纵跳中关节功率及其与人体疲劳的关系

考察了纵跳中关节功率及其与人体疲劳的关系。 2次纵跳分别在功率自行车上蹬踏 30 s之前和之后进行。纵跳动作用摄像机摄录下来 ,并在运动解析仪上加以分析。纵跳中的地面反力用测力台测量。根据采集的数据计算了关节功率。通过比较 2组数据计算了各关节处关节功率的变化 ,从而得到了对人体疲劳的一种定量描述     

跑与纵跳关节功率的研究

采用运动生物力学方法考察了跑与纵跳的关节功率及其与人体疲劳的关系。跑的数据是借鉴国外一些研究的资料；纵跳，分别在功率自行车上蹬踏30s之前和之后进行，动作用摄像机摄录下来，并在运动解析仪上加以分析。纵跳中的地面反作用力用三维测力台测量。利用上述系统的数据计算了关节功率。通过比较两组数据计算了各关节功率的变化，从而得到了对人体疲劳的一种定量描述。从而得知：在跑中当脚着地后，首先是髋关节处于屈的状态，其关节功率达到最大值；其次是踝关节屈的关节功率变化较大；最后是膝关节功率达到最大值。其中踝关节变化最大。在腾空状态中，髋关节与膝关节的关节功率处于较大值，并且变化较大。纵跳过程中，疲劳主要表现为膝关节功率的下降。     

肌肉离心收缩的后激活增强效应对纵跳能力的影响

目的：探讨不同离心负荷激活干预对后激活增强效应所产生的影响及有效作用时间。方法：通过对14名普通男性大学生运用肌肉离心收缩激活方式，观察后续纵跳表现的影响。结果：在激活干预后即刻，对照组与离心负荷（105%1RM和125%1RM）激活干预两个实验组纵跳峰值功率和纵跳的高度没有显著差异，激活干预两个组之间的纵跳表现没有显著差异。激活干预的两组在T3和T6时段的纵跳功率峰值均明显高于对照组。在T3时段两个激活干预实验组纵跳高度峰值明显高于对照组，在T6时段，105%1RM激活干预组的纵跳高度明显增加。结论：纵跳测试前加入大强度的离心负荷刺激会小幅度提高纵跳的能力，不同强度离心负荷的激活干预的后激活增强效应差异性不大，采用105%1RM强度的离心负荷激活干预在 3~6 min有明显的后激活增强效应。     

关于纵跳比立定跳远更能准确评定下肢爆发力的研究

通过对立定跳远与纵跳的动力学比较分析,探讨采用纵跳或立定跳远来评价下肢爆发力的准确性与有效性。方法:运用三维测力台对10位普通大学男生进行立定跳远和纵跳的测试。每个受试者按要求进行三次立定跳远和三次纵跳,对于每一个受试者,取其最好的测试成绩进行比较分析。结果表明:纵跳中的地面反作用力比立定跳远的地面反作用力要大12.90%,最大功率更是相差49.30%。纵跳中最大功率与纵跳成绩相关系数高达0.83,而立定跳远中最大功率与立定跳远成绩相关系数仅0.29。结论:纵跳比立定跳远能更准确有效地评价普通学生的下肢爆发力。     

原地跳纵人体重心与下肢各关节时相关系的探讨

本文旨在探索人体重心与下肢各关节在原地纵跳中的空间关系和时间关系,为人体动作的计算模拟提供生物学依据和参数。     

连续纵跳及其疲劳的生物力学研究

对２７名体育系男生３０次连续纵跳的纵跳摸高高度、动力学指标进行测定,对数据进行统计处理、对应比较。结果表明,纵跳摸高高度是评价运动性疲劳的有效指标,１０秒钟内纵跳的纵向最大力值和冲量值可作为评价疲劳的指标。本研究确定了一些生物力学的疲劳指标,为运动生物力学对运动性疲劳的研究积累了一定的数据材料。     

不同的训练方法对纵跳高度效果的实验性研究

纵跳是在各种运动项目中均有的一种动作。纵跳可分为原地纵跳和助跑纵跳。对同一个人来说,助跑纵跳要比原地纵跳高度增长约10％左右,然而原地纵跳是助跑纵跳的基础。纵跳能力的强弱直接影响到运动成绩和动作效果,而纵跳能力的强弱又取决于多方面的因素。人体形态结构和机能特别是下肢起着重要的作用。我们曾对下肢形态、膝角与纵跳关系进行探讨。人体结构的变化和机能的提高又决     

《天津体育学院学报》一九九○年总目次索引

“高原训练”的生理基础和应用刘汉杨(90 .1)纵跳无氧功率测试的可行性及间接评定法的研究刘林丰(90.1)能关节角对伸膝力矩的影响刘燕霓(90.1)针刺“常用穴”对恢复过程中脑电图等指标的影响杨缅南(90.2)非平衡态热力学在人体运动中的应用刘燕霓(90.2)家兔后肢被动运动至肌僵硬时肌肉内酶的活性变化李静先(90.3)健美操训练对人体肌纤维某些化学特征的影响傅力(90.3)不同项目的训练对血清氨基酸代谢的影响席翼(90.4)用气压疗法消除疲劳的研究李明(90.4)急性腰扭伤的综合治疗吕尤栽(90.4)高水平运动员心理衰竭现象初探赵国雄(90.4)体育科学冲…     

反复跳跃的疲劳问题

由(参加全国联赛的)一组排球运动员(n=10)反复地做纵跳和跳远,做一次简短的研究以表明效应。本研究是确定疲劳是怎样地影响这些标准的爆发力测试的。纵跳和跳远是在运动员做完准备运动,精力充沛时,在正常的情况下,受监督进行的。明确疲劳对这些爆破力参数的影响,即当疲劳     

以起跳速度测量纵跳功率的研究

功率包含有力和速度两个因素,在运动学中常称之为“爆发力”。纵跳是美国的 Sargent(1921)设计的,后来发展成为测定肌肉爆发力(musolePower)的一种常用方法,以纵跳的高度作为爆发力的指标。虽然有研究证明爆发力与跳跃高度之间有高度相关(Gray,1962),但跳跃高度本身并不是爆发力(功率)。Margaria 等认为,测量纵跳时如不考虑体重和速度就不能认为是功率。本研究试图采用一种简单易行的纵跳功率的测量方法来估测纵跳时的起跳功率。     

Conditioning exercises in ski jumping: biomechanical relationship of squat jumps,imitation jumps,and hill jumps

As hill jumps are very time-consuming, ski jumping athletes often perform various imitation jumps during training. The performed jumps should be similar to hill jumps, but a direct comparison of the kinetic and kinematic parameters has not been performed yet. Therefore, this study aimed to correlate 11 common parameters during hill jumps (Oberstdorf Germany), squat jumps (wearing indoor shoes), and various imitation jumps (rolling 4°, rolling flat, static; jumping equipment or indoor shoes) on a custom-built instrumented vehicle with a catch by the coach. During the performed jumps, force and video data of the take-off of 10 athletes were measured. The imitation and squat jumps were then ranked. The main difference between the hill jumps and the imitation and squat jumps is the higher maximal force loading rate during the hill jumps. Imitation jumps performed on a rolling platform, on flat ground were the most similar to hill jumps in terms of the force–time, and leg joint kinematic properties. Thus, non-hill jumps with a technical focus should be performed from a rolling platform with a flat inrun with normal indoor shoes or jumping equipment, and high normal force loading rates should be the main focus of imitation training.     

Influence of a horizontal approach on the mechanical output during drop jumps

This study investigated the influence of a horizontal approach to mechanical output during drop jumps. Participants performed drop jumps from heights of 15, 30, 45, and 60 cm with zero, one, two, and three approach steps. The peak summed power during the push-off phase changed quadratically across heights (6.2 +/- 0.3, 6.7 +/- 0.4, 6.4 +/- 0.4, and 6.0 +/- 0.4 kW, respectively) driven by the ankle joint response. Summed peak power was 10% greater with an approach attributed to the knee joint response. Downward phase dorsiflexion (31%), knee flexion (35%), and peak vertical force (32%) increased with drop heights. Vertical approach force (22%) increased, while knee flexion (11%) and downward duration (17%) decreased. An approach may improve drop jump training for explosive tasks.     

Mechanical parameters and flight phase characteristics in aquatic plyometric jumping

Plyometric jumping is a commonly prescribed method of training focused on the development of reactive strength and high-velocity concentric power. Literature suggests that aquatic plyometric training may be a low-impact, effective supplement to land-based training. The purpose of the present study was to quantify acute, biomechanical characteristics of the take-off and flight phase for plyometric movements performed in the water. Kinetic force platform data from 12 young, male adults were collected for counter-movement jumps performed on land and in water at two different immersion depths. The specificity of jumps between environmental conditions was assessed using kinetic measures, temporal characteristics, and an assessment of the statistical relationship between take-off velocity and time in the air. Greater peak mechanical power was observed for jumps performed in the water, and was influenced by immersion depth. Additionally, the data suggest that, in the water, the statistical relationship between take-off velocity and time in air is quadratic. Results highlight the potential application of aquatic plyometric training as a cross-training tool for improving mechanical power and suggest that water immersion depth and fluid drag play key roles in the specificity of the take-off phase for jumping movements performed in the water.     

Stiffness,intralimb coordination,and joint modulation during a continuous vertical jump test

This study analysed the modulation of jump performance, vertical stiffness as well as joint and intralimb coordination throughout a 30-s vertical jump test. Twenty male athletes performed the test on a force plate while undergoing kinematic analysis. Jump height, power output, ground contact time, vertical stiffness, maximum knee and hip flexion angles, and coordination by continuous relative phase (CRP) were analysed. Analysis of variance was used to compare variables within deciles, and t-tests were used to compare CRP data between the initial and final jumps. Results showed reduction in jump height, power output, and vertical stiffness, with an increase in contact time found during the test. Maximum knee and hip flexion angles declined, but hip angle decreased earlier (10–20% of the test) than knee angle (90–100%). No changes were observed in CRP for thigh–leg coupling when comparing initial and final jumps, but the trunk–thigh coupling was more in-phase near the end of the test. We conclude that fatigue causes reduction in jump performance, as well as changes in stiffness and joint angles. Furthermore, changes in intralimb coordination appear at the last 10% of the test, suggesting a neuromotor mechanism to counterbalance the loss of muscle strength.     

How do elite ski jumpers handle the dynamic conditions in imitation jumps?

We examined the effect of boundary conditions in imitation ski jumping on movement dynamics and coordination. We compared imitation ski jumps with – and without – the possibility to generate shear propulsion forces. Six elite ski jumpers performed imitation jumps by jumping from a fixed surface and from a rolling platform. The ground reaction force vector, kinematics of body segments, and EMG of eight lower limb muscles were recorded. Net joint dynamics were calculated using inverse dynamics. The two imitation jumps differed considerably from each other with regard to the dynamics (moments, forces), whereas the kinematics were very similar. Knee power was higher and hip power was lower on the rolling platform than on the fixed surface. Mean EMG levels were very similar for both conditions, but differences in the development of muscle activity were indicated for seven of eight muscles. These differences are reflected in a subtle difference of the alignment of ground reaction force with centre of mass: the ground reaction force runs continuously close to but behind the centre of mass on the rolling platform and fluctuates around it on the fixed surface. This likely reflects a different strategy for controlling angular momentum.     

Is vertical jump height a body size-independent measure of muscle power?

We tested the hypothesis that the performance of rapid movements represents body size-independent indices of muscle power. Physical education students (n = 159) were tested on various vertical jump (jump height and average power calculated from the ground reaction force) and muscle strength tests. When non-normalized data were used, a principal components analysis revealed a complex and inconsistent structure where jump height and muscle power loaded different components, while muscle strength and power partially overlapped. When the indices of muscle strength and power were properly normalized for body size, a simple and consistent structure of principal components supported the hypothesis. Specifically, the recorded height and muscle power calculated from the same jumps loaded the same components, separately for the jumps predominantly based on concentric actions and jumps based on a rapid stretch--shortening cycle of the leg extensors. The finding that the performance of rapid movements assesses the same physical ability as properly normalized tests of muscle power could be important for designing and interpreting the results of batteries of physical performance tests, as well as for understanding some basic principles of human movement performance.     

Kinematic and kinetic analyses of the toes in dance movements

Due to the significant amount of time dancers spend on the forefoot, loads on the metatarsophalangeal joints are likely high, yet vary between dance movements. The purpose of this study was to compare joint motion and net joint moments at the metatarsophalangeal joints during three different dance movements ranging in demands at the foot and ankle joints. Ten healthy, female dancers (27.6 ± 3.2 years; 56.3 ± 6.9 kg; 1.6 ± 0.1 m) with an average 21.7 ± 4.9 years of dance training performed relevés (rising up onto the toes), sautés (vertical bipedal jumps), and saut de chat leaps (split jumps involving both vertical and horizontal components). Metatarsophalangeal joint kinematics and kinetics in the sagittal plane were calculated. Total excursion and peak net joint moments during rising or push-off were compared between the three dance movements. Greater extension of the metatarsophalangeal joints was seen during relevés compared to sautés or saut de chat leaps, and the largest metatarsophalangeal net joint moments were seen during saut de chat leaps. The metatarsophalangeal joints frequently and repetitively manage external loads and substantial metatarsophalangeal extension during these three dance movements, which may contribute to the high rate of foot and ankle injuries in dancers.     

Contribution of the lower extremity joints to mechanical energy in running vertical jumps and running long jumps

The energy contribution of the lower extremity joints to vertical jumping and long jumping from a standing position has previously been investigated. However, the resultant joint moment contributions to vertical and long jumps performed with a running approach are unknown. metatarsophalangeal joint to these activities has not been investigated. The objective of this study was to determine the mechanical energy contributions of the hip, knee, ankle and metatarsophalangeal joints to running long jumps and running vertical jumps. A sagittal plane analysis was performed on five male university basketball players while performing running vertical jumps and four male long jumpers while performing running long jumps. The resultant joint moment and power patterns at the ankle, knee and hip were similar to those reported in the literature for standing jumps. It appears that the movement pattern of the jumps is not influenced by an increase in horizontal velocity before take-off. The metatarsophalangeal joint was a large energy absorber and generated only a minimal amount of energy at take-off. The ankle joint was the largest energy generator and absorber for both jumps; however, it played a smaller relative role during long jumping as the energy contribution of the hip increased.     

Upper extremity augmentation of lower extremity kinetics during countermovement vertical jumps

Twenty-five volleyball players (14 males, 11 females) were videotaped (60Hz) performing countermovement vertical jumps with and without an arm swing. Ground reaction force and video-based coordinate data were collected simultaneously. The resultant joint force and torque at the hip, knee, ankle and shoulder for two trials per subject per condition were computed and normalized. Average kinematic, resultant joint force and torque data were compared using repeated-measures analysis of variance. Larger values were recorded for the vertical velocity of the centre of mass at take-off in the jumps with (mean 2.75, s=0.3m.s-1) versus without (mean 2.44, s= 0.23m.s-1) an arm swing. The jumps with no arm swing produced larger torques at the hip during the first third of the propulsive phase (from zero to maximum vertical velocity of the centre of mass). During the final two-thirds of the propulsive phase, the arm swing augmented hip extensor torques by slowing the rate of trunk extension and placing the hip extensor muscles in slower concentric conditions that favoured the generation of larger forces and resultant joint torques. During the first two-thirds ofthe propulsive phase, knee extensor torque increased by 28% in the jumps with an arm swing, but maintained a relatively constant magnitude in the jumps with no arm swing.