跑节省化、无氧阈和最大摄氧量评价篮球运动员有氧能力的比较研究

以天津商务职业学院24名男篮球队员为研究对象,通过跑台测试、因子分析法等,采用跑节省化、无氧阈和最大摄氧量对篮球运动员进行评价分析。结果显示:篮球运动员跑节省化的修正值在第一公因子中载荷最大,在第二、第三公因子中跑节省化相关指标的载荷量处于相对重要位置,在第四公因子中只有跑节省化时通气量;跑节省化、无氧阈和最大摄氧量三指标在评价篮球运动员有氧耐力时,跑节省化指标优势明显。提示:跑节省化可以作为评价篮球运动员有氧耐力的首选指标。     

3-min all-out effort on cycle ergometer is valid to estimate the anaerobic capacity by measurement of blood lactate and excess post-exercise oxygen consumption

The purpose of this study was to investigate the use of a single 3-min all-out maximal effort to estimate anaerobic capacity (AC) through the lactate and excess post-exercise oxygen consumption (EPOC) response methods (AC_{[La^?]+EPOCfast}) on a cycle ergometer. Eleven physically active men (age?=?28.1?±?4.0?yrs, height?=?175.1?±?4.2?cm, body mass?=?74.8?±?11.9?kg and ?O_2max?=?40.7?±?7.3?mL?kg^?1?min^?1), participated in the study and performed: i) five submaximal efforts, ii) a supramaximal effort at 115% of intensity of ?O_2max, and iii) a 3-min all-out maximal effort. Anaerobic capacity was estimated using the supramaximal effort through conventional maximal accumulated oxygen deficit (MAOD) and also through the sum of oxygen equivalents from the glycolytic (fast component of excess post-exercise oxygen consumption) and phosphagen pathways (blood lactate accumulation) (AC_{[La^?]+EPOCfast}), while during the 3-min all-out maximal effort the anaerobic capacity was estimated using the AC_{[La^?]+EPOCfast} procedure. There were no significant differences between the three methods (p?>?0.05). Additionally, the anaerobic capacity estimated during the 3-min all-out effort was significantly correlated with the MAOD (r?=?0.74; p?=?0.009) and AC_{[La^?]+EPOCfast} methods (r?=?0.65; p?=?0.029). Therefore, it is possible to conclude that the 3-min all-out effort is valid to estimate anaerobic capacity in physically active men during a single cycle ergometer effort.     

Validity and reliability of a low-cost dynamometer to assess maximal isometric strength of upper limb

Muscle imbalance and deficit are key parameters for guiding rehabilitation and sports sessions and avoiding injuries. However, the high cost and non-portable nature of most instruments employed for muscle strength assessment frequently hamper an affordable evaluation in field conditions. This study evaluated the validity and reliability of a low-cost digital dynamometer to assess the maximal isometric strength of upper limb muscles. Fourteen physically active volunteers performed the main movements of the upper limb at maximal isometric strength: flexion-extension, internal-external rotation and abduction-adduction of the shoulder; and flexion-extension of both elbow and wrist. Validity was examined by comparing the strength values from the low-cost digital dynamometer and those measured by an isokinetic dynamometer, assumed as the gold standard. The correlation between both devices was perfect (r > 0.913), while Bland-Altman plots showed absolute agreement between both devices, the maximum range of the values of bias was ?0.99–1.00 N in wrist extension. Inter-tester and intra-tester reliability were excellent for all movements (ICC ≥ 0.855). The low-cost digital dynamometer showed strong validity and excellent reliability in assessing maximal isometric strength during the main movements of the upper limb. Professionals may use it for an affordable isometric muscle strength assessment in field situations.     

Effect of gear ratio on peak power and time to peak power in BMX cyclists

The aim of this study was to ascertain if gear ratio selection would have an effect on peak power and time to peak power production in elite Bicycle Motocross (BMX) cyclists. Eight male elite BMX riders volunteered for the study. Each rider performed three, 10-s maximal sprints on an Olympic standard indoor BMX track. The riders’ bicycles were fitted with a portable SRM power meter. Each rider performed the three sprints using gear ratios of 41/16, 43/16 and 45/16 tooth. The results from the 41/16 and 45/16 gear ratios were compared to the current standard 43/16 gear ratio. Statistically, significant differences were found between the gear ratios for peak power (F(2,14)?=?6.448; p?=?.010) and peak torque (F(2,14)?=?4.777; p?=?.026), but no significant difference was found for time to peak power (F(2,14)?=?0.200; p?=?.821). When comparing gear ratios, the results showed a 45/16 gear ratio elicited the highest peak power,1658?±?221?W, compared to 1436?±?129?W and 1380?±?56?W, for the 43/16 and 41/16 ratios, respectively. The time to peak power showed a 41/16 tooth gear ratio attained peak power in ?0.01?s and a 45/16 in 0.22?s compared to the 43/16. The findings of this study suggest that gear ratio choice has a significant effect on peak power production, though time to peak power output is not significantly affected. Therefore, selecting a higher gear ratio results in riders attaining higher power outputs without reducing their start time.     

振动力量训练对跳远运动员膝关节肌力变化影响的实验

为了拓宽专项力量训练途径,丰富和创新力量训练方法,通过振动力量训练组(II组)和传统力量训练组(I)对比实验研究来探索振动力量训练对跳远运动员下肢肌肉力量训练效果的影响规律,为进一步振动力量训练发展和应用提供实验依据。实验结果表明:振动力量训练法能在同等的负荷条件下,能更有效地发展运动员膝关节屈肌群的最大力量、快速力量、爆发力,其中伸肌表现不明显;振动力量训练也提高了运动员的膝关节肌群力量耐力水平,同时使膝关节屈伸肌群得到协调发展。     

向量组的秩的概念引入教学

对于向量组的秩的概念的教学，给出了教学方法．先从分析向量组的线性相关性入手，引出向量组的秩的概念，使得向量组的秩这一抽象的概念变得简单易懂。     

中、外女子100m跑优秀运动员成绩演变及技术特征的比较分析

采用文献资料、录像分析、数理统计和逻辑分析的研究方法，对中、外女子100m跑优秀运动员成绩演变及技术特征进行了比较研究，分析了影响我国优秀100m跑运动员成绩落后的原因，并提出了若干改进建议。研究的一些结果可以为我国女子100m跑运动员的科学训练和选材提供参考。     

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.     

解析滑轮的转动

在滑轮问题中,绳的张力并没有直接作用在滑轮上。分析定滑轮和动滑轮的转动,发现绳的张力是通过转化为摩擦力矩或支承力矩间接起作用的。并且在滑轮的转动中。摩擦力矩总是在发挥着作用。