Influence of bench angle on upper extremity muscular activation during bench press exercise

This study compared the muscular activation of the pectoralis major, anterior deltoid and triceps brachii during a free-weight barbell bench press performed at 0°, 30°, 45° and –15° bench angles. Fourteen healthy resistance trained males (age 21.4 ± 0.4 years) participated in this study. One set of six repetitions for each bench press conditions at 65% one repetition maximum were performed. Surface electromyography (sEMG) was utilised to examine the muscular activation of the selected muscles during the eccentric and concentric phases. In addition, each phase was subdivided into 25% contraction durations, resulting in four separate time points for comparison between bench conditions. The sEMG of upper pectoralis displayed no difference during any of the bench conditions when examining the complete concentric contraction, however differences during 26–50% contraction duration were found for both the 30° [122.5 ± 10.1% maximal voluntary isometric contraction (MVIC)] and 45° (124 ± 9.1% MVIC) bench condition, resulting in greater sEMG compared to horizontal (98.2 ± 5.4% MVIC) and –15 (96.1 ± 5.5% MVIC). The sEMG of lower pectoralis was greater during –15° (100.4 ± 5.7% MVIC), 30° (86.6 ± 4.8% MVIC) and horizontal (100.1 ± 5.2% MVIC) bench conditions compared to the 45° (71.9 ± 4.5% MVIC) for the whole concentric contraction. The results of this study support the use of a horizontal bench to achieve muscular activation of both the upper and lower heads of the pectoralis. However, a bench incline angle of 30° or 45° resulted in greater muscular activation during certain time points, suggesting that it is important to consider how muscular activation is affected at various time points when selecting bench press exercises.     

振动训练对速滑运动员下肢肌力影响的实验研究

将振动训练运用在速滑运动员力量训练中,经过8周训练后观察训练效果,以探讨振动训练对速滑运动员下肢力量的改善效应。将16名吉林省速滑队女运动员分为两组,分别采用常规力量训练与常规训练和振动训练相结合的方式训练。实验结果表明:8周振动频率为30Hz,振幅为2mm的振动训练与常规力量训练相结合,能够有效地提高速滑运动员力量的训练效果。尽管8周振动力量训练对提高速滑运动员下肢肌群的最大力量无明显优势,但能显著性提高下肢肌群爆发力与耐力水平,同时能够有效提高速滑运动员的下蹲跳成绩。     

阻力训练及超等长阻力训练对下肢肌肉活性和力量的影响

目的:观察阻力训练和超等长阻力训练后下肢肌肉力量变化,比较肌肉激活模式的不同.方法:将16名男性篮球运动员随机分成两组,分别实施8周下肢阻力训练和超等长阻力训练.采用3-D测力台测试训练前、后最大随意收缩值,用表面肌电记录训练前、后6次重复训练动作的胫骨前肌、腓肠肌外侧头、股直肌、股外侧肌、股二头肌的激活信号,计算积分肌电值和髋、膝、踝关节周围拮抗肌共激活.结果:两组下肢肌肉力量均显著提高,阻力训练组效果较明显.超等长阻力训练组肌肉活性显著高于阻力训练组.训练后超等长阻力训练组肌肉活性出现适应性变化,髋、踝关节拮抗肌共激活显著升高,膝关节拮抗肌共激活训练前、后没有显著性差异.阻力训练组训练前、后肌肉活性及拮抗肌共激活没有显著变化.结论:超等长阻力训练有助于提高肌肉间协调性,可以优化肌肉动作的运动策略.     

腰髋肌肉力量对学生学习田径运动技术的影响及分析

通过对湖北大学2002级体育类学生进行为期1a的田径运动技术学习情况调查，结合技术成绩评分，从运动解剖学，运动技术原理角度加以分析，得出增强腰髋肌肉力量对学生学习运动技术有一定的影响。     

补充肌酸和抗阻训练促进人体股外侧肌废用性肌肉萎缩恢复的组织化学和生物化学机制研究

研究了健康大学生外固定腿 2周使肌肉愈接近废用性萎缩 ,并在固定期和恢复期 10周过程中连续补充肌酸和抗阻训练 ,测定股外侧肌组织化学和生物化学的变化 ,同时测定了骨骼肌表达的生肌调节因子 (MRFs) MyoD ,Myo genin和Myf 5的变化 ,探讨肌酸加速骨骼肌废用性萎缩后恢复的分子机制。研究结果显示 :补充肌酸使股外侧肌废用性肌肉萎缩后恢复期各亚型肌纤维增粗 ,Ⅱ型肌纤维较Ⅰ型肌纤维增粗显著。在恢复期第 3周肌肉磷酸肌酸 (CP)和肌酸 (C )及总肌酸均达到高水平。骨骼肌表达的生肌调节因子 (MRFs) MyoD ,Myf 5的变化与股外侧肌各亚型的的增粗具有一致的结果 ,Myogenin变化不显著。提示 :补充肌酸可以促进股外侧肌各亚型肌纤维增粗可能由促进肌肉收缩蛋白和结构蛋白合成所致。     

血中乳酸浓度与迟发性肌肉酸痛的关系

把15位3年级学生分成3组为研究对象,在离心收缩式运动前分别实施伸展操及热身运动,再以离心收缩式运动诱发迟性肌肉酸痛,并用High氏肌肉酸痛量表探讨辅助运动是否有助于减轻离心式运动所造成的迟发性肌肉酸痛.同时检查运动前后各种肌细胞内酶(如AST,LDH,CPK)释放的情形,以评估了心收缩式运动造成的肌肉伤害的程度以及肌肉伤害是否因运动前的辅助运动而减轻,同时还检查了血中乳酸和迟发性肌肉酸痛的关系及不同的辅助运动对运动后血中乳酸浓度的影响.     

不同快速降体重量对肌肉功能的影响

目的:探讨不同快速降体重量对肌肉功能的影响;方法:以12名健康男生为实验对象,测定脱水前(0%bw l)、桑拿脱水快速降体重2%(2%bw l)、桑拿脱水快速降体重4%(4%bw l)这3种不同体重状态下最大等速肌力、等速肌耐力与无氧作功能力;在测定无氧作功能力时,结合运用主观用力程度等级评价量表(RPE),对肌肉功能进行系统评价;结果:1)2%bw l和4%bw l对肌肉的最大等速力量均没有削弱作用;2%bw l后,屈肘肌群的最大等速肌力反而增大。2)2%bw l对屈、伸肘肌群以及屈、伸膝肌群的等速肌耐力均没有影响;4%bw l后,屈肘肌群与屈、伸膝肌群的等速肌耐力不变,而伸肘肌群的等速肌耐力显著性下降。3)2%bw l和4%bw l对下肢的无氧耐力没有削弱作用。     

The Alteration of Morphology and Histochemity of Neuromuscular Junction Following Experimental Immobilization and Rehabilitation of Rats

We investigated the morphological changes of motor-endplate of rats during skeletal muscle disuse atrophy and natural or exercise rehabilitation. Qualitative and quantitative analysis indicated that with the atrophy of skeletal muscle, a series of changes appeared in nerve ending, the perimeter and maximum diameter of motor-endplate decreased. Endurance exercise may help the rehabilitation of skeletal muscle, stimulating the recovery of perimeter and maximum diameter of motorendplate and the budding of nerve ending. A suitable stimulation to local nerve system and endplate could reduce the atrophy of muscle during disuse.     

蚯蚓素9203的一般药理学研究

蚯蚓素9203的一般药理学研究表明,对小鼠的中枢神经系统和空肠无明显影响,对回肠则有减缓蠕动的作用．对大鼠的血压、心电频率、P波、QRS波、ST段和T波、呼吸的深度和频率无明显影响．     

The association of socio-economic factors with physical fitness and activity behaviours,spinal posture and retinal vessel parameters in first graders in urban Switzerland

Socio-economic status during childhood has been shown to be a strong predictor of adult health outcome. Therefore, we examined associations of parental educational level, household income and migrant background with physical fitness, spinal flexibility, spinal posture as well as retinal vessel diameters in children of an urban Swiss region. A total of 358 first graders of the Swiss canton Basel-Stadt (age: 7.3, SD: 0.4) were examined. Physical fitness (20 m shuttle run test, 20 m sprint, jumping sidewards and balancing backwards), spinal flexibility and spinal posture (MediMouse^®, Idiag, Fehraltdorf, Switzerland) and retinal microcirculation (Static Retinal Vessel Analyzer, Imedos Systems UG, Jena, Germany) were assessed. Parental education, household income, migrant background and activity behaviour were evaluated with a questionnaire. Parental education was associated with child aerobic fitness (P = 0.03) and screen time (P < 0.001). Household income was associated with jumping sidewards (P = 0.009), balancing backwards (P = 0.03) and sports club participation (P = 0.02). Migrant background was associated with BMI (P = 0.001), body fat (P = 0.03), aerobic fitness (P = 0.007), time spent playing outdoors (P < 0.001) and screen time (P < 0.001). For spinal flexibility and retinal vessel diameter, no associations were found (0.06 < P < 0.8). Low parental education, low household income and a migrant background are associated with poor physical fitness, higher BMI and body fat percentage and low-activity behaviour.