Effects of Athlete’s Posture on Aerodynamic Characteristics During Flight in Ski Jumping / 医用生物力学

Objective To investigate the effects of athlete’s posture (including bending angle of upper body and angle between body and skis) on aerodynamic characteristics during flight in ski jumping. Methods The athlete and skis were regarded as a multi-body system. By using partially averaged Navier-Stokes (PANS) turbulence model and numerical simulation of computational fluid dynamics (CFD), the aerodynamic characteristics during flight under different postures were predicted. The calculation conditions for bending angle of upper body were 10°, 14°, 18°, 22° and 26°, and the calculation conditions of angle between body and skis were 8°, 12°, 16°, 20° and 24°. Results As the bending angle of upper body increased, the lift force and drag force of the multi-body system, the athlete and skis, and the pitch moment of skis all showed a monotonously decreasing trend, but the ratio of total lift force to total drag force increased first and then decreased. Meanwhile, the pitch moment of the multi-body system decreased first and then increased, and the pitch moment of athlete increased slightly and then decreased. As the angle between body and skis increased, the lift force and drag force of the multi-body system and skis increased first, then decreased and then increased, but the ratio of total lift force to total drag force decreased first, then increased and then decreased. Meanwhile, the lift force, drag force and pitch moment of the athlete increased monotonously, and the pitch moment of the multi-body system and the skis increased first and then decreased. The effect of bending angle of upper body on aerodynamic characteristics during flight in ski jumping was generally significantly larger than that of angle between body and skis. Conclusions The optimal range for bending angle of upper body is 14°-18°, and the optimal range of angle between body and skis is 16°-20°. The influence mechanism for bending angle of upper body and angle between body and skis on aerodynamic characteristics during flight in ski jumping can provide effective auxiliary support for on-the-spot prediction and decisionmaking,

Comparison of electromyographic activity during the bench press and barbell pullover exercises / Comparação da atividade eletromiográfica entre os exercícios supino horizontal e pull-over na barra / Comparación de la actividad electromiografíca entre los ejercicios press de banca horizontal y pull-over barra

The aim of the study was to compare the electromyographic (EMG) activity of the following muscles: clavicular portion of pectoralis major, sternal portion of pectoralis major, long portion of triceps brachii, anterior deltoid, posterior deltoid and latissimus dorsi during dynamic contractions between flat horizontal bench press and barbell pullover exercises. The sample comprised 12 males individuals experienced in resistance training. The volunteers made three visits to the laboratory. The first one consisted of 12 repetitions of the exercises for the electromyographic data collection. The results showed a higher EMG activation of the pectoralis major and anterior deltoid muscles in the flat horizontal bench press in comparison with the barbell pullover. The triceps brachii and latissimus dorsi muscles were more activated in the barbell pullover...

O objetivo do estudo foi comparar a atividade eletromiográfica dos músculos peitoral maior porção clavicular, peitoral maior porção externa, porção longa do tríceps braquial, deltóide anterior, deltóide posterior e grande dorsal durante contrações dinâmicas entre os exercícios supino horizontal e pull-over. A amostra foi composta por 12 indivíduos do sexo masculino experientes em treinamento resistido. Os voluntários fizeram três visitas ao laboratório; a primeira consistiu na avaliação antropométrica e no teste de 1RM em ambos os exercícios, e a segunda e terceira consistiram na realização de 12 repetições para a coleta dos dados da eletromiografia. Após a análise dos resultados foi possível identificar uma ativação eletromiográfica superior dos músculos peitoral maior e deltóide anterior no supino horizontal em relação ao pull-over barra. Já as musculaturas do tríceps braquial e grande dorsal foram mais ativadas no pull-over barra...

El objetivo del estudio fue comparar la actividad electromiografíca de los músculos pectoral mayor en la porción clavicular, pectoral mayor porción esternal, porción larga del tríceps braquial, deltoides anterior, deltoides posterior y dorsal ancho durante las contracciones dinámicas entre los ejercicios press de banca y pullover. Hicieron parte de la muestra 12 individuos del sexo masculino expertos en el entrenamiento con pesas. Los voluntarios hicieran tres visitas al laboratorio, la primera, consistió en la evaluación antropométrica y en el teste de 1RM en los dos ejercicios, y la segunda y tercera, consistió en la realización de 12 repeticiones para la recolecta de los datos de la electromiografía. Después del análisis de los resultados fue posible identificar una activación electromiografíca superior en las porciones del musculo pectoral mayor y en el deltoides anterior en el press de banca horizontal en relación al pull-over barra. Ya las musculaturas del tríceps braquial y del dorsal ancho fueron las más activadas en el pull-over barra...

3-D center of gravity mapping:a new method for assessment of FES-assisted paraplegic walking efficiency / 中华物理医学与康复杂志

Objective To explore a new method for assessing the walking efficiency of the paraplegic patients assisted by functional electrical stimulation (FES). Methods The measurement system based on a standard walker was developed. During FES assisted walking of the paraplegic, the real time of the upper limb support were obtained and transformed into a 3 D center of gravity (CG) motion map with a paraplegic upper body mechanical model to describe the CG motion locus. Then the FES efficiency indicated by walking balance condition was assessed objectively and quantitatively. Results In this design, the pilot study of a paraplegic patient undergoing walking training with FES showed that the force accuracy was better than 1.01%, nonlinearity was less than 0.8%, and crosstalk was less than 3.2%. Conclusion The results showed that this system may be used as 1) an evaluation index of FES assisted paraplegic walking efficiency, 2) a balance control indicator during FES assisted paraplegic walking training and 3) a feed back signal to choose an efficient FES pattern and sequence.

A Comparision of Normocholesterolemia and Hypercholesterolemia in Middle-Aged Men in Kwang-ju / 대한지역사회영양학회지

The purpose of this study was to investigate the differences in anthropometric, hematologic, and lipidologic data between normocholesterolemia and hypercholesterolemia and influencing factors in hypercholesterolemia in middle-aged men in Kwang-ju. 179 middle-aged men were involved. Anthropometric data(body weight, height, body circumferences and skinfold thickness) and hematologic data(blood pressure, fasting blood glucose, albumin and hemoglobin) were measured. Bleed lipid profile(total cholesterol, triglyceride, phospholipid, HDI-cholesterol, LDL-cholesterol and VLDL-cholesterol) were analyzed. To determined using questionnaire. The subjects were classified as hypercholesterolemic based on The Guideline for Korean Hyperlipidemia. body mass index, systolic blood pressure, waist and hip circumference, and triceps, subcostal, abdomen, subscapular and suprailliac skinfold thicknesses of the hypercholesterolemic group were significantly higher than in the normocholesterolemic group. The concentration of cholesterol, triglyceride, phospholipod. HDL-cholesterol, LDL-cholesterol and VLDL -cholesterol of the hypercholesterolemic group were significantly higher than normocholesterolemic group. The concentration of cholesterol has a significantly positive correlation with body mass index, diastolic blood pressure, waist circumference, waist/thigh ratio and skinfold thickness(triceps, subcostal, abdomen, and supraillic skin-fold thickness). The general tendency of socioeconomec status, frequencyu of meat intake, smoking amounts and duration and duration and drinking frequencies and amount were higher in the hypercholesteolemic group but not significant. In conclusion, hypercholesterolemia in middle-aged men was closely correlated with upper body fat obesity and most of them had an accompanied high triglyceride level tendency.