Physiological responses in different intensities of resistance exercise – Critical load and the effects of aging process

Aim was to identify critical load (CL) in young and elderly apparently healthy male cohorts. To contrast the metabolic, cardiovascular and perceptual responses on CL according to age. We evaluated 12 young (23 ± 3 years) and 10 elderly (70 ± 2 years) apparently healthy active males, who underwent: (1) 1 repetition maximum (1RM) test on a 45° Leg Press; (2) on different days, three high-intensity resistance exercise constant load tests (60%, 75% and 90% 1RM) until fatigue (Tlim). Absolute values of both the CL asymptote and curvature constant (kg) were significantly lower in elderly subjects (P < 0.05). In contrast, elderly subjects demonstrated a significantly higher number of repetitions at CL when compared with young subjects (P < 0.05). As expected, oxygen uptake (VO₂) and heart rate (HR) during maximal aerobic exercise testing were significantly reduced in older subjects. However, percent-predicted aerobic capacity were higher in older subjects (P < 0.05). In addition, blood lactate ([La^?]) corrected to Tlim and rating of perceived exertion values were greater in younger subjects at all intensities (P < 0.05). These findings, despite reduced force production in older subjects, endurance-related parameters are well preserved according to age-adjusted percent-predicted values in apparently healthy males.     

Determination of peak cardiorespiratory fitness parameters in children: which averaging method should we use?

The purpose of this study was to identify which averaging methods most accurately measures peak cardiorespiratory fitness (CRF) parameters [peak O₂ uptake (VO₂), peak O₂pulse and peak respiratory exchange ratio (RER)] in a sample of healthy children and adolescents. In this cross-sectional multicenter study, we recruited 278 healthy children aged 12–17 years. We compared the mean peak value of three CRF parameters using the recommended averaging methods (30-second block average) with alternative averaging methods such as moving averages or shorter smoothing periods. We also assessed averaging methods for accuracy by individually reviewing breath-by-breath scatter plots. The 30-second block average method resulted in a lower mean peak VO₂ and in an increased proportion of underestimated peak values. Using a 30-second moving average significantly increased mean peak values which increased accuracy. Similar results were found for peak RER and peak O₂pulse. In conclusion, the currently recommended averaging method (30-second block average) increased the risk of misinterpretation of peak CRF values in children. Using a moving average approach decreased misinterpretation and increased accuracy.     

免费师范生生物学实验教学能力培养模式研究

文章总结了华中师范大学生命科学学院3年来对免费师范生生物学实验教学能力培养的教学实践经验,提出以"引导→体验(模拟教学实践和参与教学实践)→反思"为主线的"引导—体验"式生物学实验教学能力培养模式,对华中师范大学师范生的生物学实验教学能力进行具有时空观的连贯培养。文章详细阐述了该模式的具体流程和对应的评价体系,以期对实验性学科的师范生实验教学能力培养提供参考。     

中小学教师师德观的内隐研究

师德对教师的教育教学行为有着重要的作用,而教师师德的好坏又直接取决于教师的师德观.通过对86名中小学特级教师的师德观及其影响因素的实证研究发现,教师的师德观存在很大的不平衡性和个体差异,在"严谨治学"、"有责任心"、"积极性"、"拥有新知识、积极创新"方面存在明显的性别差异,在"热爱学生"、"有责任心、积极性"方面存在明显的职称差异,在"热爱教育、热爱学校、热爱本专业方面"存在明显的地区差异,而年龄、教龄和学历对教师的师德观没有显著影响.在中小学教师师德培养中,应加强对教师"严谨治学"、"公平对待学生"、"提高科研水平"等的培养.     

Effect of different recovery patterns on repeated-sprint ability and neuromuscular responses

We examined the effect of recovery pattern on mechanical and neuromuscular responses in active men during three repeated-sprint ability tests consisting of ten 6-s cycling sprints. Within each test, the recovery duration was manipulated: constant, increasing, and decreasing recovery pattern. Maximal voluntary contractions of the knee extensors were performed before and after the repeated-sprint ability tests to assess strength and electromyographic activity [root mean square (RMS)] of the quadriceps muscle. We observed different fatigue patterns for peak and mean power output between recovery patterns, with earlier decrements recorded during the increasing recovery pattern. Total work performed over the ten sprints was also lower in the increasing recovery pattern (43.8 +/- 5.4 kJ; P < 0.05). However, the decreasing recovery pattern induced a greater overall power output decrement across the sprints (-15.8%; P < 0.05), compared with the increasing recovery pattern (-5.1%) but not the constant recovery pattern (-10.1%). The decreasing recovery pattern was also associated with higher post-sprint RMS values (+16.2%; P < 0.05). Therefore, the recovery pattern within successive short sprints may influence repeated-sprint ability, and may lead to greater post-sprint neuromuscular adjustments when recovery intervals decrease between sprints. We conclude that peripheral impairments caused the major differences in repeated-sprint ability between recovery patterns.     

How should cultural diversity be measured? An application using the French publishing industry

Despite the lack of a clear definition of the concept, “cultural diversity” has remained a core issue for more than a decade (WTO, UNESCO, etc.). The aim of this paper is to begin to fill this gap. We argue that cultural diversity is a multi-dimensional concept and that accurate metrics must rely on three criteria: variety, balance and disparity. We also stress that supplied and consumed diversity have to be distinguished. We apply this set of multiple measures of diversity to publishing data for France over the period 1990–2003. Our main result is that the situation of the publishing industry in terms of cultural diversity is highly dependent on the dimension considered. Hence, diversity increases when variety is the sole consideration, whereas taking balance or disparity into account leads to the opposite conclusion. This issue raises a series of questions about the use of diversity measures in a policy debate concerned with furthering cultural diversity.

Do achievement goals mediate stereotype threat?: an investigation on females' soccer performance

This research investigated stereotype threat effects on women's performance in sports and examined the mediation of this effect by achievement goals. The influence of two stereotypes-relative to the poor athletic ability and the poor technical soccer ability of women-were studied. Fifty-one female soccer players were randomly assigned to one of three conditions, introducing the task as diagnostic of athletic ability, technical soccer ability, or sports psychology. Next, they filled out a questionnaire measuring achievement goals and performed a soccer dribbling task. Results showed that compared with the control condition, females' performance significantly decreased in the athletic ability condition and tended to decrease in the technical soccer ability condition. Moreover, participants endorsed a performance-avoidance (relative to performance-approach) goal when the stereotypes were activated. However, this goal endorsement was not related to performance. The implications of these results for understanding the role of stereotypes in gender inequalities in sports are discussed.     

Increasing hip and knee flexion during a drop-jump task reduces tibiofemoral shear and compressive forces: implications for ACL injury prevention training

Although most ACL injury prevention programmes encourage greater hip and knee flexion during landing, it remains unknown how this technique influences tibiofemoral joint forces. We examined whether a landing strategy utilising greater hip and knee flexion decreases tibiofemoral anterior shear and compression. Twelve healthy women (25.9 ± 3.5 years) performed a drop-jump task before and after a training session (10–15 min) that emphasised greater hip and knee flexion. Peak tibiofemoral anterior shear and compressive forces were calculated using an electromyography (EMG)-driven knee model that incorporated joint kinematics, EMG and participant-specific muscle volumes and patella tendon orientation measured using magnetic resonance imaging (MRI). Participants demonstrated a decrease in peak anterior tibial shear forces (11.1 ± 3.3 vs. 9.6 ± 2.7 N · kg^?1; P = 0.008) and peak tibiofemoral compressive forces (68.4 ± 7.6 vs. 62.0 ± 5.5 N · kg^?1; P = 0.015) post-training. The decreased peak anterior tibial shear was accompanied by a decrease in the quadriceps anterior shear force, while the decreased peak compressive force was accompanied by decreased ground reaction force and hamstring forces. Our data provide justification for injury prevention programmes that encourage greater hip and knee flexion during landing to reduce tibiofemoral joint loading.     

基于虚拟现实技术的救助船对外消防培训仿真系统

针对救助船消防训练中存在的海况复杂,对外消防炮射流受风影响大,往往无法准确控制其射向目标区域的问题,在理想状态下射流理论的基础上探究风对射流轨迹的影响,建立自然风条件下射流轨迹的数学模型,模拟对外消防炮射流的运动情况。应用3ds Max构建船舶模型,用Unity3D构建救助船在面临大风浪、遇险船着火等状况时对外消防系统的工作场景,提出一种精确构建粒子系统轨迹的方法,使射流模型能精确体现在场景中。通过虚拟现实设备能实现救助船对外消防培训仿真系统的立体显示和人机交互,起到更好的虚拟仿真和培训效果。