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PubMed1980

Distribution and size of myofibers in quadriceps muscle of Syrian hamster.

Formalin-fixed myosin adenosine triphosphatase preparations of Syrian hamster quadriceps muscle showed myofibers distributed as follows: (1) vastus intermedius--light and dark fibers; (2) vastus medialis, rectus femoris, and vastus lateralis--light, intermediate, and dark fibers in the deep portion; and intermediate fibers with scattered dark fibers in the superficial portion. Transverse diameters varied among fibers in different portions of the quadriceps. These findings must be considered in experiments of muscle or motor endplates in hamster quadriceps muscle.

Animals↗

PubMed1984

Effects of hyperoxia and hypoxia on dynamic and sustained static performance of the human quadriceps muscle.

The influence of variations in inspired PO2 on dynamic and static muscle performance of the left quadriceps muscle was studied. Eight subjects performed (1) 60 maximal consecutive dynamic contractions and (2) one sustained exhaustive static contraction at 27% of maximal voluntary contraction (MVC). Breathing mixtures containing 11%, 21% or 99% O2, were administered. Peak torque as an average of the 60 knee extensions was higher (p less than 0.01) during hyperoxia (mean +/- SE = 104 +/- 4 Nm) than during normoxia (98 +/- 4 Nm), but did not differ significantly between hypoxia (95 +/- 5 Nm) and normoxia. Peak torque of individual extensions declined more rapidly during hypoxia than during normoxia, differing in the final 12 extensions by 11% from normoxic values. Static endurance time was reduced (p less than 0.02) during hypoxia (152 +/- 12 s) as compared to normoxia (189 +/- 13 s) and hyperoxia (169 +/- 11 s). No significant difference in endurance time was demonstrated between hyperoxia and normoxia. Thus, hypoxia impaired muscle performance in both dynamic and sustained static exercise, whereas acute hyperoxia improved dynamic but not static muscle performance. The results are interpreted in terms of differences in rate of intramuscular H+ accumulation.

Adult↗

PubMed1993

A musculotendon model of the fatigue profiles of paralyzed quadriceps muscle under FES.

In a previous work, we studied the mechanical and the metabolic profiles of fatigue of paralyzed quadriceps muscle under activation by FES. The metabolic state of the muscle during stimulation of paraplegic patients was monitored, simultaneously with the decaying force, by using 31P nuclear magnetic resonance spectroscopy. In the present work, a musculotendon model was developed to enable prediction of the force output during continuous electrical stimulation. The model consisted of five elements, including the tendon, the parallel elastic, contractile and damper muscle elements, as well as the muscle mass. The mechanism of the contractile element was based upon the length-tension and the velocity-tension curves, the activation trajectory, and the experimentally obtained relationship between force and intracellular pH. In the equations obtained, three sets of parameters were used: 1) general muscle parameters, associated with the length-tension curves of tendon, fascia, and muscle and the velocity-tension curve of the contractile element; 2) specific anthropometric parameters of the muscle; and 3) fatigue parameters which were obtained from our previously recorded experimental data. The model was formulated to allow prediction of the quadriceps muscle force under dynamic activation and at various levels of stimulation. The model solution was for isometric contraction in supermaximal stimulation, and it provided the force decaying profiles, which were compared to those obtained experimentally. The parameters yielding the best fit between the model and the experimental results were indicated. Particularly, two muscle nonspecific parameters, namely, the muscle stress parameter and the parameter representing the ratio between the muscle's slack length and its length in vivo at various knee angles, were determined using the model. The muscle stress parameter was found to be between 60 and 64 N/cm2, and the length ratio was 0.952, 0.935, 0.920, and 0.901 for the 0, 30, 60, and 90 degrees knee angle, respectively. Finally, a sensitivity analysis was conducted of the model to perturbations of these two estimated parameters, revealing that the model was sensitive to these parameters.

Biomechanical Phenomena↗

PubMed1972

Effect of temperature on muscle energy metabolism and endurance during successive isometric contractions, sustained to fatigue, of the quadriceps muscle in man.

1. The effects of altered tissue temperature on muscle metabolism during successive isometric contractions, sustained to fatigue, have been studied in the quadriceps muscle of man by combining biochemical analyses of metabolites in needle biopsy samples with measurements of endurance time with a force of 2/3 maximum voluntary contraction. Fatigue and recovery were observed repeatedly in a series of seven contractions at intervals of 20 sec, following immersion of the test leg in water at 12, 26 or 44 degrees C for 45 min. Muscle temperatures corresponding to these water temperatures were 22.5, 32.6 and 38.6 degrees C respectively.2. Increased levels of several glycolytic intermediates at rest in the heated muscle suggested an increased rate of glycolysis. ATP and phosphoryl creatine were lower at the end of the first contraction and the calculated rate of ATP utilization (including the contribution from anaerobic glycolysis) was highest in the heated nuscle.3. Significantly shorter endurance times were found for the heated muscle. These could not be attributed to depletion of local energy resources in muscle. Fatigue may be due to a reduction in the rate of regeneration of ATP from anaerobic glycolysis below that needed to maintain the contraction force. Lower values for the ratio of fructose 1,6-diphosphate: fructose 6-phosphate at the end of contractions, particularly at the highest temperature, are compatible with the hypothesis that there is partial inhibition of the rate controlling enzyme phosphofructokinase, possibly due to the accumulation of hydrogen ions in muscle.

Adenosine Diphosphate↗

PubMed2006

Exercise capacity and quadriceps muscle metabolism following training in subjects with COPD.

The aim of the study was to determine whether 16 sessions of exercise training, completed twice weekly, alters exercise capacity, quadriceps muscle metabolism, cross-sectional area (CSA) and strength in subjects with chronic obstructive pulmonary disease (COPD). We studied (a) 10 COPD subjects (mean age+/-sem = 71+/-2 years; FEV1 = 0.99+/-0.1 L) before and after 16 sessions of exercise training, and (b) 10 healthy subjects (age = 68+/-3 years). The COPD subjects underwent an incremental peak exercise test using a cycle ergometer and a 6-min walk test: both improved following exercise training (P < 0.05). Magnetic resonance spectroscopy measurements, in quadriceps muscle, of post-exercise phosphocreatinine (PCr) recovery kinetics were used to assess mitochondrial function in vivo: in the COPD subjects pre-training this was 19+/-8% lower than in healthy subjects (P = 0.03), but a 38+/-12% increase was seen in the COPD subjects following training (P = 0.003). Magnetic resonance imaging was used to assess quadriceps CSA: after training in the COPD subjects this showed a 7+/-2% increase (P = 0.03). Quadriceps strength, measured by the best of five maximum voluntary contractions, also showed a 32+/-11% increase in the COPD subjects (P = 0.007). Sixteen sessions of exercise training, performed twice weekly, increased exercise capacity as well as quadriceps mitochondrial capacity, CSA and strength in the subjects with COPD.

Aged↗

PubMed2003

Variability in fibre properties in paralysed human quadriceps muscles and effects of training.

A spinal cord injury usually leads to an increase in contractile speed and fatigability of the paralysed quadriceps muscles, which is probably due to an increased expression of fast myosin heavy chain (MHC) isoforms and reduced oxidative capacity. Sometimes, however, fatigue resistance is maintained in these muscles and also contractile speed is slower than expected. To obtain a better understanding of the diversity of these quadriceps muscles and to determine the effects of training on characteristics of paralysed muscles, fibre characteristics and whole muscle function were assessed in six subjects with spinal cord lesions before and after a 12-week period of daily low-frequency electrical stimulation. Relatively high levels of MHC type I were found in three subjects and this corresponded with a high degree of fusion in 10-Hz force responses (r=0.88). Fatigability was related to the activity of succinate dehydrogenase (SDH) (r=0.79). Furthermore, some differentiation between fibre types in terms of metabolic properties were present, with type I fibres expressing the highest levels of SDH and lowest levels of alpha-glycerophosphate dehydrogenase. After training, SDH activity increased by 76+/-26% but fibre diameter and MHC expression remained unchanged. The results indicate that expression of contractile proteins and metabolic properties seem to underlie the relatively normal functional muscle characteristics observed in some paralysed muscles. Furthermore, training-induced changes in fatigue resistance seem to arise, in part, from an improved oxidative capacity.

Adult↗

PubMed2001

Characterization of the human quadriceps muscle in active elders.

OBJECTIVE: To compare muscle activation deficits and muscle physiology in older versus younger adults. DESIGN: A maximal volitional isometric contraction of the quadriceps muscle with burst-superimposition was used to assess strength and activation. In addition, force-frequency testing during fresh, fatigue, and recovery conditions and electrically elicited fatigue testing were performed. SETTING: Muscle performance laboratory. PATIENTS: Healthy, active young (age range, 20-28 yr) and older (age range, 66-83 yr) subjects. MAIN OUTCOME MEASURES: Torque production, activation of the quadriceps, F50 values from the force-frequency relationships (frequency at which 50% of the maximum normalized force is produced), and the average amount of fatigue. RESULTS: Older subjects were weaker (574.4 +/- 156 N) than younger subjects (900.9 +/- 295 N) and had significantly greater deficits in central activation in the quadriceps muscles (elderly = 95.5% activation; younger = 98.1% activation). The force-frequency curves for the elderly were to the left of the younger subjects for all 3 testing conditions. Aged muscles fatigued to the same extent as younger muscle (young = 49.8% +/- 2.6%, elderly = 51.1% +/- 2.8%). CONCLUSIONS: These results can be used to modify high-intensity strength training protocols designed to optimize sustainable strength gains in the elderly during rehabilitation.

Adult↗

PubMed1993

Ultrasound measurement of quadriceps muscle in the first year of life. Normal values and application to spinal muscular atrophy.

Using real-time ultrasound imaging normal values were obtained for quadriceps muscle thickness and subcutaneous tissue depth in the first year of life from 120 normal infants. These values were corrected for weight and height by introduction of a "correcting factor". In addition, a "modified muscle index" was calculated by multiplying the ratio of muscle to subcutaneous tissue thickness with the correcting factor and showed a steady increase from birth (mean 2.1) to the end of the first year (mean 4.8). The study of 12 patients with spinal muscular atrophy type I (SMA I) revealed that 9 out of 12 SMA I patients failed to reach the 3rd percentile for the muscle to subcutaneous tissue ratio and 10 out of 12 were well below the 3rd percentile for the modified muscle index due to their muscle atrophy. Only the two youngest SMA I patients aged 4 and 6 weeks reached values on the 3rd percentile. In contrast, 10 patients with myopathy and one patient with holoprosencephaly showed values within the normal percentiles even in the presence of severe clinical muscle weakness and signs of atrophy on muscle histology. In the differential diagnosis of early onset myopathy, atrophy of the quadriceps muscle during the first months of life in the absence of markedly increased echodensity seems to be a pathognomonic finding for SMA.

Body Weight↗

PubMed1999

Non-uniform mechanical activity of quadriceps muscle during fatigue by repeated maximal voluntary contraction in humans.

To determine the non-uniform surface mechanical activity of human quadriceps muscle during fatiguing activity, surface mechanomyogram (MMG), or muscle sound, and surface electromyogram (EMG) were recorded from the rectus femoris (RF), vastus lateralis (VL), and vastus medialis (VM) muscles of seven subjects during unilateral isometric knee extension exercise. Time- and frequency-domain analyses of MMG and of EMG fatigued by 50 repeated maximal voluntary contractions (MVC) for 3 s, with 3-s relaxation in between, were compared among the muscles. The mean MVC force fell to 49.5 (SEM 2.0)% at the end of the repeated MVC. Integrated EMG decreased in a similar manner in each muscle head, but a marked non-uniformity was found for the decline in integrated MMG (iMMG). The fall in iMMG was most prominent for RF, followed by VM and VL. Moreover, the median frequency of MMG and the relative decrease in that of EMG in RF were significantly greater (P < 0.05) than those recorded for VL and VM. These results would suggest a divergence of mechanical activity within the quadriceps muscle during fatiguing activity by repeated MVC.

Adult↗

PubMed1993

Knee function after operation for malignancy of the distal femur. Quadriceps muscle mass and knee extension strength in 21 patients with hinged endoprostheses.

We evaluated quadriceps muscle mass and knee extension strength in 21 patients after resection and endoprosthetic replacement of the distal femur for malignant bone tumor. In all cases, a modular cementless, hinged prosthesis had been used. The mean follow-up period was 4 (2-9) years. Muscle mass was measured ultrasonographically, and strength isokinetically with a Cybex 6000 dynamometer. All the data for the operated side are given as percentage of the non-operated side. The average quadriceps mass was 48 (27-70) percent. The average peak torque was 31 (14-48) and 36 (18-55) percent at the speed of 30 degrees/s and 90 degrees/s, respectively. The reduction in extension strength became greater with increasing flexion. There was a moderate correlation between muscle mass and muscle strength. Most of the patients who had kept more than 40 percent of the quadriceps mass had more than 30 percent peak torque. Patients with excellent function (Enneking 1987) had more quadriceps muscle mass and higher strength than those that were merely good with the borderline at about 40 percent muscle mass.

Adolescent↗

PubMed1997

[Dynamic 31phosphorus magnetic resonance spectroscopy of the quadriceps muscle: metabolic changes under 2 different forms of loading].

PURPOSE: The aim of the present investigation was to examine the metabolism of the quadriceps muscles of normal young individuals using dynamic 31phosphorus magnetic resonance spectroscopy. METHODS: 22 normal individuals were examined in a 1.5T-MRT using a 6 cm surface coil. The metabolic changes in the quadriceps muscle as shown by the phosphorus spectrum were evaluated during rest, exercise (isometric and isotonic exercise) and during a 36-second period of recovery. RESULTS: The Pi/PCr quotient rose from its resting value of 0.11 +/- 0.02 following exercise to a maximum of 0.83 +/- 0.47 (isometric) or 1.40 +/- 0.59 (isotonic) (difference p = 0.0001). Half-time recovery of Pi/PCr was 35 +/- 11 s or 31 +/- 10 s, respectively (p = 0.13). During the recovery phase Pi/PCr fell briefly but significantly below its rest value. Following an initial rise in pH, there was a continual fall. Minimum pH (6.68 +/- 0.21 and 6.53 +/- 0.27 respectively; p = 0.01) occurred in the early recovery phase. The recovery process of pH values lasted longer following isotonic than after isometric exercise (half-value recovery time 229 +/- 72 s and 146 +/- 55 s, respectively; p = 0.001). CONCLUSION: Compared with isometric exercise, isotonic stress is more expensive in terms of metabolism. Dynamic 31phosphorus MRT spectroscopy can differentiate changes in muscle metabolism during different forms of exercise.

Adult↗

PubMed1987

Ultrastructural relationship of quadriceps muscle degeneration with a distant peroneal nerve conduction in human myotonia dystrophica.

The association of motor nerve conduction velocity (MNCV) to (1) duration of symptoms, (2) deep tendon reflex responses, (3) clinical muscle atrophy, and (4) ultrastructure of quadriceps muscle was studied in 18 patients with myotonia dystrophica of Steinert and nine normal controls. These patients had neither diabetes mellitus nor any other type of muscle dystrophy. Ultrastructural features of muscle fibers and intercellular spaces between atrophic fibers provided a basis for identifying degenerative changes and evaluating them semi-quantitatively. Our study indicates presence of an association between the pattern of muscle degeneration and both MNCV (correlation coefficients, gamma = +0.60) and duration of symptoms (gamma = -0.62), but not between MNCV and duration of symptoms (gamma = +0.28). Further analysis of the association between the degeneration of quadriceps and the MNCV of a distant peroneal nerve (which does not innervate quadriceps) suggested that the systemic nerve degeneration occurred in some groups of myotonia patients. Our study indicates that while in some patients the muscle degeneration may have been associated with the impairment of neurogenic elements, in others it occurred in the absence of any MNCV abnormality. Our findings favor the role of both neuropathic and myopathic factors in the muscle degeneration seen in myotonia dystrophica.

Adult↗

PubMed2006

Congenital contracture of the quadriceps muscle: confirming the diagnosis with magnetic resonance imaging.

Congenital contracture of the quadriceps muscle can be defined as progressive loss of knee flexion due to fibrosis within the muscle without a history of trauma or intramuscular injection into the thighs. In the course of time, secondary changes might develop and vitiate the end result so this rare childhood disease needs particular attention for early diagnosis and treatment. Herein, we report a 14-year-old girl presented with inability to bend her knees completely. The clinical and radiological assessment was detailed with magnetic resonance imaging findings.

Adolescent↗

PubMed1999

Quadriceps muscle strength, contractile properties, and motor unit firing rates in young and old men.

Changes with age in the voluntary static and dynamic strength of the quadriceps muscle group have been well characterized, and the importance of the muscle group for locomotion and independent living have been highlighted in both normal human aging and in clinical studies. Surprisingly few studies of this muscle group have described age-related changes in voluntary activation ability using twitch interpolation and changes in stimulated contractile properties, and none have assessed the influence of old age on motor unit firing rates. We compared in 13 young (mean age 26 years) and 12 old (mean age 80 years) men the voluntary isometric strength, stimulated contractile properties, and average steady state motor unit firing rates in the quadriceps muscle. Maximum voluntary contraction (MVC) force and twitch tension were approximately 50% lower in the old men, but contractile speed was only approximately 10% slower than in the young men. There was no difference in the ability of either group to activate the quadriceps to a high degree (94-96%). At all isometric force levels tested (10%, 25%, 50%, 75%, and 100% MVC), there were no differences in mean motor unit firing rates. In both groups, the range of firing rates was similar and not large ( approximately 8 Hz at 10% MVC and 26 Hz at MVC). Thus, the substantial age-related weakness in this muscle does not seem to be related to changes in neural drive.

Adult↗

PubMed1999

Quadriceps muscle strength and dynamic stability in elderly persons.

Several measures of dynamic stability during two functional activities correlated to quadriceps femoris muscle strength. A total of 34 disabled elders (aged 60-88) living in the Boston area consented to maximum isometric quadriceps muscle strength testing, chair rise and gait analysis. During chair rise, quadriceps strength significantly correlated with maximum upper body vertical linear momentum, r=0.53, P<0.005, anterior posterior linear momentum, r=0. 38, P<0.05, and the time to complete the chair rise, r=-0.48, P<0.05, n=29. Stride length and gait velocity correlated (r=0.56, P<0.001 and r=0.51, P<0.002, n=34) with quadriceps muscle strength. The maximum range of whole body anteroposterior (A/P) linear momentum during gait also correlated with quadriceps strength (r=0.47, P=0. 004, n=31). Dynamic stability during chair rise and gait, at preferred speed, correlates directly with quadriceps femoris muscle strength in functionally limited elderly individuals. In our sample, elders performed one of three movement strategies to arise from a chair, and quadriceps strength did not statistically differ between the chair rise strategy groups. However, persons with the greatest quadriceps strength values were more stable regardless of which chair rise strategy they performed. Our data indicate that clinicians should not suggest that patients use compensatory momentum inducing locomotor strategies unless the patient has sufficient strength to control these induced forces.

Age Factors↗

PubMed1996

A model of fatigue and recovery in paraplegic's quadriceps muscle subjected to intermittent FES.

The objective of this paper was to propose a mathematical model for the fatigue and recovery phases of a paraplegic's quadriceps muscle subjected to intermittent functional electrical stimulation (FES). The model is based on in vivo, noninvasive, recording of fatigue related metabolic parameters recorded during stimulation and recovery. Records of the time variations of the muscle's phosphorus metabolites, particularly the phosphocreatine (PCr) and inorganic phosphorus (Pi), obtained from 31P magnetic resonance spectroscopy (MRS), were used to calculate the intracellular pH level in the muscle and this latter parameter was incorporated in a musculo-tendon model. The fatigue-recovery model allows the transition from the fatiguing phase to the recovery phase as soon as the stimulation terminates and vice versa. This model was incorporated into a Huxley type muscle model expressing the dynamics of the muscle. Two ordinary differential equations describing the musculo-tendon dynamics and the dynamics of the activation were solved simultaneously and records of the force trajectory during intermittent stimulations were obtained. Study cases ranging from 5 to 30 s for each of the stimulation and recovery alternating phases were stimulated. The force and the total impulse in the modeled quadriceps muscle were computed. It was found that the greatest impulse was produced in intermittent stimulation of 40-50 s duty cycle, with a 50 percent ratio between the stimulation and recovery intervals. An additional series of six runs, including two contractions, one of 3 min and one of 1 min, separated by rest periods of 3, 6, 9, 12, 15, and 30 min was performed. From the predicted force trajectories obtained, the maximal force values served for comparison with measured values made on one patient.

Electric Stimulation↗

PubMed1981

Variations in single fibre areas and fibre composition in needle biopsies from the human quadriceps muscle.

Cross-sectional area of a single fibres and the fibre distribution were measured for the two main types of fibres in needle biopsies from the quadriceps muscle of ten healthy young males. Methodological errors expressed as coefficient of variation (CV) of a single value for the area measurements were analysed and found to be 2.4% including the intraindividual error in handling the planimeter. An inhomogeneity in distribution and size of the fibres within the quadriceps muscle was indicated by a CV within the same section of 6-8% and between repeated biopsies of 15-20%.

Biopsy, Needle↗

PubMed1984

Size and strength of the quadriceps muscles of old and young women.

Muscle weakness and wasting may be evaluated objectively by dynamometry and compound ultrasound imaging. We have measured the voluntary isometric strength of the quadriceps muscles of healthy women in their 70s (n = 25) and in their 20s (n = 25) and have compared it with the mid-thigh cross-sectional area of the same muscles. The two groups of women showed similar variability when strength was measured on consecutive days (coefficients of variation: 8%). The older women were 35% weaker than the young women (P less than 0.001) and their quadriceps cross-sectional area was 33% less (P less than 0.001). Quadriceps strength and cross-sectional area were correlated (r = 0.66, P less than 0.001, elderly; r = 0.53, P less than 0.01, young) and the principal axis of the relationship was closely similar for the two groups of women. There is therefore no difference in the intrinsic strength of the quadriceps muscles of healthy women in their third and eighth decades. This report also provides normative data for the objective evaluation of quadriceps weakness and/or wasting in female patients. The techniques involved are straightforward, the dynamometer is easily made, and compound ultrasound imaging is widely available.

Adult↗