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.     

INFLUENCE OF PATTERNED ELECTRICAL NEUROMUSCULAR STIMULATION ON QUADRICEPS ACTIVATION IN INDIVIDUALS WITH KNEE JOINT INJURY

Background:

Neuromuscular Electrical Stimulation is a common intervention to address muscle weakness, however presents with many limitations such as fatigue, muscle damage, and patient discomfort that may influence its effectiveness. One novel form of electrical stimulation purported to improve neuromuscular re‐education is Patterned Electrical Neuromuscular Stimulation (PENS), which is proposed to mimic muscle‐firing patterns of healthy individuals. PENS provides patterned stimulating to the agonist muscle, antagonist muscle and then agonist muscle again in an effort to replicate firing patterns.

Purpose:

The purpose of this study was to determine the effect of a single PENS treatment on knee extension torque and quadriceps activation in individuals with quadriceps inhibition.

Methods:

18 subjects (10 males and 8 females: 24.2±3.4 years, 175.3±11.8cm, 81.8±12.4kg) with a history of knee injury/pain participated in this double‐blinded randomized controlled laboratory trial. Participants demonstrated quadriceps inhibition with a central activation ratio of ≤90%. Maximal voluntary isometric contraction of the quadriceps and central activation ratio were measured before and after treatment. The treatment intervention was a 15‐minute patterned electrical stimulation applied to the quadriceps and hamstring muscles with a strong motor contraction or a sham group, who received an identical set up as the PENS group, but received a 1mA subsensory stimulation. A 2×2 (group × time) ANCOVA was used to determine differences in maximal voluntary isometric contraction and central activation ratio between groups. The maximal voluntary isometric contraction was selected as a covariate due to baseline differences.

Results:

There were no differences in change scores between pre‐ and post‐intervention for maximal voluntary isometric contraction: (PENS: 0.09±0.32Nm/kg and Sham 0.15±0.18Nm/kg, p=0.713), or central activation ratio:(PENS: ‐1.22±6.06 and Sham: 1.48±3.7, p=0.270).

Conclusions:

A single Patterned Electrical Neuromuscular Stimulation treatment did not alter quadriceps central activation ratio or maximal voluntary isometric contraction. Unlike other types of muscle stimulation, PENS did not result in a reduction of quadriceps torque.

Level of Evidence:

Level III     

A Comparison of Functional Electrical and Magnetic Stimulation for Propelled Cycling of Paretic Patients

Szecsi J, Schiller M, Straube A, Gerling D. A comparison of functional electrical and magnetic stimulation for propelled cycling of paretic patients.

Objective

To compare isometric torque and cycling power, smoothness and symmetry using repetitive functional magnetic stimulation (FMS) and functional electrical stimulation (FES) in patients with paretic legs with preserved sensibility and in patients without sensibility.

Design

Repeated-measures design.

Setting

Laboratory setting.

Participants

Eleven subjects with complete spinal cord injury (SCI) and 29 subjects with chronic hemiparesis (16.6±5.5mo poststroke) volunteered.

Interventions

Using a tricycle testbed, participants were exposed to isometric measurements and ergometric cycling experiments, performed during both 20Hz FMS and FES stimulation. Subjects with hemiparesis and with complete SCI were stimulated at maximally tolerable level and maximal intensity, respectively.

Main Outcome Measures

Maximal isometric pedaling torque and mean ergometric power, smoothness, and symmetry were recorded for voluntary, FES, and FMS conditions.

Results

Two different patterns of the efficacy of FMS were identified. (1) Patients with complete SCI did not benefit (less torque and power was evoked with FMS than with FES, P<.003 and 10⁻⁴ respectively). (2) Patients with hemiplegia and preserved sensibility could improve their torque output (P<.05), smoothness, and symmetry of pedaling (P<.05) with FMS more than with FES.

Conclusions

FMS is a potential alternative to surface FES of the large thigh musculature in stimulation-supported cycling of patients with partially or completely preserved sensibility.     

Mechanomyography responses characterize altered muscle function during electrical stimulation-evoked cycling in individuals with spinal cord injury

BackgroundInvestigation of muscle fatigue during functional electrical stimulation (FES)-evoked exercise in individuals with spinal cord injury using dynamometry has limited capability to characterize the fatigue state of individual muscles. Mechanomyography has the potential to represent the state of muscle function at the muscle level. This study sought to investigate surface mechanomyographic responses evoked from quadriceps muscles during FES-cycling, and to quantify its changes between pre- and post-fatiguing conditions in individuals with spinal cord injury.MethodsSix individuals with chronic motor-complete spinal cord injury performed 30-min of sustained FES-leg cycling exercise on two days to induce muscle fatigue. Each participant performed maximum FES-evoked isometric knee extensions before and after the 30-min cycling to determine pre- and post- extension peak torque concomitant with mechanomyography changes.FindingsSimilar to extension peak torque, normalized root mean squared (RMS) and mean power frequency (MPF) of the mechanomyography signal significantly differed in muscle activities between pre- and post-FES-cycling for each quadriceps muscle (extension peak torque up to 69%; RMS up to 80%, and MPF up to 19%). Mechanomyographic-RMS showed significant reduction during cycling with acceptable between-days consistency (intra-class correlation coefficients, ICC = 0.51–0.91). The normalized MPF showed a weak association with FES-cycling duration (ICC = 0.08–0.23). During FES-cycling, the mechanomyographic-RMS revealed greater fatigue rate for rectus femoris and greater fatigue resistance for vastus medialis in spinal cord injured individuals.InterpretationMechanomyographic-RMS may be a useful tool for examining real time muscle function of specific muscles during FES-evoked cycling in individuals with spinal cord injury.     

Muskuläres Aktivierungsverhalten des M. quadriceps femoris

Background

After knee joint injuries, joint function disturbances often persist which might be caused by disturbed neuromuscular interaction.

Methods

We investigated 31 healthy subjects (16 female, 15 male). Surface EMG of the quadriceps muscle was taken using EMG interference mapping during isokinetic extension movements, with maximum effort at angle velocities of 60° and 180° per second.

Results

Activation patterns of the quadriceps femoris were influenced by gender. Women showed maximum activity in the region of the vastus medialis and rectus femoris muscles, whereas in men the maximum activity was always located over the vastus medialis region. With increasing extension the maximum activation moved distally in the women’s group, whereas men developed relevant activity levels in their rectus femoris muscle.

Conclusions

Gender-related evaluation of quadriceps activation patterns appears to be necessary.     

Electrically elicited co-contraction of thigh musculature after anterior cruciate ligament surgery. A description and single-case experiment

The purpose of this article is to describe a method for strengthening the quadriceps femoris muscle in a patient after anterior cruciate ligament (ACL) surgery. The method incorporates electrically elicited co-contraction of the quadriceps femoris and hamstring muscles. A single-case experimental design based on a split-middle (ABAB) technique was used to assess the effects of the systematic administration and withdrawal of electrical stimulation with respect to changes in knee isometric extension and flexion torque and circumferential measurements of the thigh in a patient six weeks after ACL reconstruction. Results show increases in extension and flexion torque and thigh circumferential measurements that are associated with both stimulation (treatment) phases in addition to a maintenance effect demonstrated during the withdrawal phase. In this patient, the technique appears to be effective in increasing muscle strength and circumferential measurements, particularly quadriceps femoris muscle torque. Implications and suggestions for future research are included.     

The use of electrical stimulation to increase quadriceps femoris muscle force in an elderly patient following a total knee arthroplasty.

BACKGROUND AND PURPOSE: Persistent residual quadriceps femoris muscle force deficits after total knee arthroplasty (TKA) are commonly reported and can prevent patients from returning quickly and fully to functional activities. Neuromuscular electrical stimulation offers a potentially more effective means of increasing muscle force than current rehabilitation protocols. CASE DESCRIPTION: The patient was a 66-year-old man. Neuromuscular electrical stimulation for increasing quadriceps femoris muscle force was initiated 3 weeks after TKA for 11 sessions to supplement stretching exercises and a high-intensity volitional strengthening program. OUTCOME: The patient's isometric quadriceps femoris muscle force increased from 50% (involved/uninvolved) at 3 weeks after surgery to 86% at 8 weeks after surgery. A concurrent increase in his uninvolved quadriceps femoris muscle force concealed the patient's true increase in his involved quadriceps femoris muscle force in a side-to-side comparison. The patient's final involved quadriceps femoris muscle force (10 weeks after surgery) was 93% of the initial uninvolved quadriceps femoris muscle force. DISCUSSION: Our patient was able to return to independent activities of daily living and recreational activities, with force gains that surpassed those reported in the literature.     

表面肌电结合等速测试仪评价功能性电刺激对脑卒中患者下肢痉挛及其功能影响的临床研究

目的:运用表面肌电结合等速测试仪探讨基于正常行走模式的功能性电刺激(FES)对脑卒中患者下肢痉挛及功能的影响.方法:54例脑卒中患者随机分为2组,FES组及安慰刺激组(对照组).2组患者均接受常规的临床及康复治疗.FES组在此基础上接受基于正常行走模式的FES治疗,安慰刺激组给予无电流输出的电刺激.治疗前及治疗4周后,...     

Comparison of two electrical stimulation protocols on quadriceps muscle after anterior cruciate ligament surgery. Feasability study]

OBJECTIVES: To evaluate the feasibility of a study comparing the effects of two protocols of electrical stimulation of the quadriceps femoris after anterior cruciate ligament surgery. MATERIAL: Seven sportsmen with a mean age of 26 yrs were randomly grouped in two: a 20 Hz stimulated group (4 patients) and a 80 Hz stimulated group (3 patients). After surgery all patients received electrical stimulation of the quadriceps femoris, five days a week, for 12 weeks, and had a standard program of voluntary contractions. The main outcome assessed before and three months after surgery were: quadriceps and hamstring peak torque at 90, 180 and 240 degrees /second, maximal isometric quadriceps at 75 degrees of flexion and muscle and subcutaneous fat volumes of the thigh using MRI. RESULTS: After 12 weeks of rehabilitation, the thigh muscle volume deficit of the operated limb was between 3 and 9% in the 20 Hz stimulated group and between 1 and 2% in the 80 Hz stimulated group. Quadriceps peak torque deficit was less than 30% except for two patients in the 20 Hz stimulated group. Maximal isometric quadriceps deficit of the operated limb was higher than 30% except for two patients in the 20 Hz stimulated group. CONCLUSION: The study showed that comparison of two protocols of electrical stimulation of the quadriceps femoris after anterior cruciate ligament surgery is possible if stimulation period is not more than four weeks.     

Quadriceps force production during straight leg raising at different hip positions with and without concomitant ankle dorsiflexion

Objective

Due to the significant prevalence of knee disorders and patellofemoral pain syndrome, as well as the importance of quadriceps strengthening in knee rehabilitation programs, it is necessary to specify the best method to activate and strengthen the quadriceps muscles. The current study aimed at comparing the maximum generated isometric force during an active straight-leg-raising (SLR) maneuver in a sitting position by changing the hip rotational position with and without the simultaneous contraction of the ankle dorsiflexor muscles.

Using customized rate-coding and recruitment strategies to maintain forces during repetitive activation of human muscles

BACKGROUND AND PURPOSE: During functional electrical stimulation (FES), clinicians typically increase stimulation intensity to offset fatigue and maintain functional levels of force production. However, recent studies have suggested that increasing the stimulation frequency is an effective strategy for overcoming fatigue during FES. The purpose of this study was to compare the effectiveness of 5 stimulation strategies on maintaining forces during repetitive isometric muscle activation. SUBJECTS AND METHODS: The right quadriceps femoris muscles of 12 subjects with no history of lower-extremity orthopedic, neurological, or vascular problems were tested. The 5 stimulation strategies were: progressively increasing the frequency, progressively increasing the intensity, and 3 combination protocols that first increased the intensity and then increased the frequency. The only difference among the 3 combination protocols was the starting frequency used in each protocol (20, 30, or 40 Hz). For all protocols, the stimulation frequency or intensity was increased progressively every time the peak force declined more than 10% from a targeted force level. The specific step increases in frequency or intensity were customized for each subject. A contraction was defined as successful when its peak force exceeded 90% of the targeted force level. RESULTS: The results showed that progressively increasing only the frequency produced 59% more successful contractions than progressively increasing only the intensity. In addition, the combination stimulation protocol that began with 30-Hz trains produced the most successful contractions (mean=1,205 contractions; 35%-74% more than the other 4 protocols tested). DISCUSSION AND CONCLUSION: The results suggest that increasing the stimulation intensity and then the frequency is the best strategy to maintain muscle performance and could help clinicians design optimal stimulation protocols to use for each patient during FES.     

Clinical evaluation of computerized functional electrical stimulation after spinal cord injury: a multicenter pilot study

This study investigated the safety and effects of computerized functional electrical stimulation (FES) on spinal cord injured individuals. Nineteen subjects two to ten years postinjury, with clinically complete motor and sensory lesions between C4 and T10, participated. All subjects met the specific selection criteria. None had received lower extremity electrical stimulation before. In phase I, subjects received surface electrical stimulation to the quadriceps muscle bilaterally for resistive knee extension 3 times a week for four weeks. The resistance and number of completed lifts was recorded daily. In phase II, 36 sessions provided sequential surface electrical stimulation to the quadriceps, hamstrings, and gluteus muscles bilaterally in order for subjects to pedal a lower extremity ergometer with resistance varied depending on completed run time. For each session, heart rate, blood pressure, temperature, and work performance were recorded. Tests done before and after the training program included fasting blood chemistries, 24-hour urinalysis, arm-crank ergometer stress testing, and midthigh girth measurement. Results indicate that this form of FES is safe, that quadriceps strength and endurance is increased, that endurance for ergometer pedaling is increased, and that there may be a training effect as more work is done at a similar heart rate and systolic blood pressure and as muscle bulk is increased. The FES effect on cardiovascular conditioning and general health requires further research to precisely determine its benefits.     

Selective hypertrophy of the quadriceps musculature after 14 weeks of isokinetic and conventional resistance training

One of the fundamental adaptations observed with resistance training (RT) is muscle hypertrophy. Conventional and isokinetic machines provide different forms of mechanical stress, and it is possible that these two training modes could promote differing degrees of hypertrophic adaptations. There is a lack of data comparing the selective hypertrophy of the quadriceps musculature after training with a conventional knee extension machine versus an isokinetic machine. The purpose of this study was to evaluate the selective hypertrophy of the quadriceps musculature and knee extension maximal isometric torque after 14 weeks of conventional versus isokinetic RT. Thirty-five men were assigned to three groups: control group and training groups (conventional and isokinetic) performed three sets of unilateral knee extensions per session with a progressive loading scheme twice a week. Prior to and following the intervention, maximal isometric knee extensor torque was measured using an isokinetic dynamometer, and muscle thickness (MT) of quadriceps femoris muscles was assessed via ultrasound. The results indicated non-uniform changes in MT between the muscles that comprise the quadriceps femoris group. For the conventional group, significantly greater increases in rectus femoris thickness were evident versus all other quadriceps muscles (14%). For the isokinetic group, increases in RF thickness (11%) were significantly greater in comparison with the vastus intermedius only. Although the muscle thickness did not increase for all the quadriceps femoris muscles, the relative rectus femoris adaptation suggested a selective hypertrophy favouring this portion.     

Electrical stimulation versus electromyographic biofeedback in the recovery of quadriceps femoris muscle function following anterior cruciate ligament surgery

Both electrical stimulation and electromyographic biofeedback have been shown to be more effective than voluntary isometric exercise alone in the recovery of quadriceps femoris muscle force following anterior cruciate ligament (ACL) reconstruction. In a comparison of these two modalities, 30 patients with ACL reconstruction were randomly assigned to either a group receiving electrical stimulation in conjunction with voluntary isometric exercise or a group receiving biofeedback in conjunction with voluntary isometric exercise. Following 6 weeks of a rehabilitative exercise protocol, the quadriceps femoris muscle isometric peak torque in the operative limb was compared with that in the nonoperative limb. A t test of independent samples indicated that the biofeedback group recovered a significantly greater percentage of their nonoperative limb's peak torque than did the electrical stimulation group. Measurements of active knee extension were taken at weeks 1, 2, 4, and 6 of the exercise program. A two-way analysis of variance (groups x weeks) indicated no significant difference between the rate at which each group recovered full active extension. The authors concluded that biofeedback is more effective than electrical stimulation in facilitating the recovery of peak torque and that biofeedback is comparable to electrical stimulation in the recovery of active knee extension.     

Effects of feedback on activation of the quadriceps during weight-bearing tasks of the Wii

[Purpose] This investigation evaluated the effect of real-time feedback on electrical activation of the quadriceps during 3 weight-bearing tasks of the Wii Fit Plus^®. [Subjects] Thirty male healthy volunteers were recruited. [Methods] Activation of the vastus medialis, vastus lateralis, and rectus femoris muscles was recorded during virtual lunge, single leg extension, and single leg reach exercises. Each exercise was performed twice in 3 randomized experimental conditions (with visual feedback, with auditory feedback, and with no feedback). The normalized electromyographic data (using maximum voluntary isometric contraction) were analyzed using repeated measures analysis of variance and Tukey’s test. [Results] No significant difference was found in the muscles among the feedback conditions during the 3 exercises. However, the variation in the muscle activity of the vastus medialis and vastus lateralis (18.23–29.20% of maximum voluntary isometric contraction) was higher (47–62%) than that in the rectus femoris (7.35–12.98% of maximum voluntary isometric contraction). [Conclusion] Real-time feedback did not alter quadriceps activation during the Wii tasks. Additionally, these games showed electromyographic activation levels similar to those for the same tasks outside the virtual environment. The Wii weight-bearing tasks could therefore constitute a physical activity program but without the additional benefit of feedback.Key words: Electromyography, Functional exercises, Exergames     

Improvement in isometric strength of the quadriceps femoris muscle after training with electrical stimulation

The purpose of this investigation was to determine if training isometrically with electrical stimulation (ES) alone would significantly increase isometric strength of the quadriceps femoris muscle. The relationships between the strength changes and the relative force and duration of training contractions were also studied. An experimental group (Group 1) and a control group (Group 2), 12 subjects in each, underwent pretesting and posttesting to obtain their maximum voluntary isometric contractions (MVICs). Group 1 trained with maximally tolerable isometric contractions induced by ES, three days a week for four weeks. Results showed that although both groups demonstrated increases in isometric strength of their quadriceps femoris muscles, training isometrically with ES produced a significantly greater increase (p less than .01) than not training with ES. The relative strength improvement in Group 1 was positively and significantly correlated with training-contraction intensity and duration. The relative increase in isometric strength, using only ES, may be determined by the ability of the subjects to tolerate longer and more forceful contractions. Suggestions for further research and implications for the clinical use of ES for strength-training are discussed.     

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.     

Feasibility Study of a Take-Home Array-Based Functional Electrical Stimulation System With Automated Setup for Current Functional Electrical Stimulation Users With Foot-Drop

Objective

To investigate the feasibility of unsupervised community use of an array-based automated setup functional electrical stimulator for current foot-drop functional electrical stimulation (FES) users.

Design

Feasibility study.

Setting

Gait laboratory and community use.

Participants

Participants (N=7) with diagnosis of unilateral foot-drop of central neurologic origin (>6mo) who were regular users of a foot-drop FES system (>3mo).

Intervention

Array-based automated setup FES system for foot-drop (ShefStim).

Main Outcome Measures

Logged usage, logged automated setup times for the array-based automated setup FES system and diary recording of problems experienced, all collected in the community environment. Walking speed, ankle angles at initial contact, foot clearance during swing, and the Quebec User Evaluation of Satisfaction with Assistive Technology version 2.0 (QUEST version 2.0) questionnaire, all collected in the gait laboratory.

Results

All participants were able to use the array-based automated setup FES system. Total setup time took longer than participants' own FES systems, and automated setup time was longer than in a previous study of a similar system. Some problems were experienced, but overall, participants were as satisfied with this system as their own FES system. The increase in walking speed (N=7) relative to no stimulation was comparable between both systems, and appropriate ankle angles at initial contact (N=7) and foot clearance during swing (n=5) were greater with the array-based automated setup FES system.

Conclusions

This study demonstrates that an array-based automated setup FES system for foot-drop can be successfully used unsupervised. Despite setup's taking longer and some problems, users are satisfied with the system and it would appear as effective, if not better, at addressing the foot-drop impairment. Further product development of this unique system, followed by a larger-scale and longer-term study, is required before firm conclusions about its efficacy can be reached.     

Effects of combined application of progressive resistance training and Russian electrical stimulation on quadriceps femoris muscle strength in elderly women with knee osteoarthritis

[Purpose] The aim of this study was to investigate the effects of combined application of progressive resistance training and Russian electrical stimulation on quadriceps femoris muscle strength in elderly women with osteoarthritis of the knee. [Subjects] Thirty women over 65 years of age diagnosed with knee osteoarthritis participated in the present study. The subjects were randomly assigned to a control group (n=10), a progressive resistance training group (n=10), or a Russian electrical stimulation group (n=10). [Methods] Each group was treated 3 times weekly for 8 weeks, and each session lasted 45 minutes. Muscle strength was assessed by measuring the peak torque of the quadriceps femoris muscle. Outcome measurements were performed at baseline and at the fourth and eighth weeks of the treatment period. [Results] All groups showed significant intragroup differences in the quadriceps femoris muscle peak torque after the treatment intervention. There were significant intergroup differences between the Russian electrical stimulation group and the other groups. [Conclusion] The results of this study suggest that combined application of progressive resistance training and Russian electrical stimulation can be effective in strengthening the quadriceps femoris muscle in elderly women with knee osteoarthritis.Key words: Knee osteoarthritis, Progressive resistance training, Russian electrical stimulation     

Comparative comfort of three waveforms used in electrically eliciting quadriceps femoris muscle contractions

The purpose of this study was to compare the relative comfort levels of electrical stimulation having different waveforms, but otherwise identical current characteristics, delivered percutaneously to normal quadriceps femoris muscles contracting at the same intensity level. The quadriceps femoris muscles of 20 healthy subjects were stimulated to a torque level 60% of that obtained in a maximal voluntary isometric contraction, using pulsed current with a carrier frequency of 2,500 Hz, at 50 pulses per second of 10-msec pulse duration. Three different waveforms were used: sinusoidal, sawtooth (triangular), and square. The relative comfort level of each electrically elicited contraction for each waveform was determined for each subject using a 20-cm-long visual analog scale. The results showed that no one waveform was most comfortable (least uncomfortable) and the difference was significant in what the subjects perceived to be the most comfortable contraction, regardless of waveform (p less than .01). These results indicate that a subject's perception of discomfort changes as the waveform of stimulation varies and that individual preferences exist for different waveforms. Selection of the most comfortable waveform could prove beneficial when the intensity of muscle stimulation is increased.