下肢肌在踏跳动作中的储能

下肢肌肉储能大小和再利用率反映了运动员下肢肌的力量素质和动作技术的优劣 ,也是评定运动员下肢肌肉力量素质的动力学指标。我们采用高速摄影和三维测力 ,对 6名运动员在跳跃踏跳中 ,下肢肌肉的储能大小、负功利用率及其影响因素进行了研究。试验结果表明 :1 .外负荷变化时 ,踏跳缓冲结束瞬时肌肉的力值不同 ,且存在极值 ,此极值的大小与运动员的力量素质有关。 2 .下肢肌肉的储能与缓冲结束瞬时的力值之间有一定的比例关系 ,当肌肉受到一个最佳的拉伸力时 ,肌肉储能最多。 3.肌肉在向心收缩过程 ,对其在离心收缩过程中肌肉所做的负功的利用率 ,随着外负荷的增大而降低     

The role of engineering in fatigue reduction during human locomotion — a review

The purpose of this review is to discuss how an athlete’s fatigue can be limited by using recent innovations in sports engineering. The review focuses on human locomotion, i.e. mainly fatigue during endurance sports. First, through a general definition and illustrations of means of locomotion such as running, cycling, walking/hiking or speed skating, several aspects of fatigue reduction will be presented. With regards to the mechanical stress, it has been shown that (i) contrary to ‘invitro’ experiments and, in comparison with hard shoes, soft shoes do not appear to reduce impact forces during running and (ii) too much cushioning can have side effects in terms of energy cost and thus in terms of fatigue in running and mountain biking. On the contrary, the equipment weight-that also depends on the weight repartition may have dramatic effects in terms of fatigue. Any equipment allowing better mechanical efficiency (e.g. chainrings, klapskate) or work distribution (e.g. walking with poles) can potentially reduce an athlete’s fatigue under similar conditions without this equipment. However, among elite athletes, the use of technical innovation does not seem to affect fatigueper se but provides performance improvement with similar fatigue occurrence. It appears that fatigue-related improvements caused by technical innovations only occur among sportsmen exercising for leisure. In the second part of this review, recent textile innovations aimed at decreasing fatigue by the use of elastic compression stockings or at regulating temperature will be discussed. Finally, two methods designed to improve recovery after training or competition (elastic compression and electromyostimulation) will be discussed. Both these techniques are widely used by elite athletes despite relatively poor scientific evidence of their efficiency, with the exception of recovery after eccentric exercise.     

运动性疲劳与乙酰胆碱脂酶研究进展

乙酰胆碱脂酶是位于突触间隙水解乙酰胆碱的分解酶,它能高效、迅速地水解胆碱能神经末稍所释放的乙酰胆碱,保证神经兴奋与抑制的协调统一.综述乙酰胆碱脂酶的分子组成、表达调控、分子之间的相互作用及与运动性疲劳的关系.     

RF-II型椎弓根螺钉系统加横突间植骨治疗腰椎滑脱

目　的 :观察RF -Ⅱ型椎弓根螺钉系统加横突间植骨治疗腰椎滑脱的疗效。方法 :自 1998年 2月～ 2 0 0 1年 2月采用RF -Ⅱ型椎弓根螺钉系统复位内固定加横突间植骨术治疗腰椎滑脱症 2 1例 ,男性 15例 ,女性 6例 ,峡部型 17例 ,退变型 3例 ,创伤型 1例 ,Ⅰ度 5例 ,Ⅱ度 12例 ,Ⅲ度 4例 ,滑脱部位L515例 ,L4 6例。结果 :全部病例均获随访平均 3.2年 ( 2 .4～5年 ) ,复位率 90 %～ 10 0 % ,无感染 ,无神经根损伤或神经症状加重 ,术前畸形得以改善 ,19例术前症状消失 ,2 0例 ( 95 % ) 4～ 6个月脊柱融合。结论 :RF -Ⅱ系统强度可靠 ,三维固定方式理想 ,可明显提高横突间植骨的融合率 ,是目前治疗腰椎滑脱的理想方式。     

大鼠骨骼肌废用性萎缩与运动恢复中内源性IGF-Ⅰ的作用

探讨骨骼肌废用性萎缩、恢复中内源性IGF-I的影响,及小强度耐力锻炼对肌萎缩恢复的有效性。SD大鼠30只,建立吊尾拟失重及失重后耐力性跑台训练恢复模型,计量肌湿重、横截面积及肌内IGF-I含量。结果去负荷4周(U组)肌湿重、横截面积高度显著低于对照组(C组),去负荷后运动恢复(UE组)与自然恢复(UC组)相应指标显著高于U组;U组IGF-I含量显著低于C组,和U组相比,IGF-IUE组高度显著增加、UC组显著增加;UE、UC组间三项指标变化均无显著差异。结论去负荷大鼠比目鱼肌萎缩可能与内源性IGF-I多肽下降有关,且随后小强度耐力练习使比目鱼肌恢复更快可能由IGF-I多肽表达增加实现;小强度耐力性练习在肌萎缩恢复中未见显著作用,提示实践中这可能不是抗肌萎缩的最合适练习方法。     

Physical fitness predicts the academic achievement over one-school year follow-up period in adolescents

The purposes of this study were to examine how fitness at the baseline could predict both academic achievement and academic achievement changes one school year in advance. A total of 194 adolescents (mean age: 14.15 ± 0.97 years old, 112 boys) who attended secondary school participated in our study. Cardiorespiratory fitness was measured with the 20 m endurance shuttle-run test. We also assessed the lower-limbs muscular strength with the standing long jump test and flexibility with the sit-and-reach test. The academic achievement was assessed by school grades. We performed linear regression analyses. Additionally, we examined the relationship between fitness and changes in the academic performance following the same statistical methodology. Cardiorespiratory fitness was positively associated with mathematics one school year in advance (p = 0.025). Cardiorespiratory fitness was also positively associated with changes in Spanish language (p = 0.005), mathematics (p = 0.023), and the grade point average (p = 0.006). Muscular strength was also positively associated with changes in Spanish language (p = 0.040) and mathematics (p = 0.010), while flexibility was associated with changes in Spanish language (p = 0.039) and the grade point average (0.027). Our results suggest that cardiorespiratory fitness was positively associated with academic achievement in adolescents.     

短跑支撑阶段运动生物力学分析

采用测力、高速录像及特殊的数据平滑处理方法研究短跑运动员途中跑技术的运动学和动力学特征,进行田径技术原理的探索。结果表明,支撑时期可以分为着地阶段和蹬伸阶段,蹬伸阶段可分前蹬,后蹬前段,后蹬后段。途中跑前蹬段是人体重心垂直方向向上加速的重要时刻,前蹬时下肢一定程度的垂直加速用力虽影响水平速度,但对提高垂直速度有积极意义,前蹬和后蹬前段是身体重心垂直向上加速运动的阶段。着地缓冲后的前蹬用力也是实现良好成绩的技术之一。途中跑着地和前蹬阶段失去的水平速度损失完全可以从后蹬中得到补充。着地点过近对前支撑阶段获得重要的垂直速度不利,支撑阶段离地前的20ms身体重心速度已经开始下降。     

牛磺酸和／或递增负荷训练对大鼠骨骼肌不同肌纤维线粒体Ca^2＋-ATP酶活性的影响

以大鼠力竭性运动为模型，观察了牛磺酸和／或递增负荷训练对大鼠力竭运动后即刻红、白肌线粒体Ca^2 -ATP酶活性的影响。结果显示：1)安静时白肌纤维线粒体Ca^2 -ATP酶活性较红肌的高；2)力竭运动使白肌纤维线粒体Ca^2 -ATP酶活性降低，红肌的则升高；3)5周递增负荷训练对白肌纤维线粒体Ca^2 -ATP酶活性影响较大，而对红肌的几乎没有什么影响；4)牛磺酸能使力竭运动后白肌和红肌张维线粒体Ca^2 -ATP酶活性升高，结合训练其作用更明显。结果提示：递增负荷训练中慢运动单位可能较少参与运动，所以该方法可能只对白肌起到积极的锻炼作用，牛磺酸和／或训练有保护白肌和红肌线粒体的功能和防止红肌线粒体功能损伤的作用。     

Lumbar spinal loading during bowling in cricket: a kinetic analysis using a musculoskeletal modelling approach

The objective of the study was to evaluate two types of cricket bowling techniques by comparing the lumbar spinal loading using a musculoskeletal modelling approach. Three-dimensional kinematic data were recorded by a Vicon motion capture system under two cricket bowling conditions: (1) participants bowled at their absolute maximal speeds (max condition), and (2) participants bowled at their absolute maximal speeds while simultaneously forcing their navel down towards their thighs starting just prior to ball release (max-trunk condition). A three-dimensional musculoskeletal model comprised of the pelvis, sacrum, lumbar vertebrae and torso segments, which enabled the motion of the individual lumbar vertebrae in the sagittal, frontal and coronal planes to be actuated by 210 muscle-tendon units, was used to simulate spinal loading based on the recorded kinematic data. The maximal lumbar spine compressive force is 4.89 ± 0.88BW for the max condition and 4.58 ± 0.54BW for the max-trunk condition. Results showed that there was no significant difference between the two techniques in trunk moments and lumbar spine forces. This indicates that the max-trunk technique may not increase lower back injury risks. The method proposed in this study could be served as a tool to evaluate lower back injury risks for cricket bowling as well as other throwing activities.