关节内损伤后膝关节屈伸肌群的等速向心训练

用Ｃｙｂｅｘ－６０００）型等速肌力测试系统对２０例膝关节内损伤后患者的股四头肌绳肌进行等速向心训练。结果表明：经过约５周的训练，患膝屈伸肌群的峰力矩、总作功量、平均功率和力矩加速能量均显著提高，但伸肌群较屈肌群进步慢，且出现屈伸肌群肌力失衡。等速向心训练对伤后肌肉功能恢复具有促进作用。伸肌群进步缓慢可能与损伤的内在性质有关，加强股四头肌训练对维持屈伸肌力平衡和膝关节稳定性具有重要意义。     

青年军人腰椎间盘突出症患者下肢肌力等速测试分析

采用ＣＹＢＥＸ６０００型等速测力系统,对腰椎间盘突出症引起单侧下肢受累的１９名男性青年军人患者,进行双下肢膝屈伸肌力的对照测试,结果表明：与健肢相比,患肢在６０°／ｓ速度测试时,腘绳肌和股四头肌肌力分别平均下降了４５％和３１％,在１８°／ｓ时分别下降了５７％与３５％。提示患肢屈肌力下降明显,治疗康复期内应加强腘绳肌群锻炼。     

前十字韧带损伤后股四头肌腘绳肌等速肌力评价(附5例报告)

用Ｃｙｂｅｘ－６０００型等速测力系统对５例前十字韧带（ＡＣＬ）损伤后患者股四头肌绳肌肌肉功能进行评价。结果表明：患膝屈伸肌群峰力矩在６０°／ｓ、１２０°／ｓ和１８０°／ｓ时均较健侧明显降低；在１８０°／ｓ时，股四头肌绳肌的总作动量、平均功率和力矩加速能量亦显著下降；绳肌股四头肌峰力矩比值（Ｈ／Ｑ）较健侧略有增高，但患者间差异较大。废用性肌肉萎缩、关节不稳及关节源性肌肉抑制可能是导致肌肉功能下降的重要原因。ＡＣＬ损伤后应强调患膝肌力训练，以增强关节稳定性，预防或延迟膝关节骨关节炎的发生；并把Ｈ／Ｑ作为肌力训练中一个评价和监测指标。     

膝关节损伤后期屈膝肌与伸膝肌力矩比值的远期评价研究

测试并评价膝关节损伤后期膝屈伸肌峰力矩、屈膝肌峰力矩／伸膝肌峰力矩比值（Hamstring／quadriceps,H／Q）,以便明确不同测试速度时的H／Q比值与膝关节损伤后期膝关节功能之间的关系。应用Cybex－330型等速肌力测试训练系统对41例单侧膝关节损伤后期病人的双侧膝屈伸肌进行等速肌力测试评定;采用Lysholm膝评定量表对患侧膝主观及临床功能情况进行评定。膝关节损伤后期膝屈伸肌峰力矩、单次最大做功量、平均功率及相应的W／Q比值在不同测试速度（60°s、180°s）时患膝与健膝之间差异不明显;患膝W／Q比值在低（＜50％）、最佳（50％～80％）、高（＞80％）时相应的膝评定量表得分之间的相差也不明显;然而,患膝与健膝比较,当H／Q比值相差（≤15％与＞15％）时的膝评定量表得分之间差异才有显著性（P＜0．01）。膝关节损伤后H／Q比值是一个不确定值,患膝与健膝H／Q比值之间的相差应在15％以内;膝关节损伤后康复训练应达到的最佳W／Q比值应该是对未受损伤的健侧膝的H／Q值。     

强化循环训练对新兵膝屈伸肌功能影响的等速测试研究

目的　研究强化循环训练对新兵膝屈伸肌功能的影响。方法　 16 0名新兵进行 8周强化循环训练 ,训练前后采用Cybex 6 0 0 0型等速运动测试仪对膝屈伸肌肌力、肌爆发力及肌耐力进行等速测试并加以比较。结果　新兵训练后双膝屈伸肌的峰力矩、力矩加速能和耐力比在不同测试速度 (6 0°/s,180°/s)时有不同程度的提高 ,训练前后相比差异有统计学意义 (P <0 0 5 )。结论　 8周的强化循环训练能达到全面发展新兵膝屈伸肌肌力、肌爆发力和肌耐力的目的。     

耐力速度复合训练对新兵膝屈伸肌功能影响的等速测试研究

为探讨耐力速度复合训练对新兵膝屈伸肌功能的影响，对20名新兵进行为期4周的耐力速度复合训练，训练前后采用Cybex-6000型等速运动测试仪对新兵的膝屈伸肌肌力、肌爆发力及肌耐力进行等速测试并加以比较。结果发现，新兵训练后左膝屈肌的PT、TAE和ER值在快速测试中有明显的提高（P＜0．05）；左膝伸肌的PT和ER值在快速测试中有明显的提高（P＜0．05）；右膝屈伸肌除屈肌的PT、TAE值在快速测试中有明显的提高外余检测指标无改变。提示为期4周的耐力速度复合训练可使部分膝屈伸肌产生适应，但不能达到全面发展新兵膝屈伸肌肌力、肌爆发力和肌耐力的目的。     

老年女性膝骨关节炎患者膝屈伸等速肌力及其与BMI的相关性研究

目的:探讨膝骨关节炎患者(KOA)膝关节屈伸等速肌力特点及其与BMI之间的相关性。方法:利用等动肌力测试系统测试47名老年女性(KOA组25名、对照组22名)的膝关节肌力。另外,通过计算两组受试者的BMI,考察该指标与膝关节屈伸肌力之间的相关性。结果:KOA组膝关节伸展绝对峰力矩显著小于对照组(P<0.05),屈伸相对峰力矩均显著小于对照组(P<0.05),而KOA组的相对峰力矩屈伸比显著大于对照组(P<0.05)。两组受试者BMI与膝关节屈伸相对峰力矩呈显著负相关(P<0.01)。结论:膝骨关节炎可降低老年女性膝关节伸肌肌力和屈肌肌力,且对伸肌肌力的影响更甚。并且可显著影响膝关节的稳定性。无论有无膝骨关节炎,随着BMI的增加,老年女性膝关节肌力均下降,且膝骨关节炎患者下降更加明显。     

膝关节屈肌和伸肌等速向心、等速离心及等长测试的研究

本文通过运用Ｃｙｂｅｘ－６０００型等速测力系统对２５名健康男青年膝屈肌和伸肌进行等速向心、等速离心及等长测试，来比较膝肌肉向心收缩、离心收缩和等长收缩的功能，并探讨其相互间的关系。结果表明：等速测试时，膝屈肌和伸肌离心收缩的肌力明显大于向心收缩。在膝屈曲６０°时，离心收缩和等长收缩的肌力同样明显大于向心收缩，但离心收缩与等长收缩相比无显著性差异。随运动速度增加，屈肌和伸肌向心收缩的肌力明显下降，而离心收缩的肌力无明显变化。     

躯干屈伸肌群等速肌力和耐力的初步研究

采用Ｃｙｂｅｘ－ＴＥＦ系统对４０例年轻人躯干屈伸肌群的肌力和耐力进行等速测试。结果表明：随着测试速度的增加,女性屈伸肌群和男性伸肌群的ＰＦ值逐渐降低,而男性屈肌群ＰＴ值随速度的变化不大。两性伸肌群的ＥＲ和女性的ＲＲ均低于屈肌群。本研究提供了一组正常年人的数据,对了解其躯干肌肉功能特点、指导运动训练及预防下腰痛和运动伤病具有参考意义。     

优秀击剑运动员下肢三关节等速肌力测试分析

目的:研究我国优秀击剑运动员下肢髋、膝、踝三关节肌群等速肌力表现,找出薄弱肌群。方法:国家击剑队备战2008年奥运会重点队员26名,男女各13名,年龄23.1±2.36岁。在60°/s、240°/s速度下测定运动员双侧下肢髋、膝、踝屈伸肌群等速向心峰力矩。结果发现:(1)髋关节:在240°/s下双侧伸肌峰力矩均明显低于60°/s(P<0.05),60°/s和240°/s下双侧髋关节屈肌峰力矩无显著差异(P>0.05);男运动员两个速度下前腿伸肌峰力矩均显著高于后腿(P<0.05),女运动员无显著差异(P>0.05);两个速度下,运动员双腿屈伸肌峰力矩比值低于正常。(2)膝关节:60°/s时男运动员双腿屈伸肌峰力矩有显著差异(P<0.05),240°/s时双侧伸肌峰力矩有显著差异(P<0.05),女运动员两个速度下均无显著差异(P>0.05);60°/s时,女运动员前后腿屈伸肌峰力矩比值分别为0.56和0.54,男运动员分别为0.63和0.67;240/°s时男女前后腿屈伸肌峰力矩比值均在正常范围。(3)踝关节:60°/s时男运动员前腿踝关节屈伸肌峰力矩显著大于后腿(P<0.05),240°/s时无显著差异(P>0.05);两个速度下,女运动员踝关节屈伸肌峰力矩均无显著性差异(P>0.05);运动员踝关节屈伸峰力矩比值在两个速度下均低于正常。结论:优秀男子击剑运动员下肢关节等速肌力双侧不对称,女运动员不对称表现不明显;击剑运动员下肢薄弱肌群为后腿髋关节伸肌群、股后肌群、前腿股后肌群及踝关节背伸肌群。     

Sex- and osteoarthritis-related differences in muscle co-activation during weight-bearing tasks

BackgroundIndividuals with knee osteoarthritis (OA) demonstrate impairments in muscle function (i.e. muscle weakness, high muscle co-activation believed to have detrimental effects on joint integrity). Women with knee OA exhibit poorer health outcomes than men. Sex and muscle function are known risk factors for knee OA. It is unclear how these risk factors are associated with muscle function in knee OA and the implications for disease aetiology.Research questionHow does sex and knee osteoarthritis disease status relate to muscle function, specifically strength and muscle co-activation, during walking, stair negotiation and sit-to-walk activities.MethodsA cross-sectional study assessed muscle co-activation in 77 individuals with knee OA (mean[SD], 62.5[8.1] years; 48/29 women/men) and 18 age-matched controls (62.5[10.4] years; 9/9 women/men), during a series of walking, stair ascent and descent and sit-to-walk activities. Muscle strength of the knee extensors and flexors was assessed using maximal voluntary isometric contractions (MVIC). Electromyography was recorded from the vastus lateralis/medalis, rectus femoris, biceps femoris, semitendinosus, medial/lateral gastrocnemius normalised to MVIC. Multiple regression assessed the relationship between sex, disease status, and muscle strength on muscle co-activation.ResultsIndividuals with knee OA were weaker than controls, had higher hamstrings-quadriceps and medial-lateral co-activation for specific phases of gait. Women were weaker than men with higher muscle co-activation across all activities. Sex and muscle weakness, but not age or disease status predicted high muscle co-activation.SignificanceHigh muscle co-activation was associated with female sex and muscle weakness regardless of disease status and age. High muscle co-activation is believed to be a compensatory mechanism for muscle weakness to maintain a certain level of function. High muscle co-activation is also thought to have detrimental effects on cartilage and joint integrity this may explain high muscle co-activation in women with muscle weakness and contribute to increased risk of incidence and progression of knee OA in women.     

Effects of long term Tai Chi practice and jogging exercise on muscle strength and endurance in older people

Objectives

To investigate the influence of regular Tai Chi (TC) practice and jogging on muscle strength and endurance in the lower extremities of older people.

Methods

Twenty one long term older TC practitioners were compared with 18 regular older joggers and 22 sedentary counterparts. Maximum concentric strength of knee flexors and extensors was tested at angular velocities of 30°/s and 120°/s. Ankle dorsiflexors and plantar flexors were tested at 30°/s and the dynamic endurance of the knee flexors and extensors was assessed at a speed of 180°/s.

Results

The differences in the muscle strength of the knee joint amongst the three experimental groups were significant at the higher velocity. The strengths of knee extensors and flexors in the control group were significantly lower than those in the jogging group and marginally lower than those in the TC group. For the ankle joint, the subjects in both the TC and jogging groups generated more torque in their ankle dorsiflexors. In addition, the muscle endurance of knee extensors was more pronounced in TC practitioners than in controls.

Conclusion

Regular older TC practitioners and joggers showed better scores than the sedentary controls on most muscle strength and endurance measures. However, the magnitude of the exercise effects on muscles might depend on the characteristics of different types of exercise.     

Does muscle inhibition after knee injury increase the risk of osteoarthritis?

Knee pathologies are commonly associated with muscle inhibition, an inability to fully activate the knee extensors during voluntary contractions. This inhibition results in knee extensor weakness, and is thought to limit the functional recovery of the knee joint structures. The possible contribution of persistent knee extensor inhibition to osteoarthritis is discussed.     

Muscle strength and size balances between reciprocal muscle groups in the thigh and lower leg for young men

The present study investigated whether the muscle size balance affects the muscle strength balance between reciprocal muscle groups in the thigh and lower leg. 18 young men volunteered as subjects. The joint torques developed during isometric maximal voluntary knee extension and flexion, plantar flexion and dorsiflexion were measured using a dynamometer. The muscle volumes of knee extensors and flexors, plantar flexors and dorsiflexors were determined by magnetic resonance imaging. For each of the muscle groups, the joint torque was significantly correlated with the muscle volume (r=0.644-0.847) and the y-intercept of the regression line between them was not significantly different from zero. Based on these observations, the dependencies of muscle strength balance on muscle size balance between the knee extensors and flexors and between the plantar flexors and dorsiflexors were investigated using the joint torque and muscle volume. The correlation between muscle volume ratio and joint torque ratio was significant between the plantar flexors and dorsiflexors (r=0.622) but not between the knee extensors and flexors (r=0.128). Thus, it is suggested that the strength balance is strongly affected by the size balance between the reciprocal muscle groups in the lower leg but not in the thigh.     

Velocity‐specific and time‐dependent adaptations following a standardized Nordic Hamstring Exercise training

The Nordic Hamstring Exercise (NHE ) is effective for selective hamstring strengthening to improve muscle balance between knee flexors and extensors. The purpose of this study (within subject design of repeated measures) was to determine the effects of a standardized 4‐week NHE training on thigh strength and muscle balance with concomitant kinetic and kinematic monitoring. Sixteen male sprinters (22 years, 181 cm, 76 kg) performed a standardized 4‐week NHE training consisting of three sessions per week (each 3×3 repetitions). Six rope‐assisted and six unassisted sessions were performed targeting at a constant knee extension angular velocity of ~15°/s across a ~90‐100° knee joint range of motion. Kinetic (peak and mean moment, impulse) and kinematic parameters (eg, ROM to downward acceleration, ROM_DWA ) were recorded during selected sessions. Unilateral isokinetic tests of concentric and eccentric knee flexors and extensors quantified muscle group‐, contraction mode‐, and velocity‐specific training adaptations. Peak moments and contractional work demonstrated strong interactions of time with muscle group, contraction modes, and angular velocities (η²>.150). NHE training increased eccentric hamstring strength by 6%‐14% as well as thigh muscle balance with biggest adaptations at 150°/s 2 weeks after NHE training. Throughout the training period significant increases (P <.001) of peak (η²=.828) and mean moments (η²=.611) became apparent, whereas the impulse and the ROM_DWA of unassisted NHE repetitions remained unchanged (P >.05). A 4‐week NHE training significantly strengthened the hamstrings and improved muscle balance between knee flexors and extensors. Despite the slow training velocity, biggest adaptations emerged at the highest velocity 2 weeks after training ended.     

Effects of aquatic resistance training on neuromuscular performance in healthy women

PURPOSE: The purpose of this study was to investigate the effects of a progressive 10-wk aquatic resistance training on neuromuscular performance and muscle mass of the knee extensors and flexors in healthy women. METHODS: Twenty-four healthy women (34.2 +/- 3.9 yr) were randomly assigned into aquatic exercise (N = 12) and control group (N = 12). Maximum knee extension and flexion torques were measured isometrically and at constant angular velocities of 60 degrees x s(-1) and 180 degrees x s(-1) (isokinetic) with simultaneous electromyography (EMG) recordings of the quadriceps and hamstrings. The lean muscle mass (LCSA) of the quadriceps and hamstring muscles was determined by computed tomography scanning. RESULTS: Significant interaction of group by time was observed in each of the measured parameters. The change in extension and flexion isometric/isokinetic torque varied between 8 and 13% and in EMGs between 10 and 27% in the exercise group. The change in the quadriceps LCSA of the exercise group was 4% and in hamstrings 5.5%. CONCLUSIONS: The results of the present study showed that 10 wk of progressive aquatic resistance training resulted in significant improvement in muscle torque of the knee extensors and flexors accompanied with proportional improvement in neural activation and with significant increase in the LCSA of the trained muscles. Aquatic training can be recommended for neuromuscular conditioning in healthy persons.     

Gains in flexibility related to measures of muscular performance: impact of flexibility on muscular performance.

OBJECTIVE: Studies that investigated possible correlations between flexibility and muscular performance are scarce in the literature. Therefore, the purpose of this study was to investigate the impact of a program of static stretching on the flexibility of the hamstrings and on muscular performance of the knee flexors and extensors. DESIGN: Pre-post experimental design. SETTING: University laboratory. PARTICIPANTS: Thirty subjects aged 22.8 +/- 4.9 years with bilaterally shortened hamstrings. INTERVENTION: Using a protocol that has been previously described, the intervention consisted of 30 sessions of static stretching, performed bilaterally five times a week for 6 weeks. MAIN OUTCOME MEASUREMENTS: Measures of knee range of motion and isokinetic muscular performance (peak torque, angle of peak torque, and work) of knee flexors and extensors at speeds of 60 and 300 degrees/s. RESULTS: After intervention, significant gains in measures of flexibility (P < 0.0001) were observed, with an average gain of the knee-extension angle of 12.6 degrees, ranging from -1.2 to 30.7 degrees. In addition, we found significant increases in the following parameters of muscular performance: angle of peak torque of hamstrings at 60 and 300 degrees/s (P < 0.0001 and 0.018) and for work at 60 and 300 degrees/s for knee flexors (P = 0.012 and 0.005) and for knee extensors (P < 0.0001). CONCLUSIONS: The intervention resulted in gains in measures of flexibility, and these gains had a positive impact on some parameters of muscular performance.     

Effects and mechanisms of strength training in children

It has been demonstrated that strength training can be organized in children in a safe and effective way. However, there is limited data regarding its impact on muscle hypertrophy. This study investigated the effects of a high-intensity strength training (HIS) on knee extensor/flexor strength, countermovement (CMJ) jumping height, postural control, soft lean mass and muscle cross-sectional area (CSA) of the dominant leg in prepubertal children. Thirty-two children participated in this study and were assigned to an intervention (INT; N=17) or a control class ( N=15). The INT participated in 10 weeks of weight-machine based HIS integrated in physical education. Pre/post tests included the measurements of peak torque of the knee extensors/flexors at 60 and 180°/s, CMJ jumping height, postural sway, soft lean mass of the leg by bioelectrical impedance analysis, and CSA (m. quadriceps) by magnetic resonance imaging. HIS resulted in significant increases in knee extensor/flexor peak torque (60°/s and 180°/s). HIS did not produce significant changes in CMJ jumping height, postural sway, soft lean mass, and CSA. Although HIS was effective at increasing peak torque of the knee extensors/flexors in children, it was unable to affect muscle size. It appears that neural factors rather than muscle hypertrophy account for the observed strength gains in children.