Different visual stimuli affect muscle activation at the knee during sidestepping

Increasing knee stability via appropriate muscle activation could reduce anterior cruciate ligament (ACL) injury risk during unplanned sidestepping. High-level athletes may activate their knee muscles differently from low-level athletes when responding to quasi-game realistic versus non game-realistic stimuli. Eleven high-level and 10 low-level soccer players responded to a non game-realistic arrow-planned condition (AP), a quasi game-realistic one-defender scenario (1DS) and two-defender scenario (2DS), and an arrow-unplanned condition (AUNP), that imposed increasing time constraints to sidestep. Activation from eight knee muscles during sidestepping was measured during pre-contact and weight-acceptance. Knee flexor-extensor co-activation ratios were established. Muscle activation levels increased by approximately 27% solely in the 1DS in both sidestepping phases. In the 2DS, the shift from a flexor dominant co-activation strategy in pre-contact toward extensor dominance in weight-acceptance commenced earlier for the high-level players. Quasi game-realistic information allowed for anticipatory increases in knee muscle activation regardless of expertise levels but only when the time demands to respond were low (1DS). High-level players were better at interpreting complex game-realistic information (2DS) to activate their knee extensors earlier in preparation for single-leg landing during weight-acceptance.     

优秀散打运动员下肢关节等速肌力特征研究

运用IsoMed2000型肌力测试系统，选择60°/s和240°/s，对23名优秀男子散打运动员（健将级9名为A组，国家一级14名为B组）支撑腿和进攻腿髋、膝、踝屈伸肌群各项等速肌力指标进行测量。探讨优秀散打运动员支撑腿和进攻腿髋、膝、踝关节等速肌力特征，分析两腿的肌力差异，判断肌力平衡、关节稳定，运动员等级水平对肌力的影响。结果：国家健将级散打运动员双侧下肢髋、膝、踝关节等速肌力及稳定性显著优于国家一级运动员，支撑腿主要体现力的有效传递及稳定性，进攻腿主要体现屈伸肌力大小。     

Biomechanical characterization of the Junzuki karate punch: indexes of performance

The aims of this study were: (i) to determine kinematic, kinetic, and electromyographic characteristics of Junzuki karate punch in professional karate athletes; (ii) to identify biomechanical parameters that correlate with punch force and lead to a higher punching performance; (iii) to verify the presence of muscle co-activation in the upper limb, trunk, and lower limb muscles. Data were collected from nine experienced karatekas from the Accademia Italiana Karate e Arti Marziali during the execution of the specific punch. Mean punch forces (181.2?N) delivered to the target, the range of motion of both right and left knees (1.13 and 0.82?rad) and right elbow (1.49?rad) joints, and the angles at impact (knee: 0.81 and 0.91?rad; elbow: 1.19?rad) in the sagittal plane were computed. Furthermore, the trunk rotational angular acceleration (63.1?rad^?s^?2), force related to the lower limbs (550.2 and 425.1?N), and co-activation index for the upper limb (36.1% and 34.7%), trunk (24.5% and 16%), and lower limbs (16.0% and 16.1%) muscles were evaluated bilaterally. Significant positive correlations were found between the punch force and both right and left knee flexion at the instant of impact and right and left leg force. Significant negative correlation was found between the punch force and maximum trunk angular acceleration. Significant differences (p?=?.03) in the co-activation index among the upper limb, trunk, and lower limbs muscles highlighted a rostro-caudal gradient on both body sides. This research could be of use to performers and coaches when considering training preparations.     

高水平女子散打运动员不同赛前时期膝关节屈伸肌等动力量变化研究

为了解我国高水平女子散打运动员不同赛前时期膝关节屈伸肌等动力量的水平与特征,选择上海体育学院女子散打运动员19名作为研究对象,选取整个赛前集训中一个周期的训练作为训练周期,按经典分期理论进行训练分期。等速肌力的测试采用CONTREX等动测试系统,以向心和离心60°/s的恒定角速度下进行右膝关节测试,同时测试0.2s快速屈伸时的最大伸肌力矩。研究结果:优秀女子散打运动员屈肌相对峰力矩值是(1.13±0.15)Nm/kg,伸肌相对峰力矩值为(2.11±0.33)Nm/kg,屈伸肌力矩比值是(53.0±4.0)%,比赛期达到最高值。健将级女子散打运动员的0.2s最大相对屈肌力矩为(1.053±0.207)Nm/kg,伸肌相对最大力矩健将级为(1.795±0.295)Nm/kg。结论:运动员水平越高,膝关节屈肌力量越高,屈伸肌力矩比值越大,不同赛期屈肌力量不同,比赛期达到最高。     

优秀短跑、自行车、游泳运动员膝关节拮抗肌群工作特征

为了探讨运动员膝关节拮抗肌群在不同实验速度下的工作特点,通过CYBEX600等速测试系统,对辽宁省优秀短跑、自行车、游泳运动员25人(男14人、女11人)进行了等速相心膝关节肌力测试,经过统计对比分析结果如下:(1)膝关节屈伸肌相对峰力矩随着收缩速度的增加呈下降趋势,而且伸肌下降的幅度大于屈肌。(2)短跑运动员屈膝肌的相对力量较强,而自行车运动员有很强的伸膝力量。(3)膝关节肌肉达到预定速度所需的时间随着速度加快而加快,其中短跑自行车运动员蹬伸速度大于游泳运动员。(4)自行车运动员腿部的单位体重屈伸力量大于短跑游泳运动员,尤其在快速情况下,其差值高达82%。     

速滑运动员左右髋关节屈伸肌张力比较研究

采用CYBEX6000等速测力仪,对30名优秀的速滑运动员髋关节屈伸肌群峰值力矩、平均功率、总功输出及屈/伸肌比值(%)进行了比较与分析。结果表明:双髋关节屈伸肌峰值力矩、总功输出均随角速度增加而下降,平均功率则升高;同一速度区髋关节屈伸肌的峰值力矩、平均功率、总功伸肌大于屈肌;不同速度区伴有"优势交换"现象,即低速区左侧屈伸肌大于右侧,高速区则以右侧伸肌增强为主。速滑运动员髋关节屈/伸肌比值(%)随角速度增加而下降。     

不同项目女运动员膝关节屈伸肌群肌力特征的比较

利用等速测力技术探讨优秀女子手球、足球和自行车运动员膝关节屈伸肌群肌力特征。结果发现:不同类型的运动项目的运动员膝关节在运动中的作用明显不同,导致膝关节屈伸肌群的力量成分要求也有所不同。因此结合专项特点,合理发展专一性力量素质,才是提高专项力量素质和预防运动性伤病的关键。     

竞技舞龙运动员肩关节屈伸肌群等速肌力特征研究

采用文献资料法、专家访谈法、测试法、数理统计法,探讨和研究了舞龙运动员等速运动状态下肩关节屈伸肌群的力学特征以及肌力的相互关系。结果表明:舞龙运动员肩关节屈伸肌的峰值力矩和相对峰力矩随着测试角速度的增加而下降;且左侧肩关节屈伸肌的峰值力矩和相对峰力矩均大于另一侧;肩关节屈伸肌峰力矩和相对峰力矩值均表现为伸肌群明显大于屈肌群;肩关节伸肌的峰力矩均大于屈肌的峰力矩;伸肌群的平均功率也明显大于屈肌群的平均功率。     

青年女子柔道运动员等速肌力特征研究

运用等速测试方法分析青年女子柔道运动员的肌力特征,为针对性力量训练和伤病预防提供依据。研究发现:躯干相对峰力矩偏低,屈肌1.7,伸肌2.46。肩关节内外旋拮抗比0.7-0.9,左侧显著高于右侧。膝关节屈伸肌群拮抗比0.5-0.6,内外旋拮抗比0.6-0.8,双侧差异显著。踝关节屈伸肌群拮抗比0.4-0.5,内外旋拮抗比0.5-0.8,双侧差异显著。结果表明:青年女子柔道运动员的肩、膝、踝关节双侧差异和拮抗肌群肌力比率均为高损伤风险指征,提示青少年阶段就应当开始加强薄弱肌群的训练,提前降低受伤风险。     

Isometric training with maximal co-contraction instruction does not increase co-activation during exercises against external resistances

Abstract

The present investigation verified that strength is improved by a training programme consisting of repetitions of maximal isometric voluntary co-contractions without increasing co-activations during contractions against external resistances. Ten participants performed 12 training sessions (four sets of 6 × 4 second maximal isometric co-contraction of the elbow flexor and extensors, 3 days a week for 4 weeks). Surface electromyograms of triceps and biceps brachii were collected during maximal voluntary isometric elbow flexion and extension against a force transducer. Maximal voluntary isometric force increased significantly after training, by 13.8 ± 6.0% (extension) and 9.6 ± 9.5% (flexion), but the observed increases in EMG of agonist muscles during maximal voluntary contraction were not significant. No significant changes in the levels of co-activation of the elbow flexors and extensors were observed. No significant change was observed for all the parameters in a control group of ten participants. These results indicated that the strength improvements after co-contraction training occur without increases in co-activation level.     

优秀男子手枪运动员上肢关节屈伸肌群等速肌力测试研究

通过录像观察法、实验测试法,利用德国Isomed 2000等速力量测试系统对男子速射和男子慢射运动员右侧肩关节、肘关节、腕关节依次进行角速度为60°/s等速向心肌肉力量测试,选取屈肌肌群、伸肌肌群的相对峰力矩和相对峰值功率为指标,对手枪男子速射和慢射项目运动员的上肢肌肉力量进行了研究,比较分析了男子速射和男子慢射肩、肘、腕关节屈伸肌群的肌力特征。发现肘关节伸肌肌群、腕关节屈肌肌群分别为速射和慢射影响最大的关节肌群。     

我国优秀划艇运动员肩、肘关节肌力特征的比较研究

运用等速测试系统对备战伦敦奥运会的国家划艇运动员的肩关节、肘关节肌力进行测试与分析。结果表明:1)从力矩角度来看,优秀运动员与一般运动员在肩、肘关节肌力特征中存在显著性差异(P<0.05),且屈肌和伸肌的力矩角度分别呈现不同的特征;2)从峰力矩比值来看,在不同速度运动下,国家队优秀运动员和一般运动员均存在屈伸比的失衡问题,即最大力量上存在屈伸肌群发展的不合理化现象(<50%),随着测试速度的增加,屈伸比呈递减趋势;3)在肘关节两侧同名肌群的比较中同样存在不均衡现象,尤其是伸肌的两侧差值较大;4)肩关节的肌力特征也存在类似的现象,但屈肌明显不如伸肌力量。结论:应逐步加强划艇运动员肩、肘关节同侧屈伸肌群和异侧同名肌群的力量均衡性训练,并提高肩关节的屈肌力量能力。     

高水平武术运动员心理健康现状及影响因素

以参加全国运动会武术比赛的195名优秀运动员为调查对象,采用SCL-90问卷调查,发现优秀武术运动员各项因子分值大于3的仅占2％～9%;9个因子得分优秀男运动员低于优秀女运动员（P〈0．05）;C组（普通高校武术特长生）和B组（体工队退役队员）运动员对文化知识的迫切度高于A组（体工队现役队员）武术运动员。优秀武术运动员心理健康状况良好;运动员的心理健康状况与性别、文化层次有关,建议在训练中根据运动员性别进行心理调整,并不断提高运动员的文化水平,以创造优异的运动成绩。     

青年男子足球运动员膝关节肌力特征与损伤的关系

利用等速测力技术探讨青年足球运动员膝关节屈伸肌群肌力特征与损伤的关系。结果显示,无论慢速运动还是快速运动条件下,均表现出运动员膝关节优势侧与非优势侧屈伸肌力的显著差异性,膝关节屈伸峰力矩比值和平均功率比值随运动速度增加而增大的趋势。提示,以上结果符合青年足球运动员惯用腿踢球的运动习惯,是随着运动年限的延长容易发生膝关节及屈伸肌群损伤的重要原因,因此,我们推断早期注重膝关节前后及双侧肌力的均衡发展是预防足球运动中膝关节损伤的有效措施。     

Contribution of upper limb muscles to two different gripping styles in elite indoor tug of war athletes

To investigate characteristic upper limb muscle use between two common tug of war (TOW) gripping styles, 20 elite athletes from two high school TOW teams were recruited. Under conditioned attack pulling (with 90% maximal force) on a tug machine, participants used their own habitual gripping style to pull for five 15-s trials. Force and kinematic measurements showed a significantly better force performance and higher centre-of-gravity tilting angle with the gripping style one than with the gripping style two (GS2) (both p < 0.05). However, an overall higher and more symmetrical muscle activation detected by normalised surface electromyography signal amplitude was found in the GS2 group (both p < 0.05). In both groups, the distal and flexor muscles were more activated than the proximal and extensor muscles, respectively (p < 0.05). Higher co-contraction ratio was found in the wrist joints of the latter arm in both groups (p < 0.05). As higher muscle activation level and co-contraction indicate higher muscle and joint injury incidences, we suggest that gripping style factors should be considered in training to prevent muscle and joint injury. Future study concerning segmental kinematics, ground reaction force, moment arm and muscle endurance during the defence phase are warranted.     

加压力量训练对排球运动员下肢肌力影响的个例研究

目的探讨加压力量训练对排球运动员下肢肌肉力量的影响,为进一步优化增强下肢肌力方案、探索新的有效的训练方法提供依据。方法通过实验法,筛选身体健康,无下肢运动损伤及其它限制上下肢运动的疾病的专项排球运动员1人,对其下肢进行加压力量训练。使用Biodex System3.0等速测试系统测量他训练前后的伸髋肌群,屈髋肌群,伸膝肌群和屈膝肌群的最大肌力,比较训练前后肌力的变化,从而确定加压训练对排球运动员的下肢肌力的影响。结果经4周加压力量训练后,受试者下肢肌肉力量均明显增强。结论 4周加压力量训练对排球运动员下肢肌力有促进作用。     

跳远运动员髋关节振动力量训练效果的研究

对10 名跳远专项二级运动员进行振动力量训练。研究表明：在刺激频率为30~35Hz,加速度25~30 m/s2 条件下,经过8 周系统的振动力量 训练,试验组髋关节的屈伸肌群与对照组屈肌肌群最大功增长都非常明显,表现出髋关节屈肌最大功比试验前有显著性地提高,试验组髋关节 屈伸肌最大功增长幅度比对照组屈伸肌最大功幅度大。试验组髋关节伸肌对照组屈伸肌峰力矩前4 周比后4 周增长幅度大,后4 周增长幅度有 所减缓,试验组后4 周髋关节屈伸肌峰力矩增长幅度比对照组高。髋关节伸肌相对峰力矩力量增长幅度比屈肌要大。     

优秀攀岩运动员肘关节屈伸肌等速肌力测试研究

利用德国Isomed2000等速肌力测试系统对优秀攀岩运动员左右肘肘关节进行等速测试,探析攀岩运动员肘关节屈伸肌群的生物力学特征,为运动训练科学选材及康复提供理论依据。结果：优秀攀岩运动员屈伸峰力矩（PT）随测试速度的增大而减小,且屈伸峰力矩屈肌大于肘伸肌;最大功率随测试速度的增大而增加,左右侧做功无明显差异,表明两侧肌力平衡;屈或伸的向心/离心（ECC/CON）随给定运动速度的增加而增大,屈肌的向心/离心（ECC/CON）比值小于1.0。     

Isokinetic imbalance of hip muscles in soccer players with osteitis pubis

Abstract

In this study, we compared the isokinetic torques of hip flexors/extensors and abductors/adductors in soccer players suffering from osteitis pubis (OP), with normal soccer players. Twenty soccer male athletes with OP and 20 normal soccer athletes were included in this study. Peak torque/body weight (PT/BW) was recorded from hip flexor/extensor and abductor/adductor muscles during isokinetic concentric contraction modes at angular velocity of 2.1 rad · s^?1, for both groups. The results showed a significant difference between the normal and OP groups for hip flexors (P < 0.05). The normal group had significant, lower PT/BW value than the OP group for their hip flexors (P < 0.05). The hip flexor/extensor PT ratio of OP affected and non-affected limbs was significantly different from that of normal dominant and non-dominant limbs. There were no significant differences between the normal and OP groups for hip extensor, adductor and abductor muscles (P > 0.05). Regarding the hip adductor/abductor PT ratio, there was no significant difference between the normal and OP groups of athletes (P > 0.05). The OP group displayed increase in hip flexor strength that disturbed the hip flexor/extensor torque ratio of OP. Therefore, increasing the hip extensor strength should be part of rehabilitation programmes of patients with OP.     

大蒜素与联合抗氧化剂干预对运动员DOMS和CK-MM、CK等的影响

目的:探讨大蒜素与联合抗氧化剂干预对运动员大强度离心运动后不同时相肌肉酸痛程度、血CK-MM、CK、LDH活性的影响。方法:运动员24名,随机均衡分为实验对照组(A组)、联合抗氧化剂干预组(B组)和大蒜素干预组(C组),运动前2周至运动后2天每天分别口服安慰剂、联合抗氧化剂和大蒜素肠溶胶丸。服药两周后进行一次大强度离心跑台运动,建立运动员运动延迟性肌肉酸痛(DOMS)模型,在服药前、运动前和运动后即刻、运动后24h、运动后48h分别抽取各组运动员肘正中静脉血,测定CK-MM、CK、LDH活性及运动后相应时相肌肉酸痛程度。结果:三组运动员运动后肌肉酸痛程度均呈递增趋势,B、C组运动员运动后各时相肌肉酸痛程度与血CK-MM、CK、LDH活性均低于A组同时相。结论:大强度离心跑台运动可诱发运动员DOMS。大蒜素和联合抗氧化剂可减少运动员大强度离心运动后骨骼肌细胞内CK-MM、CK、LDH的大量逸出,对保护细胞膜完整性、降低运动应激程度、防治运动性骨骼肌微损伤有积极作用,可有效减轻运动员大强度运动后DOMS程度。