Load-dependent mechanical demands of the lower extremity during the back and front squat

ABSTRACT

The purpose of this study was to examine load-dependent differences in lower-extremity biomechanics between the back squat (BS) and front squat (FS) exercises. Eleven NCAA Division-I athletes performed three repetitions of the BS and FS at loads of 40%, 60%, and 80% of their FS one repetition maximum (FS-1RM). Kinematic and kinetic data were collected during each squat repetition and used to calculate lower extremity peak joint angles and peak net joint moments (NJM). Peak angles and NJM were compared with a 2 × 3 repeated measures ANOVA. Peak hip extensor NJM were greater during the BS at 60% and 80% of FS-1RM. In comparison, peak knee extensor NJM were greater during the FS at 80% of FS-1RM. However, regression-based prediction of NJM at 100% of FS and BS 1RM indicated that at maximal loads, peak knee NJM are (~3%) higher during the BS. The experimental results suggest that when performed at the same absolute load, the BS and FS are characterized by greater respective mechanical demands imposed on the hip and knee extensors muscles groups. However, prediction-based results suggest that the knee extensor NJM demands are comparable when performed at the same relative load (i.e., with respect to each exercise’s RM).     

Utilizing Motivational Interviewing to Address Resistant Behaviors in Clinical Supervision

Motivational interviewing is presented as an approach to address resistant behaviors in clinical supervision. A case example is used to illustrate the process in which the relational and technical elements of motivational interviewing can be applied to supervisee resistance. Implications for supervisors and researchers are discussed.     

碳纤维增强型摩擦材料的制备及性能研究

选取最佳含量的短切碳纤维作为增强材料,采用精密预成型工艺、固化工艺等关键技术制备的碳纤维增强型摩擦材料,使用MM1000-II摩擦磨损试验机模拟不同工况对其进行摩擦性能、抗衰性能及磨损率试验。实验表明该摩擦材料摩擦系数受外界工况条件影响小,磨损率小、不损伤对偶。碳纤维含量为15%时,材料的摩擦磨损性能最佳。     

冻融环境下补偿收缩混凝土抗冻性能试验研究

为了研究补偿收缩混凝土的抗冻性能,采用慢冻法对普通混凝土和补偿收缩混凝土进行冻融对比试验。通过对比研究普通混凝土和补偿收缩混凝土冻融后质量损失、强度损失和相对动弹性模量变化趋势,从而得出补偿收缩混凝土的抗冻性能。试验结果表明,普通混凝土冻融100次后,质量损失率为2.09%,抗压强度下降35.2%,相对动弹性模量下降到60.8%;补偿收缩混凝土质量损失率为1.62%,抗压强度下降30.3%,相对动弹性模量下降到64.8%;试验三个参数指标表明添加膨胀剂有助于提高混凝土抵抗冻融破坏的能力,改善混凝土结构的损伤程度,体现了膨胀剂对混凝土的增强机理。     

临床重要细菌的抗菌素耐受性机理

在临床实践中,抗菌素的大量使用导致了细菌的药物耐受性形成。细菌通过先天或获得性耐受机制实现对自身的保护。获得性耐受性来源于突变和水平基因转移。细菌获得性耐受性形成的生物化学机制(途径)包括:抗菌素失活或修饰、靶向修饰、外排泵和外膜渗透性改变及"迂回"代谢途径。本文将对目前临床重要细菌的抗菌素耐受性机理进行阐述。     

代谢综合征与运动干预对中心性肥胖影响的研究进展

代谢综合征（metabolicsyndrome,MS）是一系列代谢异常成分在同一个体聚集的临床综合症状,中心性肥胖是其重要的发病危险因素和临床表现之一。此外,有诸多研究显示中心性肥胖还是胰岛素抵抗（insulinresistance,IR）的一个重要发病基础。中心性肥胖症患者实施运动干预,对MS、IR有着显著的影响。本文通过文献资料法就中心性肥胖的危害和运动干预对中心性肥胖的影响进行综述。     

复合镀层的摩擦磨损特性和机理

研究了电刷镀多层Ni-Cr2 O3复合镀层的磨损特性与磨损机理。结果表明 ,电刷镀多层Ni-Cr2 O3复合镀层具有良好的耐磨性。     

Assessment of Insulin Resistance and Metabolic Syndrome in Drug Naive Patients of Bipolar Disorder

The levels of fasting glucose, fasting insulin, insulin resistance (IR) and the prevalence of metabolic syndrome (MS) in a sample population of bipolar disorder (BPD) patients who were newly diagnosed and psychotropically naïve were assessed and compared with an age, sex and racially matched control population. 55 BPD-I patients (15–65 years) who were non-diabetic, nonpregnant, and drug naïve for a period of at least 6 months were included in the study. Diagnosis was made using the structured clinical interview for DSM-IV axis I disorders (SCID IV). IR was assessed using homeostasis model of insulin resistance (HOMA-IR); MS was defined according to National Cholesterol Education Program-Adult Treatment Panel III (NCEP-ATP III). Data were compared with 25 healthy controls. BPD patients had significantly higher mean levels of fasting plasma insulin (13.2 ± 9.2 vs. 4.68 ± 3.1 μIU/ml, p < 0.05), postprandial plasma insulin (27.2 ± 14.5 vs. 18.1 ± 9.3 μIU/ml, p < 0.05) and a higher value of HOMA-IR (3.16 ± 2.2 vs. 1.19 ± 0.8, p < 0.05) when compared to the controls. A significantly higher proportion of patients of BPD compared to controls were manifesting levels of fasting plasma glucose, serum triglyceride and blood pressure higher than the cut off while waist circumference and serum HDL cholesterol failed to show any significant difference in the proportion. There was a significantly higher proportion of prevalence of IR between BPD cases and controls (26/55 vs. 2/25, z value 9.97, p < 0.05) while there was no significant difference in proportion of prevalence of MS between these two groups. Within BPD patients, logistic regression analysis showed that age, sex or current mood status (depressed/manic) were not significantly predictive of presence or absence of MS or increased IR.     

肺内重度感染病毒抗药性分析

目的:对肺内重度感染病毒的抗药性进行分析。方法:选择呼吸内科患者入院后12小时内的痰标本共100例,将采集到的受试病毒和标准对照病毒在培养皿中进行活化及培养,静置至干燥后采用标准药敏纸片对其进行检测,依据测量的抑菌圈宽度对受试肺炎链球菌、冠状病毒、埃可病毒以及巨细胞病毒的抗药性进行判断。结果:肺炎链球菌对相关药物较为敏感,对一些药物有较低的抗药率。结论:一些肺内重度感染病毒对药物的抗药性很高,治疗时应谨慎用药,尽量不采用病毒抗药性较高的药物。     

Comparison Between Serum Insulin Levels and Its Resistance With Biochemical,Clinical and Anthropometric Parameters in South Indian Children and Adolescents

There is a rising trend in the prevalence of insulin resistance among obese, overweight children and adolescents. The serum insulin and its correlation with biochemical, clinical and anthropometric parameters were evaluated in 185 children and adolescents (59 control, 52 obese, 49 overweight, 25 congenital heart disease) of age group 10–17 years. The levels of serum insulin were measured by ELISA. Serum insulin levels were found to be significantly increased in children who were obese, overweight and had congenital heart disease, than controls. Serum insulin levels positively correlated with BMI, WHR, and serum C-peptide, serum leptin, total cholesterol, triglycerides, LDL-cholesterol, systolic and diastolic blood pressure. Fasting glucose levels were found to be negatively correlated with serum insulin levels. HDL-cholesterol levels were non-significant among the study groups. We identified nine obese children (five girls and four boys) with the features of metabolic syndrome and 69% of obese and overweight children were identified with insulin resistance. Insulin resistance was strongly associated with metabolic syndrome and its components, especially with central obesity and hypertriglyceridemia.