ObjectiveThe objective of this investigation is to examine the contribution of key muscle groups in the lower limbs to vertical jumping performance in elite male volleyball players. Specifically, the study focuses on the rectus femoris (RF), vastus lateralis (VL), and lateral gastrocnemius (LG), as well as exploring differences between attack jump and other vertical jump types.MethodsTo achieve this, we employed B-mode ultrasound to evaluate the anatomical cross-sectional area (ACSA), muscle thickness (MT), pennation angle (PA), and fascicle length (FL) of the RF, VL, and LG in the participants. Fifteen elite male volleyball players were recruited as participants for this study. Jump heights were measured for four types of vertical jumps: attack jump (AJ), countermovement jump (CMJ), squat jump (SJ), and drop jump (DJ). We conducted regression analyses to assess whether the previously mentioned muscle structures could predict jump performance.ResultsOur findings reveal that the muscle structure of the RF does not exhibit any significant correlation with the height of any jump. However, VL-ACSA displays a significant and the most potent predictive effect on jump height for all four jump types (AJ: R2 = 0.32, p = 0.001; CMJ: R2 = 0.37, p = 0.005; SJ: R2 = 0.52, p = 0.001; DJ: R2 = 0.25, p = 0.021). Conversely, LG-FL only demonstrates a significant and stronger predictive effect on AJ jump height (R2 = 0.18, p = 0.009). Combining VL-ACSA, LG-FL, and training age through multiple linear regression analysis resulted in a highly significant model for predicting AJ jump height (F = 13.86, R2 = 0.73). Moreover, the model incorporating VL-ACSA and training age is also important for predicting CMJ, SJ, and DJ jump heights (F = 8.41, R2 = 0.51; F = 13.14, R2 = 0.63; F = 5.95, R2 = 0.41; respectively).ConclusionThe muscle structure indicators in the lower limbs significantly predict jump performance among elite male volleyball players. However, different jump types are influenced by distinct indicators, particularly in the case of AJ, which is associated with LG-FL. This suggests that enhancing LG-FL may positively impact AJ ability, thereby emphasizing the importance of specificity in training. To optimize specialized jump performance in volleyball players, practitioners are advised to assess VL-ACSA and LG-FL and incorporate step-up and eccentric strength training targeting the calf muscles to yield considerable benefits.

Objective:Joint stiffness results from the coupling of the nervous system and joint mechanics, and thus stiffness is a comprehensive representation of joint stability. It has been reported that moxibustion can alleviate general weakness and fatigue symptoms and subsequently may influence joint stiffness. This study investigated whether moxibustion could enhance knee joint stiffness in recreational athletes pre- and post-fatigue. Methods:Eighteen participants were randomized into intervention (5 males: 20.6 ± 1.5 yr; 4 females: 20.8 ± 1.5 yr) and control groups (5 males: 19.4 ± 0.9 yr; 4 females: 20.5 ± 0.6 yr). The intervention group received indirect moxibustion applied to acupoints ST36 (bilateral) and CV4 for 30 min every other day for 4 consecutive weeks. The control group maintained regular exercise without moxibustion. Peak torque (PT) of right knee extensor, relaxed and contracted muscle stiffness (MS) of vastus lateralis, and knee extensor musculoarticular stiffness (MAS) was assessed with an isokinetic dynamometer (IsoMed 2000), myometer, and free oscillation technique, respectively. Measurements were taken at three time points: pre-intervention, post-intervention/pre-fatigue, and post-fatigue. Results:MAS (P = 0.006) and PT (P = 0.007) in the intervention group increased more from pre-to post-intervention compared with the control group. Post-fatigue MAS (P = 0.016) and PT (P = 0.031) increased more in the intervention group than in the control group. Conclusion:Moxibustion enhanced PT and knee MAS, suggesting that this intervention could be used in injury prevention and benefit fatigue resistance in young recreational athletes.

目的:对比跳深(drop jump,DJ)动作中髋、膝、踝关节之间在生物力学指标上的差异,探究下肢关节生物力学指标与跳深动作表现指标之间的关系,明确影响跳深动作表现指标的下肢关节生物力学因素.方法:招募16名运动等级为一级及以上的男子短跑运动员完成0.45 m落地高度跳深动作测试并同步采集三维运动学和动力学数据.结果:1)高水平男子短跑运动员跳深动作中髋、膝和踝关节在力矩、负功率、正功率、负功、正功以及刚度(stiffness)指标上的差异均具有统计学意义(P＜0.001);2)踝关节跖屈力矩和膝关节刚度对地面接触时间的影响(调整R2=0.801,P=0.011)、膝关节正功对腾空高度的影响(调整R2=0.677,P＜0.001)、踝关节正功率对平均功率输出的影响(调整R2= 0.554,P＜0.001)、膝关节刚度和踝关节正功率对反应力量指数的影响(调整R2=0.842,P=0.004)均具有统计学意义.结论:高水平男子短跑运动员在完成跳深动作时,膝关节刚度主要影响跳深动作离心阶段动作时间,而踝关节跖屈力矩和正功率主要影响跳深动作向心阶段动作时间,进而导致跳深动作完成时间和反应力量的差异;膝关节正功和踝关节正功率作为主要功率来源可调控跳深动作的腾空高度和力学功率输出.

Stable adhesion and comfort for long-term use are the main challenges currently limiting wearable in real-time health monitoring, especially in disturbed state such as exercise and sweating. Here, A biomimetic microneedles-based adhesive electrode is designed, which utilizes the mechanical locking of the microneedle array and the adhesion property of the mimic tree frog foot pad microstructures on the rough and wet substrate to synergistically enhance the stable adhesion performance of electrode on the skin surface. This adhesion-mechanical locking synergistic enhancement effect of the electrode through experiments is verified; the synergistic enhancement mechanism of the electrode is analyzed, and successfully electrocardiograph and electromyogram on human body skin is monitored. The electrode presented here provides a new path to solve the problem of stable signal acquisition under the condition of sweating and exercise, and realizing comfortable, low-noise, and continuous health monitoring.

目的:本文旨在探究改变急停起跳动作的助跑速度对排球运动员膝关节生物力学特征的影响,为排球项目中的下肢损伤机制以及损伤预防和康复工作提供科学依据.方法:使用8镜头Qualisys 500万像素的三维红外运动捕捉系统和两块Kistler三维测力台同步采集受试者在不同助跑速度下完成急停起跳动作时膝关节的运动学和动力学信号,采样频 率分别为200Hz和1000Hz.通过Qualisys Track Manager 2019.2和Visua13D软件收集、处理并获取了膝关节在矢状面、额状面和水平面的关节角度、关节力矩以及地面反作用力.结果:慢速助跑下膝关节伸展峰值角度、膝关节内旋峰值角度显著小于中速和快速助跑(P＜0.05).助跑速度越快,膝关节伸展峰值力矩和水平制动力峰值越大(P＜0.05).女子排球运动员膝关节外翻峰值角度、膝关节内翻峰值力矩和水平制动力峰值显著大于男子排球运动员,而膝关节内翻峰值角度、膝关节屈曲峰值力矩显著小于男子排球运动员(P＜0.05).在快速助跑下,男子排球运动员的膝关节外翻峰值力矩显著小于慢速助跑,且垂直地面反作用力峰值显著大于慢速和中速助跑(P＜0.05).结论:①随着助跑速度的增加,排球运动员膝关节损伤的风险也随之增加;②急停起跳时,女子排球运动员较男子排球运动员有更高的膝关节损伤风险.

等长大腿中部拉(Isometric Mid-thigh Pull,IMTP)是一种多关节等长测试,常用于评价运动员的下肢力量和爆发力水平.近年来,随着测试设备的便携化,IMTP测试在国际竞技体育领域的广泛应用.对国外相关文献的梳理与总结表明,IMTP测试相较于传统动态测试与单关节等长测试有着简单高效且不易疲劳的特点,通过分析IMTP测试力——时间曲线得到的峰值力、发力率和冲量等指标信度较高,并与力量、爆发力、冲刺与变向等动态运动能力之间呈中度至高度相关关系.教练员和科研人员可以通过IMTP测试评价运动员的运动能力并监控其训练过程,准确掌握运动员的身体状态和对训练刺激的适应程度,并据此优化训练方案以进一步提升运动员的运动能力.

The adaptation of neural contractile properties has been observed in previous work. However, the neural changes on the motor unit (MU) level remain largely unknown. Voluntary movements are controlled through the precise activation of MU populations. In this work, we estimate the neural inputs from the spinal motor neurons to the muscles during isometric contractions and characterize the neural adaptation during training by comparing the MU properties decomposed from sprinters and nonathletes. Twenty subjects were recruited and divided into two groups. The high-density surface electromyography (EMG) signals were recorded from the lateralis vastus muscle during the isometric contraction of knee extension and were then decomposed into MU spike trains. Each MU's action potentials and discharge properties were extracted for comparison across subject groups and tasks. A total of 1097 MUs were identified from all subjects. Results showed that the discharge rates and amplitudes of MUAPs from athletes were significantly higher than those from nonathletes. These results demonstrate the neural adaptations in physical training at the MU population level and indicate the great potential of EMG decomposition in physiological investigations.

为通过科学调控运动训练来实现对运动损伤的有效控制,对运动负荷与损伤风险间关系的研究成为近些年体育科学领域的热点之一.长期训练使机体发生定向改造以适应专项特征,运动负荷刺激机能水平提高的同时也会使运动员发生损伤的风险产生变化,运动负荷与损伤风险具有一定的相关性.在绝对负荷中,负荷累积与损伤风险表现出剂量-效应关系;在相对负荷中,负荷变化对损伤风险具有一定的预测能力.为了降低损伤风险,在训练安排时应避免长时间使用较低水平负荷或使用极高水平负荷,以及避免负荷的过快增长.

目的 通过对文献资料进行系统地检索和分析,系统分析头低位卧床期间抗阻训练对下肢肌肉萎缩的改善效果的研究进展.方法 在Web of Science、EBSCO、Pubmed、EMBASE等数据库中检索英文文献,在中国知网和万方数据库中搜索中文文献共870篇,另手动检索文献1篇,受试者共计290名.根据纳入标准筛选后剔除文献852篇,共筛选出18篇文献纳入最终meta分析.结果 以Ⅰ型纤维为主的肌肉在头低位卧床过程中萎缩程度较大,协同肌的萎缩虽具有相关性但也存在差异,激活程度较高肌肉萎缩程度较大,单关节肌肉比双关节肌肉萎缩程度大,抗阻训练显著改善伸膝肌群横截面积(P=0.006)、跖屈肌群横截面积(P=0.007)、屈膝肌群体积(P=0.001)、伸膝肌群体积(P＜0.001)和跖屈肌群体积(P=0.006);未显著改善屈膝肌群横截面积(P=0.170)、背屈肌群横截面积(P=0.410)、背屈肌群体积(P=0.160).结论 卧床期间抗阻运动不能避免下肢肌肉的萎缩,但对部分下肢肌肉萎缩情况有显著改善.目前的训练应注意增加抗阻训练的重复次数,以改善Ⅰ型纤维为主的肌肉,另外还需要对协同肌中各部分肌肉进行孤立的抗阻训练以改善协同肌萎缩的差异.现有的训练方案仍缺乏胭绳肌和胫前肌针对性训练,还需要设计更丰富的抗阻训练动作.

[目的]探究青少年男子篮球运动员体成分与力量、爆发力、速度之间的关系.[方法]对13名专业青少年男子篮球运动员进行体成分、30m冲刺、CMJ、深蹲最大重量、卧推最大重量等测试,采用Pearson相关系数检验体成分与各体能指标的相关性.[结果]青少年男子篮球运动员体脂率与卧推最大重量(P=0.009)、30m跑时间呈正相关(P=0.003),与深蹲体重比呈负相关(P=0.005);瘦体重与垂直纵跳(P=0.040)、深蹲体重比(P=0.001)、卧推体重比呈负相关(P=0.026),与30m跑时间呈正相关(P=0.027);肌肉比例与30m跑时间(P=0.008)、卧推最大重量(P=0.010)呈负相关,与深蹲体重比呈正相关(P=0.015).[结论]青少年男子篮球运动员体脂率、瘦体重与直线速度和上肢最大力量呈正相关,与下肢相对力量呈负相关;瘦体重与下肢爆发力和上肢相对力量呈负相关;肌肉比例与直线速度、上肢最大力量呈负相关,与下肢相对力量呈正相关.

本文旨在研究青年篮球运动员变向能力与直线速度、力量和爆发力之间的相关性以及性别差异.方法:本研究对31名青年篮球运动员(男子17名,女子14名)进行传统5-0-5变向测试和20 m冲刺、深蹲最大力量、垂直纵跳、助跑摸高等测试,并计算变向赤字.结果:男子篮球运动员变向赤字占比显著高于女子篮球运动员;男子、女子篮球运动员5-0-5测试时间与变向赤字均呈正相关;男子篮球运动员5-0-5测试时间、变向赤字与体重呈正相关,与深蹲体重比、垂直纵跳及助跑摸高净高度呈负相关;女子篮球运动员5-0-5左侧测试时间与垂直纵跳及助跑摸高净高度呈负相关,5-0-5左侧变向赤字与助跑摸高净高度呈负相关.结论:青年男子篮球运动员变向能力与体重呈正相关,与下肢相对力量、下肢爆发力呈负相关,而青年女子篮球运动员变向能力仅与下肢爆发力呈负相关,且呈现出左右侧肢体差异.此外,对于青年男子篮球运动员来说,仅用5-0-5测试可能无法准确评价其变向能力,推荐使用变向赤字作为其变向能力的评价方法;对青年女子篮球运动员来说,5-0-5测试与变向赤字均可以作为其变向能力的评价方法.

Content: Distance running is one of the most popular physical activities, and running-related injuries (RRIs) are also common. Foot strike patterns have been suggested to affect biomechanical variables related to RRI risks. Objective: To determine the effects of foot strike techniques on running biomechanics. Data Sources: The databases of Web of Science, PubMed, EMBASE, and EBSCO were searched from database inception through November 2018. Study Selection: The initial electronic search found 723 studies. Of these, 26 studies with a total of 472 participants were eligible for inclusion in this meta-analysis. Study Design: Systematic review and meta-analysis. Level of Evidence: Level 4. Data Extraction: Means, standard deviations, and sample sizes were extracted from the eligible studies, and the standard mean differences (SMDs) were obtained for biomechanical variables between forefoot strike (FFS) and rearfoot strike (RFS) groups using a random-effects model. Results: FFS showed significantly smaller magnitude (SMD, −1.84; 95% CI, −2.29 to −1.38; P < 0.001) and loading rate (mean: SMD, −2.1; 95% CI, −3.18 to −1.01; P < 0.001; peak: SMD, −1.77; 95% CI, −2.21 to −1.33; P < 0.001) of impact force, ankle stiffness (SMD, −1.69; 95% CI, −2.46 to −0.92; P < 0.001), knee extension moment (SMD, −0.64; 95% CI, −0.98 to −0.3; P < 0.001), knee eccentric power (SMD, −2.03; 95% CI, −2.51 to −1.54; P < 0.001), knee negative work (SMD, −1.56; 95% CI, −2.11 to −1.00; P < 0.001), and patellofemoral joint stress (peak: SMD, −0.71; 95% CI, −1.28 to −0.14; P = 0.01; integral: SMD, −0.63; 95% CI, −1.11 to −0.15; P = 0.01) compared with RFS. However, FFS significantly increased ankle plantarflexion moment (SMD, 1.31; 95% CI, 0.66 to 1.96; P < 0.001), eccentric power (SMD, 1.63; 95% CI, 1.18 to 2.08;P < 0.001), negative work (SMD, 2.60; 95% CI, 1.02 to 4.18; P = 0.001), and axial contact force (SMD, 1.26; 95% CI, 0.93 to 1.6; P < 0.001) compared with RFS. Conclusion: Running with RFS imposed higher biomechanical loads on overall ground impact and knee and patellofemoral joints, whereas FFS imposed higher biomechanical loads on the ankle joint and Achilles tendon. The modification of strike techniques may affect the specific biomechanical loads experienced on relevant structures or tissues during running.

等长大腿中部拉(Isometric Mid-thigh Pull,IMTP)测试近年来在国际竞技体育的应用越发广泛.通过分析IMTP测试力-时间曲线得到的峰值力、发力率和冲量等指标具有较高的信度,并与力量、爆发力、冲刺和变向等动态运动表现之间呈中度至高度相关关系.然而,相关研究中模棱两可或相互矛盾的研究结果在一定程度上影响了IMTP测试的应用.对国外相关文献的梳理与总结表明,采样频率、身体姿势、语言提示、基线测量、信号处理、力-时间曲线分析等方法学因素均会影响IMTP测试和分析过程,进而影响测试的准确性和研究的可重复性.因此,在进行IMTP测试时应选择信效度较高的测试方法,并在研究中报道所使用的具体方法以确保后续研究的可重复性.此外,对于一些具有争议的方法学因素仍需进一步研究加以证实,为更准确地评估与监控运动员并提高其运动成绩奠定基础.

目的:检查落地高度对高水平短跑运动员跳深动作下肢生物力学和反应性力量的影响并进一步确定下肢生物力学指标与反应性力量指标之间的关联性以及跳深动作的最佳负荷高度.方法:14名男子高水平短跑运动员参与四种落地高度下(0.15m、0.30m、0.45m和0.60m)的跳深动作测试.6台红外高速摄像机和2块三维测力台同步采集跳深动作的运动学和地面反作用力信号.结果:落地高度显著影响跳深动作的碰撞力和蹬伸阶段的垂直地面反作用力峰值(p=0.000和0.039),髋关节伸力矩(p=0.038)、踝关节跖屈力矩(p=0.030)和下肢支撑力矩(p=0.010),髋、膝和踝关节离心功率(p均为0.000),平均功率输出(p=0.009),反应力量指数(p=0.006)和反应力量比(p=0.029);落地高度与平均功率输出显著相关,最佳负荷高度为0.465m(R2=0.117,p=0.037);蹬伸阶段的垂直地面反作用力峰值(r=0.816,声=0.000;r=0.927,p=0.000)和平均功率输出(r=0.961,p=0.000;r=0.770,p=0.000)与反应力量指数和反应力量比均显著相关.结论:落地高度显著影响跳深动作的下肢生物力学和反应性力量指标,蹬伸阶段垂直地面反作用力和平均功率输出与反应性力量指标均存在非常显著的相关性,在0.15m～0.60m的落地高度范围内存在实现跳深动作最大平均力学功率输出的最佳负荷高度.建议针对高水平短跑运动员跳深训练时应该根据个体运动员的最大平均功率输出、反应力量指数和反应力量比等指标确定最佳负荷高度,以实现最佳训练效果并预防运动损伤.

目的:比较不同助跑条件下男、女性运动员在45°急停变向动作中膝、踝关节肌肉激活特征的差异性并进一步分析预激活和后激活阶段膝、踝关节肌肉共激活比之间的相关性.方法:46名青年篮球和排球运动员分别以3、4和5 m/s的助跑速度完成45°急停变向动作.采用Delsys无线表面肌电仪收集股四头肌(股直肌、股外侧肌、股内侧肌)、腘绳肌(半腱肌、股二头肌长头和短头)、胫骨前肌以及腓肠肌外侧头的肌电信号.分析3种助跑速度条件下预激活和后激活阶段膝、踝关节肌肉的标准化均方根振幅以及肌肉共激活比.结果:助跑速度显著增加预激活阶段股四头肌和腓肠肌外侧头的激活水平(P<0.05),后激活阶段股四头肌、腘绳肌、胫骨前肌和腓肠肌外侧头的激活水平(P<0.05),但显著降低预激活阶段膝、踝关节肌肉共激活比(P<0.05).女性运动员预激活和后激活阶段股四头肌和胫骨前肌的激活水平显著高于男性运动员(P<0.05),但预激活和后激活阶段膝关节肌肉共激活比显著低于男性运动员(P<0.05).膝、踝关节预激活和后激活阶段的肌肉共激活比显著相关(P<0.05).结论:随助跑速度的提高,中枢神经系统通过调节预激活和后激活机制来提高肌肉激活水平.预激活和后激活机制之间在45°急停变向动作中存在较高关联性,这提示,通过协调预激活和后激活策略能够调节肌肉和关节的刚度以达到保护下肢关节和组织并提高运动表现的目的.后激活阶段更低的膝关节肌肉共激活比以及股四头肌为主导的激活模式提示,女性运动员在完成45°急停变向动作时具有更高的ACL损伤风险.膝关节肌肉激活模式的性别差异性可能在一定程度上解释ACL损伤风险的性别差异性.

It was reported that the risks of non-contact anterior cruciate ligament (ACL) injury in female basketball athletes are significantly higher than that of male basketball athletes. However, the neuromuscular control mechanisms of gender differences in risk of ACL injury for side step cutting task are still not clear. In this study, muscle synergy analysis was used to explain the different neuromuscular control strategies between male and female basketball athletes in the 45° side step cutting task. In the experiment, electromyogram (EMG) data were recorded from 11 muscles of a dominant leg for each subject. The preliminary results showed that the female athletes exhibit lower hamstring activation and higher quadriceps activation during the 45° side step cutting task than that of male athletes. These differences may explain, to some extent, the gender disparity of anterior cruciate ligament injury rate.

[方法]运用二维定点拍摄方法对11名高水平皮艇运动员200米划起航、途中和冲刺阶段桨和艇的运动学参数进行采集和分析.[结果]起航、途中和冲刺阶段,拉水、抓水和回桨阶段之间的平均艇速均存在显著性差异,拉水阶段的桨距显著大于其它阶段.起航阶段的桨频显著高于途中和冲刺阶段,起航、途中和冲刺阶段的平均艇速和最大艇速参数之间均存在显著差异.桨频和平均艇速之间存在显著性正相关关系,桨频和桨距之间存在显著性负相关关系.[结论]一个拉桨周期内运动员通过提高抓水时间产生较高的艇速,拉水阶段较高的桨距表明艇在这一阶段的推进效果最佳.起航阶段运动员通过高桨频输出将艇速提高到最大以获得一定的领先位置;而在不同阶段运动员通过调整桨频和艇速以实现相对较稳定的桨距.

目的:探究不同助跑速度下45°变向动作中男、女运动员下肢生物力学参数的变化情况.方法:运用三维红外高速摄像机和测力台对26名篮球运动员在不同助跑速度下45°变向动作中下肢生物力学运动学和动力学信号进行采集.运用Visual-3D分析软件对采集的信号进行处理并计算相关生物力学参数.结果:男、女运动员在快速助跑下足与地面接触时刻的膝关节外展角显著大于低速助跑(p＜0.05).快速助跑下男子运动员的最大膝关节外展角显著增加(p＜0.05).助跑速度显著影响男、女运动员的垂直地面反作用力、膝关节屈力矩和外展力矩参数(p＜0.05).女子运动员在膝关节屈角和最大膝关节外展角参数方面与男子运动员存在显著性差异(p＜0.05).快速助跑时女子运动员的垂直地面反作用力和膝关节屈力矩峰值均显著高于男子运动员(p＜0.05).中速助跑时,女子运动员的垂直地面反作用力峰值参数显著大于男子运动员(p＜0.05).结论:不同助跑速度对45°变向动作中男、女运动员部分下肢生物力学参数具有显著性影响.另外,同一助跑速度下部分下肢生物力学负荷参数也存在明显的性别差异性.