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PubMed1999

Biomechanics of human quadriceps muscles during electrical stimulation.

The quadriceps muscles of neurologically intact and spinal cord injured (SCI) human subjects were stimulated with constant current pulses. Up to three, separately adjustable stimulating electrodes over the motor points for vastus medialis (VM), vastus lateralis (VL) and rectus femoris (RF) muscles were used to maximize torque generation while minimizing discomfort. The torque generated by stimulation increased as the knee was slowly flexed to about 1 rad (50-60 degrees) and decreased beyond that point (a 'negative slope' on a torque-angle curve). Despite this region of negative slope the force generated by small oscillations remained positively correlated to the angle changes. When the knee was slowly extended again from a flexed position, the torque continued to decline and therefore showed a large degree of 'hysteresis'. Of the three heads studied, only stimulation of RF muscle generally produced this behavior. VL and VM had torques that increased monotonically with knee flexion over the range studied. The torques generated with electrical stimulation of normal subjects represented up to about 30% of maximum voluntary contraction. When subjects generated similar torques voluntarily, the negative slope region and substantial hysteresis were not observed. Thus, SCI subjects may be adversely affected by hysteresis during electrically-induced transitions from sitting to standing and vice versa, while normal subjects are not.

Adult↗

PubMed1987

Quadriceps muscle atrophy and long-term recovery after knee ligamentous injury.

The aim of the study was to clarify if atrophy of the quadriceps muscle was in itself related to clinical and radiological long-term outcome of primary knee ligament surgery. At Tampere University Central Hospital clinical and radiological reexamination was performed in 61 patients on an average 40 months after primary operation of acute knee ligament injury. The study group consisted of 26 patients having clear quadriceps muscle atrophy in the injured knee at the follow-up. Thirty four patients, having equal circumference of the thighs, served as controls. One patient was excluded. The groups did not differ significantly from each other in respect to age, sex, physical activity, type of ligament injury, meniscectomy, and follow-up time. In clinical reexamination the patients with quadriceps atrophy were placed significantly more often in groups of fair or poor healing than the patients with normal quadriceps muscle, and they had also more posttraumatic osteoarthritic changes in the injured knee. According to this study it seems that quadriceps muscle atrophy plays an important role as a poor prognostic factor of knee ligament injuries being thus a good target for efforts to stop the continuous deterioration of the injured knee.

Adult↗

PubMed2004

Recruitment of fibre types and quadriceps muscle portions during repeated, intense knee-extensor exercise in humans.

To investigate recruitment of slow-twitch (ST) and fast-twitch (FT) muscle fibres, as well as the involvement of the various quadriceps femoris muscle portions during repeated, intense, one-legged knee-extensor exercise, 12 healthy male subjects performed two 3-min exercise bouts at approximately 110% maximum thigh O2 consumption (EX1 and EX2) separated by 6 min rest. Single-fibre metabolites were determined in successive muscle biopsies obtained from the vastus lateralis muscle (n = 6) and intra-muscular temperatures were continuously measured at six quadriceps muscle sites (n = 6). Creatine phosphate (CP) had decreased (P < 0.05) by 27, 73 and 88% in ST fibres and 25, 71 and 89% in FT fibres after 15 and 180 s of EX1 and after 180 s of EX2, respectively. CP was below resting mean-1 SD in 15, 46, 84 and 100% of the ST fibres and 9, 48, 85 and 100% of the FT fibres at rest, after 15 and 180 s of EX1 and after 180 s of EX2, respectively. A significant muscle temperature increase (deltaTm) occurred within 2-4 s at all quadriceps muscle sites. DeltaTm varied less than 10% between sites during EX1, but was 23% higher (P < 0.05) in the vastus lateralis than in the rectus femoris muscle during EX2. DeltaTm in the vastus lateralis was 101 and 109% of the mean quadriceps value during EX1 and EX2, respectively. We conclude that both fibre types and all quadriceps muscle portions are recruited at the onset of intense knee-extensor exercise, that essentially all quadriceps muscle fibres are activated during repeated intense exercise and that metabolic measurements in the vastus lateralis muscle provide a good indication of the whole-quadriceps muscle metabolism during repeated, intense, one-legged knee-extensor exercise.

Adenosine Triphosphate↗

PubMed2004

Quadriceps muscle endurance in patients with chronic obstructive pulmonary disease.

The purpose of this study was to compare quadriceps muscle strength (maximal voluntary contraction, MVC), endurance (T(LIM)), and dynamic work capacity (W(LIM)) in 89 patients (57 men and 32 women) with chronic obstructive pulmonary disease (COPD) to 31 healthy controls (20 men and 11 women). Compared with the healthy subjects, COPD patients demonstrated statistically significant (P < 0.05) lower values for MVC, T(LIM) and W(LIM). The MVC was 20-30% lower, whereas T(LIM) and W(LIM) were 70-80% lower in the patients. Stepwise multiple regression analysis revealed that pulmonary function variables contributed only partially to the explanation of variance in MVC, T(LIM), and W(LIM). Our results indicate that in patients with COPD, quadriceps muscle endurance and dynamic work capacity are impaired to a greater extent than is quadriceps muscle strength. For rehabilitation purposes, the findings may lead to more specific exercise programs, further enhancing rehabilitation outcomes in terms of functional abilities and social participation.

Aged↗

PubMed1992

[Evaluation of nutritional status in patients with esophageal cancer by measurement of sternocleidomastoid, rectus abdominis and quadriceps muscles on ultrasound imaging].

To assess the nutritional status of the patients with esophageal cancer, we measured the areas of sternocleidomastoid and rectus abdominis muscles (SMA, RAMA) on real time ultrasound imaging and calculated muscle index (MI = (SMA+RAMA/Height)). Eighty-three patients with esophageal cancer were included in the present study. Preoperatively, significant Spearman's coefficients were found between MI and the percentage of standard arm circumference (R = 0.52) and between MI and the percentage of standard arm muscle circumference (R = 0.51). Postoperatively, patients with wide muscle area showed high values of prealbumin, transferrin and fibronectin. To study the changes after surgery, we also measured the area of quadriceps muscle in patients with esophageal cancer. The areas of quadriceps muscle in patients with dysphagia were much diminished than in those without dysphagia. Measurement of areas of muscles such as SMA, RAMA and quadriceps muscle was proved to be a useful procedure in evaluating the nutritional status of patients with esophageal cancer.

Abdominal Muscles↗

PubMed2001

Quadriceps muscle weakness following acute hemiplegic stroke.

OBJECTIVE: To determine whether quadriceps muscle weakness develops on the side ipsilateral to the brain lesion in the first week following acute ischaemic hemiplegic stroke. DESIGN: A prospective study of muscle strength. SETTING: Acute stroke unit (ASU) in a teaching hospital. SUBJECTS: Ten patients admitted within 48 hours of stroke onset, and 10 healthy age-matched controls. INTERVENTIONS: Repeat nonvolitional measurements of quadriceps muscle strength of the unaffected limb in patients and the right leg in normal subjects using magnetic femoral nerve stimulation (MS), prospectively one week apart. In addition the level of voluntary activation was assessed during a maximum voluntary contraction (MVC) manoeuvre. The Trunk Control Test (TCT) was measured in the patients. RESULTS: The median (95% confidence interval, (CI)) baseline quadriceps twitch tension (Tw Q) and MVC in the control group were 9.4 kg (6.1-12.5 kg) and 37.2 kg (23.8-54.6 kg), and in the stroke group were 7.6 kg (4.4-9.9 kg) and 12.15 kg (7.9-30.8 kg). The median (95% CI) change in Tw Q and MVC respectively between baseline and one week later were 1.75% (-9.8 to 8%) and 5.45% (-15.1 to 22.7%) (NS) in the control group and -16.2% (-6 to -25.9%) and -30.45% (0 to -78.6%) (p < 0.01) in the stroke patients. There was a significant correlation between the percentage fall in Tw Q and both change in TCT (rs = 0.83, p < 0.01) and percentage change in body weight (rs = 0.83, p < 0.01). CONCLUSION: In the first week after acute hemiplegic stroke, weakness develops in the unaffected leg.

Aged↗

PubMed1993

Surface electromyogram power spectrum in human quadriceps muscle during incremental exercise.

Spectral electromyographic (EMG) changes in human quadriceps muscles were studied to reinvestigate discrepant results concerning mean power frequency (MPF) changes during dynamic exercise. An incremental test consisting of a quasi-linear increase in mechanical power on a bicycle ergometer (for 20-100% of maximal aerobic power) was performed by forty subjects. During this test, surface EMGs from the quadriceps muscles showed that EMG total power (PEMG) increased with a curvilinear pattern for every subject, whereas MPF kinetics varied from one subject to another. PEMG changes had the same shape, which would lead to disappointing results in terms of discrimination between subjects. The ability of normalized MPF kinetics to define significant clusters of subjects was tested using a principal component analysis. This analysis led to the projection of all experiments onto a plane and revealed a relevant grouping of MPF profiles. Differences in MPF kinetics between clusters are interpreted in terms of various possibilities of balance between physiological events leading to an increase or a decrease in MPF.

Adult↗

PubMed1994

[An electromyographic study of quadriceps muscle force using turns and amplitude analysis].

The relationships between the quadriceps muscle force and electromyographic parameters during isometric and isokinetic knee extension were studied using "turns and amplitude analysis". Two groups of subjects were studied. One group was 40 healthy volunteers whose ages ranged from 16 to 58 years, with a mean of 30.6 years. The other group was 14 patients with unilateral muscle atrophy whose ages ranged from 16 to 53 years, with a mean of 34.2 years. The muscle force was measured using a Cybex II dynamometer, and electromyograms were recorded using a concentric needle electrode, for both groups. In the healthy group, an electromyogram was recorded in the vastus lateralis and vastus medialis, while in the patient group the electromyogram in the vastus lateralis was compared between the atrophied side and the normal side. During isometric knee extension, the muscle showed a significant correlation with amp/turn and turns/sec and the regression curve was expressed as a cubic function. The isokinetic knee extension showed a significant correlation between the muscle force and the amp/turn. In the atrophic muscle, the relationship between the electromyographic parameters and the muscle force was similar to that observed in the normal muscle. The average relative error between the actual muscle power and the calculated muscle power was less for amp/turn than for turns/sec. These results suggest that amp/turn can be used as an electromyographic indicator of quadriceps muscle force.

Adolescent↗

PubMedDate not supplied

Acute quadriceps muscle strains: magnetic resonance imaging features and prognosis.

BACKGROUND: There has been no research examining the magnetic resonance imaging findings, and in turn the prognosis, for a series of acute quadriceps muscle strains. HYPOTHESIS: The magnetic resonance imaging findings of acute quadriceps muscle strain injuries are helpful in predicting their prognosis. STUDY DESIGN: Causal-comparative study. METHOD: Forty professional players of Australian Rules football were followed over 3 years. Magnetic resonance imaging examinations were performed within 24 to 72 hours of muscle-strain injury. Imaging features of muscle strain injury included the anatomical location, size (cross-sectional area and length), and site (proximal, middle, or distal). The time from injury to return to full training was termed the rehabilitation interval. RESULTS: 25 clinical quadriceps muscle strain injuries occurred, with 15 cases involving the rectus femoris. The rectus femoris injuries could be further categorized into cases with straining about the central tendon (n = 7, mean rehabilitation interval = 26.9 days) or cases with straining in the periphery (n = 8, mean rehabilitation interval = 9.2 days). Six cases involved one of the vastus muscles (mean rehabilitation interval = 4.4 days). Three players had normal magnetic resonance imaging examinations (mean rehabilitation interval = 5.7 days). CONCLUSIONS: The rectus femoris-central tendon injury is the red flag diagnosis associated with a significantly longer rehabilitation interval. CLINICAL RELEVANCE: Magnetic resonance imaging is helpful in predicting the prognosis for acute quadriceps strains.

Acute Disease↗

PubMed1998

Mechanomyogram from the different heads of the quadriceps muscle during incremental knee extension.

To investigate the time- and frequency-domain responses of mechanomyograms (MMGs) during the progressive fatigue induced by intermittent incremental contractions, a surface MMG was obtained from the three muscle heads of the quadriceps muscle in seven subjects while they performed isometric knee extensions lasting 7.6 min. Isometric intermittent incremental contractions started at 1% of the maximal voluntary contraction (MVC) for 3 s, with a 3-s relaxation period in between each contraction, and the contraction level was increased by 1% of MVC for every contraction (by 10% of MVC per min) up to exhaustion. Separate contractions with sufficient rest periods were also conducted to serve for the MMG characteristics without fatigue. The integrated MMG (iMMG) was linearly related to force in all of the muscles when fatigue was not involved. With regard to the incremental contractions, the relationship exhibited an ascending-descending shape, but the behavior was not the same for the individual muscle heads, especially for the rectus femoris muscle. A steep increase in the median frequency of MMG from around 60% of MVC corresponded to a decrease in iMMG. These results suggest that analysis of MMG in the time- and frequency-domain during an incremental protocol is a useful way of characterizing the motor unit recruitment strategy and fatigue properties of individual muscles.

Adult↗

PubMed1977

Intracellular pH and bicarbonate concentration as determined in biopsy samples from the quadriceps muscle of man at rest.

1. A method for measuring intracellular pH and bicarbonate concentration of human muscle is described. 2. Muscle biopsies from the quadriceps muscle of 13 healthy subjects at rest were analysed for acid-labile carbon dioxide and volume of extra- and intra-cellular water. Extracellular water volume was estimated from the chloride content and intracellular water volume from the potassium content, or alternatively derived from the sample weight. 3. The measured total carbon dioxide content in muscle was 9-84+/-1-39 mmol/kg. 4. Assuming a normal membrane potential (88 mV) and PCO2 of muscle equal to venous blood, calculated intracellular pH was 7-00+/-0-06 and intracellular bicarbonate concentration was 10-2+/-1-2 mmol/l of water.

Adult↗

PubMed1994

Use of dynamic tests of muscle function and histomorphometry of quadriceps muscle biopsies in the investigation of patients with chronic alcohol misuse and chronic fatigue syndrome.

Ischaemic lactate/ammonia tests, serum carnosinase and creatine kinase assays and percutaneous needle muscle biopsies were performed on 10 patients with chronic fatigue syndrome (CFS), and 10 with chronic alcohol misuse complaining of muscular symptoms. Basal serum lactate levels were significantly elevated in the alcohol misusers compared to the CFS patients, but all were within the reference range. Lactate profiles after ischaemic forearm exercise did not differ significantly for the two patient groups. In one patient previously diagnosed as having CFS, myoadenylate deaminase deficiency was identified on the basis of a flat ammonia response to ischaemia and absent muscle adenosine monophosphate deaminase activity. In addition, two further patients in the CFS group were subsequently shown to have other disorders: one had polymyositis and one had myopathy with mild type II fibre atrophy of unknown cause. Histomorphometric examination of muscle needle biopsy in the alcohol misusers showed features of chronic alcohol-induced skeletal myopathy in six patients and polymyositis in one patient. Type II fibre atrophy factors were significantly elevated in the alcohol group but were within the reference range in CFS patients. Dynamic tests of muscle function and muscle histology are valuable tools in excluding alternative pathology in CFS, whereas muscle histomorphometry is of the greatest value in the diagnosis of chronic alcoholic myopathy.

AMP Deaminase↗

PubMed1984

Selective activation of quadriceps muscle fibers according to bicycling rate.

Moving average electromyography (MA) of quadriceps muscle bellies has been recorded during bicycling at different rates (30-70 cycles/min) or forces (1-3 kg). For power increments (50-100%) achieved by increasing force at constant rate, MA during pedal downstroke always increased. For similar power increments achieved by increasing the rate at constant force, MA did not increase (37% of cases), increased less (37%), or increased similarly (26%). Investigations by others on the rat suggest that the lack of increase of MA despite power increment was not compensated by other muscle activity; hence it indicates a shift from slow to fast fibers, which provide greater power per unit stimulus. Smaller increase of MA with increasing rate rather than force at isopower could depend on this shift or on muscle properties, if operating on ascending limb of power-velocity curve. This, however, does not seem the case for slow fibers, which should develop peak power at about 25 cycles/min. Hence, fibers of quadriceps muscle of humans seem selectively activated according to movement speed, as previously found in inspiratory muscles of rabbits.

Adult↗

PubMed1997

Mechanomyography of the human quadriceps muscle during incremental cycle ergometry.

The mechanical activity of the human quadriceps muscle during maximal incremental cycle ergometry was investigated by mechanomyography (MMG). MMG and surface electromyography (EMG) recordings of vastus lateralis muscle activity were obtained from nine males. Cycle ergometry was performed at 60 rev/ min and work load was incremented step wise by 20 W (3.2 Nm) every minute until volitional fatigue. The mean amplitudes of MMG (mMMG) and EMG (mEMG) during the contraction phase were calculated from the last six contractions in each load. The duration, load and work rate of exercise at exhaustion were 13.3 (1.6) min, 44.1 (5.5) Nm, 276.7 (34.7) W, respectively. A linear relationship between mMMG and load was evident in each subject (r = 0.868-0.995), while mEMG seemed to dissociate as the load became greater. In the grouped mean data, mMMG was linearly related to load whether aligned to the absolute (r = 0.995) or maximal (r = 0.995) load. Involvement of the noise component was further investigated by studying passive cycling by four subjects. Pedals were rotated passively for the first half of each stage (PAS) and the subject then pushed the pedals for the second half (ACT). In the lighter load region, the mMMG of ACT was as small as that of PAS. However, the change in the mMMG of PAS was very small compared with that of ACT. In conclusion, this study demonstrates a linear relationship between the mMMG of the quadriceps muscle and work load during maximal incremental cycle ergometry. The effect of movement noise was thought to be small and stable.

Adult↗

PubMed1995

Effects of prolonged exercise on the contractile properties of human quadriceps muscle.

The contractile properties of the quadriceps muscle were measured in seven healthy male subjects before, during and after prolonged cycling to exhaustion. Special efforts were made to obtain measurements immediately after exercise. The exercise intensity corresponded to about 75% of estimated maximal O2 uptake and time to exhaustion was mean 85 (SEM 9) min. At the end of the cycling heart rate and perceived exertion for the legs were 94% and 97% of maximal values, respectively. Maximal voluntary isometric force (MVC) had decreased after 5 min of exercise to a mean 91 (SEM 4)% of the pre-exercise value (P < 0.05) and decreased further to a mean 82 (SEM 6) and mean 66 (SEM 5)% after 40-min cycling and at exhaustion, respectively. A new finding was that during recovery reversal of MVC occurred in different phases where the half recovery time of the initial rapid phase was about 2 min. The MVC was a mean 80 (SEM 2)% of the pre-exercise value after 30 min and was not affected by superimposed electrical stimulation. Maximal voluntary concentric and eccentric forces decreased to 74% and 80% of initial values at exhaustion (P < 0.05). The kinetics of isometric contraction expressed as the time between 5% and 50% of tension (rise time) and the time between 95% and 50% of tension (relaxation time) were not significantly affected by the prolonged cycling. The electromechanical delay measured as the time between the first electrical stimulus and 5% of tension decreased from a mean 32 (SEM 1) ms at rest to a mean 26.6 (SEM 0.6) ms at fatigue (P < 0.05).(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗

PubMed1975

Femoral nerve compression syndrome with paresis of the quadriceps muscle caused by radiotherapy of malignant tumours. A report of four cases.

Four patients showed signs of femoral nerve compression with subsequent paresis of the quadriceps muscle, after radiation therapy of malignant tumours. The compression was caused by scar tissue due to radiation treatment of the inguinal region. The first symptom was radiating pain in the front of the thigh and lower leg which appeared 12-16 months after X-ray treatment. A decrease in the strength of quadriceps muscle occurred some months later. In one case the femoral nerve was decompressed, another patient was treated by an intradural phenolglycerin injection and one patient was treated with cortisone and oxiphenbutazone. In these cases the pain decreased considerably, but in one case only the paresis of the quadriceps muscle improved after treatment.

Adult↗

PubMed2000

Study of the control strategy of the quadriceps muscles in anterior knee pain.

Anterior knee pain (AKP) is a common pathological condition, particularly among young people and athletes, associated to an abnormal motion of the patella during the bending of the knee and possibly dependent on a muscular or structural imbalance. A lack of synergy in the quadriceps muscles results in a dynamic misalignment of the patella, which in turn produces pain. AKP rehabilitative therapy consists of conservative treatment whose main objective is to strengthen the Vastus Medialis. The aim of this article is to study the quadriceps muscle control strategy in AKP patients during an isokinetic exercise. Analysis of the muscle activation strategy is important for an objective measurement of the knee functionality in that it helps to diagnose and monitor the rehabilitative treatment. Surface electromyography (EMG) from the three superficial muscles of the femoral quadriceps during a concentric isokinetic exercise has been analyzed along with the signals of knee joint position and torque. A group of 12 AKP patients has been compared with a group of 30 normal subjects. Analysis of the grand ensemble average of the EMG linear envelopes in AKP patients reveals significant modifications in Vastus Medialis activity compared to the other quadriceps muscles. In order to study the synergy of the muscles, temporal identifiers have been associated to the EMG linear envelopes. To this end, EMG linear envelope decomposition in Gaussian pulses turned out to be effective and the results highlight an appreciable delay in the activation of the Vastus Medialis in AKP patients. This muscular unbalance can explain the abnormal motion of the patella.

Adolescent↗

PubMed2005

The efficacy of EMG-biofeedback training on quadriceps muscle strength in patients after arthroscopic meniscectomy.

AIMS: In 40 patients, we attempted to investigate the efficacy of electromyography-biofeedback (EMG-B) on quadriceps muscle strength after arthroscopic meniscectomy. METHODS: The patients were randomly divided into two groups each consisting of 20 subjects. For the control group, a classical exercise program was given (five sessions of EMG-B application for 2 weeks postoperatively). Range of motions, Lysholm knee score, EMG electrical activity values of vastus medialis obliques (VMO), and vastus lateralis (VL) were measured pre- and postoperatively on the 3rd and 14th day, and at the 6th week. RESULTS: When the ranges of motion values were compared, a significant difference (for average values of knee flexion angle) was found on the 14th day and 6th week in favour of biofeedback group (p<0.05). When Lysholm knee scores on the 14th day and 6th week were compared in the control and biofeedback groups, and maximum contraction and average contraction values of VMO, VL muscles were compared with operated/non-operated %age ratios, there was a statistically significant difference in favour of the biofeedback group (p<0.05). CONCLUSIONS: Our results showed that EMG-B was an effective treatment modality in improving quadriceps muscle strength after arthroscopic meniscectomy surgery.

Adult↗