Alternative assessment of knee joint muscle balance of soccer players through total work-based hamstring: quadriceps ratios

Isokinetic hamstring-to-quadriceps (H:Q) ratios are frequently used to assess knee muscle strength imbalances and risk of injuries/re-injuries. The use of peak torque (PT) or total work (TW) to estimate joint stability may lead to different results because of the differences between these two neuromuscular variables. Thus, the current study aimed to compare the conventional and functional H:Q ratios calculated by PT and TW. Ninety-three male professional soccer players from Brazilian first division teams performed isokinetic concentric and eccentric contractions of the quadriceps and the hamstrings at 60°/s. Muscle strength balance was calculated using the conventional torque ratio (CTR) and conventional work ratio (CWR), functional torque ratio (FTR) and functional work ratio (FWR) were highly and moderately correlated between them (r?=?0.83 and r?=?0.73, respectively). The Wilcoxon statistical test revealed significant differences between CTR and CWR, as well as FTR and FWR (p?T-test demonstrated significant differences in mean CTR–CWR and FTR–FWR, whereas Bland–Altman plots showed non-consistent bias. In addition, the chi-square test demonstrated significant differences between players below the conventional reference values and functional reference values (p?相似文献   

Near-infrared spectroscopy-derived total haemoglobin as an indicator of changes in muscle blood flow during exercise-induced hyperaemia

ABSTRACT

Blood flow changes in response to exercise have been attributed, among other factors, to the effect of vasodilators factors on the microvasculature, suggesting a close relationship between small blood vessels and conducting arteries. The main purpose of this study was to determine the relationship between the changes in near infrared spectroscopy (NIRS)-derived total haemoglobin ([tHb]) and muscle oxygen saturation (SmO₂) signals and femoral artery blood flow in response to resistance exercise at fast- and slow-velocity muscle contraction. The study randomised crossover design included twelve participants. NIRS and blood flow measurements were continuously monitored before, during, and 5 min after the exercise protocol. There was a significant correlation between [tHb] reperfusion slope ([tHb]_slope) and peak blood flow (BF_peak) after slow- and fast-velocity muscle contraction (r = 0.83, p = 0.0008 and r = 0.72, p = 0.0080, respectively). No significant correlation existed between the SmO₂ reperfusion slope (SmO_{2_slope}) and BF_peak after both slow- and fast-velocity muscle contraction exercise (r = ?0.46, p = 0.1253 and r = 0.33, p = 0.2841, respectively). This study demonstrated a strong relationship between the NIRS-derived [tHb] and Doppler ultrasound BF during the recovery period of dynamic resistance exercise at both slow- and fast-velocity contraction.     

论京剧声腔源于陕西

关于京剧声腔的起源,过去一般认为是二黄调和西皮调在北京合体而成,本文认为这个观点缺乏事实依据,京剧声腔的产地不是安徽或湖北,而是陕西,陕西历史上存在前后两个秦腔,前秦腔即陕西二黄(又称汉调二黄,今称陕西汉剧)早在乾隆55年四大徽班进京之前已广泛流传于北京和东南各地,四大徽班中的三庆班,春台班进京所唱的腔调主要是前秦腔;细考京剧与陕西二黄的声腔,二者确实同类.京剧的声腔是从陕西二黄的母体中孕育出来的.     

沉睡的天使

曾经的＂96黄金一代＂正在慢慢从舞台的中央移向大幕之侧,即使曾经无所不能的科比,本赛季也明显露出了疲态。小奥从来都不是这一代中的顶尖球员,现在伤病又无情地袭扰着他,不轰轰烈烈却绵绵长长。但小奥尼尔这位沉睡的天使,终有一天会回复青春。     

对推行和完善高校本科生导师制度的思考

实施本科生导师制度是中国高校教学改革和发展的必然要求。我国本科生导师制度在实践中取得了一定的成效,但同时也存在一些问题。本科生导师制度在教育实践中需要不断完善。     

Validity of a portable force platform for assessing biomechanical parameters in three different tasks

The aim of this study was to determine the precision and accuracy of the vertical and anterior–posterior force components of the portable PASCO PS-2142 force plate. Impulse, peak force, and time to peak force were assessed and compared to a gold standard force plate in three different tasks: vertical jump, forward jump, and sprint start. Two healthy male participants performed ten trials for each task, resulting in 60 trials. Data analyses revealed good precision and accuracy for the vertical component of the portable force plate, with relative bias and root mean square (RMS) error values nearly the same in all tasks for the impulse, time to peak force, and peak force parameters. Precision and accuracy of the anterior–posterior component were lower for the impulse and time to peak force, with relative bias and RMS error values nearly the same between tasks. Despite the lower precision and accuracy of the anterior–posterior component of the portable force plate, these errors were systematic, reflecting a good repeatability of the measure. In addition, all variables presented good agreement between the portable and gold standard platforms. Our results provide a good perspective for using the aforementioned portable force plate in sports and clinical biomechanics.     

脱口秀

小牛多少带有点爆冷嫌疑的夺冠,令现场的情绪瞬间爆棚,马克·库班成了首先的采访对象,接下来,无论是更衣室外的通道,还是新闻发布会的现场,无论是胜利者还是失意人,都得到了宣泄情绪的机会。请相信我,这也许是NBA总决赛历史中最沉重的一次赛后发布会,相比较媒体送给胜利者的歌颂和恭维,失利一方得到的却是一轮又一轮的重磅炸弹,炸得他们体无完肤、无地自容。     

无水乙醇夹带剂超临界CO2萃取荔枝核

以无水乙醇为夹带剂,采用超临界CO2萃取荔枝核,并用气相色谱．质谱联用仪（GC—MS）对荔枝核萃取物的挥发性成分进行了分析．结果表明,以无水乙醇为夹带剂超临界CO2萃取荔枝核的萃取率为5．47％,GC—MS鉴定出32种化合物,主要为甾醇类、萜类、不饱和脂肪酸、棕榈酸、脂肪酸酯、芳香醇,相对质量分数分别为38．8％,26.4％,8．60％,7．54％,8．44％,6．11％．和无夹带剂相比,夹带剂无水乙醇可以提高荔枝核的超临界萃取率．     

Experimenting with spirituality: analyzing The God Gene in a nonmajors laboratory course

References linking genes to complex human traits, such as personality type or disease susceptibility, abound in the news media and popular culture. In his book The God Gene: How Faith is Hardwired into Our Genes, Dean Hamer argues that a variation in the VMAT2 gene plays a role in one's openness to spiritual experiences. In a nonmajors class, we read and discussed The God Gene and conducted on a small scale an extension of the study it describes. Students used polymerase chain reaction to replicate a portion of their VMAT2 genes, and they analyzed three polymorphic sites in the sequence of these products. Associations between particular VMAT2 alleles and scores on a personality test were assessed by t test. The course, of which this project was a major part, stimulated student learning; scores on a test covering basic genetic concepts, causation/correlation, and laboratory methodology improved after completion of the course. In a survey, students reported the laboratory project aided their learning, especially in the areas of statistics and the linking of genes to behaviors. They reported high levels of engagement with the project, citing in particular its personal nature as motivating their interest.     

史诗《格萨尔》的文化启蒙与教育功能

《格萨尔》作为藏族传统教育的一种重要形式,不仅发挥着传承藏族文化的重要作用,而且也将对藏族现代教育产生深刻影响。文章旨在强调新时期应充分发挥其实际存在的文化启蒙功能和教育作用,批判地吸收《格萨尔》中的积极成份,用以推动藏族社会物质文明和精神文明建设。