America's Cup yacht racing: Race analysis and physical characteristics of the athletes

Abstract

The America's Cup is the oldest competing trophy in sport, yet little is known of the nature and intensity of racing or the physical characteristics of the athletes. In this study, aspects of the physical demands of America's Cup yacht racing were analysed, including the intensity of exercise and activity pattern of “grinding”. Anthropometric data were collected from 92 professional male America's Cup sailors, and fitness data from a top-4 and a lower-7 ranking team during the 32nd America's Cup. Over the 135 races, mean race duration was 82 min (s = 9), with 20 tacks (s = 10) and 8 gybes (s = 3) per race. Grinding bouts were 5.5 s (s = 5.4; range: 2.2–66.3) long, with 143 exercise bouts per race and an exercise-to-rest ratio of 1:6. Mean and peak heart rate was 64% and 92% of maximum for all positions, with bowmen highest (71% and 96%). Grinders were taller, heavier, and stronger than all other positions. Body fat was similar between positions (13%, s = 4). The higher-standard team was stronger and had greater strength endurance, which probably contributed to their quicker manoeuvres. Intensity of exercise was dependent on the similarity of competing boats and the role of the athlete. The short duration and intermittent nature of grinding is indicative of predominantly anaerobic energy provision.     

A comparison of ratio and allometric scaling methods for normalizing power and strength in elite rugby union players

Abstract

In this study, we compared the effectiveness of ratio and allometric scaling for normalizing power and strength in elite male rugby union players. Rugby union forwards (n = 18) and backs (n = 20) were assessed for squat jump and bench throw peak power, and box squat and bench press one-repetition maximum strength. The performance data for the forwards and backs were compared using ratio (P/BM) and allometric scaling (P/BM^b ), where P represents performance, BM is body mass in kilograms, and b is a power exponent. A proposed allometric exponent (0.67) and exponents (±95% confidence intervals) derived for the box squat (0.33 ± 0.31), bench press (0.45 ± 0.30), bench throw (0.46 ± 0.36), and squat jump (0.64 ± 0.31) exercises were used. In general, the absolute expression of power and strength was superior for the heavier forwards, but after ratio scaling these performance measures then favoured the lighter backs. There were no performance differences between the forwards and backs after allometric scaling using either the proposed or the derived exponents. Thus, allometric scaling may provide a more effective method for normalizing power and strength in elite athletes when body size is a confounding variable.     

Bunny Hill or Black Diamond: Differences in Advanced Course‐Taking in College as a Function of Cognitive Ability and High School GPA

College students commonly have considerable course choice, and they can differ substantially in the proportion of their coursework taken at an advanced level. While advanced coursework is generally viewed as a desirable component of a student's education, research has rarely explored differences in student course‐taking patterns as a measure of academic success in college. We examined the relationship between the SAT, high school grade point average (HSGPA), and the amount of advanced coursework taken in a sample of 62 colleges and 188,985 students. We found that both the SAT and HSGPA predict enrollment in advanced courses, even after controlling for advanced placement (AP) credits and demographic variables. The SAT subtests of Critical Reading, Writing, and Math displayed differential relationships with advanced course‐taking dependent on student major. Gender and race/ethnicity were also related to advanced course‐taking, with women taking more advanced courses in all major categories except for science, technology, engineering, and mathematics (STEM) where they took fewer, even after controlling for other variables. Socioeconomic status had a negligible relationship with advanced course‐taking. This research broadens our understanding of academic achievement in college and the goals of admissions in higher education.     

Predicting Freshman Grade‐Point Average from Test Scores: Effects of Variation Within and Between High Schools

Most studies predicting college performance from high‐school grade point average (HSGPA) and college admissions test scores use single‐level regression models that conflate relationships within and between high schools. Because grading standards vary among high schools, these relationships are likely to differ within and between schools. We used two‐level regression models to predict freshman grade point average from HSGPA and scores on both college admissions and state tests. When HSGPA and scores are considered together, HSGPA predicts more strongly within high schools than between, as expected in the light of variations in grading standards. In contrast, test scores, particularly mathematics scores, predict more strongly between schools than within. Within‐school variation in mathematics scores has no net predictive value, but between‐school variation is substantially predictive. Whereas other studies have shown that adding test scores to HSGPA yields only a minor improvement in aggregate prediction, our findings suggest that a potentially more important effect of admissions tests is statistical moderation, that is, partially offsetting differences in grading standards across high schools.     

Temporal trends in the sit-ups performance of 9,939,289 children and adolescents between 1964 and 2017

ABSTRACT

We estimated international/national temporal trends in sit-ups performance for children and adolescents, and examined relationships between national trends in sit-ups performance and national trends in health-related/sociodemographic indicators. Data were obtained by systematically searching studies reporting on temporal trends in sit-ups performance for apparently healthy 9–17 year-olds, and by examining nationally representative fitness datasets. Trends at the country-sex-age level were estimated by sample-weighted regression models relating the testing year to mean sit-ups performance. International/national trends were estimated by a post-stratified population-weighting procedure. Pearson’s correlations quantified relationships between national trends in sit-ups performance and national trends in health-related/sociodemographic indicators. A total of 9,939,289 children and adolescents from 31 countries/special administrative regions between 1964 and 2017 collectively showed a large improvement of 38.4% (95% CI: 36.8 to 40.0) or 7.1% per decade (95% CI: 6.8 to 7.4). Large international improvements were experienced by all age and sex groups, with the rate of improvement slowing from 1964 to 2000, stabilizing near zero until 2010, before declining. Trends differed between countries, with national trends in vigorous physical activity a strong, positive correlate of national trends in sit-ups performance. More sit-ups data are needed from low- and middle-income countries to better monitor trends in muscular fitness.     

大学生在校期间4年的身体素质变化分析

大学生在校期间的身体素质状况被《国家体育锻炼标准》测试所监测。此项研究的目的是为了分析大学生在校4年期间身体素质的变化情况。研究对象是江西农业大学的632名大学生,其中28.64%为女生。方差分析(repeated measures ANOVA)检测了大学生4年期间身体素质的变化情况。多元方差分析(MANOVA)则被用来检测五项测试中的性别差异。研究结果表明:大学生在大学2年级得分最高,而在4年级得分最低;此外,MANOVA测试表明:在每年的5项测试中,男生得分明显低于女生。此研究的结果表明,应有重点的提高男生和4年级学生的身体素质,并制定出明确的措施。     

军事体能训练中骨骼肌变化及功能评价

阅读近20年来国内外相关科研文献,从运动机理上对体能训练引起的骨骼肌变化进行详细的阐述,说明了等速测力法是目前用来作为运动肌肉系统的机能状态和运动损伤的治疗效果评定的一种客观指标,并对我军新兵不同训练模式下体能训练前后肌肉功能评价进行了阐述。     

基于数据格式支持机制的自动化渗透测试框架

Backtrack4是功能最全面的一款测试平台,但由于数据交换处理机制的缺失使得它难以胜任高效的测试需求.设计了相应的数据格式支持机制,并依此开发了一个渗透测试框架(PTF).该框架会自动使用有关的渗透测试工具进行信息探测、漏洞评估、报告生成.真实网络环境中的实验验证了PTF能高效完成自动化渗透测试,进而大幅提升了使用Backtrack4进行渗透测试的有效性.