Estimating fat-free mass in elite-level male rowers: a four-compartment model validation of laboratory and field methods     

Kristina L. Kendall  David H. Fukuda  Parker N. Hyde  Abbie E. Smith-Ryan  Jordon R. Moon  Jeffrey R. Stout 《Journal of sports sciences》2017,35(7):624-633

The purpose of this study was to investigate the accuracy of fat-free mass (FFM) estimates from two-compartment (2C) models including air displacement plethysmography (ADP), ultrasound (US), near-infrared interactance (NIR), and the Jackson and Pollock skinfold equation (SKF) against a criterion four-compartment (4C) model in elite male rowers. METHODS: Twenty-three elite-level male rowers (mean± SD; age 24.6 ± 2.2 years; stature: 191.4 ± 7.2 cm; mass: 87.2 ± 11.2 kg) participated in this investigation. All body composition assessments were performed on the same day in random order, except for hydrostatic weighing (HW), which was measured last. FFM was evaluated using a 4C model, which included total body water from bioimpedance spectroscopy, body volume from HW, and total body bone mineral via dual-energy X-ray absorptiometry. The major findings of the study were that the 2C models evaluated overestimated FFM and should be considered with caution for the assessment of FFM in elite male rowers. Future studies should use multiple-compartment models, with measurement of TBW and bone mineral content, for the estimation of FFM.  相似文献   

A comparison of methods to determine bilateral asymmetries in vertical leg stiffness     

Sean J. Maloney  Iain M. Fletcher  Joanna Richards 《Journal of sports sciences》2016,34(9):829-835

Whilst the measurement and quantification of vertical leg stiffness (K_vert) asymmetry is of important practical relevance to athletic performance, literature investigating bilateral asymmetry in K_vert is limited. Moreover, how the type of task used to assess K_vert may affect the expression of asymmetry has not been properly determined. Twelve healthy males performed three types of performance tasks on a dual force plate system to determine K_vert asymmetries; the tasks were (a) bilateral hopping, (b) bilateral drop jumping and (c) unilateral drop jumping. Across all the three methods, K_vert was significantly different between compliant and stiff limbs (P < 0.001) with a significant interaction effect between limb and method (P = 0.005). Differences in K_vert between compliant and stiff limbs were ?5.3% (P < 0.001), ?21.8% (P = 0.007) and ?15.1% (P < 0.001) for the bilateral hopping, bilateral drop jumping and unilateral drop jumping methods, respectively. All the three methods were able to detect significant differences between compliant and stiff limbs, and could be used as a diagnostic tool to assess K_vert asymmetry. Drop jumping tasks detected larger K_vert asymmetries than hopping, suggesting that asymmetries may be expressed to a greater extent in acyclic, maximal performance tasks.  相似文献   

目击时间的深渊——《野蔷薇》及其他     

黄彩文 《河北师范大学学报(哲学社会科学版)》2007,30(1):90-99

《野蔷薇》颇富思辨色彩,比较自觉集中地表达了那一时期茅盾的"时间哲学",同时比较早地提出了反思现代性这一历史课题.迁移与错位、直线与循环、潜隐与彰显等诸时间形态的对立与连接构成了文本的内在的叙事理路,也彰显了作者时间意识的深厚蕴含.  相似文献   

相平衡与CO2在水中的扩散速率--CO2排水集气法   总被引：1，自引：0，他引：1  

郑萍  陈明元 《贵州教育学院学报》2004,15(2):69-70

根据相平衡等的有关计算可知，常压下CO2溶于水的过程为物理吸收，CO2的饱和水溶液为稀溶液，而且溶液里碳酸的生成和电离可以忽略不计。CO2在水中的扩散系数非常小，其数量级为10^-5cm^2／s，在CO2排水集气法操作中，CO2气体不被水吸收。  相似文献   

真空-堆载联合预压法加固软土地基     

范新荣  叶海霞 《洛阳工业高等专科学校学报》2004,14(4):33-35

真空-堆载联合预压法是加固饱和软粘土的理想方法，通过试验，观测路基的表面沉降和水平位移，说明真空预压能使地基产生较大的沉降速率，同时提高路基的稳定性，侧向位移量和位移速率与荷载大小的相关性比较明显。  相似文献   

基于Matlab的散斑干涉分析及应用   总被引：1，自引：0，他引：1  

王凤鹏  曾祥志 《赣南师范学院学报》2007,28(3):35-37

介绍了电子散斑干涉测量离面位移的原理和利用Matlab得到散斑“相关条纹”的方法,并利用电子散斑干涉法测得了玻璃在一定压力下的形变量.实验结果表明,将散斑干涉场中的固定部分作为0级条纹位置,可以有效地对物体的形变进行定量分析.  相似文献   

储油罐的变位识别与罐容表标定     

吴叶  张飞群  景昱波  李亚辉 《浙江教育学院学报》2011,(5):99-106

研究了储油罐的变位识别与罐容表标定的问题.针对问题一,利用求体积的定积分法,求出了罐体在无变位与纵向变位两种情况下分别关于油位高度及纵向倾斜角的体积表达式,得出了无变位和纵向倾斜角为α=4.1°两种情况下的罐容表标定值.针对问题二,利用非线性最小二乘法得到两个偏转角,并制定出罐体变位后油位高度的罐容表标定值.  相似文献   

由M_w7.8昆仑山地震地表位错推断滑动位移     

米琦  李彦恒  申文豪  史保平 《中国科学院大学学报》2015,32(5):652-660

2001年MW7.8昆仑山口西地震形成约400 km的地震破裂带,主震断层为一长度350 km、呈东西走向且近直立的走滑断层.主震断层附近的同震滑动位错为研究断层内部的力学性质及几何形态提供了重要参考.本文根据Freund的III-型位错模型,以实地测量和卫星测量的地表错动数据为约束条件,求取沿主震断层走向断层内部各点的滑动位移分布以及破裂面沿断层深度方向的扩展宽度.计算结果表明:III-型位错模拟结果所得断层面滑动位移分布特征和由有限断层模型体波反演得到的结果有较高的吻合程度,且在深度方向上呈现强烈的不均匀性.由III-型位错模型给出的断层内部的破裂宽度小于20 km,其平均值为8.4 km.进一步的对比分析表明:地表同震位移量的大小同断层的破裂宽度在尺度上存在明确的比例关系,沿断层走滑方向各点的滑动位移随深度的变化特征具有自相似性的分形特征.结合III-型位错模拟和体波反演结果,基于Andrews方法计算断层面上静态应力变化的分布,其分布特征同样具有很高的吻合度.  相似文献   

激光三角法测量的误差研究   总被引：5，自引：0，他引：5  

常城  张志峰 《中国科技信息》2006,(23):61-62,64

激光三角法测量是三维曲面非接触测量的主要方法之一，但测量精度受到本身结构和被测物体特性及环境因素等多方面的影响。本文简要介绍了激光三角法测量的原理，通过对一种型号的激光位移传感器的实验，对激光三角法测距由于被测物体表面特性不同和变化所引起的误盖进行了全面地分析和研究，井针对不同误差原因提出了改进的方法。  相似文献   

拟静力试验桥墩的损伤评价     

杨玄  彭建中 《黑龙江科技信息》2011,(25):29-29

钢筋混凝土构件的抗震性能,包括强度、刚度、强度退化、刚度退化、延性、能量耗散、构件破坏等的变化规律。本文从地震作用下结构（构件）损伤评价出发,采用九个墩柱的破坏性试验数据,通过基于位移延性系数的损伤评价模型和经典损伤评价模型对试验墩柱的损伤程度进行了评价,并比较了两种评价方法的适用性。  相似文献