Temporal specificity of training: intra-day effects on biochemical responses and Olympic-Weightlifting performances

The aim of this study was to investigate the performance of an Olympic-Weightlifting session training at three times of the day on the performance related to biochemical responses. Nine weightlifters (21 ± 0.5 years) performed, in randomised order, on three Olympic-Weightlifting training (snatch, clean and jerk) sessions (08:00 a.m., 02:00 p. m., 06:00 p. m.). Blood samples were collected: before, 3 min and 48 h after each training session. Haematological parameters and markers of muscle injury were assessed. Resting oral temperature and rating of perceived exertion (RPE) were also assessed during each session. ANOVA showed that the performance was better (P < 0.001) at 02:00 p. m. with a less RPE (P < 0.01) compared to the morning and the evening sessions while there was higher (P < 0.05) oral temperature at 06:00 p. m. versus 08:00 a.m. and 02:00 p. m. Muscle damage changed immediately (without significant effect after 48 h) after the training sessions with lower values ??in the evening compared to the morning. In conclusion, the afternoon training is more effective than morning or evening sessions for weightlifters. Therefore, coaches and weightlifters should be advised to schedule their training session in the afternoon hour.     

MTL代数中素滤子集上的拓扑

通过研究MTL代数M中滤子、极大滤子的性质,在M的全体素滤子集P(M)上引进拓扑T并研究拓扑空间(P(M),T)的紧致性、分离性、连通性等拓扑性质,证明了(P(M),T)是紧致的T0空间.如果把P(M)上拓扑T限制在M的全体极大滤子集M(M)上,则(M(M),TIM(M)是紧致的Hausdorff空间.     

线性边界条件下二维Sturm-Liouville算子的特征展开

研究了一个带有特殊线性边界条件2×2 Sturm-Liouville算子的特征展开问题,证明与它相联系的积分算子为全连续算子,于是得到了这个问题的特征展开定理.     

一类复矩阵线性组合的幂等性

讨论了关于复矩阵的一类特殊线性组合的幂等性问题。当组合系数为复数时,给出了矩阵线性组合是幂等的两个充要条件。并在所得结论的基础上,考虑组合系数为实数,研究了矩阵线性组合是幂等阵时,复矩阵及其特征值所具备的特性。     

Changes in repeated-sprint performance in relation to change in locomotor profile in highly-trained young soccer players

Abstract

The aim of this study was to examine the effects of changes in maximal aerobic (MAS) and sprinting (MSS) speeds and the anaerobic reserve (ASR) on repeated-sprint performance. Two hundred and seventy highly-trained soccer players (14.5 ± 1.6 year) completed three times per season (over 5 years) a maximal incremental running test to approach MAS, a 40-m sprint with 10-m splits to assess MSS and a repeated-sprint test (10 × 30-m sprints), where best (RSb) and mean (RSm) sprint times, and percentage of speed decrement (%Dec) were calculated. ASR was calculated as MSS-MAS. While ?RSb were related to ?MSS and ?body mass (r² = 0.42, 90%CL[0.34;0.49] for the overall multiple regression, n = 334), ?RSm was also correlated with ?MAS and ?sum of 7 skinfolds (r² = 0.43 [0.35;0.50], n = 334). There was a small and positive association between ?%Dec and ?MAS (r² = 0.02 [?0.07;0.11], n = 334). Substantial ?MSS and ?MAS had a predictive value of 70 and 55% for ?RSm, respectively. Finally, ?ASR per se was not predictive of ?RSm (Cohen’s = +0.8 to ?0.3 with increased ASR), but the greater magnitude of ?RSm improvement was observed when MSS, MAS and ASR increased together (0.8 vs. +0.4 with ASR increased vs. not, additionally to MSS and MAS). Low-cost field tests aimed at assessing maximal sprinting and aerobic speeds can be used to monitor ?RS performance.     

最大吸氧量对青少年100m和800m训练项目的影响

采用文献资料法、实验法、数理统计法对某重点中学体育训练队的16名男女学生进行Pwc170台阶实验测试分别推算出各受试学生的Vo2m ax,然后对男女各组100m和800m进行相关性分析,根据测试结果及分析显示,Vo2m ax对男生100m与800m成绩的线性关系达到了显著水平,男女生存在差异。对青少年的最大吸氧量的预测有非常重要的意义。     

武术、体操女运动员最大有氧工作能力的预测

为准确预测运动员的最大吸氧量,本文对武术、体操女运动员定量工作时的心率、氧脉搏、肺通气量等生理指标,通过计算机分析处理,选择其中较显著的因素建立了三个最优逐步回归方程。通过验证,其预测结果能准确反映运动员的身体工作能力。     

大运动量训练对心脏心钠素基因表达影响的研究

冷酚法提取心房总RNA，用α-32P标记的大鼠心房肽互补DNA探针与之杂交，检测ANP-mRNA的含量结果表明，2周大运动量训练，大鼠的ANP-mRNA含量增加，4、6周大运动量训练大鼠的ANP-mRNA含量减少；心室RNA含量都减少。提示，合理的运动负荷存在着一个适宜的强度范围。     

交变负荷训练法对下肢肌肉力量训练效果的影响

目的:采用自制振动台为干预手段对下肢肌肉进行力量交变负荷力量训练,研究交变负荷力量训练对肌肉力量增长效果的影响.方法:上海体育学院体育教育专业男子跳远运动员10名,随机分为1)"交变负荷训练组"(Ⅰ组,n=5),振动刺激的频率为20～25 Hz,加速度为15～20m/s2;2)"传统力量训练组"(Ⅰ组,n=5),两组共接受8周训练,实验前后一周内利用Biodex对原地纵跳能力和下肢三大关节屈伸肌肌群的一般、快速力量和功率等指标进行测定.结果:振动刺激训练能够有效地提高受试者的原地纵跳能力、肢三大关节屈伸肌肌群的一般和快速力量,组间比较具有显著性差异.结论:交变负荷力量训练法能有效地提高肌肉力量训练的效果.     

上海汉族优秀耐力运动员ACE基因I/D多态性与最大有氧能力(O_2max)的关联研究

采用PCR和breath by breath方法,对上海汉族55名优秀游泳运动员、60名优秀赛艇运动员和85名汉族普通人的ACE基因I/D多态性和V。O2max进行检测。结果显示1)上海汉族优秀游泳和赛艇运动员ACE基因的基因型和等位基因频率与上海和成都地区汉族普通人组无明显差异(P>0.05);与Caucasian人群相比,均存在非常显著性差异(P<0.0001),表现出明显的民族和地区的差异性;游泳和赛艇项目健将和一级运动员间的基因型和等位基因频率分布,存在明显差异(P<0.05);游泳运动员水平越高,II型所占比例就越高,赛艇运动员中水平越高,ID型的比例越大;2)不同基因型的游泳运动员的O2max、O2max/kg、CO2max、Emax、O2-plusemax、Wmax和Tmax等指标,均表现为II型>DD型>ID型,II型明显优于ID型(P<0.05~0.01),而赛艇运动员则表现为ID型>II型>DD型,ID明显优于DD型(P<0.05~0.01)。结果提示,游泳项目中具有II基因型或I等位基因的运动员,赛艇项目中具有ID基因型或I等位基因的运动员,可能属于运动训练敏感的高反应群体,经过多年系统科学的训练,具有成为优秀运动员的可能。ACE基因I/D多态性可作为运动训练和选材中高敏感的、非常重要的遗传标记之一。