Changes in the force-frequency relationship of the human quadriceps femoris muscle following electrically and voluntarily induced fatigue.

The purpose of this study was to identify the changes in the force-frequency relationship (FFR) of the human quadriceps femoris muscle following electrically and voluntarily induced fatigue. Twenty nondisabled subjects each participated in one experimental session to test the effects of electrically induced fatigue on the FFR; 10 of these subjects participated in a second session in which voluntarily induced fatigue was produced. Fatigue was induced by having subjects perform repeated, 8-second, isometric contractions followed by 12-second rests until 50% of the initial force was produced. Markedly decreased forces were seen at all frequencies tested following fatigue. Low frequency fatigue was observed following both fatiguing protocols. The frequencies needed to produce near-maximum forces did not shift with fatigue. These results suggest that the most appropriate stimulation frequency to use when activating skeletal muscle depends on both the percentage of tetanic force desired and the fatigue state of the muscle. This study also provides the clinician with data on the FFR of healthy human quadriceps femoris muscle prior to fatigue. [Binder-Macleod SA, McDermond LR. Changes in the force-frequency relationship of the human quadriceps femoris muscle following electrically and voluntarily induced fatigue.     

Electrical stimulation in exercise of the quadriceps femoris muscle

Thirty-seven healthy subjects took part in an investigation to determine if the application of electrical stimulation to normal muscle, in combination with exercise, augments strength. Subjects were divided into three groups. Grwoup A (n = 14) was a control group (no exercise, no electrical stimulation). Group B members (n = 11) engaged in 10 sessions of maximum isometric exercise, and Group C subjects (n = 12) performed 10 sessions of maximum isometric exercise while simultaneously receiving electrical stimulation. The knee extensor muscles of subjects in Groups B and C increased in strength. However, the strength gains for Groups B and C were equivalent, suggesting that electrical stimulation combined with maximum isometric contractions has no greater effect on enhancing strength than does conventional static exercise.     

Effects of length on the catchlike property of human quadriceps femoris muscle.

BACKGROUND AND PURPOSE: Recent reports have suggested that electrical stimulation trains that take advantage of the catchlike property of skeletal muscle can produce higher forces from skeletal muscle than traditionally used constant-frequency trains. This study investigated the effects of catchlike-inducing trains on human quadriceps femoris muscles while the kneejoint was held at 15 degrees of flexion. SUBJECTS AND METHODS: Subjects (N=12) were tested with constant-frequency trains that had interpulse intervals ranging from 10 to 160 milliseconds and comparable catchlike-inducing trains. Data were collected during the control condition (1 train every 10 seconds) and during repetitive contractions (1 train per second). RESULTS: During control and repetitive activation conditions, catchlike-inducing trains produced approximately 5% to 110% greater peak forces than comparable constant-frequency trains, depending on the frequencies being compared. Total forces produced (ie, force-time integrals) were increased up to 59% and 49% during the control and repetitive activation conditions, respectively. CONCLUSION AND DISCUSSION: These results support earlier findings that catchlike-inducing trains may be advantageous in functional electrical stimulation applications.     

Effect of trunk stabilization on quadriceps femoris muscle torque

The purpose of this study was to determine if differences exist in angle-specific torque, torque-velocity relationships, and power-velocity relationships of the quadriceps femoris muscle group when the trunk was and was not stabilized and the starting position was varied. We calculated isokinetic torques from seven adult men while the trunk was and was not stabilized for nine combinations of velocity of movement 0, 30, and 105 degrees/sec) and starting position (40, 60, and 100 degrees of knee flexion). The results suggest that peak angle-specific torques and instantaneous power are greater when the trunk is stabilized, the increase in the trunk-stabilized torque and power was greater at the higher velocity and for the larger ranges of motion, and the testing movement should not begin beyond 30 degrees of the angle of interest.     

Development of a mathematical model for predicting electrically elicited quadriceps femoris muscle forces during isovelocity knee joint motion

Background  

Direct electrical activation of skeletal muscles of patients with upper motor neuron lesions can restore functional movements, such as standing or walking. Because responses to electrical stimulation are highly nonlinear and time varying, accurate control of muscles to produce functional movements is very difficult. Accurate and predictive mathematical models can facilitate the design of stimulation patterns and control strategies that will produce the desired force and motion. In the present study, we build upon our previous isometric model to capture the effects of constant angular velocity on the forces produced during electrically elicited concentric contractions of healthy human quadriceps femoris muscle. Modelling the isovelocity condition is important because it will enable us to understand how our model behaves under the relatively simple condition of constant velocity and will enable us to better understand the interactions of muscle length, limb velocity, and stimulation pattern on the force produced by the muscle.     

Modification of quadriceps femoris muscle exercises during knee rehabilitation

Rehabilitation of the quadriceps femoris muscle is the cornerstone of full recovery after inactivity, immobilization, or surgery of the knee. Muscle strengthening programs often are interrupted by patients' complaints of pain experienced during exercise, which frequently prolong the patients' convalescence period. Specific modifications of standard quadriceps femoris muscle exercises often allow completely pain-free exercise, thus providing a faster progression of treatment and a subsequently shorter rehabilitation period. The purposes of this article are to review briefly patellofemoral biomechanics as it relates to quadriceps muscle rehabilitation and to summarize several modifications that in our clinical experience repeatedly have reduced pain during exercise.     

Effect of quadriceps femoris muscle stretch on knee extension torque

Peak and angle specific knee extension torques produced after a quadriceps femoris muscle stretch and after a 15-second rest were compared to determine the effect of stretch on knee extension torque. Twenty healthy subjects performed eight maximum voluntary knee extensions at 90 degrees/sec under each condition. Although peak torque and torques at 15, 30, 45, and 60 degrees from full extension were measured, knee extension torque was only significantly greater (p less than .02) at 60 degrees of knee flexion after quadriceps femoris muscle stretch. The absolute difference, which was only a mean 4.9 N X m (3.6 ft-lb), was not substantial. When quadriceps femoris muscle stretch is a consequence of passive knee flexion at 90 degrees/sec, knee extension torque is apparently facilitated only during the initial part of the knee extension movement. Therefore, in healthy patients, a muscle stretch, such as used in this study, is probably of little therapeutic value.     

Contractile properties and the force-frequency relationship of the paralyzed human quadriceps femoris muscle

BACKGROUND AND PURPOSE: Following spinal cord injury (SCI), paralyzed muscles undergo physiological changes that alter their force responses to electrical stimulation. The purpose of this study was to investigate the effects of SCI on the contractile properties and force-frequency relationship (FFR) of the paralyzed human quadriceps femoris muscle of adolescents and young adults. SUBJECTS: Thirteen subjects (11 male, 2 female; age range=11-24 years) with motor complete SCIs and 13 matched control subjects (11 male, 2 female; age range=9-23 years) without SCI participated in the study. METHODS: Both groups of subjects underwent the same testing protocol using similar equipment. RESULTS: The paralyzed muscles of the subjects with SCI produced 62% of the peak twitch force and had a fatigue ratio that was 65% of that of the control subjects. The paralyzed muscles contracted 14% and 25% faster and relaxed 38% and 46% faster than the nonparalyzed muscles in nonfatigued and fatigued conditions, respectively. Compared with the control subjects, the subjects with SCI had twitch-to-tetanus ratios that were 84% and 127% greater in nonfatigued and fatigued conditions, respectively. Relative to the control subjects, the FFR of the subjects with SCI was shifted to the left in the fatigued condition. Relative to their respective nonfatigued conditions, the FFR of both groups of subjects shifted to the right with fatigue. DISCUSSION AND CONCLUSION: These findings may have important implications for designing stimulation strategies to reduce the rapid fatigue that limits the clinical efficacy of functional electrical stimulation.     

MyotonPRO用于评估健康青年人股四头肌肌肉弹性的信度研究

目的:检验MyotonPRO肌肉弹性测试仪测量健康青年人股直肌、股内侧肌及股外侧肌肌肉弹性的复测信度和测试者间信度.方法:本研究纳入了38例健康青年人,采用MyotonPRO评估放松状态下的股直肌、股内侧肌及股外侧肌肌肉弹性,计算组内相关系数(ICC)、绝对信度,两次测量结果绘制成Bland-Altman图并进行系统偏...     

股四头肌肌力与髌股关节稳定性关系的研究

目的:了解组成股四头肌的4块肌在维持髌骨稳定性中的作用,为临床治疗髌股关节不稳提供理论依据。方法:对6例新鲜膝关节标本,在不同屈曲度下,分4种工况进行加载分别模拟组成股四头肌的4块肌在生理及不同病理状态下的肌力。对髌骨施加外侧方移位载荷,记录使髌骨向外移位1cm的载荷。结果:生理状态下,在膝关节屈曲过程中,20°时使髌骨向外侧半脱位的载荷最小(61±13N),约为屈曲90°时的1/3;在松解股内侧肌后,屈膝10°—30°半脱位载荷明显减小(P<0.05),进一步松解股外侧肌导致整个屈膝过程中半脱位载荷均明显减小(P<0.05)。结论:整个股四头肌在髌骨外侧半脱位的预防、治疗及康复过程中具有重要作用,手术治疗不宜破坏股外侧肌,康复尤其应重视股内侧肌肌力的恢复。     

An electromyographic analysis of quadriceps femoris muscle setting and straight leg raising

Physical therapists routinely advise patients to perform quadriceps femoris muscle setting or straight leg raising or both following knee surgery or trauma from knee injury. Little information exists, however, about the intensity of effort required from knee and hip musculature during the exercises. This study was designed to compare the level of electromyographic activity during maximally resisted straight leg raises with the level during quadriceps femoris muscle setting exercises for the vastus medialis, rectus femoris, gluteus medius, and biceps femoris muscles. Forty healthy young adult men and women performed randomly ordered trials of each exercise in the supine position. Electromyographic activity was recorded from surface electrodes and normalized to values derived from maximal isometric trials. Statistical analysis demonstrated significantly greater (p less than .0001) vastus medialis, biceps femoris, and gluteus medius muscle activity during quadriceps femoris muscle setting. The rectus femoris muscle was significantly more active (p less than .0001) during the straight leg raise. The study demonstrated remarkably different muscle activation levels between the exercises studied and clearly indicates that selection of the exercises needs to be based on the therapeutic objectives.     

Factors influencing quadriceps femoris muscle torque using transcutaneous neuromuscular electrical stimulation

Quadriceps femoris muscle torque was measured in 40 subjects during transcutaneous neuromuscular electrical stimulation (NMES). Three different electrode types (carbonized rubber, sponge, and adhesive) were used on each subject, permitting determination of the factors that influenced the magnitude of quadriceps femoris muscle torque induced by NMES. This goal was accomplished by entering the various factors into a multiple-regression model. The electrodes differed significantly in their characteristics. The carbonized-rubber electrode delivered the greatest current with the lowest impedance, resulting in the highest knee extension torque. We found that the most important factor in determining torque generation level was the quadriceps femoris muscle's intrinsic ability to be activated (as opposed to electrode size, current, current density, or skin impedance). These data suggest that NMES efficacy is primarily determined by the intrinsic tissue properties of the individual (defined in this study as "efficiency") and is not dramatically changeable by using high stimulation currents or large electrode sizes. The precise physiological basis for interindividual differences in efficiency is not known.     

Physical function and properties of quadriceps femoris muscle in men with knee osteoarthritis

Liikavainio T, Lyytinen T, Tyrväinen E, Sipilä S, Arokoski JP. Physical function and properties of quadriceps femoris muscle in men with knee osteoarthritis.

Objectives

To examine the objective physical function of the lower extremities, to measure the properties of quadriceps femoris muscle (QFM), and to assess subjective disabilities in men with knee osteoarthritis (OA) and to compare the results with those obtained from age- and sex-matched control subjects.

Design

Cross-sectional study.

Setting

Rehabilitation clinic in a university hospital.

Participants

Male volunteers (n=54) (age range, 50-69y) with knee OA and randomly selected healthy, age- and sex-matched control subjects (n=53).

Interventions

Not applicable.

Main Outcome Measures

Physical function evaluated with a test battery including the QFM composition measurement, the Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC), and the RAND 36-Item Short-Form Health Survey, version 1.0.

Results

Knee OA patients had 13% to 26% poorer (P range, .050-.001) physical function and muscle strength compared with the controls. There were also significant differences in QFM composition. WOMAC (P range, .050-.001) and muscle strength (P<.001) associated with physical function tests, but subjective pain correlated with neither physical function nor muscle strength in knee OA patients. The radiographic knee OA grade did not have any significant effect on physical function, but passive knee motion, knee extension strength, and WOMAC were related to the severity of the disease (P<.05).

Conclusions

The patients with knee OA exhibited impaired physical function and muscle strength and QFM composition compared with healthy controls. The severity of radiographic knee OA clearly had adverse effects on functional ability at the later stages of the disease. The results highlight the effect of QFM strength on physical function as well as the importance of patient's subjective and objective physical function when deciding on knee OA treatment policy.     

Assessment of quadriceps femoris muscle atrophy and hypertrophy in neuromuscular disease in children

Midthigh muscle and subcutaneous tissue thickness were measured using a real-time linear array ultrasound scanner in 50 patients attending our Muscle Clinic; 28 had muscular dystrophy and 21 spinal muscular atrophy. In muscular dystrophy the muscle thickness was found to be normal or increased, whereas in spinal muscular atrophy it was reduced, with an associated increase in subcutaneous tissue thickness that did not relate to obesity. Measurement of muscle and subcutaneous tissue thickness provides a more accurate way of assessing muscle atrophy and hypertrophy than clinical assessment, and is a useful guide in the discrimination between muscular dystrophy and spinal muscular atrophy.     

Voluntary activation and decreased force production of the quadriceps femoris muscle after total knee arthroplasty

BACKGROUND AND PURPOSE: Quadriceps femoris muscle weakness as manifested by a decrease in force-generating capability is a persistent problem after total knee arthroplasty (TKA). The authors hypothesized that (1) patients with a TKA would have decreased quadriceps femoris muscle performance (weakness) and impaired volitional activation when compared with a group of older adults without knee pathology, (2) pain and age would account for a large portion of the variability in volitional activation after surgery, and (3) volitional activation in the TKA group would account for a large portion of the variability in force production. SUBJECTS: Comparison subjects were 52 volunteers (mean age=72.2 years, SD=5.34, range=64-85). The TKA group comprised 52 patients (mean age=64.9 years, SD=7.72, range=49-78) with a diagnosis of osteoarthritis who had undergone a tricompartmental, cemented TKA. METHODS: Knee extension force was measured using a burst superimposition technique, where a supramaximal burst of electrical stimulation was superimposed on a maximal voluntary isometric contraction (MVIC). The amount of failure of volitional activation is determined by the amount of electrical augmentation of force beyond a person's MVIC at the instant of the application of the electrical burst. RESULTS: The average normalized knee extension force of the TKA group was 64% lower than that of the comparison group. The average volitional activation deficit in the TKA group (26%) was 4 times as great as the comparison group's deficit (6%). Age did not correlate with quadriceps femoris muscle activation, and knee pain explained only a small portion of the variance in knee extension force (r2=.17). Volitional activation was highly correlated with knee extension force production (r2=.65). DISCUSSION AND CONCLUSION: Considerable quadriceps femoris muscle inhibition after surgery has several implications for recovery. Rehabilitation programs that focus on volitional exercise alone are unlikely to overcome this pronounced failure of activation. Early interventions focused at improving quadriceps femoris muscle voluntary activation may improve efforts to restore muscle force.     

Magnetic stimulation of the quadriceps femoris muscle: comparison of pain with electrical stimulation

OBJECTIVE: The objective of this study was to compare pain induced by magnetic stimulation of the quadriceps femoris (QF) muscle with that induced by transcutaneous neuromuscular electrical stimulation (NMES). DESIGN: Magnetic stimulation and transcutaneous NMES were applied to QF muscles of 17 normal volunteers. The intensity of each mode of stimulation was increased in a stepwise manner. Peak torque values of isometric contractions of QF muscles and visual analog scale (VAS) scores were recorded at each intensity level. The VAS scores of the two stimulating modalities were compared at the intensity-generating same peak torque values. RESULTS: The median VAS scores for electrical and magnetic stimulation were 5.7 and 0.3, respectively. The median difference between the VAS scores for electrical and magnetic stimulation was 3.7 (range, 1.7-8.5). The mean of the maximum peak torque obtained from each subject was higher in magnetic stimulation than in electrical stimulation (9.5 +/- 4.8 vs. 4.4 +/- 2.9 Nm). CONCLUSIONS: Magnetic stimulation of the QF muscle produced less pain at the same level of isometric peak torque than did transcutaneous NMES. Magnetic stimulation is a potential alternative to transcutaneous NMES, especially for persons with intact or residual sensory function.     

肌电生物反馈在半月板切除术后股四头肌功能恢复中的应用

将２５名半月板切除术后的患者，随机分成肌电生物反馈治疗线及对照组，指导患者进行股四头肌等长训练，训练前后均进行股四头肌的肌电水平、患肢负重及股四头肌徒手肌力测定。结果表明：训练后股四头肌的肌电增加增度肌电生物反馈组明显大于对照组（Ｐ＜０．０１）；在患肢负重能力方面，两组对比，反馈治疗组明显成于对照组（Ｐ＜０．０１）；训练前后的肌力测定显示；反馈治疗组训练后股四头肌肌力达到Ｖ组的百分率是６４．２％，     

Muscle wasting in intensive care patients: ultrasound observation of the M. quadriceps femoris muscle layer

OBJECTIVE: Patients in intensive care exhibit a high degree of loss of muscle mass. Appropriate instruments are needed to document muscle wasting in these patients. The aim of this pilot study was to describe muscle wasting in patients in the intensive care unit. DESIGN: Two-fold study setting: prospective longitudinal and cross-sectional single-blind. PATIENTS: A total of 118 patients in the intensive care unit (length of stay 1-98 days; male:female ratio 88:30; age 55 +/- 17 years) were included in a two-fold study setting. METHODS: Muscle layer thickness of the M. quadriceps femoris was documented using ultrasound measurement at well-defined points. Seventeen pilot-patients were measured twice; at baseline and after 28 days. In another group of 101 patients, muscle layer thickness was determined once after a random length of stay. The results of both groups were compared and correlated. RESULTS: In both groups, M. quadriceps femoris thickness showed a significant negative correlation with length of stay in the intensive care unit (p < 0.01). Furthermore, muscle wasting in intensive care patients could be described using a logarithmic function. CONCLUSION: Loss of muscle mass shows a negative correlation with length of stay, and seems to be higher during the first 2-3 weeks of immobilization/intensive care unit stay. Ultrasound is a valid and practical measurement tool for documenting muscle mass (e.g. muscle layer thickness) as part of the daily routine at an intensive care unit.     

Electromyographic biofeedback and recovery of quadriceps femoris muscle function following anterior cruciate ligament reconstruction

The purpose of this study was to compare the effects of biofeedback-facilitated exercise with exercise alone on the recovery rate of quadriceps femoris muscle function following anterior cruciate ligament (ACL) reconstruction. Functional measures included 1) a dynamometric test of quadriceps femoris muscle isometric peak torque during the 12th postoperative week and 2) the number of days post-operatively that a patient achieved full active extension of the knee. Twenty-two patients with acute ACL injury were randomly assigned to a Treatment (biofeedback) Group (n = 11) or a Control (nonfeedback) Group (n = 11) during the first therapy session one week after reconstructive surgery. After the patients had completed the 12-week exercise program, the quadriceps femoris muscle isometric peak torque in the operative limb was compared with that in the nonoperative limb at three angles (90 degrees, 60 degrees, and 45 degrees) of extension. An analysis of variance revealed significant differences between the Treatment and Control Groups at all three angles. Mean recovery time was calculated for each group, and a t test for independent samples indicated a significant difference between the groups. These results demonstrate that the addition of biofeedback to muscle strengthening exercises facilitates the rate of recovery of quadriceps femoris muscle function following ACL reconstruction.