ISOLATED PRIMARY TUBERCULOSIS OF VASTUS LATERALIS MUSCLE IN SEVERE OSTEOARTHRITIS PATIENT: A CASE REPORT

Extra pulmonary Tuberculosis involving soft tissues and affecting the joints and surrounding structures (tuberculous arthritis) is well known. However, Tubercular myositis is a rare condition with skeletal muscle involvement without underlying osseous or extra osseous involvement in extremely rare presentation. Due to atypical presentation the diagnosis is often delayed. We report and present a case of isolated tubercular myositis of Vastus lateralis muscle in severe osteo arthritis knee patient without evidence of any primary focus

Effect Of Functional Stabilization Training On Pain And Muscle Activation Ratio Of Vastus Medialis Obliqus And Vastus Lateralis In Individuals With Patellofemoral Pain: A Randomized Control Trial

Background: Patients with patellofemoral pain(PFP) demonstrate impaired lower-limb and trunk movement control along with hip and trunk muscle weakness. Functional stabilization training (FST) is a treatment focused on hip muscle strengthening and lower-limb and trunk movement control. The objective of the study is to examine the effectiveness of functional stabilization training on pain and electromyographic muscle activation ratio for VMO and VL in individuals with PFP. Methodology: Study has been conducted on 60 patients diagnosed with PFP. Written informed consent was obtained from the patients. All the patients were randomly allocated into two groups for 8 weeks of intervention. Outcome measurements were numeric pain rating scale (NPRS) and electromyographic muscle activation ratio for VMO and VL. Results: The results showed that there is statistically high significant difference(p<0.05) showing improvement in means of NPRS and electromyographic muscle activation ratio for VMO and VL before and after intervention in both the groups but FST group shows more significant improvement in NPRS(p=0.000) and in VMO:VL(p=0.000) compared to CT group. Conclusion: FST group showed more benefits then CT group in individuals with PFP in relieving pain and improving balance in the activity of VMO and VL.

Treatment of huge empyema by free vastus lateralis muscle flap transplantation: analysis of 3 cases / 中华整形外科杂志

Objective@#To study the treatment of huge empyema with free vastus lateralis muscle flap.@*Methods@#From May 2015 to December 2015, 3 cases of empyema were treated with free vastus lateralis muscle flaps, (unilateral vastus lateralis muscle flap, n=2; bilateral vastus lateralis muscle flaps with Flow-through technique, n=1). The volumes of defects were 12.4 cm×5.1 cm×6.4 cm, 11.8 cm×6.9 cm×5.6 cm, and 14.4 cm×7.6 cm×9.4 cm, respectively.@*Result@#All flaps was survived after 23-29 months follow-up. The pus cavities were filled well. There was no empyema reoccurred. The patients felt good, without chest distress. The donor site of flap healed well. The function of lower limb was not affected.@*Conclusions@#Vastus lateralis muscle can fill the pus cavity of empyema successfully, without the sacrifice of chest shape. Free vastus lateralis muscle flap is an ideal choice to repair large empyema defection. For young patient, bilateral free vastus lateralis muscle flap can be used if the cavity is too large to fill with one flap.

Lateral Structure Release for the Treatment of Mild to Moderate Habitual Dislocation of Patella: A Retrospective Study / 中国运动医学杂志

Objectives To evaluate the clinical outcome of lateral structure release in the treatment of patients with mild or moderate habitual dislocation of patella(HDP).Methods From 51 HDP patients undergoing surgical treatment between April 2010 and 2014,23 patients were chosen and given the lateral structure release,including isolated lateral retinaculum release (LRR) and LRR combined with vastus lateralis oblique(VLO) lengthening.Other auxiliary surgeries included medial patellofemoral ligament(MPFL) reconstruction and tibial tubercle medialization.Radiological,objective and subjective evaluations were performed at 4 and 8 weeks,as well as and 1 year after the surgery and every year afterwards.Results There were 21 patients followed for a minimum of 2 years.Their average age was 25.0 + 7.4 years (ranging from 17 to 38 years old),and the mean follow-up period was 30.5 ± 5.8months(ranging from 24 to 36 months).Isolated LRR was performed in 42.9％(9/21) of the patients,and LRR combined with VLO lengthening was performed in 57.1％(12/21) of them.No redislocation was reported.Significant improvement was observed in the subjective evaluation score.Conclusions For patients with mild to moderate HDP,lateral structure release can achieve satisfactory results.

Tibial Tubercle Proximalization for the Treatment of Severe Habitual Dislocation of Patella: A Retrospective Study / 中国运动医学杂志

Objective To evaluate the clinical outcome of tibial tubercle proximalization in the treatment of patients with severe habitual dislocation of patella (HDP).Methods Among 51 HDP patients treated surgically in our hospital between April 2010 and 2014,28 were eligible for retrospective evaluation.All patients underwent tibial tubercle proximalization and lateral structure release.Additional surgeries included medial patellofemoral ligament (MPFL)reconstruction and tibial tubercle medialization.Radiological and subjective evaluations were performed at 4th and 8th weeks after the operation,as well as 1 year and every year afterwards.Results Twenty-eight patients,with an average age of (27.2 ± 9.4)(ranging from 18 to 39)were followed up for a minimum of 2 years,the mean follow-up period being (26.4 ± 5.8)months (ranging from 24 to 36).It was found 17.2％ (5/29) patients of quadriceps weakness,6.9％ (2/29)of patellofemoral pain and 6.9％ (2/29)of stiffness.No redislocation was reported.Significant improvement was observed in all subjective evaluation scores.Conclusions For patients with severe HDP,tibial tubercle proximalization can achieve satisfactory results.

Pennation angle of vastus laterallis during isometric contractions performed at two knee angles / Ângulo de penação do vasto lateral durante contrações isométricas executadas em dois ângulos do joelho

Abstract Introduction: The pennation angle (PA) of a muscle is not static value, but it adapts to the conditions imposed by the contraction intensity required. Objective: This study investigates the effect of knee angle (KA) and intensity of contraction (IC) on PA of vastus lateralis (VL). Methods: Eight women and nine men executed isometric torques lasting 5s at the maximal voluntary contraction (MVC), 25%, 50% and 75% of MVC, on an isokinetic dynamometer with the KA at 90° and 120° (full extension = 180°). The PA was measured in each test, and with the subject relaxed. The effect of IC on PA was tested by means of repeated measures ANOVA and effect size (ES), and of the KA on PA by paired t test, employed on each IC, together with the statistics: intraclass correlation (ICC), standard error of measurement (SEM) and ES, all calculated with the PAs measured at both KAs. Results: The PA increased significantly and successively with the IC (p < 0.05; ES between 1.11 and 3.04), but was not influenced by KA (p > 0.05; ICC between 0.70 and 0.81; SEM between 0.7° and 1.4°; ES between 0.02 and 0.2). Conclusion: The successive increase of PA with the IC supports the existence of relation between these variables. While studies advocate the effect of PA on joint angle this was not observed in this study, probable because the 30o of between KA difference employed was not enough to provide change in PA.

Resumo Introdução: O ângulo de penação (AP) de um músculo não é estático, podendo se adaptar às condições impostas pela contração demandada. Objetivo: Este estudo investigou a influência do ângulo do joelho (AJ) e da intensidade da contração (IC) no AP do vasto lateral (VL). Métodos: Oito mulheres e nove homens executaram torques isométricos durante 5s na contração voluntária máxima (CVM), em 25%, 50% e 75% da CVM, em um equipamento isocinético, com o AJ em 90° e 120° (extensão = 180°). O AP foi medido nos testes e com o sujeito relaxado. O efeito da IC no AP foi testado por ANOVA para medidas repetidas e pelo tamanho do efeito (TE), e o do AJ no AP, por teste t pareado, aplicado a cada IC, junto com as estatísticas: coeficiente de correlação intraclasse (ICC), erro padrão da medida (SEM) e TE, todas calculadas com os APs medidos em ambos AJs. Resultados: O AP aumentou significativamente e sucessivamente com a IC (p < 0,05; TE entre 1,11 e 3,04), mas não foi influenciado pelo AJ (p > 0,05; ICC entre 0,70 e 0,81; SEM entre 0,7° e 1,4°; TE entre 0,02 e 0,20). Conclusão: O aumento sucessivo do AP com a IC corrobora a existência de relação entre estas duas variáveis. Enquanto estudos advogam efeito do ângulo articular no AP, isto não foi observado neste estudo, provavelmente porque a diferença de 30° utilizada entre os AJ não foi suficiente para produzir mudança no AP.

Morphometric study of tensor of vastus intermedius in South Indian population / 대한해부학회지

Tensor of vastus intermedius is a newly discovered muscle located between vastus lateralis and vastus intermedius. The purpose of this study was to investigate the detailed morphology of tensor of vastus intermedius, specifically to provide data pertaining to the attachments, innervations, variation in the types and its morphometry in South Indian population. The tensor of vastus intermedius was studied in thirty six cadaveric lower limbs using macrodissection techniques. The origin of the muscle was from upper part of intertrochanteric line and anterior part of greater trochanter of femur inserted to medial aspect of upper border of patella. The muscle was classified into four types based on the origin and also the aponeurosis course with independent type (type 1) being common. The mean and standard deviation of the length of tensor of vastus intermedius and aponeurosis were 145.40±37.55 mm and 193.55±42.32 mm, respectively. The results of the study suggest that tensor of vastus intermedius is variable and the information provided regarding the attachments, types and quantitative data will contribute to the existing knowledge of the muscle.

The dynamic stability of the patella in persons with patellofemoral pain / 中华物理医学与康复杂志

Objective To analyze the activity of the vastus medialis (VM) and vastus lateralis (VL) muscles in the dynamic stabilization of the patella in patients with patellofemoral pain (PFPS) using standard surface electromyographic (sEMG) tests.Methods This comparative study involved 7 patients with PFPS (13 knees) and 10 healthy subjects (20 knees).They performed weight-bearing squat movements,and sEMG was employed to measure the mean amplitude and the time before peak (TBP) of their VM and VL muscles.Results There was no significant difference between the two groups in the ratio of the mean amplitudes of the VM and VL muscles.However,the ratio in both groups in squatting was significantly higher than when simply standing.In the PFPS group the average TBP delay of the VM relative to the TBP of the VL was significantly longer than in the control group during squat movements.Conclusions The delay in the TBP of the VM relative to the VL during squat movements could serve as a standardized test for assessing treatment effect in patients with local factor PFPS.

Confiabilidade das medidas de arquitetura do músculo Vasto Lateral pela ultrassonografia / Reliability of the measurements of architecture of the Vastus Lateralis muscle by ultrasonography

As medidas de confiabilidade das análises da arquitetura muscular pela ultrasonografia são importantes referências para estudos aplicados de mecânica muscular. O objetivo deste estudo foi determinar a confiabilidade das medidas de espessura muscular (EM), ângulo de penação (AP) e comprimento da fibra (CF) do músculo Vasto Lateral (VL). As imagens de ultrassom foram obtidas em um grupo (N=14; 22 ± 1,75 anos) em duas visitas (sessenta medidas por indivíduo). Foi calculado o coeficiente de correlação intraclasse (CCI), coeficiente de variação (CV) e erro típico da medida (ETM). Os resultados demonstram alta confiabilidade: CCI AP (0,83 a 0,99), EM (0,96 a 0,99) e CF (0,80 a 0,99); CV AP (3,68 a 6,34%), EM (3,12 a 3,84%) e CF (3,98 a 6,33%) e ETM AP (0,18 a 0,59º); EM (0,014 a 0,15mm) e CF (0,07 a 1,47mm). Essas medidas devem ser consideradas em estudos que analisam o impacto na arquitetura muscular em programas de condicionamento do Vasto Lateral.

Reliability of the measurements of the muscle architecture variables by ultrasound are important references for applied studies of muscle mechanics. The aim this study was to analyze the reliability of measurements of Vastus Lateralis (VL) muscle thickness (MT), pennation angle (PA) and fiber length (FL). Ultrasound images were obtained in two days (N=14, 22 ± 1,75 years) with a total of sixty measurements in each subject. Reliability was determined by intraclass correlation coefficient (ICC), coefficient of variation (CV) and typical error of measurement (TEM). Results show high reliability: MT (0,96 a 0,99), PA (0,83 a 0,99) and FL (0,80 a 0,99) ICC; MT (3,12 a 3,84%), PA (3,68 a 6,34%) and FL (3,98 a 6,33%) CV; MT (0,014 a 0,15mm), PA (0,18 a 0,59º) and FL (0,07 a 1,47mm) TEM. These measures should be considered in studies of the impact of conditioning programs in the architecture of the vastus lateralis muscle.

Anatomical Review of Anterolateral Thigh Flap for the Oral and Maxillofacial Reconstruction

Histochemistry and morphometric analysis of muscle fibers from patients with duchenne muscular dystrophy (DMD) / Histoquímica y análisis morfométrico de las fibras musculares de p0acientes con distrofia muscular de duchenne (DMD)

The aim of the study was to analyze the muscle fibers by histochemistry and morphometric methods from patients with Duchenne muscular dystrophy (DMD). Muscle biopsies were taken from the vastus lateralis muscle of five boys between 13 and 15-years of age, with clinical diagnosis of DMD. The histochemistry was performed using myofibrillar ATPases (9.6, 4.6 and 4.3). To morphometrical analysis a computerized semiautomatic system and software Image-Lab was used. ATPase staining showed atrophy of muscle fibers. Fibrosis and adipose deposition occurred in variable degree depending of muscular involvement. The morphometrical analysis showed an increase of size (percentage) to type I fiber than other types in all patients. Furthermore, the type I fiber had a larger cross-sectional area and mean diameter than type IIa and IIb fibers. Both histochemistry and morphometric analysis could be important tools for qualitative and quantitative diagnostics of muscle fibers attacked in this type of disease.

El objetivo del estudio fue analizar las fibras musculares mediante histoquímica y métodos morfométricos en pacientes con distrofia muscular de Duchenne (DMD). Se tomaron biopsias musculares del músculo vasto lateral de cinco niños entre 13 y 15 años de edad, con diagnóstico clínico de DMD. La histoquímica se realizó mediante ATPasa miofibrilar (9.6, 4.6 y 4.3). Para el análisis morfométrico se utilizó un sistema semiautomático computarizado y software de imagen de laboratorio. La tinción de ATPasa mostró una atrofia de las fibras musculares. La fibrosis y depósito adiposo se observó en grado variable dependiendo del compromiso muscular. El análisis morfométrico mostró un aumento de tamaño (porcentaje) de fibras tipo I en todos los pacientes. Además, la fibra tipo I tuvo un área de sección transversal y diámetro medio mayor que las fibras tipos IIa y IIb. Tanto la histoquímica y el análisis morfométrico pueden ser herramientas importantes para el diagnóstico cualitativo y cuantitativo de las fibras musculares comprometidas en este tipo de enfermedad.

Primary Tuberculous Abscess of Vastus Lateralis Muscle.

Skeletal muscle tuberculosis without underlying osseous or extra osseous involvement is an extremely rare presentation of tuberculosis. We present a case of isolated tubercular abscess of the vastus lateralis muscle without an evident primary focus in a 52 year old immunocompetent male. The diagnosis was confirmed by histological examination. The patient showed marked improvement with a standard fourdrug regimen.

Efeito imediato da estimulação elétrica neuromuscular seletiva na atividade eletromiográfica do músculo vasto medial oblíquo / Immediate effect of selective neuromuscular electrical stimulation on the electromyographic activity of the vastus medialis oblique muscle

A Síndrome da dor patelofemoral (SDPF) é descrita como dor anterior ou retro-patelar do joelho na ausência de outras patologias associadas, sendo freqüentemente associada à disfunção do Vasto Medial Oblíquo (VMO). Entretanto, diversos estudos têm demonstrado a impossibilidade de ativar seletivamente este músculo através de exercícios. O objetivo do presente estudo foi analisar o efeito imediato da estimulação elétrica neuromuscular (EENM) seletiva no músculo VMO por meio do comportamento eletromiográfico dos músculos VMO e vasto lateral (VL). Foram avaliadas 18 mulheres saudáveis, com idade média de 23,2 anos e IMC médio de 20 Kg/m2. Os procedimentos do estudo incluíram uma análise eletromiográfica dos músculos VMO e VL, antes e imediatamente após a EENM do músculo VMO. Durante a análise eletromiográfica, as voluntárias realizaram uma contração isométrica voluntária máxima durante a extensão do joelho a 60° em um dinamômetro isocinético. A estimulação elétrica foi realizada através da corrente Russa. A análise dos dados mostrou um aumento significativo na intensidade de ativação do músculo VMO imediatamente após a estimulação do mesmo (p=0,0125), enquanto que a intensidade de ativação do músculo VL, não mostrou aumento significativo (p=0,924). Além disso, verificou-se também um aumento significativo na relação VMO/VL (p=0,048). No presente estudo, observou-se uma modificação na relação VMO/VL após a EENM, sugerindo que a mesma tem um efeito favorável no fortalecimento seletivo do VMO...

The Patellofemoral pain syndrome (PFPS) is described as an anterior or retropatellar knee pain in the absence of other associated diseases, and has often been associated with dysfunction of the vastus medialis oblique muscle (VMO). However, several studies have demonstrated the impossibility of selectively activating this muscle with exercises. The aim of the present study was to analyze the immediate effect of neuromuscular electrical stimulation of VMO muscle by means of monitoring the electromyographic activity of the vastus medialis oblique (VMO) and vastus lateralis (VL) muscles. Eighteen healthy women with a mean age of 23.2 years and mean BMI of 20 Kg/m2 were evaluated. The study protocol included electromyographic analysis of VMO and VL muscles, before and immediately after neuromuscular electrical stimulation of the VMO muscle. During the electromyographic analysis, the volunteers performed maximal voluntary isometric contraction in a 60° knee extension on an isokinetic dynamometer. ôRussian currentõ apparatus was used for electrical stimulation. Results: The data analysis demonstrated a signifi cant increase in VMO activation intensity immediately after it had been electrically stimulated (p=0.0125), whereas VL activation intensity exhibited no signifi cant increase (p=0.924). Moreover, a signifi cant increase in the VMO/VL ratio was also detected (p=0.048). In this study it was observed that electrical stimulation modifi ed the VMO/VL ratio, which suggests electrical stimulation has a benefi cial effect on VMO muscle strength...

Electromyographic Analysis of Muscle Activities of Knee Joint in Patients with Patellofemoral Pain Syndrome / 中国康复理论与实践

@#Objective To analyze electromyographic (EMG) activities of vastus medialis obliquus (VMO) and vastus lateralis (VL) in patients with patellofemoral pain syndrome (PFPS) before and after an exercise program.Methods 26 subjects with PFPS were randomly divided into the EMG biofeedback plus exercise group (group A) and exercise only group (group B) with 13 cases in each group. All patients in two groups were trained with family exercise program, but the patients of the group A used a EMG biofeedback while training. The relative activities of VMO and VL of all patients in two groups were assessed with the EMG apparatus for a continuous 6 hours period before and 8 weeks after training. At the same time the intensity of the knee pain was also assessed.Results There was no statistics difference in VMO/VL EMG ratio of the group B ( P>0.05), whereas the group A had significantly higher VMO/VL EMG ratio ( P<0.05).Conclusion The EMG biofeedback apparatus used in home exercise program of PFPS patients can improve the recruitment of VMO.

Pedicle and Skin Territory of the Vastus Lateralis Muscle for the Anterolateral Thigh Free Flap / 체질인류학회지

The pattern of location, perforator artery and skin territory of the descending branch of the lateral circumflex femoral artery are very important to the anterolateral thigh free flap surgery. The author studied the pattern of vascularization of the anterolateral thigh in 110 Korean cadavers using macroscopic dissection and radiographic methods. The location of the points in this study were expressed as XY coordination in reference to the line between ASIS and center of the lateral margin of the patella. The location of pedicle of the vastus lateralis muscle at XY coordination valued X: 20.8+/-6.0 cm, Y: -1.2+/-1.0 cm. The length and external diameter of the pedicle were 91.7+/-54.9 mm, and 2.7+/-0.8 mm respectively. The average number of perforator artery to the vastus lateralis muscle were 3.2+/-1.5. The skin territory of the perforator of the vastus lateralis muscle was 6 x 18 cm2, its location was 20.8 cm on the line AB. The pattern of distribution and territories of the anterolateral thigh obtained in this study will provide useful anatomical backgrounds for the flap surgery of anterior and anterolateral thigh.

Treatment for Painful Bipartite Patella Using Vastus Lateralis Tendon Release / 대한정형외과학회잡지

Nine patients, who had ten painful bipartite patellae, were managed with a new operative tech nique in which the vastus lateralis insertion to the painful patellar fragment is detached subpe riosteally while the continuity of the tendon-periosteum complex to the main portion of the patella is preserved. A grossly mobile patellar fragment was removed in 3, fragment that showed minimum mobility was left in situ in 5 and fragment that had significant articular component was fixed with 4.0 mm cancellous screw in one. All of the patients had prompt relief of pain and returned to full sports activity within three months of the operation, 2 of 5 patellas that had not been removed united by bone to the main portion of the patella within 2 years post-operatively. Overall, 10 knees had excellent results at an average of four years post-operatively.

RELATIONSHP BETWEEN OXYGENATION AND MYOELECTRIC ACTIVITY AT VASTUS LATERALIS AND LATERAL GASTROCNEMIUS MUSCLES / 体力科学

In order to find the cause behind the difference in the pattern of oxygenation between thigh and calf muscles during an incremental cycling exercise, we investigated the relationship between oxygenation and surface myoelectric activity. Five healthy male subjects performed the five 6-min cycling exercises of 50, 100, 150, 200 and 250 watts. We measured oxygenated hemoglobin/myoglobin (oxy-Hb/Mb) on continuous wave near infrared spectroscopy (NIR) and myoelectric activity with surface electrodes (EMG) . The NIR probe and electrodes were positioned on the vastus lateralis muscle (VL) and lateral gastrocnemius muscle (LG) of the right leg. The relative change in oxy-Hb/Mb was estimated by regarding the oxy-Hb/Mb level in the resting condition as 100% and that obtained during thigh occlusion as 0 %. The mean values of oxy-Hb/Mb and integrated EMG (iEMG) determined ranged from 5'30'' to 6'00'' at each work rate. In the VL, the oxy-Hb/Mb level decreased slightly at 50 and 150 watts (99.2±6.8% and 84.6±12.9%), followed by a more prom-inent decrease at 200 and 250 watts (74.9±11.9 and 65.2±9.6%) . The iEMG increased slowly at 50 and 150 watts (24.9±8.8 and 38.0±8.8μV), and a rapid increment occurred at 200 and 250 watts (49.6±13.0 and 57.3±19.6μV) . In the LG, however, the oxy-Hb/Mb level was decreased slightly at 50 and 200 watts (97.3±11.1 and 87.4±6.4%) and a rapid decrement occurred at 250 watts (74.1±6.0%) . The iEMG increased slowly at 50 and 200 watts (18.3±9.4 and 30.5±8.8 μV), and a rapid increment occurred at 250 watts (38.5±8.9 μV) . There was a significant negative correlation between the oxy-Hb/Mb level and iEMG in the VL (r=-0.587, p<0.001) and in the LG (r=-0.599, p<0.001) . From these results, we speculated that the difference in the relative change of oxy-Hb/Mb between the vastus lateralis and the lateral gastrocnemius muscle was due to the difference of increase pattern of muscle activity accompanied by an increase in exercise intensity in these two muscles.

Difference in oxygen supply-consumption balance in thigh muscles working together during knee-extension exercise / 体力科学

The purpose of this study was to clarify the changes in oxygen kinetics in two different thigh muscles recruited for dynamic knee-extension exercise at varying intensities in seven female subjects. Pulmonary oxygen uptake (Vo<SUB>2</SUB>) was measured by the 10-s mixing chamber method. Changes in oxygenated hemoglobin (HbO<SUB>2</SUB>), deoxygenated hemoglobin (Hb), and total hemoglobin (HbT) contents were measured in the vastus lateralis (VL) and rectus lemons (RF) muscles using near-infrared spectroscopy, and the oxygen saturation (SO<SUB>2</SUB>) was calculated as the HbO<SUB>2</SUB> divided by HbT in percent. The surface electromyograms (EMG) of both muscles were also recorded. The integrated EMGs (iEMG) of the VL and RF increased linearly with increasing exercise intensity up to 100%VO<SUB>2peak</SUB>. However, the HbO<SUB>2</SUB> and Hb remained unchanged when exercise intensity was below 50%Vo<SUB>2peak</SUB>, above which the increase in Hb and decrease in HbO<SUB>2</SUB> were observed. Thus the decline in SO<SUB>2</SUB> occurred at 60%Vo<SUB>2peak</SUB> in the RF, and 70%Vo<SUB>2peak</SUB> in the VL. These results suggest that muscle deoxygenation is accelerated during exercise above a certain intensity, which is lower in the RF than in the VL, during dynamic knee-extension exercise.

Muscle fiber conduction velocity in human vastus lateralis during isometric contractions. Relation to muscle fiber composition / 体力科学

Relationship between muscle fiber conduction velocity and muscle fiber composition was studied in vastus lateralis of well-trained athlete students, who differed considerably regarding their fiber type distribution with averaged 69.2% fast twitch (FT) muscle fibers for sprinters (12 male subjects) and 39.7% FT muscle fibers for distance runners (7 male subjects) . Measurement of muscle fiber conduction velocity during brief and maintained isometric contraction was made directly, using the zero-crossing time delay method between two surface myoelectric signals. Muscle fiber conduction velocities increased 4.40 to 4.84 m/sec for sprinters and 3.91 to 4.31 m/sec for distance runners as developing force increased from 25 to 100% maximum voluntary contraction (MVC) . The correlation coefficients between conduction velocity and % FT fibers were 0.59, 0.63, 0.64 and 0.84 for 25, 50, 75 and 100% MVC, respectively. During maintained at 50% of MVC conduction velocities in sprinters decreased linealy from 4.77 to 4.38 m/sec and in distance runners decreased from 4.11 to 3.96 m/sec at only last stage. It was suggested that the individual difference in conduction velocity was caused by different muscle fiber composition and that the changes of conduction velocity depended on the recruitment of muscle fibers.