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PubMed1999

Contractile properties of the quadriceps muscle in individuals with spinal cord injury.

Selected contractile properties and fatigability of the quadriceps muscle were studied in seven spinal cord-injured (SCI) and 13 able-bodied control (control) individuals. The SCI muscles demonstrated faster rates of contraction and relaxation than did control muscles and extremely large force oscillation amplitudes in the 10-Hz signal (65 +/- 22% in SCI versus 23 +/- 8% in controls). In addition, force loss and slowing of relaxation following repeated fatiguing contractions were greater in SCI compared with controls. The faster contractile properties and greater fatigability of the SCI muscles are in agreement with a characteristic predominance of fast glycolytic muscle fibers. Unexpectedly, the SCI muscles exhibited a force-frequency relationship shifted to the left, most likely as the result of relatively large twitch amplitudes. The results indicate that the contractile properties of large human locomotory muscles can be characterized using the approach described and that the transformation to faster properties consequent upon changes in contractile protein expression following SCI can be assessed. These measurements may be useful to optimize stimulation characteristics for functional electrical stimulation and to monitor training effects induced by electrical stimulation during rehabilitation of paralyzed muscles.

Adult↗
PubMed1986

Quantitative analysis of quadriceps muscle biopsy. Results in 7 definite and 45 possible carriers of Duchenne muscular dystrophy.

Quadriceps muscle biopsy was performed in 7 definite and 45 possible carriers of Duchenne muscular dystrophy. Unequivocal morphological changes were observed in 8 women; all but one of them were already detected as carriers by increased serum CK. Histometric analysis of muscle biopsy was performed on two fibre types (type 1 and type 2) in all 52 women; in 38 of them the two subgroups of type 2 fibres (type 2a and type 2b) were also quantified. Results of histometric analysis were matched with control values obtained from 30 healthy females in the same age as the carriers (20-50 yr). Histometric analysis on two fibre types detected a percentage of carriers (27%) much lower than that detected by serum CK determination (44%). The detection rate of combined serum CK determination and histometric analysis of muscle biopsy was: 100% in definite carriers, 65% in mothers possible carriers, 38% in sisters and 25% in the group of cousins and aunts. The histometric parameters most frequently altered were atrophy factor and variability coefficient of mean diameter. Histometric analysis carried out on three fibre types in 38 women detected 2 more carriers showing atrophy of type 2b fibres. The results indicate that quantitative analysis of muscle biopsy may be used to detect some possible carriers with normal serum CK. However, an adequate number of controls is mandatory; in fact the detection rate of histometric analysis of muscle biopsy decreased by increasing the number of controls, resulting much lower than previously reported.

Adult↗
PubMed1991

Relaxation and force during fatigue and recovery of the human quadriceps muscle: relations to metabolite changes.

Force and relaxation were measured during electrical stimulation of the quadriceps muscle of 14 volunteers. Stimulation produced 51.2 s of intermittent ischaemic contractions either as 16 3.2-s tetani or as 64 0.8-s tetani. Changes during recovery were followed for 180 s. On 8 subjects muscle biopsies were taken during work and after the rest period for determination of ATP, phosphocreatine and intermediates in glucolysis. The stimulation using 0.8-s contractions gave more pronounced fatigue and slowing of relaxation. There was a good correlation between force and relaxation during work but this relation changed during recovery, indicating that no general relation exists between these two contraction characteristics. In the 0.8-s stimulation more ATP was utilized and there were more profound changes in metabolite levels. We found a correlation between estimated [H2PO4-] and relaxation covering both work and recovery and hypothesize that inorganic phosphate and its removal by phosphocreatine resynthesis during recovery might be important. Since stimulation patterns differ in force and relaxation even after the recovery period we suggest that additional factors, such as pH, are of importance in this work model.

Adenosine Triphosphate↗
PubMed1985

Thickening of the capillary basement membrane of the quadriceps muscle in Vacor-induced diabetic patients.

The effect of Vacor diabetes mellitus on the quadriceps muscle capillary basement membrane thickness has been examined by the electron microscopic method. With this procedure, it was possible to obtain an objective evaluation of the significance of capillary basement membrane thickening in Vacor diabetes mellitus. The results of such a study on the muscle capillary basement membrane in 10 normal subjects and 9 Vacor-poisoned patients have demonstrated the following: (1) the average basement membrane width of Vacor patients (2801 A +/- SD 614) is over twice that of normal subjects (1300 +/- 185 A), and all 9 cases demonstrated muscle capillary basement membrane thickening; (2) there is a significant association of basement membrane width with age (P less than 0.01), but not with the duration of the disease or fasting blood glucose values in the Vacor group. The results of the present study indicate that diabetes mellitus induced by Vacor poisoning can lead to microangiopathy, and that such basement membrane thickening is an early and consistent finding.

Adolescent↗
PubMed1979

The effect of long-term arterial occlusion on energy metabolism of the human quadriceps muscle.

The effect of 1.5 to 2.5 h tourniquet ischemia on energy metabolism of the quadriceps muscle was studied using percutaneous needle biopsy technique in sixteen patients operated on for an inveterated knee injury. During occlusion there was a moderate decrease in ATP with an increase in ADP and AMP. This change resulted in a decreased energy charge potential. At the same time phosphorylcreatine (PC) decreased markedly while creatine (Cr) increased giving a constant total creatine (TCr). An accumulation of lactate during occlusion with values up to 80 mmol/kg d.m. (dry muscle) was seen. A 15% reduction in glycogen was calculated. After release of the tourniquet the active phosphate concentration and the energy charge potential returned to basal levels within 5 min and most of the metabolites in the glycolytic sequence were also normalized. Muscle lactate content was normal after 30 min of intact circulation. The results suggest that longterm tourniquet ischemia induces marked changes in energy metabolism in skeletal muscle, but that the changes are rapidly and completely reversible with restoration of blood flow.

Adenosine Diphosphate↗
PubMed1990

Recruitment, force and fatigue characteristics of quadriceps muscles of paraplegics isometrically activated by surface functional electrical stimulation.

This study deals with the recruitment characteristics of unfatigued electrically stimulated quadriceps muscles of paraplegic subjects and with the time-dependent force output of these muscles under sustained stimulation conditions. Both these aspects of the performance of paralysed stimulated muscles were studied under isometric conditions and at different muscle lengths. The forces in the knee joint resulting from stimulation of the quadriceps were also calculated. Recruitment force curves due to a ramp-like stimulation function indicated a strong dependence on muscle length and demonstrated a sigmoid-shaped curve with three distinct regions: negligible force up to threshold stimulation intensity; rapid force increase; and levelling-off of the curve after which the force remains constant even though intensity is further increased. When normalized to the maximal force, recruitment was found to be independent of muscle length, generating a typical recruitment curve for every patient, under isometric stimulation. The peak forces were obtained at the same flexion angles previously published for normal subjects, but with much lower values. Muscle fatigue in tetanic isometric conditions, defined as the decrease in force due to sustained stimulation with fixed parameters, was found to be length dependent and to have a double exponential decay. The first is the acute force loss and is the more significant for functional purposes; the second is the more moderate and asymptotic region, in which partial force recovery in the form of bursts is observed.

Biomechanical Phenomena↗
PubMed2000

Altered pathological progression of diaphragm and quadriceps muscle in TNF-deficient, dystrophin-deficient mice.

We have previously demonstrated a role for T cells in Duchenne muscular dystrophy (DMD) using the mdx mouse and have shown that T cell killing of dystrophic muscle can occur through perforin-dependent and perforin-independent mechanisms. In this investigation, we explore the possibility that one perforin-independent mechanism utilized by the T cells is cytokine-based killing, specifically by tumor necrosis factor (TNF). We tested this hypothesis by generating mice that are TNF-deficient and dystrophin-deficient (TNF-/mdx). Body mass and muscle mass of the TNF-/mdx mice were significantly less than TNF+/mdx mice at 8 weeks of age. Creatine kinase levels and overall muscle strength were unchanged. Histopathology measurements showed different results in the diaphragm and quadriceps muscles. These data suggest that removal of TNF in vivo in dystrophic mice has differential effects on diaphragm and quadriceps suggesting that TNF is an unfavorable target for immunotherapy for DMD.

Age Factors↗
PubMed2005

The impact of foot position on electromyographical activity of the superficial quadriceps muscles during leg extension.

This study investigated variations in electromyographic (EMG) responses of the vastus lateralis (VL), rectus femoris (RF), and vastus medialis (VM) due to foot position during leg extension. Twenty-four men and women (23.67 +/= 4.02 years) performed 8 repetitions at 70% of 8 repetition maximum with their leg medially rotated, laterally rotated, and neutral. Repeated-measures analyses of variance indicated that the highest normalized root mean square (NrmsEMG) for the VM and VL occurred with medial rotation, and the highest NrmsEMG for the RF occurred with lateral rotation. Significant NrmsEMG increases and median power frequency decreases occurred across repetitions regardless of foot position. Therefore, medial rotation produced the greatest muscle activation for the VL and VM, whereas lateral rotation produced the greatest activation in the RF. These findings are applicable to athletes or bodybuilders who are seeking to selectively increase either the size or performance of a specific muscle of the quadriceps group.

Adolescent↗
PubMed2003

Low frequency fatigue of quadriceps muscle after sustained maximum voluntary contractions.

Immediately after sustained maximum voluntary contractions for 60 s, greater quadriceps muscle fatigue and, especially, low frequency fatigue is observed. The results of our study have shown that immediately after the exercise there was a significant (P<0.05) decrease in muscle force induced by low (20 Hz) and high (50 Hz) stimulation frequencies and maximum voluntary contractions (it is not muscle length-dependent) and it did not recover to its initial (pre-exercise) level 15 min after the end of exercise. These observations suggest the observed low frequency fatigue may consist of 2 phases: an early, rapid recovery phase (to 3 min), likely related to muscle potentiation and metabolite build-up, and a slow recovery phase, which is not dependent on metabolite levels, but is especially dependent on muscle mechanical damage. There is an increase in low frequency fatigue during a slow recovery phase and it is more pronounced when low frequency fatigue is registered at short muscle length.

Adult↗
PubMed1992

Recovery from exercise-induced desaturation in the quadriceps muscles of elite competitive rowers.

A simple muscle tissue spectrophotometer is adapted to measure the recovery time (TR) for hemoglobin/myoglobin (Hb/Mb) desaturation in the capillary bed of exercising muscle, termed a deoxygenation meter. The use of the instrument for measuring the extent of deoxygenation is presented, but the use of TR avoids difficulties of quantifying Hb/Mb saturation changes. The TR reflects the balance of oxygen delivery and oxygen demand in the localized muscles of the quadriceps following work near maximum voluntary contraction (MVC) in elite male and female rowers (a total of 22) on two occasions, 1 yr apart. TR ranged from 10 to 80 s and was interpreted as a measure of the time for repayment of oxygen and energy deficits accumulated during intense exercise by tissue respiration under ADP control. The Hb/Mb resaturation times provide a noninvasive localized indication of the degree of O2 delivery stress as evoked by rowing ergometry and may provide directions for localized muscle power output improvement for particular individuals in rowing competitions.

Capillaries↗
PubMed2003

A more efficient magnetic resonance imaging-based strategy for measuring quadriceps muscle volume.

PURPOSE: To determine the accuracy of several magnetic resonance imaging (MRI)-based strategies for assessment of quadriceps muscle volume (MV) and changes in MV with training. METHODS: Images were acquired along the length of both thighs from young (26 +/- 3 yr, N= 23) and older (69 +/- 3 yr, N= 24) men and women before and after strength training. The quadriceps cross-sectional area (QCSA) of each section was measured before and after training. MV was directly assessed using all of the sections (each 9-mm thick with a 1-mm gap). Alternative estimates of MV were calculated using increasingly greater intervals between sections: every 1.1 cm (MV2), 3.1 cm (MV4), 5.1 cm (MV6), 7.1 cm (MV8), 9.1 cm (MV10), and a single QCSA (L1). The 95% limits of agreement (LOA, +/- 2 SD) between each alternative measure and the criterion measure MV were determined with Bland and Altman plots. Regression was used to predict MV from L1 and to obtain the standard error of the estimate (SEE). RESULTS: Before training, the 95% LOA with MV for the alternative measures ranged from 0.7% to 6.36% of MV, and the prediction of MV from L1 yielded a SEE x 2 of 14.1% of MV. For change in the alternative measures, the 95% LOA ranged from 10.3% to 26.3% of the total change in MV, and the prediction of deltaMV from deltaL1 yielded a SEE x 2 of 60% of the change in MV. CONCLUSION: Increasingly greater intervals between axial MRI sections result in substantially reduced agreement with a criterion measure of MV. The use of one axial section results in relatively higher error and thus should be used only when large effect sizes are expected.

Adult↗
PubMed1997

Size and strength of the respiratory and quadriceps muscles in patients with chronic asthma.

There have been few studies of respiratory and limb muscle size and function in middle-aged patients with asthma and persistent airways obstruction. We have compared the forces generated by the respiratory and thigh muscles with their dimensions assessed by ultrasound in nine middle-aged patients with chronic asthma (mean age 56 (SD 8) yrs; functional residual capacity/total lung capacity ratio (FRC/TLC) 60 (10)%), and in nine normal subjects (aged 53 (7) yrs; FRC/TLC 55 (5)%). Diaphragm thickness was measured at the zone of apposition by B-mode ultrasound during relaxation (DiTrelax) and during a maximum-effort inspiratory manoeuvre (DiTpI,max) at FRC. Cross-sectional area of the relaxed rectus femoris muscle (ARF) was determined by ultrasound at mid-thigh level. Isometric strength of the right quadriceps muscle group was measured during maximum voluntary contraction. Asthmatic patients had preserved quadriceps strength and ARF but moderately impaired maximum inspiratory pressure (PI,max) (-52 (18) cmH2O) and thicker DiTrelax (2.2 (0.4) mm), compared to normal subjects (-73 (21) cmH2O and 1.7 (0.3) mm, respectively). Middle-aged patients with chronic asthma and a small increase in functional residual capacity/total lung capacity ratio have preserved limb muscle force and dimensions, modestly impaired inspiratory muscle strength, and slightly increased thickness of the costal diaphragm. Future studies of respiratory muscle function in asthma should be aided by measurement of diaphragm thickness and of limb muscle strength and size. Such studies are required particularly in older patients with severe hyperinflation who are most likely to have impairment of muscle function.

Airway Obstruction↗
PubMed2005

Cystic hygroma in the quadriceps muscle: a sanguine diagnosis for knee pain.

Reported here is a 28-year-old female who presented with severe right knee pain and swelling nearby the joint. Ultrasonography, magnetic resonance imaging and eventually surgery were performed. She was diagnosed to have a cystic hygroma in the vastus lateralis muscle. This is the first patient of a cystic hygroma in the quadriceps muscle.

Adult↗
PubMed1995

Contractile properties of the quadriceps muscle in growth hormone-deficient hypopituitary adults.

1. Growth hormone-deficient hypopituitary adults often complain of weakness and fatigue. The cause of the fatigue is unknown but could be an increased proportion of fast, fatiguable, type 2 fibres in the muscle. The aim of this study was to examine the contractile properties of the quadriceps muscle in a group of these patients compared with healthy controls. Changes in these properties were also examined in a small subset of the patients following growth hormone replacement. 2. Isometric strength, half-relaxation time from a twitch (t1/2) and the force-frequency relationship were measured using electrically evoked contractions in 14 growth hormone-deficient patients and 14 age- and sex-matched controls. Six patients were restudied following 6-24 month's replacement therapy with growth hormone (daily dose 0.04 +/- 0.01 i.u./kg). 3. The growth hormone-deficient patients had a significantly lower t1/2 than the controls (46.1 +/- 6.1 ms versus 56.1 +/- 10.5 ms respectively; P = 0.0072; mean +/- SD). The 10/100% ratio was also significantly lower in growth-hormone-deficient patients (38.6 +/- 9.9% versus 52.3 +/- 8.0%; P = 0.0005), as was muscle strength (349 +/- 99 N versus 493 +/- 215 N; P = 0.036). Following growth hormone replacement, muscle strength increased significantly (P < 0.05). The 10/100% ratio also increased towards control values, but this change was not significant. 4. These results demonstrate that the relaxation times of the quadriceps are significantly shorter and that the force-frequency relationship shifted to the right in growth hormone-deficient patients, which is consistent with a greater proportion of type 2 fibres within the muscles.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed2002

Complete paralysis of the quadriceps muscle caused by traumatic iliacus hematoma: a case report.

A15-year-old girl who developed traumatic iliacus hematoma and complete paralysis of the quadriceps muscle is reported. The current case and literature review revealed that incomplete quadriceps paralysis associated with traumatic iliacus hematoma is likely to progress to complete paralysis in days or weeks as a result of increased intracompartmental pressure. However, surgical decompression of the femoral nerve could produce good results even in patients who have complete quadriceps paralysis preoperatively.

Accidental Falls↗
PubMed1990

Influence of intravenous local anaesthetics upon quadriceps muscle function.

This study was undertaken to assess the effects of intravenous administration of mepivacaine and etidocaine on muscle function. Seven male volunteers were given mepivacaine (5 mg/kg) and etidocaine (50 mg) intravenously, on separate occasions. A reference group of 11 male volunteers received 0.9% saline solution intravenously. Muscle function was tested by measurements of isometric muscle force of knee extension and by quantitative electromyographic (EMG) recordings from the quadriceps muscle during knee extension at different degrees of isometric muscle force. At the end of the mepivacaine and etidocaine infusions, the mean venous plasma concentrations of the two anaesthetic agents were 2.9 and 1.2 micrograms/ml, respectively. The muscle strength remained unchanged during infusion of the two local anaesthetics. Mepivacaine had a minor effect on the mean rectified EMG amplitudes at the end of the infusion at maximal voluntary muscle contraction, but no such effect was observed at submaximal knee extension force. However, at the plasma concentrations mentioned above, the clinical influence of intravenous infusion of the local anaesthetics on muscle function was negligible.

Adult↗
PubMed2005

Coordinated collagen and muscle protein synthesis in human patella tendon and quadriceps muscle after exercise.

We hypothesized that an acute bout of strenuous, non-damaging exercise would increase rates of protein synthesis of collagen in tendon and skeletal muscle but these would be less than those of muscle myofibrillar and sarcoplasmic proteins. Two groups (n = 8 and 6) of healthy young men were studied over 72 h after 1 h of one-legged kicking exercise at 67% of maximum workload (W(max)). To label tissue proteins in muscle and tendon primed, constant infusions of [1-(13)C]leucine or [1-(13)C]valine and flooding doses of [(15)N] or [(13)C]proline were given intravenously, with estimation of labelling in target proteins by gas chromatography-mass spectrometry. Patellar tendon and quadriceps biopsies were taken in exercised and rested legs at 6, 24, 42 or 48 and 72 h after exercise. The fractional synthetic rates of all proteins were elevated at 6 h and rose rapidly to peak at 24 h post exercise (tendon collagen (0.077% h(-1)), muscle collagen (0.054% h(-1)), myofibrillar protein (0.121% h(-1)), and sarcoplasmic protein (0.134% h(-1))). The rates decreased toward basal values by 72 h although rates of tendon collagen and myofibrillar protein synthesis remained elevated. There was no tissue damage of muscle visible on histological evaluation. Neither tissue microdialysate nor serum concentrations of IGF-I and IGF binding proteins (IGFBP-3 and IGFBP-4) or procollagen type I N-terminal propeptide changed from resting values. Thus, there is a rapid increase in collagen synthesis after strenuous exercise in human tendon and muscle. The similar time course of changes of protein synthetic rates in different cell types supports the idea of coordinated musculotendinous adaptation.

Adult↗