Vastus Lateralis Muscle (vastu + laterali_muscle)

Distribution by Scientific Domains

Selected Abstracts

Resistance training increases in vivo quadriceps femoris muscle specific tension in young men

R. M. Erskine
Abstract Aim:, The present study investigated whether in vivo human quadriceps femoris (QF) muscle specific tension changed following strength training by systematically determining QF maximal force and physiological cross-sectional area (PCSA). Methods:, Seventeen untrained men (20 2 years) performed high-intensity leg-extension training three times a week for 9 weeks. Maximum tendon force (Ft) was calculated from maximum voluntary contraction (MVC) torque, corrected for agonist and antagonist muscle activation, and moment arm length (dPT) before and after training. QF PCSA was calculated as the sum of the four component muscle volumes, each divided by its fascicle length. Dividing Ft by the sum of the component muscle PCSAs, each multiplied by the cosine of the respective fascicle pennation angle, provided QF specific tension. Results:, MVC torque and QF activation increased by 31% (P < 0.01) and 3% (P < 0.05), respectively, but there was no change in antagonist co-activation or dPT. Subsequently, Ft increased by 27% (P < 0.01). QF volume increased by 6% but fascicle length did not change in any of the component muscles, leading to a 6% increase in QF PCSA (P < 0.05). Fascicle pennation angle increased by 5% (P < 0.01) but only in the vastus lateralis muscle. Consequently, QF specific tension increased by 20% (P < 0.01). Conclusion:, An increase in human muscle specific tension appears to be a real consequence of resistance training rather than being an artefact of measuring errors but the underlying cause of this phenomenon remains to be determined. [source]

The adaptive responses in several mediators linked with hypertrophy and atrophy of skeletal muscle after lower limb unloading in humans

K. Sakuma
Abstract Aim:, To determine the adaptive changes in several molecules regulating muscle hypertrophy and atrophy after unloading, we examined whether unilateral lower limb suspension changes the mRNA and protein levels of SRF-linked (RhoA, RhoGDI, STARS and SRF), myostatin-linked (myostatin, Smad2, Smad3 and FLRG) and Foxo-linked (P-Akt, Foxo1, Foxo3a and Atrogin-1) mediators. Methods:, A single lower limb of each of eight healthy men was suspended for 20 days. Biopsy specimens were obtained from the vastus lateralis muscle pre- and post-suspension. Results:, The volume of the vastus lateralis muscle was significantly decreased after unloading. The amount of RhoA, RhoGDI or SRF protein in the muscle was not significantly changed post-suspension. An RT-PCR semiquantitative analysis showed increased levels of myostatin mRNA but not Smad2, Smad3 or FLRG mRNA. Unloading did not elicit significant changes in the amount of p-Smad3 or myostatin protein in the muscle. The amount of p-Akt protein was markedly reduced in the unloaded muscle. Lower limb suspension did not influence the expression pattern of Foxo1, Foxo3a or Atrogin-1. Conclusion:, Unloading inducing a mild degree of muscle atrophy may decrease p-Akt and increase myostatin but not SRF-linked mediators. [source]

Muscle fibre size and capillarity in Korean diving women

K. A. Bae
Abstract Aim:, Effects of prolonged habitual cold-water immersion on fibre size and capillarity in vastus lateralis muscle were studied in human beings. The hypothesis tested in the present study was that cold acclimatized human skeletal muscle would have reduced muscle fibre size and higher capillarity, favouring the idea of efficacy of recruitment under cold environment. Methods:, Ten women breath-hold divers (BHDs) and 10 active women (controls CONs) participated in this study. Muscle biopsy was obtained from vastus lateralis and determined fibre type composition and capillary density. Results: A major finding was that all BHDs revealed a markedly smaller cross-sectional area (CSA) in all fibre types than the CONs, or even than any other morphological data reported in previous investigations. Furthermore, mean CSA of type II fibre (range 1205,2766 ,m2) was much smaller than type I fibre (2343,4327 ,m2). The number of capillaries per fibre in different fibre types in the BHDs was higher than in the CONs (P < 0.001), and diffusional area was smaller in type II fibres than in type I fibres (P < 0.001). The BHDs and the CONs have similarity in the percentage of type I fibres, but type II fibre was predominant in both groups. Interestingly the proportion of type IIx fibre in the BHDs was higher (31%) than in the CONs (22%). No significant difference was found in the thigh circumference between the groups. Conclusion:, The present study demonstrates that prolonged habitual cold-water immersion may induce a decrease in fibre size and an increase in capillarity in human skeletal muscle. [source]

The effect of hypoxia on pulmonary O2 uptake, leg blood flow and muscle deoxygenation during single-leg knee-extension exercise

Darren S. DeLorey
The effect of hypoxic breathing on pulmonary O2 uptake (VO2p), leg blood flow (LBF) and O2 delivery and deoxygenation of the vastus lateralis muscle was examined during constant-load single-leg knee-extension exercise. Seven subjects (24 4 years; mean s.d.) performed two transitions from unloaded to moderate-intensity exercise (21 W) under normoxic and hypoxic (PETO2= 60 mmHg) conditions. Breath-by-breath VO2p and beat-by-beat femoral artery mean blood velocity (MBV) were measured by mass spectrometer and volume turbine and Doppler ultrasound (VingMed, CFM 750), respectively. Deoxy-(HHb), oxy-, and total haemoglobin/myoglobin were measured continuously by near-infrared spectroscopy (NIRS; Hamamatsu NIRO-300). VO2p data were filtered and averaged to 5 s bins at 20, 40, 60, 120, 180 and 300 s. MBV data were filtered and averaged to 2 s bins (1 contraction cycle). LBF was calculated for each contraction cycle and averaged to 5 s bins at 20, 40, 60, 120, 180 and 300 s. VO2p was significantly lower in hypoxia throughout the period of 20, 40, 60 and 120 s of the exercise on-transient. LBF (l min,1) was approximately 35% higher (P > 0.05) in hypoxia during the on-transient and steady-state of KE exercise, resulting in a similar leg O2 delivery in hypoxia and normoxia. Local muscle deoxygenation (HHb) was similar in hypoxia and normoxia. These results suggest that factors other than O2 delivery, possibly the diffusion of O2, were responsible for the lower O2 uptake during the exercise on-transient in hypoxia. [source]

Growth Hormone Administration and Exercise Effects on Muscle Fiber Type and Diameter in Moderately Frail Older People

James V. Hennessey MD
OBJECTIVE: Reduced muscle mass and strength are characteristic findings of growth hormone deficiency (GHD) and aging. We evaluated measures of muscle strength, muscle fiber type, and cross sectional area in response to treatment with recombinant human growth hormone (rhGH) with or without a structured resistance exercise program in frail older subjects. DESIGN: Placebo-controlled, randomized, double blind trial. SETTING: Outpatient clinical research center at an urban university-affiliated teaching hospital. PARTICIPANTS: Thirty-one consenting older subjects (mean age 71.3 4.5 years) recruited as a subset of a larger project evaluating rhGH and exercise in older people, who underwent 62 quadricep-muscle biopsies. INTERVENTION: Random assignment to a 6-month course of one of four protocols: rhGH administered subcutaneously daily at bedtime, rhGH and a structured resistance exercise program, structured resistance exercise with placebo injections, or placebo injections only. MEASUREMENTS: Muscle biopsy specimens were obtained from the vastus lateralis muscle. Isokinetic dynamometry strength tests were used to monitor individual progress and to adjust the weights used in the exercise program. Serum insulin-like growth factor-I (IGF-I) was measured and body composition was measured using a Hologic QDR 1000W dual X-ray densitometer. RESULTS: The administration of rhGH resulted in significant increase in circulating IGF-I levels in the individuals receiving rhGH treatment. Muscle strength increased significantly in both the rhGH/exercise (+55.6%, P = .0004) as well as the exercise alone (+47.8%, P = .0005) groups. There was a significant increase in the proportion of type 2 fibers between baseline and six months in the combined rhGH treated subjects versus those not receiving rhGH (P = .027). CONCLUSIONS: Our results are encouraging in that they suggest an effect of growth hormone on a specific aging-correlated deficit. IGF-I was increased by administrating rhGH and muscle strength was increased by exercise. The administration of rhGH to frail older individuals in this study resulted in significant changes in the proportions of fiber types. Whether changes in fiber cross-sectional area or absolute number occur with long-term growth hormone administration requires further study. [source]

Repair of buccal defects with anterolateral thigh flaps

MICROSURGERY, Issue 3 2006
mer zkan M.D.
The ideal reconstructive method for the buccal mucosa should provide durable, stable coverage and a natural contour, while simultaneously minimizing morbidity of both the defect and donor sites. Since the first report of the anterolateral thigh flap in 1984, it has become one of the most commonly used flaps for the reconstruction of various soft-tissue defects. From March 2004,April 2005, 24 free anterolateral thigh flaps were used to reconstruct buccal defects, including the retromolar trigone and as far as the oral commissure, and in some cases with extension to the neighboring palatal region and tongue. The study comprised 1 female and 23 male patients, with ages ranging from 26,63 years (mean age, 45.8 years). Two flaps required reoperation due to vascular compromise, and both were salvaged with arterial and venous anastomosis revisions, giving an overall success rate of 100%. Primary thinning of the flap was performed in 10 cases. In 2 cases, additional vastus lateralis muscle was included in the flap to fill the large defect. In 2 cases, marginal necrosis with dehiscence of the flap was observed, one of these patients having a history of atherosclerosis and diabetes mellitus (marginal skin necrosis and infection of the donor area were also observed in this patient). In 2 patients, seroma collection was observed in the neck at the dissection site. Chart reviews showed that most patients had a history of betel-nut chewing (95.8%) or a combination of smoking and betel-nut chewing (79.2%). During the follow-up period of 4,12 months, a sufficient level of mouth-opening with interincisal distances of 34 mm, 44 mm, and 48 mm was achieved in all 3 cases reconstructed after release of the trismus. Although it has some variations in the vascular pedicle, irregularity in derivation from the main vessels, and minimal morbidity of the donor site, the anterolateral thigh flap, with its evident functional, structural, and cosmetic advantages, can be considered an excellent and ideal flap option, and a first choice for most buccal defects. 2006 Wiley-Liss, Inc. Microsurgery, 2006. [source]

Postcontraction changes of muscle architecture in human quadriceps muscle

MUSCLE AND NERVE, Issue 4 2004
Konrad Mahlfeld MD
Abstract Maximal voluntary contraction changes the mechanical properties of skeletal muscle. Using ultrasound, we investigated whether these changes are reflected by changes in muscle architecture in the vastus lateralis muscle of 8 healthy volunteers. The mean pennation angle during the time interval from 3 to 6 min after maximal voluntary contraction (late postcontraction state) was 14.4 1.11 (mean SEM) and differed significantly from the precontraction state (16.2 1.39), but the pennation angle in the early postcontraction state did not change statistically from the precontraction angle. Thus, postcontraction changes of the muscle,tendon interface appeared for 6 min after a maximal contraction, which may be important for biomechanical optimization of force transmission in vivo. Muscle Nerve 29: 597,600, 2004 [source]

Exercise rapidly increases eukaryotic elongation factor 2 phosphorylation in skeletal muscle of men

Adam J. Rose
Protein synthesis in skeletal muscle is known to decrease during contractions but the underlying regulatory mechanisms are unknown. Here, the effect of exercise on skeletal muscle eukaryotic elongation factor 2 (eEF2) phosphorylation, a key component in protein translation machinery, was examined. Eight healthy men exercised on a cycle ergometer at a workload eliciting ,67% peak pulmonary oxygen consumption with skeletal muscle biopsies taken from the vastus lateralis muscle at rest as well as after 1, 10, 30, 60 and 90 min of exercise. In response to exercise, there was a rapid (i.e. < 1 min) 5- to 7-fold increase in eEF2 phosphorylation at Thr56 that was sustained for 90 min of continuous exercise. The in vitro activity of skeletal muscle eEF2 kinase was not altered by exercise indicating that the increased activity of eEF2 kinase to eEF2 is not mediated by covalent mechanisms. In support of this, the increase in AMPK activity was temporally unrelated to eEF2 phosphorylation. However, skeletal muscle eEF2 kinase was potently activated by Ca2+,calmodulin in vitro, suggesting that the higher eEF2 phosphorylation in working skeletal muscle is mediated by allosteric activation of eEF2 kinase by Ca2+ signalling via calmodulin. Given that eEF2 phosphorylation inhibits eEF2 activity and mRNA translation, these findings suggest that the inhibition of protein synthesis in contracting skeletal muscle is due to the Ca2+ -induced stimulation of eEF2 kinase. [source]

Gross morphology of the vastus lateralis muscle: An anatomical review

Ines Becker
Abstract To understand the role of the vastus lateralis (VL) muscle in the pathogenesis of common knee disorders such as patellofemoral joint syndrome, knowledge of its anatomical structure is essential. The aim of this study was to review currently available information on the gross morphology of VL. A structured literature review was undertaken and 36 references, comprising 22 scientific papers and 14 anatomical textbooks, were included. Results of this literature review show that most of the included studies exhibited methodological limitations, and focused on different parameters of the VL muscle. Hence, reproducibility of these studies and comparison of results was difficult. This review also demonstrates a dearth of information on the muscle architecture, compartmentalization, nerve supply and fusion of VL, and that there has been no investigation of the muscle as a whole unit. Further research is required of the architecture and innervation of the VL muscle to better understand its function. Clin. Anat. 22:436,450, 2009. 2009 Wiley-Liss, Inc. [source]

Innervation of vastus lateralis muscle

S. Patil
Abstract The lateral surgical approach to the proximal femur potentially damages the nerve supply to the vastus lateralis (VL) muscle. This study describes the detailed anatomy of the nerve supply to the VL muscle based on dissection of ten cadaveric lower limbs. In all specimens, a single nerve trunk arose from the femoral nerve, which is most subsequently divided into two main divisions. These divisions gave two branches each. These branches coursed from anteriorly and proximally to posteriorly and distally within the muscle. When the muscle was reflected anteriorly from its attachment to the linea aspera, there was no damage to its innervation. Splitting of the VL in the midlateral line of the femur, however, resulted in denervation of the posterior half of the muscle. Precise knowledge of the nerve supply to the VL will help avoid iatrogenic denervation of the muscle in surgical procedures at the proximal femur through the lateral approach. Clin. Anat. 20:556,559, 2007. 2006 Wiley-Liss, Inc. [source]

Relationship between muscle oxygenation and electromyography activity during sustained isometric contraction

Eiji Yamada
Summary The purpose of this study was to clarify the relationship between electromyography (EMG) spectrum changes and muscle oxygenation measured by near-infrared time-resolved spectroscopy (TRS). Each subject performed sustained isometric knee extension at 50% of the maximal voluntary contraction load for 1 min. Surface EMG and TRS were simultaneously recorded from the right vastus lateralis muscle. Mean power frequency (MPF) of the power spectrum was calculated every 5 s during isometric contraction using fast Fourier transform, and decrease in the slope of MPF for 1 min was calculated using the least squares method. The maximal changes in oxygenated haemoglobin and myoglobin (Oxy Hb/Mb) and in deoxygenated haemoglobin and myoglobin (Deoxy Hb/Mb) from pre-contraction values of 1 min were calculated. There were significant relationships between the decrease in the slope of MPF and the maximal changes in Oxy Hb/Mb and Deoxy Hb/Mb (P < 005). These findings suggested that changes in Oxy Hb/Mb and Deoxy Hb/Mb indicate muscle fatigue assessed by EMG. [source]

Leptin receptor 170 kDa (OB-R170) protein expression is reduced in obese human skeletal muscle: a potential mechanism of leptin resistance

T. Fuentes
To examine whether obesity-associated leptin resistance could be due to down-regulation of leptin receptors (OB-Rs) and/or up-regulation of suppressor of cytokine signalling 3 (SOCS3) and protein tyrosine phosphatase 1B (PTP1B) in skeletal muscle, which blunt janus kinase 2-dependent leptin signalling and signal transducer and activator of transcription 3 (STAT3) phosphorylation and reduce AMP-activated protein kinase (AMPK) and acetyl-coenzyme A carboxylase (ACC) phosphorylation. Deltoid and vastus lateralis muscle biopsies were obtained from 20 men: 10 non-obese control subjects (mean s.d. age, 31 5 years; height, 184 9 cm; weight, 91 13 kg; and percentage body fat, 24.8 5.8%) and 10 obese (age, 30 7 years; height, 184 8 cm; weight, 115 8 kg; and percentage body fat, 34.9 5.1%). Skeletal muscle OB-R170 (OB-R long isoform) protein expression was 28 and 25% lower (both P < 0.05) in arm and leg muscles, respectively, of obese men compared with control subjects. In normal-weight subjects, SOCS3 protein expression, and STAT3, AMPK, and ACC, phosphorylation, were similar in the deltoid and vastus lateralis muscles. In obese subjects, the deltoid muscle had a greater amount of leptin receptors than the vastus lateralis, whilst SOCS3 protein expression was increased and basal STAT3, AMPK, and ACC, phosphorylation levels were reduced in the vastus lateralis compared with the deltoid muscle (all P < 0.05). In summary, skeletal muscle leptin receptors and leptin signalling are reduced in obesity, particularly in the leg muscles. [source]

Comparison of protein expression in human deltoideus and vastus lateralis muscles using two-dimensional gel electrophoresis

Daniele Capitanio
Abstract We have used two-dimensional gel electrophoresis (2-DE) and mass spectrometry (MS) to study the expression of contractile and regulatory proteins in human vastus lateralis and deltoideus muscles, in order to understand protein turnover and isoform switching in muscles with the same fiber-type composition but different functional properties. We demonstrate a two- to six-fold overexpression of enzymes associated with glycolysis, the tricarboxylic acid cycle, oxidative phosphorylation, and substrate transport in vastus lateralis compared to deltoideus. Expression levels of contractile protein isoforms correlated to the proportion of slow-twitch fibers in deltoideus compared to vastus lateralis are consistent with the different contractile properties of the two muscles. Two proteins involved in free radical homeostasis were differentially expressed, suggesting a direct relationship between radical scavenging and the muscle function. The application of 2-DE and MS to studies of muscle physiology thus offers a more comprehensive assessment of the molecular determinants of muscle function than traditional approaches. [source]

Influence of chronic hypoxemia on peripheral muscle function and oxidative stress in humans

Marion Faucher
Summary Transient re-oxygenation of humans suffering from chronic obstructive pulmonary disease (COPD) allows the assessment of the consequences of chronic hypoxemia on peripheral muscle and metabolism apart from the effects of de-conditioning. The subjects performed maximal voluntary contractions (MVC) of flexor digitorum and vastus lateralis muscles and sustained infra-maximal contractions. COPD patients repeated the whole challenge during a 50-min oxygen breathing period and after recovery to baseline hypoxemia. We measured the compound evoked muscle mass action potential (M-wave) and the medium frequency (MF) of surface electromyography (EMG) power spectrum. Blood lactate (LA) and potassium (K+), erythrocyte-reduced glutathione (GSH), and plasma thiobarbituric acid reactive substances (TBARS) were also measured. Compared with a control group, COPD patients had lower MVCs, an attenuated decrease in MF during exercise, lower resting level of GSH, no posthandgrip TBARS increase and no GSH consumption. Reoxygenation (1) increased MVCs, (2) accentuated the MF decline and (3) elicited a posthandgrip TBARS increase and GSH consumption. Thus, we conclude that chronic hypoxemia exerts specific muscular effects: a reduced force production, an attenuated ,muscle wisdom', and the suppression of the exercise oxidative stress. [source]