Specificity of a Maximal Step Exercise Test

To adhere to the principle of “exercise specificity” exercise testing should be completed using the same physical activity that is performed during exercise training. The present study was designed to assess whether aerobic step exercisers have a greater maximal oxygen consumption (max VO₂) when tested using an activity specific, maximal step exercise test (SET; arms and legs) versus a maximal running test (legs only). Female aerobic step exercisers (N=18; 20.7 ± 1.5 years) performed three maximal graded exercise tests (GXTs): 2 SETs; 1 treadmill test (TMT). The SET consisted of six 3-min progressive stages of alternate lead, basic step, basic step with biceps curls, knee raise with pull-down, repeater knee with pull-down, lateral lunge with pull-down, and side squat with shoulder presses. Stepping rate was 32 steps· min^?1 on an 8-in (20.32 cm) step for stages 1–3, and a 10-in (25.4 cm) step for stages 4–6. Submaximal and maximal heart rate (HR) and oxygen consumption (VO₂) were recorded at the end of each stage. Test–retest reliability for the first five stages of the SET ranged from .91 to .97 for HR, and from .84 to .96 for VO₂. Maximal HR was significantly greater (p =.0001) for the SET (200 ± 6.2 beats·min^?1) as compared to the TMT (193 ± 7.9 beats·min^?1). No significant difference was found for max VO₂ (42.9 ± 8.5, 41.2 ± 5.9 ml·kg^?1·min^?1, p =.14). The SET was a valid and reliable protocol for assessing responses of these aerobic step exercisers; however, max VO₂ from a TMT did not differ significantly from the SET. Conversely, max HR obtained from the criterion TMT was 7 beats·min^?1 lower than from the SET. If a training HR for step exercise (arms and legs exercise) is prescribed based on the max HR from treadmill exercise (legs only), then the training HR should be calculated from a TMT max HR that has been increased by 7 beats·min^?1 to obtain an intensity of step exercise comparable to that of running.     

不同强度运动训练对大鼠海马CA1 区神经元凋亡的影响

目的：研究不同强度运动训练对大鼠海马CA1区神经元凋亡的影响及其基因调控机制。方法：将大鼠分为对照组、中等强度运动组和大强度运动组，对大鼠进行为期8周的游泳训练，用DNA原位末端标记法检测海马神经元的凋亡，并用免疫组化的方法观察海马神经元中bcl-2、bax的免疫反应活性。结果：（1）大强度运动训练后，大鼠海马CA1区神经元凋亡显著增加而中等强度运动训练后，大鼠海马CA1区神经元凋亡不明显，海马神经元凋亡可能是大强度运动训练导致运动能力降低和中枢性运动疲劳的病理生理机制；（2）大强度运动训练后，大鼠海马CA1区神经元中bcl-2蛋白的表达显著下降，bax蛋白的表达显著增加。中等强度运动训练后，大鼠海马CA1区神经元bcl-2蛋白的表达显著上升。因此，大强度运动训练可抑制海马神经元bcl-2蛋白的表达而促进bax蛋白的表达，这可能是大强度运动训练导致大鼠海马CA1区神经元凋亡发生的基因调控机制，而中等强度运动训练可促使bcl-2蛋白的表达上升，抑制细胞凋亡。     

爆发力训练与有氧耐力评价指标的相关性研究

为研究同时进行爆发力训练与有氧耐力训练所产生的效果,本研究以14名耐力运动员为实验组(E)、14名耐力运动员为控制组(C)进12周的训练,实验组除15%爆发力训练代替传统耐力训练外,其余训练内容相同。结果发现:5 km跑成绩与RE在实验组明显提高(P<0.05),控制组无差异;5 J在实验组有非常显著性提高(P<0.01),控制组下降显著(P<0.05);VO2max在控制组显著性提高(P<0.01),对实验组变化不明显。混合控制组与实验组数据发现:5km跑时间与RE存在中度负相关(r=-0.54)。结论:同时进行爆发力与耐力训练在不改变VO2max的情况下可以提高5 km跑的成绩。     

游泳训练对Ⅱ型糖尿病Wistar大鼠肠系膜动脉舒张功能改善作用的研究

目的:通过建立wistar大鼠Ⅱ型糖尿病动物模型,观察Ⅱ型糖尿病(T2DM)模型大鼠,经游泳训练后肠系膜动脉舒张功能的变化,并探讨其内在影响机制。方法:实验材料wistar大鼠60只,造模完成后随机分成3组:正常对照组(CON),Diabetes模型组(DI),游泳运动组(SEX),每组15只。进行游泳训练共计8周。结果:T2DM可造成肠系膜动脉血管舒张功能降低(P<0.05),且存在内皮依赖性。舒张功能的降低与eNOS-NO系统活性降低直接相关。游泳训练可有效维持内皮依赖性舒张功能(P<0.05),其上调eNOS-NO系统。另外,T2DM造成的eNOS-NO系统活性降低与该系统上游蛋白PI-3K,Akt降低有关,且在加入上游蛋白抑制剂(PI-3K)LY294002及eNOS阻断剂L-NAME后保护效应消失。结论:游泳训练能改善T2DM wistar大鼠肠系膜舒动脉舒张功。其内在保护作用可能是通过部分激活PI-3K-Akt-eNOS信号通路而实现。     

运动训练对自发性高血压大鼠心肌细胞凋亡蛋白表达的影响

目的:研究运动训练对SHR心肌细胞中HSP-72、Bcl-2和蛋白激酶β(PKB)、Bax、糖原合成激酶-3(GSK-3)的影响,以探讨其对运动引起心肌细胞凋亡的作用。方法:以SHR大鼠中等强度训练为实验模型,采用Western bloting技术检测了大鼠心肌细胞中调控蛋白HSP-72、Bcl-2和蛋白激酶β(PKB)、Bax、糖原合成激酶-3(GSK-3)的表达。结果:长期中等强度训练可以提高心肌细胞中抑凋亡蛋白HSP-72、Bcl-2和蛋白激酶β(PKB)的表达,凋亡蛋白Bax、糖原合成激酶-3(GSK-3)表达显著降低,Bcl-2/Bax的表达没有显著变化,从而抑制心肌细胞的凋亡。结论:心肌细胞中HSP-72、Bcl-2和蛋白激酶β(PKB)、Bax、糖原合成激酶-3(GSK-3),Bcl-2/Bax在运动后的不同表达对心肌细胞凋亡的发生有明显的抑制作用。     

局部文本特征选取算法的比较和改进研究

本文通过实验比较了互信息、χ2统计算法和优势率三种算法在用于局部文本特征选取时对文本分类性能的影响.实验结果显示,在应用于局部特征选择的情况下,文本特征选取算法仍然可以将特征空间的维度降低90%以上,而不降低文本分类的性能.同时,我们发现在应用于局部文本特征选取时,优势率算法的性能不如互信息和χ2统计算法.另外,对于K最近邻分类算法,随着K值的增大,文本分类的查准率在增加,而查全率在降低.最后,本文详细分析了造成这三种算法性能差异的原因,并提出了一种改进算法,来提高优势率算法应用于局部文本特征选取时的性能.     

对足球训练中运用Yo-Yo测试的原理、作用和方法的研究

作为一种体能测试方法和手段，Yo—Yo目前已被中国足协作为对国内职业足球俱乐部的体能测试的内容。使用文献资料，观察、实验等方法，对Yo-Yo测试的原理及其作用方法进行了探讨和研究，为Yo-Yo测试提供理论和实践上的依据。     

Activity profile of top-class association football referees in relation to performance in selected physical tests

Abstract

The aims of the present study were (1) to analyse the physical demands of top-class referees and (2) to compare their official FIFA fitness test results with physical performance during a match. The work rate profiles of 11 international referees were assessed during 12 competitive matches at the 2003 FIFA Under-17 World Cup and then analysed using a bi-dimensional photogrammetric video analysis system based on direct lineal transformation (DLT) algorithms. In the first 15 min of matches, the referees were more active, performing more high-intensity exercise (P < 0.01) than in the first 15 min of the second half. During the second half of matches, the referees covered a shorter distance (P < 0.01), spent more time standing still (P < 0.05), and covered less ground cruising (P < 0.05), sprinting (P < 0.05), and moving backwards (P < 0.001) than in the first half. Also in the second 45 min, the distance of referees from infringements increased (P < 0.05) in the left attacking zone of the filed. There was also a decrease (P < 0.05) in performance in the period following the most high-intensity activity, compared with the mean for the 90 min. Time spent performing high-intensity activities during a match was not related to performance in the 12-min run (r ² = 0.30; P < 0.05), the 200-m sprint (r ² = 0.05; P < 0.05), or the 50-m sprint (r ² = 0.001; P < 0.05). The results of this study show that: (1) top-class referees experienced fatigue at different stages of the match, and (2) the typical field tests used by FIFA (two 50-m and 200-m sprints, followed by a 12-min run) are not correlated with match activities.     

Heart rate prescribed walking training improves cardiorespiratory fitness but not glycaemic control in people with type 2 diabetes

Abstract

In this study, we examined the effects of a supervised, heart rate intensity prescribed walking training programme on cardiorespiratory fitness and glycaemic control in people with type 2 diabetes mellitus. After receiving local ethics approval, 27 individuals (21 males, 6 females) with type 2 diabetes were randomly assigned to an experimental (“walking”) or control group. Participants completed a Balke-Ware test to determine peak heart rate, peak oxygen consumption ([Vdot]O_2peak), and peak gradient. The walking group then completed a 7-week (four sessions a week) supervised, heart rate prescribed walking training programme, whereas the control group continued daily life. After training, participants completed another Balke-Ware test. Fasting blood glucose and glycosylated haemoglobin were measured at rest. The results showed that walking training elicited 80% (s = 2) of peak heart rate and a rating of perceived exertion of 11 (s = 1). Peak heart rate and [Vdot]O_2peak were higher in the walking than in the control group after training (P < 0.05). Based on the peak gradient before training, the respiratory exchange ratio was significantly lower (P < 0.05) and there was a strong trend for [Vdot]O₂ (P = 0.09) and heart rate (P = 0.09) to be lower after training at the same gradient in the walking compared with the control group. These improvements increased walking peak gradient by 5 min (s = 4 min) compared with the control (P < 0.05). There was no change in fasting blood glucose or glycosylated haemoglobin after training. Despite no change in glycaemic control, heart rate prescribed walking improved peak and sub-maximal cardiorespiratory responses. The beneficial adaptations support the use of heart rate monitoring during walking in people with type 2 diabetes mellitus.     

Alterations in Strength and Maximal Oxygen Uptake Consequent to Nautilus Circuit Weight Training

Abstract

The purpose of this study was to determine the effects of a Nautilus circuit weight training program on muscular strength and maximal oxygen uptake ([Vdot]O ₂ max) by comparing these effects to those produced by adhering to either a free weight (FW) strength training program or a running (R) program. Male college students who voluntarily enrolled in either a FW training class (n = 11), a Nautilus (N) circuit weight training class (n= 12), or a R conditioning class (n= 13) were subjects for this investigation. All groups participated in their respective programs 3 days per week for 10 weeks. Strength was assessed using a Cybex II isokinetic dynamometer set at an angular velocity of 60° · s ^?1 and a damping of 2. The FW group served as the control group for the assessment of [Vdot]O ₂ max changes, while the R group served as controls for the assessment of strength differences. ANCOVA revealed that the N and R groups experienced significant (p < .01) increases in [Vdot]O ₂ max expressed in L · min ^?1 (10.9 and 11.4%), ml · kg ^?1 · min ^?1 (10.8 and 11.7%), and ml · kgLBW ^?1 · min ^?1 (7.1 and 7.5%) when compared to the FW group. There were no significant differences between the N and R groups. There were no significant differences among groups in final peak torque values (after covariance), and torque at the beginning and end of the range of motion for the knee extensors, knee flexors, elbow extensors, and elbow flexors. In general, isokinetic strength values elicited by the N group compared favorably to those generated by the FW group. It was concluded that for a training period of short duration, Nautilus circuit weight training appears to be an equally effective alternative to standard free weight (strength) and aerobic (endurance) training programs for untrained individuals.