膝屈伸肌群等速肌力训练改善膝骨性关节炎患者步态的效果分析

目的探讨膝屈伸肌群等速肌力训练改善膝骨性关节炎(KOA)患者步态的效果。方法采用前瞻性研究方法,为保证研究的安全性和科学性,选择2013年2月~2015年10月在我院诊治的KOA患者98例,根据入院顺序分为观察组与对照组各49例,两组都给予玻璃酸钠关节腔内注射和关节松动治疗,对照组给予积极康复训练,观察组给予膝屈伸肌群等速肌力训练,治疗观察时间都为4周。结果观察组与对照组的疗效优良率分别为93.9%和75.5%,观察组明显高于对照组(0.05)。治疗后观察组与对照组的Lysholm膝关节功能评分分别为(86.33±11.31)分和(75.84±10.71)分,都明显高于治疗前的(56.24±12.55)分和(56.24±11.12)分,组内与组间对比差异都有统计学意义(0.05)。观察组治疗后的屈肌PT与AOPT值分别为(21.87±3.67)N·m和(99.23±11.48)°,而对照组分别为(18.34±4.11)N·m和(89.02±10.45)°,都明显高于治疗前(0.05),且组间对比差异有统计学意义(0.05)。两组在治疗期间都无严重并发症,但观察组的恶心、呕吐、腹痛、腹胀等并发症发生率明显少于对照组(0.05)。结论膝屈伸肌群等速肌力训练在KOA患者中的应用能显著缓解疼痛、增强膝关节功能,具有很好的安全性,从而促进步态改善,具有重要的推广价值。     

Effects of isokinetic training of the knee extensors on isometric strength and peak power output during cycling

Summary Isokinetic training of right and left quadriceps femoris was undertaken three times per week for 16 weeks. One group of subjects (n=13) trained at an angular velocity of 4.19 rad·s^–1 and a second group (n=10) at 1.05 rad·s^–1. A control group (n=10) performed no training. Maximal voluntary contraction (MVC) of the quadriceps, and peak pedal velocity (_p,peak) and peak power output (W _peak) during all-out cycling (against loads equivalent to 9, 10, 11, 12, 13 and 14% MVC) were assessed before and after training. The two training groups did not differ significantly from each other in their training response to any of the performance variables (P>0.05). No significant difference in MVC was observed for any group after the 16-week period (P=0.167). The post-training increases in averageW _peak (7%) and _p,peak (6%) during the cycle tests were each significantly different from the control group response (P=0.018 andP=0.008, respectively). It is concluded that 16 weeks of isokinetic strength training of the knee extensors is able to significantly improve _p,peak andW _peak during sprint cycling, an activity which demands considerable involvement of the trained muscle group but with its own distinct pattern of coordination.     

The bilateral leg strength deficit is present in old, young and adolescent females during isokinetic knee extension and flexion

The bilateral limb deficit (BLD) describes the difference in maximal or near maximal force generating capacity of muscles when they are contracted alone or in combination with the contralateral muscles. A deficit occurs when the summed unilateral force is greater than the bilateral force. This study examined the presence of the BLD during isokinetic knee extensions and flexions in a group of adolescent females (n = 8, mean of 15 ± 1 years) and compared with previously reported data by this researcher of adult and older females. Data were collected from subjects during slow (45 deg/s) isokinetic knee extensions and flexions and it was found that a BLD exists during both extension and flexion regardless of age. Furthermore, this study is the first to examine the presence of the deficit in an adolescent population. Myoelectric signal (MES) data showed that there is no difference between bilateral and unilateral isokinetic knee extensions and flexions regardless of age group.     

Prerequisites and limitations to isokinetic measurements in humans

Physical and technical limitations have to be considered when measuring small torques over a wide range of angles during joint movements in humans using isokinetic methods, i.e. at constant angular velocities. In the concentric mode, during the initial phase, the subject must actively accelerate the lever of the isokinetic dynamometer to a preset velocity. To guarantee an adequate duration of the isokinetic phase at high preset velocities, greater torques are necessary to produce appropriate accelerations, otherwise the isokinetic phase will be increasingly shortened until the preset velocity can no longer be attained. The servomotor-controlled dynamometer used (LIDO-Active 2.1) continuously records torque during the whole movement, irrespective of differences between the actual and the preset velocity, but the user is not informed about which torques have been recorded outside the isokinetic phase and at which actual velocity. Thus, in the evaluation of torques in the nonisokinetic range, errors occur due to assigning torque measurements to incorrect velocities and due to the non-negligible accelerations involved. In exploratory tests on the dynamometer using physical methods to produce constant torques, an attempt has been made to ascertain the range over which isokinetic conditions were satisfied, hence providing a reliable basis for isokinetic studies in sports medicine and sports sciences.     

Effects of isokinetic training of the knee extensors on high-intensity exercise performance and skeletal muscle buffering

Twenty-three subjects isokinetically trained the right and left quadriceps femoris, three times per week for 16 weeks; one group (n=13) trained at an angular velocity of 4.19 rad · s^–1 and a second group (n=10), at 1.05 rad · s^–1. A control group (n=10) performed no training. Isometric endurance time at 60% quadriceps maximum voluntary contraction (MVC), mean power output and work done (W) during all-out cycling, and the muscle buffer value (B) and carnosine concentration of biopsy samples from the vastus lateralis, were all assessed before and after training. The two training groups did not differ significantly from each other in their training response to any of these variables (P < 0.05). No significant difference in either 60% MVC endurance time or impulse [(endurance time × force) at 60% MVC] was observed for any group after the 16 week period (P > 0.05). However, the post-training increase (9%) in W during high-intensity cycling was greater in the training group than in the control group (P=0.04). NeitherB nor carnosine concentration showed any significant change following training (P=0.56 andP=0.37, respectively). It is concluded that 16 weeks of isokinetic training of the knee extensors enables subjects to do more work during high-intensity cycling. Although the precise adaptations responsible for the improved performance have yet to be identified, they are unlikely to include an increase inB.     

Force-velocity-power characteristics and fiber composition in human knee extensor muscles

Summary To investigate the influence of skeletal muscle fiber composition on the mechanical characteristics of human skeletal muscle under isometric and dynamic conditions, ten well-trained track athletes with different muscle compositions (m. vastus lateralis) were used. The subjects were instructed to perform maximum isometric and dynamic knee extensions at maximal speed against increasing load. To determine the mechanical properties of the knee extensors a special dynamometer was used. The load was increased by adding weight discs to the electromagnetic part of the dynamometer. The load increased from 0.33–2.33 kg² moment of inertia in six stages. The data were handled on the basis of Hill's characteristic equation. The subjects were divided into two equal groups, one with more and one with less than 50% of fast twitch fibers. The force-velocity curve was found to be different in the two groups, the subjects with a predominance of fast twitch fibers being able to develop higher power output at a given load. Significant correlations between percentage of fast twitch fiber and power, as well as velocity, were found at the four greater loads only. However, when the percentage of fast twitch fiber and fast twitch fiber cross-sectional areas were combined, significant correlations were also found between this combined parameter and power output at the two lowest loads.     

Muscle activation during maximal voluntary eccentric and concentric knee extension

Summary The aim of this investigation was to study the relationships among movement velocity, torque output and electromyographic (EMG) activity of the knee extensor muscles under eccentric and concentric loading. Fourteen male subjects performed maximal voluntary eccentric and concentric constant-velocity knee extensions at 45, 90, 180 and 360° · s^–1. Myoelectric signals were recorded, using surface electrodes, from the vastus medialis, vastus lateralis and rectus femoris muscles. For comparison, torque and full-wave rectified EMG signals were amplitude-averaged through the central half (30°–70°) of the range of motion. For each test velocity, eccentric torque was greater than concentric torque (range of mean differences: 20%–146%,P < 0.05). In contrast, EMG activity for all muscles was lower under eccentric loading than velocity-matched concentric loading (7%–31%,P < 0.05). Neither torque output nor EMG activity for the three muscles changed across eccentric test velocities (P > 0.05). While concentric torque increased with decreasing velocity, EMG activity for all muscles decreased with decreasing velocity (P < 0.05). These data suggest that under certain high-tension loading conditions (especially during eccentric muscle actions), the neural drive to the agonist muscles was reduced, despite maximal voluntary effort. This may protect the musculoskeletal system from an injury that could result if the muscle was to become fully activated under these conditions.     

Metabolic and cardiorespiratory responses to maximal intermittent knee isokinetic exercise in young healthy humans

There have been many studies on the effects of isokinetic exercise on muscle performance in training and rehabilitative programmes. On the other hand, the cardiovascular and metabolic responses elicited by this type of exercise have been poorly investigated. This study was specifically designed to describe the relationships, if any, between metabolic and cardiorespiratory responses and power output during maximal intermittent knee isokinetic exercise when a steady state is reached. A group of 18 healthy subjects (10 men and 8 women, age range 25–30 years) were requested to perform at maximal concentric isokinetic knee extensions/flexions 60° · s⁻¹ and 180° · s⁻¹ for 5 min, with a 5-s pause interposed between consecutive repetitions. The power output (W˙) was calculated; before and during the tasks heart rate (f _c) and arterial blood pressure (AP_a) were continuously monitored. Pulmonary ventilation (V˙ _E) and oxygen uptake (V˙O₂) were measured at the 4th and at the 5th min of exercise and blood lactate concentration at rest and at the 3rd min of recovery. From the 4th to the 5th min only a slight decrease in W˙ was observed, both at 60° · s⁻¹ and 180° · s⁻¹. The V˙O₂, V˙ _E, f _c and AP_a showed similar values in the last 2 min of exercise, suggesting that a steady state had been reached. The V˙O₂ increased linearly as a function of W˙, showing a significantly steeper slope at 60° · s⁻¹ than at 180° · s⁻¹. The f _c, in spite of a large interindividual variation, was linearly related to metabolic demand, and was not affected by angular velocity. Systolic and diastolic AP_a were not related either to V˙O₂ or to angular velocity. In conclusion it would appear that the metabolic response to maximal intermittent knee isokinetic exercise resembles that of dynamic exercise. Conversely, the cardiocirculatory responses would seem to reflect a relevant role of the isometric postural component, the importance of which should be carefully evaluated in each subject. Accepted: 21 September 1999     

对女子手球运动员膝关节屈伸肌群进行等速测试

目的对广东省女子手球队运动员膝关节进行等速向心测试,探讨手球项目运动员膝关节屈伸肌群等速测试特征,为手球项目运动员的力量训练和相关的体育科研提供参考。方法运用CON-TREX等速测试系统对14名广东省女子手球运动员的膝关节进行等速向心测试,选取相对峰力矩、屈伸肌峰力矩比值、平均功率、总功和疲劳指数5个指标来研究手球项目运动员膝关节屈伸肌群的等速测试特征。选取独立样本t检验比较屈肌和伸肌的测试结果。结果膝关节伸肌相对峰力矩值在慢速测试(60°/s)和快速测试(240°/s)时均明显大于屈肌(P<0.01);女手队员膝关节屈伸肌峰力矩比值在快速测试(240°/s)时为76%左右;膝关节屈伸肌平均功率和总功在慢速测试(60°/s)时表现为伸肌大于屈肌(P<0.01),在快速测试(240°/s)时表现为左膝关节伸肌大于屈肌(P<0.05);女手队员膝关节屈伸肌疲劳指数范围在0～0.49之间。结论女手队员膝关节伸肌的最大力量和快速力量大于屈肌;女手队员膝关节屈伸肌峰力矩比值在快速测试(240°/s)时略微偏低,说明女手队员膝关节屈肌快速力量偏低;女手队员膝关节伸肌的快速力量和肌肉工作能力均大于屈肌;女手队员膝关节屈伸肌疲劳指数偏低,说明女手队员膝关节屈伸肌的力量耐力水平比较低。     

Maximal peak torque as a predictor of angle-specific torques of hamstring and quadriceps muscles in man

Summary This study assessed the relationship between the isokinetic peak torque (PT) (speed of movement 1.05 and 3.14 rads^–1) and the angle-specific torques (ASTs) at 0.26 and 1.31 rad of knee flexion in multiple contractions of the quadriceps and hamstrings in 70 individuals with a chronic anterior cruciate ligament (ACL) insufficiency and 78 individuals with a chronic medial collateral ligament (MCL) insufficiency in one knee. At every test speed, the Pearson product moment correlation coefficients (r) between the PT and ASTs were highly significant (P<0.001) in the uninjured knees (r=0.61–0.93) as well as in the knees with ACL (r=0.61–0.87) and MCL (r=0.74–0.91) insufficiency. In addition, in both groups the majority of the correlation coefficients exceeded 0.80, which is generally regarded as the threshold for the relationship to be considered clinically significant. Furthermore, using regression analysis, both extremities showed completely non-systematic distribution of the residuals. It is concluded that in healthy knees or knees with ACL or MCL insufficiency, the predictability of ASTs from PT was good, and, therefore, that AST analyses may offer little additional information about thigh muscle function to that obtained from a simpler and more commonly used measurement, the PT analysis.     

Specificity of training velocity and training load on gains in isokinetic knee joint strength

The present study investigated the effects of three different strength training regimes on the isokinetic strength profile of the knee extensors (quadriceps, Q) and flexors (hamstrings, H) and if increases in isokinetic strength were accompanied by an enhanced performance during a more complex leg movement, the soccer kick. Twenty-two elite soccer players performed 12 weeks of strength training (three times per week) at either high resistance (HR group: 4 sets, 8 reps, 8RM loading), low resistance (LR group: 4 sets, 24 reps, 24RM loading), loaded kicking movements (LK group: 4 sets, 16 reps, 16RM loading) while one group served as controls (CO group). Isokinetic concentric and eccentric moment of force was obtained (KinCom) as peak moment (M_peak) and moment at 50° knee flexion (M₅₀) at angular velocities of 30, 120, 240° s^-1. Isokinetic knee joint strength was unchanged in groups LR, LK, CO. However, after the HR strength training, concentric M_peak (±SD) increased (P<0.01) at 30° s^-1 (Q, 258±37 to 297±57 Nm; H, 122±22 to 140±21 Nm). Furthermore, eccentric M_peak increased at 30, 120 and 240° s^-1 (Q, 274±60 to 345±57 Nm (P<0.01), 291±56 to 309±49 Nm and 275±43 to 293±36 Nm (P<0.05), respectively; H, 143±32 to 158±25 Nm, 152±39 to 169±31 Nm and 148±27 to 163±19 Nm (P<0.05)). Corresponding increases (P<0.05) were observed for M₅₀. The H/Q ratio calculated as eccentric hamstring strength divided by concentric quadriceps strength (H_ecc/Q_con, representative for knee extension) at 240° s^-1 increased (P<0.05) from 107 to 118% (based on M_peak) and from 90 to 105% (M₅₀). Kicking performance estimated by maximal ball flight velocity was unaffected by any of the strength training regimes investigated. In conclusion, only heavy-resistance strength training induced increases in isokinetic muscle strength in the absence of learning effects. Concentric strength gains were observed at the actual velocity of training, while eccentric strength gains were found over the entire range of velocities examined. The capacity of the hamstring muscles for providing stability to the knee joint during fast extension was augmented as a result of the heavy-resistance strength training. Strength training should be integrated with other types of training involving the actual movement pattern in order to increase the performance within more complex movement patterns.     

Prediction of maximal oxygen uptake from the ratings of perceived exertion and heart rate during a perceptually-regulated sub-maximal exercise test in active and sedentary participants

This study assessed whether the accuracy of predicting maximal oxygen uptake (VO2max) from sub-maximal heart rate (HR) and ratings of perceived exertion (RPE) values was moderated by gender and habitual activity. In total, 27 men and 18 women completed two GXTs to determine VO2max and three perceptually-regulated GXTs, incremented by RPE 9, 11, 13, 15 and 17. The RPE and HR were individually regressed against VO2max (approximately 0.96) to enable predictions of VO2max. The VO2max was predicted from three RPE ranges (9-17, 9-15, 9-13). The RPE ranges were extrapolated to RPE(19), RPE(20) and age-predicted maximal HR (HRmax(pred)). ANOVA revealed no differences between measured and predicted VO2max (P > 0.05) when the RPE range 9-17 was extrapolated to RPE(19) and HRmax(pred). Extrapolation of RPE 9-17 to RPE(20) overestimated VO2max (P < 0.05), but no differences were observed when predicted from the RPE ranges 9-15 and 9-13. The prediction of VO2max was not moderated by gender or activity status. Hierarchical regression analysis revealed that HR explained additional variance in VO2max when added to the RPE (2%). Hierarchical multiple regression analysis also indicated that VO2max was significantly correlated with power output at sub-maximal RPE values of 13 and 15 (P < 0.01) in men and women. The addition of HRmax(pred) improved the accuracy of the prediction equation for men (P = 0.05) but not for women. The study confirmed the validity of estimating VO2max from perceptually-regulated, sub-maximal GXT and indicated the potential utility of regression analysis to gauge appropriate sub-maximal exercise intensities.