机械性踝关节不稳患者踝屈、伸肌群等速肌力评价

目的:评价机械性踝关节不稳(mechanical ankle instability,MAI)患者踝屈、伸肌群的等速肌力。方法:20名单侧机械性踝关节不稳患者的双侧踝关节分别接受等速肌力测试(60°/s和120°/s)。比较患侧和健侧踝关节屈、伸肌群相对峰力矩、平均功率、总功和屈伸力矩比的差异。结果:60°/s时,两侧伸肌群相对峰力矩、平均功率及总功的差别均无统计学意义(P=0.303,P=0.548,P=0.452),屈肌群相对峰力矩、平均功率和屈伸力矩比均无显著性差异(P=0.417,P=0.275,P=0.870),但屈肌群总功有显著性差异(P=0.043)。120°/s时,两侧伸肌群相对峰力矩、平均功率及总功差别均无统计学意义(P=0.096,P=0.069,P=0.233),但屈肌群相对峰力矩、平均功率、总功和屈伸力矩比有显著性差异(P=0.030,P=0.043,P=0.017,P=0.036)。结论:机械性踝关节不稳患者患侧踝关节跖屈肌群快速运动时肌力下降,这可能与其踝关节稳定性有关。     

中国女子篮球运动员膝关节等速肌力测试分析

目的:了解中国国家女子篮球队运动员膝关节等速肌力特征。方法:选用IsoMed 2000等速测试系统,采用60°/s、180°/s、240°/s三种角速度,测试18名中国女篮国家队运动员膝关节等速肌力。根据场上位置将运动员分为三组:后卫组7人(1、2号位),前锋组6人(3、4号位),中锋组5人(5号位),比较分析三组运动员的测试结果。结果:(1)女篮运动员双侧膝关节慢速测试时(60°/s)屈伸肌峰力矩(PT)显著高于快速测试(180°/s,240°/s),膝关节屈伸肌峰力矩比值(H/Q)随测试速度增加递增,左右膝H/Q无显著性差异。(2)慢速测试时(60°/s),左右膝关节峰力矩、峰力矩/体重比值、平均功率、H/Q无显著差异。(3)快速测试(240°/s)时,左膝屈肌PT、峰力矩/体重比值(PT/BW)显著高于右膝。180°/s测试时,左膝屈肌平均功率显著高于右膝。(4)60°/s测试时,后卫、前锋、中锋运动员PT、PT/BW组间比较无显著性差别。180°/s测试时,后卫运动员左膝屈肌PT与前锋、中锋运动员比较有显著性差异(P=0.02),各组间伸肌PT未见显著差异。240°/s测试时,后卫运动员右膝屈、伸肌PT/BW和中锋运动员比较均存在显著差异;后卫、前锋、中锋三组运动员平均功率、H/Q、总功与峰值功率组间比较均无显著性差别。结论:(1)女篮运动员快速测试(240°/s)时左膝屈肌力量强于右膝,反映快速运动时左右膝关节肌力不平衡。(2)不同场上位置女篮运动员膝关节等速肌力快速测试结果有差异性,提示力量训练应根据场上位置进行特异性训练。(3)女篮运动员需加强屈肌快速力量训练,以提高H/Q,预防膝关节损伤。     

不同级别男子跳高运动员髋关节屈伸峰力矩测试分析

目的:分析比较不同级别男子跳高运动员髋关节屈伸肌群向心收缩时峰力矩特点及差异。方法:采用德国ISOMED2000等速测试仪,对8名一级男子跳高运动员和8名二级男子跳高运动员髋关节肌群进行等速向心收缩测试,测试角速度120°/s,指标包括峰力矩、相对峰力矩(峰力矩/体重)、峰力矩出现角度。结果:一级跳高运动员摆动腿屈肌峰力矩和相对峰力矩显著大于二级运动员(P<0.01),起跳腿伸肌峰力矩和相对峰力矩显著大于二级运动员(P<0.05,P<0.01);一、二级运动员髋关节屈、伸肌群最大峰力矩时的角度均在85度左右。结果表明:一级运动员摆动腿向上摆腿力量和起跳腿伸髋力量大于二级运动员。     

我国优秀女子铅球运动员投掷臂三关节等速肌力特征

目的:通过对我国优秀女子铅球运动员投掷臂关节等速肌力参数进行运动生物力学测试和分析,揭示不同训练水平女子铅球运动员的上肢力量特征,通过统计对比发现其力量素质中的差距和不足,为今后女子铅球项目的专项力量训练和同类研究提供理论参考。方法:采用ISO-MED2000等速测试系统测试获取4名我国最高水平女子铅球运动员投掷臂三关节60°/s和240°/s时向心等速运动屈、伸肌群峰力矩、相对峰力矩、屈伸肌峰力矩比、平均功率等参数,结合专项技术进行分析。结果:(1)国际健将组肩关节屈肌群峰力矩、相对峰力矩在240°/s时显著大于健将组(P<0.05),屈伸肌峰力矩比健将组由60°/s时1.02降至240°/s时0.44,下降显著(P<0.01),快速屈曲能力不足;(2)国际健将组肘关节伸肌不同速度下适应性和做功效率较健将组强,屈伸肌峰力矩比由60°/s时的1.50降至240°/s时的0.74;(3)国际健将组腕关节屈肌群峰力矩、相对峰力矩随速度的加快下降显著(P<0.05),屈伸肌峰力矩比两组在60°/s时分别为1.90和1.78并降至240°/s的1.09和0.53,健将组下降显著(P<0.05)。结论:在投掷臂三关节肌肉力量特征上,女子铅球项目国际健将在肩、肘、腕三关节屈伸力矩和功率综合分析均优于健将运动员,证明了强大的投掷臂三关节肌力是女子铅球项目取得优异成绩的根本保证。     

慢性创伤性肩关节前方不稳定的等速肌力研究

目的:探讨慢性创伤性肩关节前方不稳定(Chronic Traumatic Anterior ShoulderInstability,TASI)患肩与正常肩关节在执行不同功能性动作中的等速肌力定量特征,为改善患者的临床疗效和选择治疗方案提供依据。方法:选取10名TASI右侧患肩和14名正常右侧肩关节对照,分别执行肩胛平面外展、内收,屈、伸,30°外展位内外旋,使用瑞士Contrex System-Top1000型等速肌力测试系统测试其等速向心60°/s、120°/s、180°/s的峰力矩。结果:与正常肩关节相比,TASI患肩外展、外展30°位外旋肌群峰力矩、外旋/内旋肌群峰力矩比值明显下降,并且随着角速度的增加,峰力矩呈下降趋势。结论:慢性创伤性肩关节前方不稳定的康复训练可在保护好肩关节静力性稳定结构前提下,注意增强外旋肌群和外展肌群的肌力。     

耐力力量复合训练对新兵膝屈伸肌功能影响的等速测试研究

为探讨耐力力量复合训练对新兵膝屈伸肌功能的影响 ,选择 2 0名新兵进行为期 4周的耐力力量复合训练 ,训练前后采用Cybex 6 0 0 0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。结果显示 ,训练后双膝屈肌的峰力矩、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 ,训练前后相比有显著性差异 (P <0 .0 5 ) ;双膝伸肌的TAE和ER值也有明显的提高 ;峰力矩H/Q值训练后均有提高 ,但训练前后无显著性差异 (P >0 .0 5 )。提示为期 4周的耐力力量复合训练可有效地发展双膝屈肌的肌力、肌爆发力和肌耐力 ,同时应加强力量训练的负荷以全面发展伸肌力量。     

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。     

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。     

青年男性膝关节等速向心测力研究

目的研究绳肌和股四头肌在不同测试速度下其肌力各指标的变化规律 ,同时为力量素质的评价提供正常值参考。方法利用REV90 0 0等速测力及康复系统对 30名健康男性双侧膝关节的等速向心收缩数据进行测试。结果峰力矩 (PT)及相对峰力矩 (PT/BW )均表现为股四头肌大于绳肌 ,慢速大于快速 ;惯用肢与非惯用肢峰力矩的差异 (Di)在 1 0 %左右 ;到达峰力矩的时间 (TPT)随测试速度增加而显著缩短 ;股四头肌和绳肌峰力矩角 (APT)分别为 50°～ 70°、32°～ 45°。绳肌与股四头肌峰力矩比率 (H/Q)在 50 %～ 60 %之间 ;耐力指数 (WF)在 65%左右。结论此结果为中国航天医学和生理学特别是模拟失重或微重力条件下的肌肉功能评定提供了一个新的思路。     

青年军人腰椎间盘突出症其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17名男性青年军人患者,进行双下肢膝屈伸肌力的对照测试,结果表明患侧与腱侧相比,在60°/s速度测试时,绳肌和股四头肌分别平均下降了45%和31%,在180°/s时分别下降57%与35%。提示患肢屈肌力下降明显,治疗康复期内应加强绳肌群锻炼。     

Preseason strength and flexibility imbalances associated with athletic injuries in female collegiate athletes

One hundred thirty-eight female collegiate athletes, participating in eight weightbearing varsity sports, were administered preseason strength and flexibility tests and followed for injuries during their sports seasons. Strength was measured as the maximal isokinetic torque of the right and left knee flexors and knee extensors at 30 and 180 deg/sec. Flexibility was measured as the active range of motion of several lower body joints. An athletic trainer evaluated and recorded injuries occurring to the athletes in practice or competition. Forty percent of the women suffered one or more injuries. Athletes experienced more lower extremity injuries if they had: 1) a right knee flexor 15% stronger than the left knee flexor at 180 deg/sec; 2) a right hip extensor 15% more flexible than the left hip extensor; 3) a knee flexor/knee extensor ratio of less than 0.75 at 180 deg/sec. There was a trend for higher injury rates to be associated with knee flexor or hip extensor imbalances of 15% or more on either side of the body. These data demonstrate that specific strength and flexibility imbalances are associated with lower extremity injuries in female collegiate athletes.     

Knee isokinetic muscle strength and balance ratio in female soccer players of different age groups: a cross-sectional study

ABSTRACT

Background: As a consequence of years of soccer training and sexual maturation, there is an increase in lower body muscle mass and strength especially in the knee extensors and flexors muscles. In this context, the lack of knee joint stability, resulting from strength imbalance between knee extensor and flexors muscles, has been associated with knee injuries. The aim of this study was to compare the knee flexor and extensor muscle peak torque, average power, contralateral deficit, conventional and functional balance ratios of female soccer players from different age groups.

Methods: Sixty-six female soccer players were divided into four groups: under 13 (U13), under 15 (U15), under 17 (U17) years old and professional (PRO). Flexor and extensor knee muscle strength in concentric and eccentric actions of both limbs were assessed using isokinetic dynamometer.

Results: For the dominant limb, the knee concentric extensor muscles peak torques, assessed at 60 and at 240 deg/sec, and the average power of U15 group were significantly higher than U13 group. Extensor muscle average power of the PRO group was higher than U17. Dominant knee flexor average power of U15 was significantly higher than the U13 group. Peak torque at 60 deg/sec and 240 deg/sec and average power of the PRO group were higher than the U17 group. No differences were found regarding the eccentric action for flexor and extensor muscles. Conventional and functional balance ratios were similar among all age group, except for U13, which presented higher values than the U15 group for the dominant limb.

Conclusions: The greatest improvement in muscular performance occur when the athlete starts practicing soccer (after U13) and when they become professional (after U17) and the balance ratios, and muscle balance ratios remain stable in all age groups, although they are below the recommended level in the literature, which may increase the risk for lower limb injury.     

Knee flexor strength and rate of torque development deficits in women with patellofemoral pain are related to poor objective function

BackgroundDeficits in knee flexor strength and rate of torque development (RTD) might be present in women with patellofemoral pain (PFP). In addition, maximal strength and RTD of the knee flexors and extensors might be related with subjective and objective function in women with PFP. However, both conjectures are still poorly understood.Research questionDo women with PFP have deficits in the maximal strength and RTD of the knee flexors and extensors during isometric, concentric, and eccentric contractions? Is there a relationship between maximal strength and RTD of the knee flexors and extensors with subjective and objective function in women with PFP?MethodsFifty-six women with, and 46 women without, PFP participated. Maximal strength and RTD (to 30% and 60% maximal torque) during isometric, concentric, and eccentric contractions of the knee flexors and extensors were assessed using an isokinetic dynamometer. Objective assessment included single leg hop test (SLHT) and forward step-down test (FSDT). Subjective assessment involved the anterior knee pain scale.ResultsWomen with PFP had small to large deficits in maximal strength and RTD of the knee flexors and extensors during isometric, concentric and eccentric contractions (Effect sizes: -0.43 to -1.10; p ≤ 0.016). Small to moderate correlations of maximal concentric and eccentric knee flexor strength and RTD with SLHT and FSDT (r = 0.28 to 0.41; p ≤ 0.037) were identified. Subjective or objective function were not correlated with maximal isometric knee flexor strength and RTD, or any knee extensor measures (p > 0.05).SignificanceMaximal strength and RTD deficits of the knee flexors and extensors were identified in this female PFP cohort, but they were unrelated to subjective function. The relationship of concentric and eccentric knee flexor strength and RTD deficits with poor objective function should be considered in future exercise trials for women with PFP.     

Effects of knee bracing on the sensorimotor function of subjects with anterior cruciate ligament reconstruction

The sensorimotor performance of the knee joint in 31 subjects who had undergone unilateral anterior cruciate ligament reconstruction at least 5 months previously was tested under three bracing conditions, 1) the DonJoy Legend brace, 2) a mechanical placebo brace, and 3) no brace, in random order. The accuracy of the subjects' ability to reproduce specified knee joint angles was tested as well as the isokinetic performance of their knee muscles at 60 and 180 deg/sec. The results showed that subjects with the brace or placebo brace performed similarly in reproducing the knee joint positions, but both groups performed better than the subjects without a brace. Isokinetic tests revealed no difference among the three groups in extensor and flexor peak torque production at 60 deg/sec or total work done by the extensors and flexors at 60 and 180 deg/sec. These results suggest that knee bracing can improve the static proprioception of the knee joint, but not the muscle contractile function, in subjects with anterior cruciate ligament reconstruction under isokinetic testing conditions. The finding of similar performances for joint angle reproduction in the brace and placebo brace groups suggests that the apparent improvement in proprioception with knee bracing was not due to the mechanical restraining action of the brace.     

The in vivo force-velocity relationship of the knee flexors and extensors

Previous studies have compared the torque production of the knee flexors and extensors and developed a "hamstring-quadricep" ratio. Collectively, these studies indicate that the ratio of strength between the knee flexors and extensors is a function of test speed, with the ratio increasing at the faster test speeds. Unfortunately, these studies have employed the peak torque isokinetic method for making measurements. This technique suffers from a number of problems that are biomechanical and physiological in nature. Consequently, in this study, we employed comparison of the in vivo force-velocity relationship using an angle-specific method and a gravitational correction factor to more accurately determine flexor-extensor ratios and to better describe any variations occurring as a function of test speed. Nine male subjects volunteered to participate in this study. Each of the subjects participated in two test sessions. Subjects were tested at six angular velocities of 0, 48, 96, 144, 192, 240 deg/sec. At these respective test speeds, the mean flexor torques were 95.0, 94.8, 84.1, 66.2, 56.2, and 49.2 Nm, respectively. The corresponding values for the knee extensors were 252.2, 246.5, 220.7, 184.5, 161.9, and 146.4 Nm. Normalization of these torque-velocity relationships demonstrated that the in vivo force-velocity relationships of the two muscle groups are similar at slow speeds, but become disparate at higher velocities. When examining flexor-extensor torque ratios at the various test speeds, it was found that there were significant differences (P less than 0.01).(ABSTRACT TRUNCATED AT 250 WORDS)     

Seasonal variation of selected performance parameters in épée fencers.

In this study, anthropometric measurements were carried out on seven British international male épée fencers, using a maximal treadmill running test, a 20-s Wingate-type test, and isokinetic dynamometry. Testing was conducted on two occasions, 5 to 6 months apart, during mid-off-season (preparation) and mid-in-season (competition) periods. Maximal oxygen intake (VO2max) and maximal respiratory exchange ratio (Rmax) were among the parameters obtained from the treadmill test, while peak and mean anaerobic power outputs were measured during a 20-s maximal effort. Knee extensor and flexor muscle forces from both dominant (leading) and non-dominant (trailing) legs were assessed at 1.04, 3.14 and 4.19 rad sec-1. Statistical analyses revealed lower mean VO2max (P < 0.05) and mean Rmax values (P < 0.02) at the in-season assessments compared with off-season. In-season testing also demonstrated significantly lower peak torques for both dominant and non-dominant knee extensors compared with off-season assessments at all velocities (P < 0.05 to P < 0.004). Furthermore, in-season peak torque for the non-dominant leg flexors was lower (P < 0.03) at 4.19 rad sec-1 than off-season. We conclude that current training practices may account for the observed seasonal variations in performance related physiological parameters in fencers.     

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.     

A cross-sectional analysis of sagittal knee laxity and isokinetic muscle strength in soccer players

In this cross-sectional study, sagittal knee laxity and isokinetic strength of knee extensor and flexor muscle groups were measured and differences related to leg dominance were evaluated. A total of 44 healthy male soccer players (who had trained regularly at least for the last five years) and 44 sedentary people as their control counterparts were involved in this study. All participants were tested using a KT-1000 knee arthrometer for knee laxity. Isokinetic concentric knee peak torque and hamstring/quadriceps (H/Q) ratio were also measured at 60, 180, 300 degrees/s through a Cybex 2 - 340 dynamometer. Posterior laxity in the non-dominant side of soccer players was significantly higher than in the dominant side (p < 0.005) while there were no significant anterior and total anteroposterior (total AP) laxity differences in both groups. Soccer players had significantly lower anterior and total AP laxity values than controls (p < 0.0001) while there was no significant difference between posterior laxity values in both sides. Dominant extremity demonstrated significantly higher knee flexor peak torque and H/Q ratio at 180 degrees /s in soccer players (p < 0.05). Similarly in sedentary controls, H/Q ratio at 60 degrees /s of the dominant side was significantly higher than that in the non-dominant side (p < 0.05). Soccer players had significantly higher extensor and flexor peak torque values and H/Q ratios than sedentary subjects for both extremities. In both groups, there were no significant correlations between knee laxity and isokinetic knee extensor and flexor strength and H/Q ratios except weak negative correlation between posterior knee laxity and isokinetic extensor peak torque at 60, 180 and 300 degrees /s (p < 0.005, r = - 0.43, p < 0.05, r = - 0.39, p < 0.05, r = - 0.32 respectively) in the non-dominant side of soccer players and at 300 degrees /s (p < 0.05, r = - 0.32) in the non-dominant side of controls. Soccer players demonstrated significantly less sagittal knee laxity and higher isokinetic strength of the knee flexors and extensors compared to sedentary controls. Isokinetic strength difference was found to be higher for the flexor muscle group. Further prospective studies are needed to explain whether the increased H/Q ratio decreases the risk of ligamentous injury.