-11, 11-12, 12-13 and 13-14 years old. Girls in each age group were divided into the menstruation menarche group and the non-menstruation menarche group. The results showed that the levels of height, weight, BMI, waist circumference, hip circumference, and the skin fold thickness in menstruation group were higher than those in non-menstruation group(t=2.18-10.93, P<0.05). After that, girls of each group were divided into four group：marasmus group, the normal group, the over-weight group and the obesity group according to BMI(χ2=34.66，13.37，11.09，12.60,P<0.05).@*Conclusion@#Female junior middle school students’ menarcheal age in Tianjin is related to family income, parents’education, mother’s age at menarche, obesity and physical exercise frequency.