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.     

Electromyographic and biomechanic analysis of anterior cruciate ligament deficiency and functional knee bracing

OBJECTIVE: Examine the neuromuscular response to functional knee bracing relative to anterior tibial translations in vivo. DESIGN: During randomised brace conditions, electromyographic data with simultaneous skeletal tibiofemoral kinematics were recorded from four anterior cruciate ligament deficient subjects to investigate the effect of the DonJoy Legend functional brace during activity. BACKGROUND: Knee braces do not increase knee stability but may influence afferent inputs from proprioception and therefore one might expect changes in muscle firing patterns, amplitude and timing. METHODS: Hoffman bone pins affixed with markers were implanted into the tibia and femur for kinematic measurement. The EMG data from the rectus femoris, semitendinosus, biceps femoris, and lateral head of the gastrocnemius were integrated for each subject in three separate time periods: 250 ms preceding footstrike and two consecutive 125 ms time intervals following footstrike. RESULTS: With brace, semitendinosus activity significantly decreased 17% prior to footstrike whereas bicep femoris significantly decreased 44% during A2, (P<0.05). Rectus femoris activity significantly increased 21% in A2 (P<0.05). No consistent reductions in anterior translations were evident. CONCLUSION: Our preliminary findings, based on a limited number of subjects, indicate joint stability may result from proprioceptive feedback rather than the mechanical stabilising effect of the brace. Despite a significant increase in rectus femoris activity upon landing, only one subject demonstrated an increase in anterior tibial drawer. RELEVANCE: Studies have shown functional braces do not mechanically stabilise the anterior cruciate ligament deficient knee. Perhaps bracing alters proprioceptive feedback. It has been shown that bracing the anterior cruciate ligament deficient knee may affect hamstring and quadriceps activity. Our findings stresses the importance of functional knee bracing combined with proprioceptive and muscular coordination training in order to increase joint stability.     

The effects of dorso-lumbar motion restriction on EMG activity of selected muscles during running

Abstract

The effects of restricting dorso-lumbar spine mobility on electromyographic activity of the erector spinae, quadriceps femoris, hamstrings and gastrocnemius muscles in runners was investigated. Thermoplastic casting material was fashioned into a rigid orthosis and used to restrict spinal motion during running. Volunteers ran on a treadmill at 2.78 m/sec, under normal conditions and with spinal motion restricted. Surface electromyographic data was collected during both sets of trials. Normal electromyographic data was also compared with previous authors to determine similarity with their electromyographic data.

The effects of joint damage on muscle function,proprioception and rehabilitation

SUMMARY. The paper summarizes a series of studies investigating reduced quadriceps femoris activation and its effect on rehabilitation of patients with traumatic and arthritic knee damage. It incorporates findings from related research fields and speculates on the physiological causes of reduced voluntary activation following joint damage and its clinical implications.Arthrogenic reduction in voluntary activation is the inability to maximally activate muscles acting across damaged joints. This phenomenon may cause muscle weakness by preventing complete activation of the muscle and if prolonged may result in muscle fibre atrophy, and may possibly impede rehabilitation.In patients with anterior cruciate ligament (ACL) deficient knees the reduction in quadriceps femoris activation was related to the amount of joint damage sustained and caused some quadriceps femoris weakness. Patients with isolated ACL ruptures had a small reduction of quadriceps femoris activation that did not impede conservative rehabilitation. However, patients with ACL ruptures and associated joint damage had a large reduction in activation and responded poorly to rehabilitation. Operative stabilization of ACL-deficient limbs may increase activation and improve efficacy of rehabilitation.Quadriceps femoris activation was also reduced in patients with mild knee osteoarthritis, who responded well to rehabilitation.Following joint damage, abnormal articular afferent information may decrease α-motoneurone excitability, reducing voluntary quadriceps femoris activation. If joint damage is extensive the resulting large reduction in activation may prevent the threshold for stimulation of muscle hypertrophy from being reached, which impedes rehabilitation. Abnormal articular afferent information may also decrease γ-motoneurone excitability causing proprioceptive deficits. Rehabilitation which increases α-motoneurone excitability may also increase γ-motoneurone excitability, improving proprioception.     

Effects of functional knee bracing on muscle-firing patterns about the chronic anterior cruciate ligament-deficient knee

OBJECTIVE: To examine the effects of functional knee bracing on the muscle-firing patterns about the chronic anterior cruciate ligament (ACL)-deficient knee in successful brace users. DESIGN: Cross-sectional comparative clinical trial. SETTING: Motion analysis laboratory. PARTICIPANTS: Ten active individuals with unilateral, isolated, chronic (>18mo postinjury), ACL-deficient knees who subjectively reported improved function with a functional knee bracing. INTERVENTION: Each subject completed 3 single-leg hop maneuvers on their ACL-deficient knee with and without their knee brace while surface electromyographic activity was recorded from the quadriceps, hamstring, and gastrocnemius muscles. MAIN OUTCOME MEASURES: Muscle onset latency. RESULTS: Brace use significantly delayed the average onset of vastus lateralis activation before landing (123+/-47ms vs 109+/-30ms, P<.001), though significant interindividual variations existed. Bracing significantly altered the onset latency in 1 or more muscles in 9 of 10 subjects. In 4 subjects, a favorable change in the firing pattern was seen, whereas only 1 subject exhibited an unfavorable change. Without bracing, 5 of the 10 subjects fired the hamstrings or gastrocnemius muscles first; with bracing, 7 of 10 fired these muscles first. CONCLUSIONS: Brace use in this population did not consistently result in more favorable muscle firing patterns during the single-leg hop maneuver. Interindividual responses to brace use indicate the need for further research to investigate the multiple strategies that may exist to stabilize the ACL-deficient knee. In the meantime, functional knee brace use among ACL-deficient patients remains empirical.     

Altered hamstring-quadriceps muscle balance in patients with knee osteoarthritis

BACKGROUND: To compare hamstring to quadriceps muscle coactivity during level walking, stair ascent, and stair decent between individuals with and without knee osteoarthritis. METHODS: In a cross-sectional study, subjects with grade II knee osteoarthritis (n = 26), healthy age- and gender-matched (n = 20) and healthy, young adults (n = 20) performed three activities of daily living. During the stance phase of these activities surface electromyography was measured. Two coactivity ratios were computed, the biceps femoris to vastus lateralis ratio and the ratio of the biceps femoris EMG activity relative to the EMG activity measured during contraction- and velocity-specific maximal voluntary biceps femoris contraction, i.e., biceps femoris to maximal biceps femoris activity. FINDINGS: Subjects with knee osteoarthritis had significantly higher coactivity than age-matched healthy adults and young adults and healthy adults had more coactivity than young adults regardless the type of coactivity ratio. The biceps femoris to vastus lateralis ratio yielded 25% higher coactivity value than the biceps femoris to maximal biceps femoris ratio (P < 0.0001). The EMG activity of the vastus lateralis relative to maximal vastus lateralis EMG activity was 92% in subjects with knee osteoarthritis, 57% in age-matched controls, and 47% in young adults (P < 0.0001). INTERPRETATION: Patients with knee osteoarthritis revealed increased hamstring muscle activation while executing activities of daily living. Altered muscle activation at the knee may interfere with normal load distribution in the knee and facilitate disease progression. Therapeutic interventions should focus not only on quadriceps strengthening but also on improving muscle balance at the knee.     

Electromyographic analysis of knee exercises in healthy subjects and in patients with knee pathologies

Little information exists about the intensity of contraction required from knee and hip musculature during common therapeutic exercises used for patient populations. This study, therefore, was designed to compare electromyographic data obtained from the vastus medialis, rectus femoris, gluteus medius, and biceps femoris muscles during maximally resisted straight-leg-raising (SLR) exercises with EMG data obtained from the same muscles during quadriceps femoris muscle setting (QS) exercises in healthy subjects and in patients with knee pathologies. Of the 30 participants in the study, 16 had a history of knee injury or surgery. All participants performed randomly ordered trials of the SLR and QS exercises while the EMG data were recorded from surface electrodes and normalized to values derived from maximal effort isometric contraction trials. An analysis of variance demonstrated significantly greater activity (p less than .05) of the vastus medialis, biceps femoris, and gluteus medius muscles during QS exercises than during SLR exercises. The rectus femoris muscle was significantly more active (p less than .05) during SLR exercises than during QS exercises. The study demonstrated remarkably different degrees of muscle activation between the SLR and QS exercises, indicating that the exercise selected will affect the therapeutic intention.     

Electromyographic effects of foot orthotics on selected lower extremity muscles during running.

OBJECTIVE: To study the effects of foot orthotics on the mean electromyographic amplitude of proximal and distal lower extremity muscle groups during the first 50% of the stance phase during treadmill running. DESIGN: Repeated measures. SETTING: Subjects were recruited from the general community. PARTICIPANTS: Twelve recreational runners who were symptomatic for lower extremity pain. Clinical and radiographic findings confirmed the presence of structural malalignment of the foot. INTERVENTION: Semirigid orthotics were fabricated for each subject, and like footwear provided. MAIN OUTCOME MEASURES: Surface electromyogram activity from the tibialis anterior, medial gastrocnemius, vastus medialis, vastus lateralis, and biceps femoris was collected during treadmill running at self-selected speeds for orthotic and nonorthotic conditions. Root mean square values were averaged across 10 cycles, normalized to time and expressed as a percentage of the nonorthotic condition. RESULTS: Paired t test results showed statistically significant changes (p<.05) for the biceps femoris (-11.1%) and tibialis anterior (+37.5%) muscle groups during the orthotic condition. Electromyographic activity in the medial gastrocnemius, vastus medialis, and vastus lateralis with orthotic use was not significantly different from the nonorthotic condition. CONCLUSION: Although subjects' electromyographic responses to orthotic use were highly individualized, the findings of this study may enhance our understanding of muscle activity changes associated with positive outcomes from orthotic use.     

A Study on the Differences of Quadriceps Femoris Activities by Knee Alignment during Isometric Contraction

[Purpose] This study attempted to identify how genu varum or valgum affects the electromyographic activities of the vastus medialis, vastus lateralis, and rectus femoris during knee isometric contraction. [Subjects] Fifty-two healthy young adults were enrolled in this study. They were enrolled and classified into three groups by knee alignment conditions: the genu varum, genu valgum, and control groups. [Methods] The electromyographic activity ratio of the vastus medialis to the vastus lateralis and rectus femoris were calculated using the percentage of maximum voluntary contraction. The participants contracted their quadriceps during isometric contraction at 30 and 60° of knee flexion. [Results] The genu varum group had more activity in the vastus medialis than in the vastus lateralis and rectus femoris, whereas the genu valgum group had more activity in the vastus lateralis and rectus femoris than in the vastus medialis. There was a significant difference in the muscle activity ratio between the vastus medialis and vastus lateralis by angle of knee flexion degree only in the genu valgum. There were no significant differences in any of the three groups in terms of the muscle activity ratio of the vastus medialis to the rectus femoris by angle of knee flexion. [Conclusion] The quadriceps femoris was used for different strategies according to knee alignment during isometric contraction at 30 and 60°. This study suggests that rehabilitation training programs used to strengthen the quadriceps should consider the knee alignment conditions of the target subjects.Key words: Electromyography, Quadriceps muscle, Isometric contraction     

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.     

Neuromuscular function during therapeutic knee exercise under water and on dry land

OBJECTIVES: To compare muscle activity and resistive drag force during knee extension-flexion exercises while barefoot and while wearing a Hydro Boot (increased frontal area) both under water and on dry land. DESIGN: Participants performed the exercises while seated on an elevator chair under water. SETTING: A hydrotherapy pool. PARTICIPANTS: Eighteen healthy persons (10 women, 8 men). INTERVENTIONS: Not applicable. MAIN OUTCOME MEASURES: Isokinetic and isometric forces were measured with a dynamometer. The electromyographic activity of the quadriceps (vastus medialis, vastus lateralis) and hamstring muscles (biceps femoris) was recorded. The underwater drag for the range of motion was calculated by using the general fluid equation. RESULTS: The underwater electromyographic patterns showed an early decrease in the concentric activity of the agonists with coincidental activation of the antagonists. In addition, the electromyographic amplitudes were similar between the 2 underwater conditions, but the Hydro Boot produced a higher level (p < .001) of drag than did the barefoot condition. As expected, in most cases the forces on dry land were higher (p < .001) than underwater drag. In flexion, however, the peak drag with Hydro Boot and isokinetic force did not differ. CONCLUSIONS: Increasing the frontal area of the lower leg with a Hydro Boot significantly increased the level of water resistance, thus, providing flexion forces that approach those measured on dry land. This type of water training offers stimulation to enhance the functional capacity and performance of the neuromuscular system. In addition, hydrodynamic principles and forces that influence the exercising limb must be considered to ensure appropriate progression.     

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.     

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.     

Effect of torso position on arthrometric assessment of anterior knee laxity

The purpose of the study was to examine the effect of changes in torso position on arthrometric assessment of knee laxity. Anterior tibial translation (ATT) of 12 control and 12 ACL deficient subjects was assessed using a Dynamic Cruciate Tester during five maximal isometric knee extensions and five passive tests (240 N load) on the right and left knee in each of three torso positions: vertical, reclined, and supine. Electromyographic activity of rectus femoris, vastus lateralis, biceps femoris, and semimembranosus were sampled during arthrometric assessment. Results indicated there was no significant difference in mean ATT as a function of torso position. However, subjects demonstrated significantly greater hamstring activity when seated vertically compared to reclined or supine and significantly greater hamstring activity when reclined compared to supine.     

Relationship between muscle echo intensity on ultrasound and isokinetic strength of the three superficial quadriceps femoris muscles in healthy young adults

[Purpose] The purpose of this study was to clarify the relationship between muscle echo intensity measured with ultrasound and the isokinetic strength of each of the three superficial quadriceps femoris muscles in healthy young adults. [Participants and Methods] We measured the echo intensity of the three superficial muscles of the quadriceps femoris in 25 healthy adults (10 males and 15 females; mean age, 22.3 years) using ultrasound. Moreover, we obtained the maximum force during isokinetic knee extension at 60°/s using an isokinetic dynamometer. [Results] In males and females, a significant negative correlation between echo intensity and muscle strength was found in the VM (r=−0.65 and r=−0.63, respectively). [Conclusion] In both males and females, only the muscle echo intensity of the vastus medialis was found to have a negative correlation with the maximum force during isokinetic knee extension at 60°/s. Our data lay the foundation for simplifying and rationally performing the measurement of muscle echo intensity of the quadriceps femoris. And it would therefore be sufficient to only measure the VM to clarify a relationship between EI and maximum isokinetic force in the quadriceps.Key words: Echo intensity, Isokinetic strength, Quadriceps femoris muscle     

Isokinetic, electrophysiologic, and clinical function relationships following tourniquet-aided knee arthrotomy

Few data exist pertaining to the validity of isokinetic muscle function tests, particularly in describing their interrelationships with other common clinical assessments. The purpose of this study was to critically analyze the maximal voluntary knee torque, motor unit activity, range of motion, and gait sequelae in a series of 95 patients who had tourniquet-aided meniscectomy or intra-articular loose-body removal. Prior to arthrotomy, affected and contralateral knee data differed minimally. In the first days following arthrotomy, the patients invariably demonstrated severe gait and muscle mechanical impairments, with grossly abnormal quadriceps femoris muscle motor unit activity. Of 32 patients consenting to one-month postoperative diagnostic electromyographic and nerve conduction velocity testing, 17 (53%) were found to have femoral neuropathies, with 8 of the 17 having other thigh and leg neuropathies as well. Patients with neuropathy recovered more slowly and scored significantly lower on functional and electrophysiological measures than patients without neuropathy. One month postarthrotomy, knee extensor torques, motor unit activity, and gait scores averaged about half the normal values, and knee flexion torques and ROM were about 75% of normal. Isokinetic device measurements were moderately related to other clinical measures of postarthrotomy outcome (.58 less than r less than .80). Knee torque measurements alone do not adequately characterize functional capacity.     

Gait and electromyographic analysis of patients recovering after limb-saving surgery

OBJECTIVE: Control of gait after limb-saving surgery.Design. Case series study. BACKGROUND: At the moment little is known about adaptations in patients' gait after limb-saving surgery. METHODS: Nineteen patients who underwent limb-saving surgery at least 1 yr earlier and 10 normal subjects were studied during treadmill walking. The main outcome measures were walking speed, step parameters and angular displacement of both legs and EMG of the biceps femoris, rectus femoris and medial gastrocnemius in the affected leg. RESULTS: Preferred walking speed in the patients was lower than in the controls (0.7 versus 1.1 m/s). Furthermore, stance phase of the non-affected leg was lengthened. All patients showed reduced stance phase knee flexion in the affected leg, while during the swing phase no difference was seen. The EMG signals of the rectus femoris and biceps femoris show changes, which are related to the location of surgery. CONCLUSIONS: The results showed that the gait pattern of the patients differed compared to normal gait. The reduced stance phase knee flexion in the hip group is based on a high degree of co-contraction between quadriceps and hamstring activity, while in the knee group this is based on the quadriceps avoidance pattern. The finding that there is still side-to-side asymmetry indicates that there is no complete reorganisation following the massive loss of input and output of the leg. It is possible that some reprogramming of the locomotor process occur. RELEVANCE: Gait and electromyographic analysis are essential for the quantitative assessments of the functional outcome in this type of surgery.     

Stiff-legged gait in spastic paresis. A study of quadriceps and hamstrings muscle activity.

Stiff-legged gait, ascribed to limited knee flexion during swing in spastic paresis, has previously received little detailed investigation. In this study, data from 23 patients referred for dynamic electromyographic evaluation of spastic stiff-legged gait were analyzed to identify timing of the activity of eight muscles during the gait cycle. Stride characteristics and foot switch data were also analyzed. Inappropriate activity in at least one of the quadriceps muscles during the preswing and/or initial swing phases was found in all 23 patients. Nine patients (39%) had hamstring activity during preswing. This group of 9, compared with the other 14 patients, had a significant reduction in average gait velocity and stride length (P less than 0.05) suggesting that preswing hamstring activity in stiff-legged gait may be counterproductive. No relation was found between biceps femoris (short head) activity and the amount of peak knee flexion attained in swing indicating that other factors are more important in attaining knee flexion. Delayed heel rise was observed in 21 patients (91%), which could imply insufficient calf muscle strength. Further, patients with markedly delayed heel rise achieved less peak knee flexion in swing than patients with normal or only moderately delayed heel rise (P less than 0.05). This may support the notion that adequate calf muscle strength is important in initiating knee flexion in the terminal stance/preswing phase. Results from this study provide preliminary quantitative information about stiff-legged gait that may prove useful in guiding management techniques.     

Timing and relative intensity of hip extensor and abductor muscle action during level and stair ambulation. An EMG study

The timing and relative intensity of electromyographic activity of hip abductor and extensor muscles were recorded during free and fast velocity walking and during ascent and descent of stairs. Eleven healthy subjects were tested using fine wire electrodes to record the electromyographic activity. Data were quantified by normalizing all electromyographic activity during gait with electromyographic activity occurring during a sustained maximum isometric effort resisted either manually or with a dynamometer. The results indicated that the hip extensor muscles had different phasic patterns and moments of peak activity. During level walking, the semimembranosus and long head of the biceps femoris muscles displayed the greatest swing phase activity (beginning in mid-swing). The adductor magnus muscle followed with its onset in terminal swing. Both this muscle and the gluteus maximus were the principal hip extensors active during the loading response. For ascending stairs, the lower portion of the gluteus maximus muscle proved to be the main hip extensor during the loading response and mid-stance. The findings also showed that the upper portion of the gluteus maximus muscle functioned more like the gluteus medius muscle than the lower portion of the gluteus maximus muscle during both level and stair walking.