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At least 127 records · Page 7Linked to original sources
PubMed2001

Aerobic metabolism of human quadriceps muscle: in vivo data parallel measurements on isolated mitochondria.

The aim of the present study was to examine whether parameters of isolated mitochondria could account for the in vivo maximum oxygen uptake (VO2max) of human skeletal muscle. VO2max and work performance of the quadriceps muscle of six volunteers were measured in the knee extensor model (range 10-18 mmol O2 x min(-1) x kg(-1) at work rates of 22-32 W/kg). Mitochondria were isolated from the same muscle at rest. Strong correlations were obtained between VO2max and a number of mitochondrial parameters (mitochondrial protein, cytochrome aa3, citrate synthase, and respiratory activities). The activities of citrate synthase, succinate dehydrogenase, and pyruvate dehydrogenase, measured in isolated mitochondria, corresponded to, respectively, 15, 3, and 1.1 times the rates calculated from VO2max. The respiratory chain activity also appeared sufficient. Fully coupled in vitro respiration, which is limited by the rate of ATP synthesis, could account for, at most, 60% of the VO2max. This might be due to systematic errors or to loose coupling of the mitochondrial respiration under intense exercise.

Adenosine Triphosphate↗
PubMed2002

Variability in human quadriceps muscles: quantitative study and review of clinical literature.

Knowledge of variations in normal human thigh musculature is important for the interpretation of various clinical and biomedical investigations. In this study, cross-sections from whole thighs of 34 cadavers were analyzed qualitatively and morphometrically. Sections were cut from right and left limbs at three levels in the region often used for muscle biopsy. Measurements were made of limb circumferences and cross-sectional areas of the three vasti and of the femur, and of the extent of overlap and fusion between the vasti on the lateral aspect of the thigh. Limb circumference proved to be a good predictor of total cross-sectional area of the quadriceps muscle. Large individual variations were found for most measurements but especially for the amount of fusion between the muscle bellies of vastus lateralis and vastus intermedius. Significant differences were found for most variables between the three levels, but there were few differences between sides except for the cross-sectional area of vastus lateralis which was greater on the right at the most distal level. These variations in size and form of thigh musculature should be considered when interpreting data obtained from muscle biopsy, imaging, biomechanical, electromyographic, and functional studies of the human thigh. Review of the literature on variability of quadriceps muscle and its clinical relevance showed a diversity of approaches but insufficient definitive data suitable for interpreting functional outcomes in response to exercise or following surgery. Further work is suggested combining current anatomical datasets with advanced imaging techniques capable of determining muscle fiber orientation and fiber type composition, and including 3D reconstruction.

Aged↗
PubMed1994

Assessment of quadriceps muscle performance by a hand-held dynamometer and an isokinetic dynamometer.

Assessment of muscle performance is an integral component of patient evaluation. The primary purposes of this study were to examine the relationship between isokinetic dynamometer isokinetic peak force values and hand-held dynamometer isometric peak force values when assessing quadriceps muscle performance in subjects with orthopaedic knee dysfunctions (N = 21) and to test for differences in muscle performance between injured and noninjured lower extremities using a hand-held dynamometer and an isokinetic dynamometer. An analysis of variance was used to compare injured and noninjured extremities for both testing devices. A Pearson product moment correlation was used to examine the relationship between the hand-held dynamometer and isokinetic dynamometer values. No significant difference between extremities at 0 degrees (p = 0.1224) or 60 degrees (p = 0.8267) was revealed when testing with the hand-held dynamometer. The isokinetic dynamometer, however, revealed a significant difference between extremities at 60 degrees/sec (p = 0.0041). Correlations between the two devices were significant, ranging from r = 0.57 to 0.80. We concluded that these correlations were misleading because more force was generated by the quadriceps muscles tested than a tester of average strength could resist. Further research is needed to validate the use of the hand-held dynamometer by a tester of average strength.

Adolescent↗
PubMed2001

Influence of Local Cooling on Proprioceptive Acuity in the Quadriceps Muscle.

OBJECTIVE: To test the influence of cooling on proprioceptive acuity as reflected in the ability to discriminate weights. DESIGN AND SETTING: Participants were trained to perform a weight-discrimination task. Their ability to correctly report small increments in weight was compared before and after local cooling (a 20-minute application of a crushed-ice pack) of the quadriceps muscle group. Data were collected at a university research laboratory. SUBJECTS: Twenty young, physically active adults (undergraduate students; 14 men, 6 women; mean age, 22.1 +/- 2.6 years). MEASUREMENTS: We calculated overall performance in the weight-discrimination task (percentage of discrimination correct) for each participant to estimate the differential threshold (ie, minimal increment in weight that yields a probability of 75% correct responses). RESULTS: Before local cooling, participants discriminated increments in the order of 4% to 10% from the standard weight (mean threshold, 0.17 +/- 0.06 kg). After local cooling, the discriminative performance remained, on average, very similar to that seen before cooling (mean threshold, 0.17 +/- 0.08 kg; paired t test: t = 0.24, P =.81). Only a small group of participants (n = 5) showed evidence of a decreased ability to discriminate weight after cooling. CONCLUSIONS: The perception of force signals required for weight discrimination does not appear to be affected by local cooling of the quadriceps muscle group. This finding provides additional evidence for the relative safety of cold applications and their effect on proprioceptive perceptual abilities.

Journal Article↗
PubMed1998

Quadriceps muscle injury in trans-femoral amputees.

Two male trans-femoral amputees using modular trans-femoral prostheses lost control and fell to the ground when their prosthetic knees gave way. The semi-automatic knee lock malfunctioned in the first case while the free knee stabilising mechanics gave way in the second case. This resulted in a high tensile force acting on the contralateral quadriceps muscle causing it to rupture. As there are a significant number of patients with both kinds of prostheses it is important to be aware of this possibility so that necessary actions can be taken to minimise its occurrence. Even with the currently available weight activated stance phase control, the prosthetic knee will give way if the knee is flexed more than 20 degrees on weight bearing. Good power and control of hip extensors on the amputation side is needed to control the prosthetic knee joint, especially in the early stage of the walking cycle, i.e., from heel strike to mid-stance. Quadriceps muscle injury in amputees, as far as the authors are aware, has not been reported previously.

Aged↗
PubMed1992

Effect of intraarticular glycosaminoglycan polysulfate treatment on patellofemoral pain syndrome. A prospective, randomized double-blind trial comparing glycosaminoglycan polysulfate with placebo and quadriceps muscle exercises.

OBJECTIVE: To compare the effects of intraarticular (IA) injections of glycosaminoglycan polysulfate (GAGPS) plus basic conservative treatment with the effects of placebo injections plus conservative treatment and with the effects of conservative treatment alone in patients with chronic patellofemoral pain syndrome (PFPS). METHODS: We treated 53 patients who presented with chronic PFPS in 1 knee, according to 1 of the 3 protocols, in a prospective, randomized, double-blind study. Basic conservative treatment consisted of a 6-week program of quadriceps muscle exercise, elimination of symptom-producing activities, and oral doses of nonsteroidal antiinflammatory drugs. Physiologic saline served as placebo for injection. During the 6-week treatment period, 5 injections were given 1 week apart. Along with measurements of quadriceps strength, standardized subjective, functional, and clinical assessments were performed at presentation, after 6 weeks of treatment, and after 6 months. RESULTS: Results at 6 months indicated that IA injections of GAGPS or saline did not result in significant improvement beyond the good results achieved by the basic conservative treatment alone. More than two-thirds of the patients in each group experienced complete recovery. CONCLUSION: Neither the GAGPS injections nor the physiologic saline injections are more effective than conservative therapy in the treatment of chronic PFPS. Restoration of normal quadriceps muscle function to the affected knee seems to be crucial in treating PFPS.

Adolescent↗
PubMedDate not supplied

[Diagnosis and treatment of iatrogenic retraction of the quadriceps muscle].

In the last two decades the iatrogenic retraction of the quadriceps muscle, which occurs in infants and young children following large numbers of injections performed in the thigh, has polarized the attention, especially as a result of the increasing frequency, and of the invalidating effects. The authors describe the symptoms that allow to make a diagnosis, both for the complete form, and for the form that involves the upper part of the thigh, a form that was studied and explained from the viewpoint of its mechanism, by one of the authors. Provided that the disease is correctly identified in a early stage, and the application of an adequate treatment, will led to recovery without sequels. In the case of the chronic form only surgery may lead to satisfactory results. The technique is described, of the quadriceps desinsertion, as it is performed in Clinic for Infantile Surgery and Orthopaedics from Bucharest. Since the results of the surgical treatment are of good quality in only 85% of the cases, the particular importance in stressed, of the preventive treatment.

Child, Preschool↗
PubMed1994

Knee extension strength and walking speed in relation to quadriceps muscle composition and training in elderly women.

Knee extension strength, walking speed, quadriceps muscle mass and composition of the muscle compartment were studied in 66 to 85-year-old female athletes and controls. Maximal voluntary knee extension force, force/body mass, extension torque, torque/body mass and walking speed were higher for the athletes than the controls. A muscle index indicating intramuscular fat and connective tissue measured using ultrasonography was lower for the athletes than the controls. There were no differences between the study groups in knee extension force related either to cross-sectional area (CSA) or lean tissue area (CSAL) of the quadriceps. Within the subgroups, there was no significant correlation between knee extension torque and CSA or CSAL of the same muscle. In the athletes high knee extension torque/body mass was related to a low muscle index and high walking speed to a low relative proportion of fat in the muscle. The muscle index was lower the more kilometers trained during the preceding year. In the controls high knee extension torque/body mass and high walking speed were related to a low relative proportion of fat. Knee extension torque and walking speed were higher the more kilometers walked during the preceding year. The results indicate that elderly female athletes have superior muscle performance compared to their age-peers. Performance in a maximal isometric strength test in elderly women is not clearly related to muscle mass. However, to some extent it is related to the composition of the same muscle, especially the degree to which fat is infiltrated into the muscle.

Adipose Tissue↗
PubMed2005

Switching stimulation patterns improves performance of paralyzed human quadriceps muscle.

The clinical efficacy of functional electrical stimulation (FES) is limited by the rapid onset of fatigue. Functional electrical stimulation applications typically stimulate skeletal muscles with constant-frequency trains (CFTs). Our laboratory has identified trains that we call doublet-frequency trains (DFTs) and that produce greater forces than CFTs, but more fatigue during repetitive activation than comparable CFTs. The purpose of this study was to see whether a series of CFTs followed by DFTs would reach a targeted isometric peak force more times than either train type alone during repetitive isometric activation of the paralyzed quadriceps muscles of subjects with spinal cord injuries (SCI). The combination of CFTs followed by DFTs reached the targeted isometric force 14% more often than the CFTs alone and 18% more often than the DFTs alone. These findings confirm that switching train types may be a useful strategy to offset the rapid fatigue of the functionally important quadriceps muscle that persons with SCI experience when using FES.

Adolescent↗
PubMed1985

The size and strength of the quadriceps muscles of old and young men.

The mean isometric strength of the stronger quadriceps muscles of 12 healthy men in their seventies was 39% less than that of 12 healthy men in their twenties (P less than 0.001). The cross-sectional area of the quadriceps was measured at mid-thigh, by ultrasound scanning; the older men's stronger quadriceps were 25% smaller (P less than 0.001). The ratio of the stronger quadriceps' strength to its cross-sectional area was very similar in the old men to values obtained previously for both old and young women, but averaged 19% less than in the young men (P less than 0.02). Quadriceps size and strength were correlated in the old men (r = 0.77, P = 0.03) but not in the young men (r = 0.15). The principal axis of the relationship between quadriceps size and strength in the old men was very similar to those previously reported for both old and young women. The quadriceps strength of some young men is greater than would be expected from the size of the muscle.

Adult↗
PubMedDate not supplied

Damage to the human quadriceps muscle from eccentric exercise and the training effect.

Nine participants performed two bouts of a step exercise, during which the quadriceps muscle of one leg acted eccentrically. Before and after the exercise, isokinetic torque was measured over a range of knee angles to determine the optimum angle for torque. Immediately after the first bout of exercise, the quadriceps showed a significant (P < 0.05) shift of 15.6 +/- 1.4 degrees (mean +/-sx) of its optimum angle in the direction of longer lengths, suggesting the presence of damage. A drop in peak torque, together with delayed soreness and swelling, confirmed that damage to muscle fibres had occurred. After the second bout of exercise, 8 days later, the shift in optimum angle was 10.4 +/- 1.0 degrees, which was significantly less than after the first bout (P < 0.05). Other indicators of damage were also reduced. In addition, the muscle exhibited a sustained shift in optimum angle (3.4 +/- 0.9 degrees), suggesting that some adaptation had taken place after the first bout of exercise. We conclude that muscles like the quadriceps can show evidence of damage after a specific programme of eccentric exercise, followed by an adaptation response. This is despite the fact that the quadriceps routinely undergoes eccentric contractions in everyday activities.

Adult↗
PubMed1999

Bilateral deficit of voluntary quadriceps muscle activation after unilateral ACL tear.

PURPOSE: The inability to fully activate the quadriceps femoris muscle voluntarily is known to accompany several different knee-joint pathologies. The extent of a voluntary-activation deficit in patients after isolated rupture of the anterior cruciate ligament (ACL), however, has been reported to be small or nonexistent, making it questionable if a voluntary-activation deficit is a relevant factor for these patients at all. METHODS: In this study the ability to voluntarily activate the quadriceps femoris muscles was quantified in 22 male patients with arthroscopically-proven isolated ACL ruptures using an established highly sensitive twitch-interpolation technique. Furthermore, the maximal voluntary contraction force of the quadriceps muscle was obtained by isometric knee-joint torque measurements. The results were compared with an age-, gender-, and activity-matched control group. RESULTS: There was a moderate but significant mean reduction in maximal voluntary activation (VA) in both the injured (VA: 83.9 +/- 2.3%, mean +/- SEM) and uninjured side (VA: 84.7 +/- 2.2%) in comparison with controls (VA: 91.1 +/- 0.8%). However, of the patients the 23% who presented a considerably reduced voluntary-activation of less than 80% were mainly responsible for the significant mean deficit. CONCLUSIONS: The deficit of isometric muscle strength on the injured side compared with that of controls was explained by the voluntary-activation deficit and a true muscle weakness. On the other hand, the diminished muscle strength of the uninjured side was explained sufficiently by the voluntary-activation deficit alone. Considering the bilateral voluntary-activation deficit, functional muscle tests might not be valid when the uninjured extremity serves as reference.

Adolescent↗
PubMed2002

Effects of training on contractile properties of paralyzed quadriceps muscle.

Effects of two different training regimens on the contractile properties of the quadriceps muscle were studied in six individuals with spinal cord injury. Each subject had both limbs trained with the two regimens, consisting of stimulation with low frequencies (LF) at 10 HZ or high frequencies (HF) at 50 HZ; one limb of each subject was stimulated with the LF protocol and the other with the HF regimen. Twelve weeks of daily training increased tetanic tension by approximately 20%, which was not significantly different between training regimens. Interestingly, after HF but not LF training, the unusual high forces at the low frequency range of the force-frequency relationship decreased, possibly due to a reduced activation per impulse. After LF but not HF training, force oscillation amplitudes declined (by 33%) as relaxation tended to slow, which may have opposed possible effects of reduced activation as seen after HF training. Finally, fatigue resistance also increased rapidly after LF training (by 43%) but not after HF training. These results indicate that different types of training may selectively change different aspects of function in disused muscles.

Adult↗
PubMedDate not supplied

Quantitative analysis of quadriceps muscle biopsy. Results in 30 healthy females.

Open biopsy was performed in right quadriceps muscle (vastus lateralis) in 30 healthy female volunteers between 20 and 50 years of age. Histometric analysis was carried out on ATPase stained sections preincubated at pH 4.5. Type 1, 2a, 2b, and 2 fibres were quantified taking into account the following parameters: percentage of fibre types, mean diameter, atrophy and hypertrophy factor, variability coefficient of mean diameter and mean diameter ratio of type 1: type 2 fibres. Results showed that there is a large variation in fibre type percentage, mean diameter and hypertrophy factor, and consequently ranges of normal values are wider than those previously reported. Atrophy factor and variability coefficient are the least variable parameters. The importance of normal controls is stressed to avoid false positives in histometric evaluation of muscle biopsy with minimal changes.

Adult↗
PubMed2001

[Assessment of quadriceps muscle isometric strength following operative treatment of femoral shaft fractures].

The authors investigated quadriceps muscle strength following operative treatment of femoral shaft fractures in 135 patients. Patients were categorized according to the kind of procedure performed: open Kuntscher intramedullary nailing--30 cases; Zespol--30 cases; AO plate osteosynthesis--47 cases and closed intramedullary nailing 28 cases. Two groups of patients were formed according to surgical technique: open method--107 cases and closed method--28 cases. 39 patients treated with an open method required re-operation. The best results were obtained in cases treated with closed technique--79.6%. The worst results were noted in the group requiring re-operation: 56.7%. The worst results were found in cases with comminuted fractures, and those located in the distal third of the femoral shaft.

Adolescent↗
PubMed1992

Selective involvement of the quadriceps muscle in congenital muscular dystrophies: an ultrasonographic study.

Muscle ultrasound scanning is a non-invasive and painless technique for evaluating muscle disorders in childhood. We have performed ultrasound scans of the quadriceps muscle in 26 children with various forms of congenital muscular dystrophies. There were 8 patients clearly showing selective involvement within the components of the quadriceps. In all cases showing selective involvement, the rectus femoris was spared and the vastus muscles were the affected group. Our findings support the concept of heterogeneity, often encountered in congenital muscular dystrophies.

Adolescent↗
PubMed1996

Effects of isometric strength training on quadriceps muscle properties in over 55 year olds.

Changes in strength, speed and size of the quadriceps muscle have been investigated in elderly men and women after 6 months of isometric strength training. We have also indirectly investigated the role of metabolites as a stimulus for muscle hypertrophy by studying two training protocols. One thigh was trained using short, intermittent contractions (IC), while the other trained using long, continuous contractions (CC). This meant that there should be a greater metabolite change in the muscle performing CC, as the blood flow is occluded for longer. Nine subjects [eight women, mean (SE) age, 71.8 (2.9) years] were measured for contractile properties and strength before and after training, and compared to nine age-matched controls [71.5 (2.1) years]. The training group increased quadriceps strength by 48.7 (9.1)% (P < 0.005) and 53.1 (11.3)% (P < 0.005) following the IC and CC protocols, respectively. There was no change in muscle strength in the controls. Both muscles showed significant slowing after training as measured by the relaxation times and the force-frequency ratio. There were non-significant decreases in muscle fatigability after training. The control group also showed some significant decreases in fatigability and muscle speed. The training group showed significant increases in muscle (and bone) cross-sectional area of 4.0 (1.7)% and 4.9 (1.3)% following the CC and IC protocols, respectively. These increases were significantly different from the decrease observed in the control group. These findings suggest that people over the age of 55 still have the capacity to increase muscle strength and size, and that the training causes slowing of the muscle. Muscle hypertrophy does not seem to be strongly influenced by metabolite changes in this age group, as there were no differences in measurements observed between protocols.

Aged↗