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Relationship between Muscle Architecture and Concentric Movement Velocity during Resistance ExercisePelka, Edward Zachary 03 May 2021 (has links)
No description available.
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Transformation of Muscle Architecture at the Fiber Bundle Level to Fit Parametric B-spline Volumes: Extensor carpi radialis brevis and longusRavichandiran, Mayoorendra 27 July 2010 (has links)
Most models of the musculoskeletal system incorporate individual or groups of muscles as a series of line segments, assuming all fiber bundles within a muscle have the same length and moment arm, and do not account for architectural differences throughout the muscle volume. The purpose was to develop an algorithm to fit digitized fiber bundle data from one specimen into muscle volume and intramuscular nerve distribution data from seven other specimens of extensor carpi radialis longus (ECRL) and brevis (ECRB). Coherent Point Drift (CPD) algorithm was successfully adapted for this purpose. The intramuscular nerve distribution and fiber bundle architecture was modeled in all the muscle volumes. ECRL was found to have two neuromuscular compartments, superficial and deep, while ECRB was found to have two, three or four, in a proximal to distal direction depending on the number of primary nerve branches.
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Transformation of Muscle Architecture at the Fiber Bundle Level to Fit Parametric B-spline Volumes: Extensor carpi radialis brevis and longusRavichandiran, Mayoorendra 27 July 2010 (has links)
Most models of the musculoskeletal system incorporate individual or groups of muscles as a series of line segments, assuming all fiber bundles within a muscle have the same length and moment arm, and do not account for architectural differences throughout the muscle volume. The purpose was to develop an algorithm to fit digitized fiber bundle data from one specimen into muscle volume and intramuscular nerve distribution data from seven other specimens of extensor carpi radialis longus (ECRL) and brevis (ECRB). Coherent Point Drift (CPD) algorithm was successfully adapted for this purpose. The intramuscular nerve distribution and fiber bundle architecture was modeled in all the muscle volumes. ECRL was found to have two neuromuscular compartments, superficial and deep, while ECRB was found to have two, three or four, in a proximal to distal direction depending on the number of primary nerve branches.
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Adaptações neuromusculares e funcionais do treinamento vibratório em idosasWeber, Fernanda Seganfredo January 2012 (has links)
Com o envelhecimento ocorre perda de força e potência muscular, principalmente nos membros inferiores, e consequente redução no desempenho de habilidades funcionais que envolvem a locomoção. A realização de exercícios sobre plataforma vibratória vem sendo investigada como uma possível estratégia para melhorar estas qualidades físicas na população idosa. Sendo assim, o objetivo do estudo foi comparar as adaptações neuromusculares e funcionais dos membros inferiores do grupo de idosas que treinou na plataforma vibratória com as do grupo controle que treinou sem vibração. A amostra do trabalho foi composta por 23 idosas (média de idade 63,57±4,52 anos) sendo 14 do grupo vibração e nove do grupo controle. As voluntárias realizaram 36 sessões de treinamento e foram avaliadas em três momentos, pré-treino, seis e 12 semanas pós-treino. Os testes aplicados foram para avaliação de pico de torque isométrico e dinâmico, potência, ativação e onset muscular, além da arquitetura muscular no músculo extensor de joelho (vasto lateral) e flexor plantar (gastrocnêmio medial). Também foram avaliadas as habilidades funcionais de sentar e levantar e se deslocar com agilidade. Além disso, foi feito um teste imediatamente após uma das sessões de treino para analisar a resposta imediata da vibração sobre a potência muscular dos membros inferiores (salto vertical). Os resultados mostraram que não houve diferença significativa entre o grupo vibração e o grupo controle para todas as variáveis analisadas após seis e 12 semanas de treinamento. No entanto, em ambos os grupos houve incrementos significativos (p<0,05) em algumas variáveis mensuradas (PT dinâmico de flexão plantar, tempo motor de flexão plantar, ângulo de penação e espessura muscular do vasto lateral e teste de sentar e levantar, no grupo vibratório; e no ângulo de penação do músculo vasto lateral, altura do salto com contra-movimento e sentar e levantar, no grupo controle) após 12 semanas de treinamento. Conclui-se que o treinamento vibratório não se mostrou efetivo para a melhoria das respostas neuromusculares e funcionais dos membros inferiores de idosas após 12 semanas de treino quando comparado ao grupo controle, nas condições em que foi realizado o presente trabalho. Sugere-se a realização de outros estudos com diferentes protocolos e com cargas de treino individualizadas respeitando as condições diferenciadas de cada indivíduo. / With aging there is a loss of muscle strength and power, especially in the lower limbs, and the consequent reduction in performance of functional skills that involve locomotion. The exercises on the vibration platform have been investigated as a possible strategy to increase these physical qualities in the elderly. Therefore, the aim of this study was to compare the neuromuscular and functional adaptations of the lower limbs in the experimental group of elderly women who trained on the vibration platform with the control group who trained without vibration. The sample consisted of 23 elderly (mean age 63.57 ± 4.52 years), with 14 of the vibration group and nine in the control group. The subjects performed 36 training sessions and were evaluated in three stages, pre-training, six and 12 weeks post-training. The tests were applied for evaluation of isometric and dynamic peak torque, power, muscle activation and onset of muscle activation, as well as muscle architecture in the knee extensor (vastus lateralis) and plantar flexor (medial gastrocnemius). The functional capacity to sit to stand and walk with agility was evaluated. In addition, a test was made immediately after a training session to analyze the immediate response of vibration on muscle power of lower limbs (vertical jump). The results showed no significant difference between the vibration group and control group for all variables after six and 12 weeks of training. However, both groups showed significant increases (p <0.05) in some of the measured variables (PT dynamic plantar flexion, plantar flexion motor time, pennation angle and muscle thickness of vastus lateralis and testing of sitting and standing, in the vibration group, and the muscle pennation angle of the vastus lateralis, heel height with counter-movement, sitting and standing in the control group) after 12 weeks of training. In conclusion that vibration training was not effective for the improvement of neuromuscular and functional responses of the lower limbs of elderly women after 12 weeks of training compared to the control group. It is suggested that further studies with different protocols and individualized training load respecting the different conditions of each individual should be performed.
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Adaptações neuromusculares e funcionais do treinamento vibratório em idosasWeber, Fernanda Seganfredo January 2012 (has links)
Com o envelhecimento ocorre perda de força e potência muscular, principalmente nos membros inferiores, e consequente redução no desempenho de habilidades funcionais que envolvem a locomoção. A realização de exercícios sobre plataforma vibratória vem sendo investigada como uma possível estratégia para melhorar estas qualidades físicas na população idosa. Sendo assim, o objetivo do estudo foi comparar as adaptações neuromusculares e funcionais dos membros inferiores do grupo de idosas que treinou na plataforma vibratória com as do grupo controle que treinou sem vibração. A amostra do trabalho foi composta por 23 idosas (média de idade 63,57±4,52 anos) sendo 14 do grupo vibração e nove do grupo controle. As voluntárias realizaram 36 sessões de treinamento e foram avaliadas em três momentos, pré-treino, seis e 12 semanas pós-treino. Os testes aplicados foram para avaliação de pico de torque isométrico e dinâmico, potência, ativação e onset muscular, além da arquitetura muscular no músculo extensor de joelho (vasto lateral) e flexor plantar (gastrocnêmio medial). Também foram avaliadas as habilidades funcionais de sentar e levantar e se deslocar com agilidade. Além disso, foi feito um teste imediatamente após uma das sessões de treino para analisar a resposta imediata da vibração sobre a potência muscular dos membros inferiores (salto vertical). Os resultados mostraram que não houve diferença significativa entre o grupo vibração e o grupo controle para todas as variáveis analisadas após seis e 12 semanas de treinamento. No entanto, em ambos os grupos houve incrementos significativos (p<0,05) em algumas variáveis mensuradas (PT dinâmico de flexão plantar, tempo motor de flexão plantar, ângulo de penação e espessura muscular do vasto lateral e teste de sentar e levantar, no grupo vibratório; e no ângulo de penação do músculo vasto lateral, altura do salto com contra-movimento e sentar e levantar, no grupo controle) após 12 semanas de treinamento. Conclui-se que o treinamento vibratório não se mostrou efetivo para a melhoria das respostas neuromusculares e funcionais dos membros inferiores de idosas após 12 semanas de treino quando comparado ao grupo controle, nas condições em que foi realizado o presente trabalho. Sugere-se a realização de outros estudos com diferentes protocolos e com cargas de treino individualizadas respeitando as condições diferenciadas de cada indivíduo. / With aging there is a loss of muscle strength and power, especially in the lower limbs, and the consequent reduction in performance of functional skills that involve locomotion. The exercises on the vibration platform have been investigated as a possible strategy to increase these physical qualities in the elderly. Therefore, the aim of this study was to compare the neuromuscular and functional adaptations of the lower limbs in the experimental group of elderly women who trained on the vibration platform with the control group who trained without vibration. The sample consisted of 23 elderly (mean age 63.57 ± 4.52 years), with 14 of the vibration group and nine in the control group. The subjects performed 36 training sessions and were evaluated in three stages, pre-training, six and 12 weeks post-training. The tests were applied for evaluation of isometric and dynamic peak torque, power, muscle activation and onset of muscle activation, as well as muscle architecture in the knee extensor (vastus lateralis) and plantar flexor (medial gastrocnemius). The functional capacity to sit to stand and walk with agility was evaluated. In addition, a test was made immediately after a training session to analyze the immediate response of vibration on muscle power of lower limbs (vertical jump). The results showed no significant difference between the vibration group and control group for all variables after six and 12 weeks of training. However, both groups showed significant increases (p <0.05) in some of the measured variables (PT dynamic plantar flexion, plantar flexion motor time, pennation angle and muscle thickness of vastus lateralis and testing of sitting and standing, in the vibration group, and the muscle pennation angle of the vastus lateralis, heel height with counter-movement, sitting and standing in the control group) after 12 weeks of training. In conclusion that vibration training was not effective for the improvement of neuromuscular and functional responses of the lower limbs of elderly women after 12 weeks of training compared to the control group. It is suggested that further studies with different protocols and individualized training load respecting the different conditions of each individual should be performed.
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Adaptações neuromusculares e funcionais do treinamento vibratório em idosasWeber, Fernanda Seganfredo January 2012 (has links)
Com o envelhecimento ocorre perda de força e potência muscular, principalmente nos membros inferiores, e consequente redução no desempenho de habilidades funcionais que envolvem a locomoção. A realização de exercícios sobre plataforma vibratória vem sendo investigada como uma possível estratégia para melhorar estas qualidades físicas na população idosa. Sendo assim, o objetivo do estudo foi comparar as adaptações neuromusculares e funcionais dos membros inferiores do grupo de idosas que treinou na plataforma vibratória com as do grupo controle que treinou sem vibração. A amostra do trabalho foi composta por 23 idosas (média de idade 63,57±4,52 anos) sendo 14 do grupo vibração e nove do grupo controle. As voluntárias realizaram 36 sessões de treinamento e foram avaliadas em três momentos, pré-treino, seis e 12 semanas pós-treino. Os testes aplicados foram para avaliação de pico de torque isométrico e dinâmico, potência, ativação e onset muscular, além da arquitetura muscular no músculo extensor de joelho (vasto lateral) e flexor plantar (gastrocnêmio medial). Também foram avaliadas as habilidades funcionais de sentar e levantar e se deslocar com agilidade. Além disso, foi feito um teste imediatamente após uma das sessões de treino para analisar a resposta imediata da vibração sobre a potência muscular dos membros inferiores (salto vertical). Os resultados mostraram que não houve diferença significativa entre o grupo vibração e o grupo controle para todas as variáveis analisadas após seis e 12 semanas de treinamento. No entanto, em ambos os grupos houve incrementos significativos (p<0,05) em algumas variáveis mensuradas (PT dinâmico de flexão plantar, tempo motor de flexão plantar, ângulo de penação e espessura muscular do vasto lateral e teste de sentar e levantar, no grupo vibratório; e no ângulo de penação do músculo vasto lateral, altura do salto com contra-movimento e sentar e levantar, no grupo controle) após 12 semanas de treinamento. Conclui-se que o treinamento vibratório não se mostrou efetivo para a melhoria das respostas neuromusculares e funcionais dos membros inferiores de idosas após 12 semanas de treino quando comparado ao grupo controle, nas condições em que foi realizado o presente trabalho. Sugere-se a realização de outros estudos com diferentes protocolos e com cargas de treino individualizadas respeitando as condições diferenciadas de cada indivíduo. / With aging there is a loss of muscle strength and power, especially in the lower limbs, and the consequent reduction in performance of functional skills that involve locomotion. The exercises on the vibration platform have been investigated as a possible strategy to increase these physical qualities in the elderly. Therefore, the aim of this study was to compare the neuromuscular and functional adaptations of the lower limbs in the experimental group of elderly women who trained on the vibration platform with the control group who trained without vibration. The sample consisted of 23 elderly (mean age 63.57 ± 4.52 years), with 14 of the vibration group and nine in the control group. The subjects performed 36 training sessions and were evaluated in three stages, pre-training, six and 12 weeks post-training. The tests were applied for evaluation of isometric and dynamic peak torque, power, muscle activation and onset of muscle activation, as well as muscle architecture in the knee extensor (vastus lateralis) and plantar flexor (medial gastrocnemius). The functional capacity to sit to stand and walk with agility was evaluated. In addition, a test was made immediately after a training session to analyze the immediate response of vibration on muscle power of lower limbs (vertical jump). The results showed no significant difference between the vibration group and control group for all variables after six and 12 weeks of training. However, both groups showed significant increases (p <0.05) in some of the measured variables (PT dynamic plantar flexion, plantar flexion motor time, pennation angle and muscle thickness of vastus lateralis and testing of sitting and standing, in the vibration group, and the muscle pennation angle of the vastus lateralis, heel height with counter-movement, sitting and standing in the control group) after 12 weeks of training. In conclusion that vibration training was not effective for the improvement of neuromuscular and functional responses of the lower limbs of elderly women after 12 weeks of training compared to the control group. It is suggested that further studies with different protocols and individualized training load respecting the different conditions of each individual should be performed.
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Do Changes In Muscle Architecture Effect Post- Activation PotentiationReardon, Danielle 01 January 2013 (has links)
Purpose: To examine the effect of three muscle potentiation protocols on changes in muscle architecture and the subsequent effect on jump power performance. Methods: Maximal (1RM) squat strength (Mean SD=178.3 ± 36.6kg), vertical jump power, and muscle architecture were obtained in 12 resistance trained men (25.2±3.6y; 90.67±12.7kg). Participants randomly completed three squatting protocols at 75% (3 x 10 reps), 90% (3 x 3 reps) or 100% (1 x 1) of their 1RM, or no workout (CON), with each protocol being separated by one week. During each testing session ultrasound and vertical jump testing were assessed at baseline (BL), 8min post (8P) and 20min post (20P) workout. Ultrasound measures of the rectus femoris (RF) and vastus lateralis (VL) muscles included; cross sectional area (CSA) and pennation angle (PNG). Following each ultrasound, peak (PVJP) and mean (MVJP) vertical jump power (using hands for maximum jump height) were measured using an accelerometer. Results: Magnitude based inferences analysis indicated that in comparison to CON, 75% resulted in a likely greater change in RF-CSA and VL-CSA (BL-8P and BL–20P), 90% resulted in a likely greater RF-CSA and VL-CSA (BL–20P), and 100% resulted in a very likely or likely decrease in VL-PNG at BL-8P and BL–20P, respectively). Meanwhile, changes in PVJP and MVJP for the 75% trial was likely decreased at BL-8P and BL–20P; and for the 90% trial MVJP was likely decreased at BL-8P and BL–20P. Analysis of the magnitude of the relationships indicated a likely negative relationship between VL-PNG and MVJP (r = -0.35; p < 0.018) at BL-8P, while at BL–20P, a negative relationship was observed between PVJP and RF-CSA (r = - 0.37; p < 0.014). iii Conclusion: Acute increases in muscle size and acute decreases in pennation angle did not result in any potentiation in vertical jump power measures. Although the inverse relationships observed between muscle architecture variables and power suggests a potential effect, the change in position (i.e. movement from standing to supine for ultrasound measures) may negate, as a result of potential fluid shifts or muscle relaxation, the potentiating effects of the exercise. It is also possible that the fatiguing nature of the squat protocols in trained but not competitive participants may have also contributed to the results.
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Supraspinatus Musculotendinous Architecture: A Cadaveric and In Vivo Ultrasound Investigation of the Normal and Pathological MuscleKim, Soo Young 24 September 2009 (has links)
The purpose of the study was to investigate the static and dynamic architecture of supraspinatus throughout its volume in the normal and pathological state. The architecture was first investigated in cadaveric specimens free of any tendon pathology. Using a serial dissection and digitization method tailored for supraspinatus, the musculotendinous architecture was modeled in situ. The 3D model reconstructed in Autodesk MayaTM allowed for visualization and quantification of the fiber bundle architecture i.e. fiber bundle length (FBL), pennation angle (PA), muscle volume (MV) and tendon dimensions. Based on attachment sites and architectural parameters, the supraspinatus was found to have two architecturally distinct regions, anterior and posterior, each with three subdivisions. The findings from the cadaveric investigation served as a map and platform for the development of an ultrasound (US) protocol that allowed for the dynamic fiber bundle architecture to be quantified in vivo in normal subjects and subjects with a full-thickness supraspinatus tendon tear. The architecture was studied in the relaxed state and in three contracted states (60º abduction with either neutral rotation, 80º external rotation, or 80º internal rotation). The dynamic changes in the architecture within the distinct regions of the muscle were not uniform and varied as a function of joint position. Mean FBL in the anterior region shortened significantly with contraction (p<0.05) but not in the posterior. In the anterior region, mean PA was significantly smaller in the middle part compared to the deep (p<0.05). Comparison of the normal and pathological muscle found large differences in the percentage change of FBL and PA with contraction. The architectural parameter that showed the largest changes with tendon pathology was PA. In sum, the results showed that the static and dynamic fiber bundle architecture of supraspinatus is heterogeneous throughout the muscle volume and may influence tendon stresses. The architectural data collected in this study and the 3D muscle model can be used to develop future contractile models. The US protocol may serve as an assessment tool to predict the functional outcome of rehabilitative exercises and surgery.
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Adaptações neuromecânicas ao treinamento de força utilizando ações excênctricas e concêntricas em idosos saudáveis do sexo masculinoBaptista, Rafael Reimann January 2011 (has links)
O objetivo deste estudo foi comparar o efeito de um programa de treinamento excêntrico versus concêntrico nas propriedades morfológicas, mecânicas e mioelétricas da unidade músculo-tendão do quadríceps de idosos. Vinte e três sujeitos do sexo masculino (62,74±2,20 anos de idade, 80,21±14,82 kg de massa corporal e 172,02±6,11 cm de estatura) participaram de um programa de treinamento de força durante 12 semanas, duas vezes por semana, realizando extensão unilateral concêntrica em uma articulação do joelho e flexão unilateral excêntrica na articulação do joelho contralateral, a 80% de 5 Repetições Máximas (5 RM). O tratamento estatístico foi composto por teste t de Student nas comparações das diferenças obtidas entre o período pré versus pós treinamento e por ANOVA de dois fatores para comparar as diferenças entre os treinamentos concêntrico versus excêntrico nos dois períodos (pré-treinamento versus pós-treinamento), utilizando o programa de estatística GraphPad Instat versão 3.06, adotando-se um nível de significância de 5%. Nas articulações treinadas excentricamente a força medida pelo teste de 5 RM aumentou de forma significativa (p<0,05) ao longo do programa de treinamento de força, enquanto que com o treinamento concêntrico houve um aumento da força nas primeiras 6 semanas (p<0,05) que não se repetiu nas últimas 6 semanas de treinamento. Avaliando a arquitetura do músculo vasto lateral por meio da ultrassonografia (ALOKA SSD 4000), verificamos que ambos os tipos de treinamento causaram uma redução no comprimento dos fascículos e um aumento no ângulo de penação (p<0,05) sem diferença entre os tipos de treinamento e sem alterar significativamente a espessura muscular (p>0,05). Ao utilizar a ultrassonografia para avaliar a arquitetura do tendão patelar, verificamos um aumento no comprimento do tendão com os dois tipos de treinamento e um aumento na área de seção transversa do tendão apenas da articulação treinada excentricamente (p<0,05). Utilizando um dinamômetro isocinético (Biodex System 3 PRO) verificamos que tanto o treinamento concêntrico quanto o treinamento excêntrico causaram um aumento significativo do torque articular nos ângulos de 50, 60, 70 e 90° (p<0,05), mas não no ângulo de 30° (p>0,05). Adicionalmente, verificamos que o treinamento concêntrico causou um aumento significativo nas velocidades articulares de -240, -180, -120 e -60°/seg e nas velocidades de 180 e 240°/seg (p<0,05). Já o treinamento excêntrico causou um aumento significativo apenas nas velocidades de 60, 120 e 180°/seg, tanto positivas quanto negativas (p<0,05). Utilizando a eletromiografia (Bortec Medical Systems) para comparação da ativação muscular não encontramos diferença significativa em nenhuma das análises. Nossos resultados nos permitem concluir que no que tange a arquitetura muscular o treinamento concêntrico e excêntrico proporcionam adaptações muito semelhantes, enquanto que na arquitetura tendinosa isso é válido para o comprimento muscular, mas não para a área de seção transversa. Todavia o treinamento excêntrico parece trazer um aumento de força mais consistente ao longo do treinamento, ainda que nas propriedades mecânicas não tenha sido constatadas diferenças significativas entre os tipos de treinamento. No que diz respeito as propriedades mioelétricas não encontramos diferenças significativas nas adaptações tanto ao treinamento concêntrico quando excêntrico. / The purpose of this study was to compare the effects of an eccentric training versus a concentric training concerning the morphological, mechanical and mioelectric properties of the muscle-tendon unit of the quadriceps muscle in older men. Twenty three male subjects (62.74±2.20 years old, 80.21±14.82 kg of body mass and 172.02±6.11 cm height) have participated of a strength training program for 12 weeks, two times a week, performing unilateral concentric extension of one knee joint and unilateral eccentric flexion of the other knee joint, at 80% of 5RM. The statistica analyses was perfomed by Student t test to compare the differences obtained between the pre-training versus post-training period and by two-way ANOVA to compare the diferences obtained between the concentric versus eccentric training in both periods (pre-training versus post-training) using the statistical software GraphPad Instat version 3.06 assuming a 5% level of significance. On the eccentrically trained joints the strength measured by the 5RM tests increased significantly (p<0.05) during the strength training program, while with the concentric training there was an increase in strength on the first 6 weeks (p<0.05) that didn’t repeat on the last 6 weeks of training. Through the evaluation of the muscle architecture of the vast lateral muscle (ALOKA SSD 4000), we verified that both types of training have caused a shortening of the fascicle length and an increase of the penation angle (p<0.05) without differences between the types of training and without altering significantly the muscle width (p>0.05). When we used the ultrasonography to evaluate the architecture of the patellar tendon, we have verified an increase on the tendon length with both types of training and an increase of the cross-sectional area of the tendon only on the joint trained eccentrically (p<0.05). Using an isokinetic dynamometer (Biodex System 3 PRO) we verified that both the concentric and the eccentric training have caused a significant increase of the joint torque in the angles of 50°, 60°, 70° and 90° (p<0.05), but not in the angle of 30° (p>0.05). Additionally, we verified that the concentric training did cause a significant joint speed increase of -240°, -180°, -120° and -60°/sec and on the speeds of 180° and 240°/sec (p<0.05). In the case of the eccentric training, it caused a significant increase only on the speeds of 60°, 120° and 180°/sec, both positive and negative (p<0.05). Using the electromyography (Bortec Medical Systems) to compare the muscle activation of the vast lateral in different joint angles in the pre and post concentric training periods, we have not verified significant difference in any of the analysis. Our results allow us to conclude that concerning the muscle architecture, concentric and eccentric training produce very similar adaptations, whereas in the tendon architecture this is valid for the muscle length, but not for the cross-sectional area. However, the eccentric training seems to bring a more consistent gain in strength during the training, despite that on the mechanical properties there were no significant differences stated between the types of training. Concerning to the myoelectrical properties we were not able to find any significant adaptation either in concentric or eccentric training.
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Functional Partitioning of the Human Lumbar Multifidus: An Analysis of Muscle Architecture, Nerve and Fiber Type Distribution using a Novel 3D in Situ ApproachRosatelli, Alessandro L. 01 September 2010 (has links)
Muscle architecture, innervation pattern and fiber type distribution of lumbar multifidus (LMT) throughout its volume was quantified. Musculotendinous (n=10) and neural components (n=3) were dissected and digitized from thirteen embalmed cadaveric specimens. The data were imported into Autodesk® Maya® 2008 to generate 3D neuromuscular models of each specimen. Architectural parameters (fiber bundle length, FBL; fiber bundle angle, FBA; tendon length) were quantified from the models using customized software. The medial branch of the posterior rami (L1-L5) was traced through LMT to determine its distribution. Using immunohistochemistry, Type I/II muscle fibers were identified in 29 muscle biopsies from one fresh frozen specimen. The total area and number of each cell type was calculated using Visiopharm® (image analysis software). Architectural and fiber type data were analyzed using ANOVA with Tukey’s post-hoc test (p ≤ 0.05).
From L1-L4, LMT had three architecturally distinct regions: superficial, intermediate and deep. At L5, intermediate LMT was absent. Mean FBL decreased significantly from superficial (5.8 ± 1.6cm) to deep regions (2.9 ± 1.1cm) as did volume (superficial, 5.6 ± 2.3ml; deep, 0.7 ± 0.3ml). In contrast, mean FBA increased from superficial to deep. The medial branch of the posterior ramus (L1-L5) supplied the five bands of LMT. Each medial branch in turn divided to supply the deep, intermediate and superficial regions separately. The area occupied by Type I fibers was significantly less (p< 0.01) in the deep (56%) compared with the superficial regions (75%).
Based on architecture and morphology, superficial LMT with the longest FBL and relatively small FBA is well designed for torque production and controlling the lumbar lordosis. Intermediate LMT with significantly longer FBL compared with the deep region and with its caudal to cranial line of action may help to control intersegmental stability. Furthermore, the absence of intermediate LMT at L5 and may contribute to the higher incidence of instability observed at the lumbosacral junction. Deep LMT with its short FBL, large FBA and proximity to the axis of spinal rotation may function to provide proprioceptive input to the CNS rather than a primary stabilizer of the lumbar spine.
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