对“core strength”是“核心力量”或“中心力量”的辩析

近年来,国内竞技体育中对核心力量、核心稳定性的研究甚为流行,而这种概念是源自国外"core、core strength、core stabil-ity"的理解与翻译。通过对大量国内外文献资料的研究发现:我国目前对核心、核心力量、核心稳定性的提法并不准确,对"core、core strength、core stability"重新提出了新的理解与观点,提出了中心、中心力量、中心稳定性的概念,并且对中心肌肉群、中心力量进行了划分和归类,进一步完善了运动训练中对"core、core strength、core stability"的定义,为进一步准确指导运动员力量训练提供可行的理论依据和帮助。

The role of Core strength training on Basketball Players

Core strength training is mainly directed against the entire trunk and pelvic muscles, with special emphasis on training those in the deep small muscle group. Human torso plays an important role of rigid connection during exercise. It can effectively converge and integrate the power of the body parts, which plays a strong leverage for the athletes of the coordinated development of motor skills. As far as basketball is concerned, strong core strength can be more stable, and cab fix basketball athlete＇ s body posture, integrating the body organically with the development of all aspects, and making the upper and lower extremities more coordinated with each other, helping improve athletic level.

Discussion on the Core Strength Training Method for 100-Meter Event in Track and Field Sports

In track and field sports,the 100-meter race is an extremely intense sport that requires effective training of athletes’core strength.From the perspective of adolescents,in order to enhance core strength,it is necessary to effectively fix the pelvic position in the process of exercise,so that the core stability,balance,and coordination of athletes can be improved.The training process of the 100-meter event is mainly an anaerobic metabolic exercise,it is necessary to ensure that athletes maintain a high level of physical readiness during the exercises and concentrate highly on their core strength,so that they can achieve excellent results.This paper analyzes the core strength training for the 100-meter event in track and field sports,discusses its importance,and puts forward specific training methods,hoping to provide guidelines for relevant researchers.

Research on the Impact of Core Strength Training on the Motor Skills of Tennis Beginners

With the popularity of tennis in the sports world,more and more beginners are joining this sport.However,for beginners,how to improve motor skills and game performance is still an important issue.Core strength training has potential as a potential adjunct to improve overall fitness and skill in athletes.Therefore,this research aimed to explore the potential impact of core strength training on the motor skills of tennis beginners to provide better training strategies and guidance for coaches and athletes.

Strategies for Core Strength Training in Free Combat Teaching

Since free combat is a competitive sport that flexibly utilizes kicking,punching,wrestling,and holding techniques to defeat the opponent,a good core strength of athletes can help to improve the technical level,enhance the quality of movements,and protect the joints and muscles.In order to carry out core strength training in free combat teaching with high quality,firstly,it is necessary for coaches to carry out simple training,centralized training,and extended training according to the basic planning of adaptation-stabilization-improvement.Secondly,it is also important to test the athlete’s physical and athletic qualities before implementing the specific training plan,optimize the training program,and carry out statistical analysis of the stage training data in order to achieve the best training effect.

Effect of kaolin on tensile strength and humidity resistance of a water-soluble potassium carbonate sand core

Water soluble cores(WSCs) have been widely applied in manufacture of complex metal components with hollow configurations or internal channels. However, the WSCs without any additons have low tensile strength and low humidity resistance. The purpose of this study is to prepare a water-soluble potassium carbonate sand core with addition of kaolin by the hot-temping method. The effects of kaolin on tensile strength, humidity resistance, fracture mechanism, as well as the gas evolution and collapsibility of WSCs were investigated. Results show that both the crystal morphology and the fracture mechanism of the inorganic salt are changed under the participation of kaolin, contributing to the increase of the tensile strength and the humidity resistance of the core. With the addition of 3wt.% kaolin, the tensile strength could be increased by a factor of 2, reached 1.50 MPa and the hygroscopic rate could be decreased by 14%, achieved 0.559%(after stored for 8 h), respectively. As the addition amount of kaolin increases from 0wt.% to 3wt.%, the main fracture mechanism changes from a adhesive to a cohesive fracture mechanism. The water-soluble potassium carbonate core obtained has the low gas evolution and excellent collapsibility, which makes it suitable for casting low melting metal with complex cavities and crooked channels.

Mass concrete strength assessment method by Sonreb and Core combined method using artificial neural network

The Sonreb and Core (SRC) combined method is proposed to assess the concrete compression strength of mass concrete structures.Artificial neural network is employed together with the SRC combined method to obtain the optimal core number.The artificial neural network is trained based on data from different testing methods.The procedure of using artificial neural network to assess the concrete strength is described.It proves that the SRC combined method is superior in many aspects and artificial the presented neural network has a high efficiency and reliability.The combined method using artificial intelligence is promising in the strength assessment of mass concrete structures such as the dam,the anchor of the suspension bridge,etc.

Numerical simulation of temperature and strength distributions of mold(core) on heating

By using Visual C++, a model with post processing was carried out to simulate the temperature and strength distributions of the mold(core). The results are shown in 256 color graphic mode. With this model, the temperature and strength distributions of the mold(core) both in case of heating process for core in the furnace and solidification process for a thin wall aluminum alloy casting in the mold(core) are numerically simulated. The results show that the temperature and strength distributions of the mold(core) were uneven because the thermal conductivity of the resin sand was much small. This study laid a basis for the optimum design of the mold(core) properties. [

Schroth疗法联合核心力量训练改善轻度青少年特发性脊柱侧凸患者的侧凸角度

背景:青少年特发性脊柱侧凸明确的发病原因尚未可知,寻找解决青少年特发性脊柱侧凸的临床方法迫在眉睫。目的:探讨Schroth疗法联合核心力量训练对轻度青少年特发性脊柱侧凸的效果,为轻度青少年特发性脊柱侧凸的临床治疗提供更多依据。方法:选择2022年7月至2024年1月在南通大学附属医院康复医学科与脊柱外科就诊的轻度青少年特发性脊柱侧凸患者110例作为研究对象,根据患者及家长意愿,分为试验组和对照组,每组55例。对照组观察随访,试验组进行Schroth疗法联合核心力量训练,每天45 min,坚持24周。比较两组患者治疗前后影像学参数、体表指标、三维超声成像角度和生活质量的差异。结果与结论:①治疗24周后,试验组主弯Cobb角、顶椎偏距、颈椎前凸角均较治疗前有显著改善(P<0.05),而对照组无显著差异(P>0.05);试验组主弯Cobb角、顶椎偏距明显优于对照组(P<0.05);②治疗24周后,试验组躯干旋转角度明显低于治疗前(P<0.05),而对照组无显著差异(P>0.05);试验组躯干旋转角度明显低于对照组(P<0.05);③治疗24周后,试验组三维超声成像椎板中心法角度明显减小(P<0.05),而对照组无显著差异(P>0.05);试验组三维超声成像椎板中心法角度明显低于对照组(P<0.05);④治疗24周后,在生活质量上,试验组的疼痛维度评分显著增高(P<0.05),试验组和对照组的自我形象维度评分均较治疗前显著增高(P<0.05),两组的心理健康维度评分较治疗前显著降低(P<0.05);疼痛、自我形象、心理健康和满意度维度评分,试验组均明显高于对照组(P<0.05);⑤提示Schroth疗法联合核心力量训练能改善轻度青少年特发性脊柱侧凸患者的主弯Cobb角、顶椎偏距、颈椎前凸角,降低躯干旋转角度,减少三维超声成像角度,提高生活质量,对轻度青少年特发性脊柱侧凸治疗有效。

Web Shear Strengthening Technique of Deep Precast Prestressed Hollow Core Slabs under Truck Loads

Precast prestressed Hollow Core Slabs (HCS), are one of the famous and widely used slabs for concrete structures all over the world and widely implemented in the Middle East. HCS are used in industrial, commercial, residential buildings, as well as, in the parking structures. This paper succeeded to present new special details for deep HCS to enhance and strengthen the web shear strength capacity of HCS 400 and 500 mm depths respectively at the open parking area. This is subjected to heavy truck wheel loads so as to achieve the LRFD Code’s requirements. However, it is noticed many web shear cracks of HCS are used at parking area at many projects in Gulf Region. On the other hand, ACI318-14 permits no shear reinforcement in prestressed HCS thickness of less than 12.5 in (320 mm). The paper presents experimental tests program, to verify the numerical finite element of deep HCS under maximum design uniform loads, in addition to the new strengthening techniques. New strengthening techniques succeed to enhance the web shear capacity by significant percentage, due to the new details for HCS 400 by 68% up to 256% increasing of the web shear capacity compared to the ordinary HCS section. Also, HCS 500 shear capacity is enhanced with different percentages of strengthening techniques by 55%, up to 197% based on the different cases of strengthening. Furthermore enhancing deep HCS shear performance;the new techniques have an advantage of an easy execution at the site;casting with structural topping, otherwise the preparation can be done in precast factory before site handover, which saves time and cost compared to the others traditional strengthening techniques.

焊缝宽度对激光焊接Ⅰ-core全钢三明治板强度的影响

在自行设计的弯曲实验装置上,分别对焊缝宽度较窄和较宽的激光焊接Ⅰ-core全钢三明治板进行三点弯曲实验,并对其进行有限元模拟,分析焊缝宽度对三明治板强度的影响.结果表明:当载荷与挠度开始不再是线性关系时,接头上形成了第一个塑性铰,当载荷达到最大承载力时,接头发生开裂,三明治板完全失效.增加焊缝宽度,可提高Ⅰ-core三明治板的接头屈服载荷和最大承载力,同时失效形式也随之改变.在Ⅰ-core三明治板的强度设计和评价中考虑焊缝宽度是必要的.

Endurance tests are the most reliable core stability related measurements

Purpose:To determine the intra-tester reliability of clinical measurements that assess five components related to core stability:strength. endurance,flexibility,motor control,and function. Methods:Participants were 15 college-aged males who had not suffered any orthopedic injury in the past year.Core strength measurements included eight isometric tests and a sit-up test.The four core endurance tests were the trunk flexor test,trunk extensor test,and bilateral side bridge tests.Flexibility tests included the sit-and-reach test and active range of the trunk and hip joint motions.Proprioception via passive reposition tests of the hips and a single limb balance test on an unsteady platform were used to evaluate core motor control.Functional measurements consisted of a squat test and a single leg hop test for time and distance.Measurements were performed during two data collection sessions with a week’s rest between the sessions.Intra-class correlation coefficients were calculated to establish reliability. Results:The overall intra-rater reliability for all core stability related measurements ranged from low(ICC = 0.35,left hip reposition) to very high(ICC = 0.98,sit-and-reach).As a group,the core endurance tests were observed to be the most reliable. Conclusion:There are highly reliable tests in each of the five groups.Overall,core endurance tests are the most reliable measurements,followed by the flexibility,strength,neuromuscular control,and functional tests,respectively.

Material Properties and Mold Folded Core Based on Ultra-violet Cured Resins

Ultra-violet(UV)curing is an efficient method for composite molding.Firstly,thermophysical properties of UV cured glass-fiber reinforced plastics are conducted.Material properties are studied for various kinds of postcuring modes.Then the UV curing method is suggested in manufacturing V-crimp folded core for sandwich panels.Two kinds of processing schemes for V-crimp folded core manufacturing using UV curing are presented.Finally,the effect of post-curing on the mechanical properties of folded core sandwiches is experimentally studied,and optimum modes of post-curing are determined.The experimental results show that the ultimate compressive strength of the folded sandwiches is increased by 60% after post-curing with the optimum post-curing mode.

An in Vitro Investigation of Acid Etching Treatment Prior to Post and Core Cementation and Teeth Fracture Resistance

In order to investigate how to enhance the teeth fracture resistance after the post and core treatment, an in vitro study was conducted to measure the fracture resistance of endodontically treated teeth restored with cast post and core with two kinds of surface treatment technology and acid etching preparation on the dentinal surface. Sixty-four recently extracted human single-rooted first premolars were endodontically treated and sectioned approximately 1.5 mm above the cementoenamel junction to remove the coronal portion. Each specimen received a cast post, core build-up and a metal alloy crown restoration. All teeth were randomly divided into the smooth surface post, core repair group, the sand blasting surface post, and core repair group, each group was divided into 10 s, 30 s, 60 s acid corrosion treatment group and control group. In acid test groups, an acid etching solution was applied for 10, 30 and 60 seconds, respectively, to the root canal wall surface. Each specimen was embedded in acrylic resin block and tested in an electronic universal testing machine. Fracture loads results showed that canal acid etching could increase teeth fracture resistance strength both in smooth groups and sandblasting group, and achieved the best effect when acid etching for 30 s. Sand spray treatment on the surface of the cast metal post can improve the flexural strength of the teeth after postcrown restoration. Acid etching on the root canal wall surfaces and sand spray treatment on the surface of the cast metal post can improve the flexural strength of the root after post-crown restoration. Therefore, these two methods could be used to strengthen the tooth fracture resistance, and maintain the long-term therapeutic effect of cast post and core restoration.

EFFECT OF PROCESSING METHOD ON THE IMPACT STRENGTH OF POM/TPU/CaCO_3 TERNARY COMPOSITES

Polyoxymethylene （POM）/elastomer/filler ternary composites were prepared, in which thermoplastic polyurethane （TPU） and inorganic filler, namely, CaCO3, were used to achieve balanced mechanical properties of POM. The dispersion and phase morphology of POM/elastomer/filler composites were found to depend largely on processing method, CaCO3 content in masterbatch and the filler size. Two processing methods were employed to prepare POM/elastomer/filler ternary composites. One is called the one-step method, in which elastomer and the filler directly melt blended with POM matrix. The other is called the two-step method, in which the elastomer and the filler were mixed to get masterbatch first, which was then melt blended with pure POM of different content. The effect of phase morphology and processing method on impact strength was investigated. It was found that the two-step method results in an increase in impact strength but not for the one-step method. Additionally, the impact strength of POM ternary composites decreases with the increase in the size of CaCO3 particles.

我国城乡高中一、二年级学生体质健康测试状况的调查研究

背景目前有关高中生体质健康测试成绩的研究以各省、市内局部地区较为多见,多中心大样本量的全域研究甚少。各类学校在普遍开展线上与线下混合式教学时,势必延长了高中生本已较长的静坐时间。这种趋势是否对高中生的体质健康产生一定的影响,亟待开展全域范围的调查研究。目的调查并分析我国七大地区城乡高中一、二年级学生的体质健康测试成绩水平及相关影响因素,探索出高中一、二年级学生的体质健康水平均衡提升的赋能路径。方法采用分层随机整群抽样方法,于2019年1—3月在我国31个省(直辖市、自治区)七大地区(华东、华南、华北、华中、西北、西南、东北)高中学校按照市区县与乡镇村进行分层抽样,然后随机整群分别选取市区县高中学校和乡镇村高中学校各1所,共62所学校42523名在读的高一、高二年级学生进行调研,同时收集学生的体质健康测试成绩数据(BMI反映身体发育水平,肺活量反映身体功能,坐位体前屈反映躯体柔韧度,引体向上、50 m跑、立定跳远反映上下肢爆发力量水平,1 min仰卧起坐反映躯体核心力量水平,800 m跑、1000 m跑反映心肺耐力水平),并运用非参数检验及多元线性回归分析探讨体质健康测试成绩水平的影响因素。结果42523名高中生的中位年龄为16.0(16.0,17.0)岁;男生20074名(47.2%)、女生22449名(52.8%),市县区21725名(51.1%)、镇乡村20798名(48.9%)。七大地区高中生性别、城乡分布比较,差异有统计学意义(P<0.05)。七大地区高中男生各项体质健康测试成绩比较,差异均有统计学意义(P<0.05);各项体质健康测试成绩前三的地区如下:身高(华北>东北>华中)、体质量(东北>华北>华中)、BMI(华中>东北>华北)、肺活量(东北>华中>华南)、50 m跑(华南>华中>华东)、立定跳远(华南>华北>西北)、坐位体前屈(华南>西南>华中)、引体向上(华南>西南>西北)、1000 m跑(华南>华中>西南)。市县区高中男生的肺活量成绩高于镇乡村,50 m跑、立定跳远、坐位体前屈、引体向上、1000 m跑成绩低于镇乡村(P<0.001)。七大地区高中女生各项体质健康测试成绩比较,差异均有统计学意义(P<0.05);各项体质健康测试成绩前三的地区如下:身高(华北>东北>西北)、体质量(东北>华北>西北)、BMI(东北>华北>西北)、肺活量(东北>华南>华中)、50 m跑(华南>华中>华东)、立定跳远(华南>华北>华中)、坐位体前屈(东北>华中>华南)、1 min仰卧起坐(华北>华中>华东=西南)、800 m跑(东北>华中>华南)。市县区高中女生的身高、体质量、BMI成绩高于镇乡村,肺活量、50 m跑、立定跳远、坐位体前屈、1 min仰卧起坐、800 m跑成绩低于镇乡村(P<0.001)。多元线性回归分析结果显示,男生引体向上成绩与BMI、1000 m跑成绩呈负相关,与50 m跑、立定跳远、坐位体前屈成绩呈正相关(P<0.05),坐位体前屈为最主要的影响因素,1000 m跑次之;1000 m跑成绩与BMI、肺活量、引体向上成绩呈负相关,与50 m跑、立定跳远、坐位体前屈成绩呈正相关(P<0.05),引体向上为最主要的影响因素,坐位体前屈次之。女生1 min仰卧起坐成绩与BMI、肺活量、立定跳远、800 m跑成绩呈正相关,与50 m跑、坐位体前屈成绩呈负相关(P<0.05),BMI为最主要的影响因素,坐位体前屈次之;800 m跑成绩与BMI、50 m跑、坐位体前屈成绩呈负相关,与立定跳远、1 min仰卧起坐成绩呈正相关(P<0.05),坐位体前屈为最主要的影响因素,BMI次之。结论我国市县区高中一、二年级男生的身体发育水平与镇乡村相当,但市县区高中一、二年级女生的身体发育水平高于镇乡村女生。市县区高中一、二年级学生的上下肢爆发力量、躯体核心力量、心肺耐力水平均显著低于镇乡村。除身体发育水平以外,华南地区的高中一、二年级男生的体质健康各项测试成绩水平的优势十分明显。

Effect of Molecular Weight and Molecular Distribution on Skin Structure and Shear Strength Distribution near the Surface of Thin-Wall Injection Molded Polypropylene

In this study, the relationship between skin structure and shear strength distribution of thin-wall injection molded polypropylene (PP) molded at different molecular weight and molecular distribution was investigated. Skin-core structure, cross-sectional morphology, crystallinity, crystal orientation, crystal morphology and molecular orientation were evaluated by using polarized optical microscope, differential scanning calorimeter, X-ray spectroscopic analyzer and laser Raman spectroscopy, respectively, while the shear strength distribution was investigated using a micro cutting method called SAICAS (Surface And Interfacial Cutting Analysis System). The results indicated that the difference of molecular weight and molecular weight distribution showed own skin layer thickness. Especially, high molecular weight sample showed thicker layer of the lamellar orientation and molecular orientation than low molecular weight sample. In addition, wide molecular distribution sample showed large crystal orientation layer.

形体训练中核心力量训练策略研究

随着社会对美学标准和身体健康认识的不断提升,个体对优化身体形态、提高身体功能,以及维持良好身体姿态的需求日益增长。核心力量能够维护身体稳定性、提升运动效率、预防伤害以及改善身体形态,然而,传统的形体训练方法往往未能充分发挥核心力量训练在身体塑造中的潜力。因此,该研究旨在深入分析核心力量训练在形体训练中的应用现状及其潜在价值,探索更为科学、有效的核心力量训练策略,从而为运动员、舞者及广大健身爱好者提供理论依据和实践指南,以期达到提高身体功能性、美观性及整体健康水平的目标。

高中体育运动训练核心力量提升策略

高中阶段作为学生学习成长的关键时期,良好的运动理念与身体素质是促进学生综合素质发展,为未来发展奠定基础的重要内容。但是,以往的高中体育运动训练效果并不理想,无法发挥出其对学生成长的积极作用。在素质教育理念以及健康中国战略的引导下,高中体育教学的重要性愈发提升,体育运动训练发挥的作用也愈发明显。在这样的背景下,高中体育运动训练中的核心力量提升尤为关键。基于此,该文在核心力量概念基础上,分析了高中体育运动训练中核心力量训练的重要性,并对核心力量提升原则与策略进行了探讨。

黏结剂喷射制备陶瓷型芯抗弯强度、尺寸精度及表面质量影响因素的研究进展

黏结剂喷射因具有低成本和可控性优势而在陶瓷型芯的制备中得到广泛的应用,但制备陶瓷型芯的抗弯强度、尺寸精度和表面质量一般较低,而这些不足可以通过改变制备工艺参数来进行改进。综述了粉末、黏结剂、成形工艺和后处理工艺这4个方面的参数对陶瓷型芯抗弯强度、尺寸精度和表面质量的影响,提出了提高黏结剂喷射制备陶瓷型芯抗弯强度、尺寸精度和表面质量的未来发展方向。