Comparative Analysis on Two Different Algorithms for Estimating Muscle Forces / 医用生物力学

Objective To explore the differences between the result of static optimization (SO) and computational muscle control (CMC) algorithms for estimating muscle forces, so as to provide references for researchers to choose the appropriate algorithm and make horizontal comparison of the results from different studies. Methods Targeting at a single gait cycle running at four different speeds, SO and CMC algorithms were used to calculate forces and activations of the major muscles in lower limbs, and the results were compared and analyzed. Results Among the 10 major muscles participating in running, except for anterior tibial and rectus femoris, muscle forces and muscle activations solved by the two algorithms had similar curves with correlation coefficients more than 0.91, and the peak value of muscle forces solved by SO was higher and the positions of peak muscle activation had a 10 ms delay. Conclusions In movement analysis, if the research focuses on the timing of muscle forces and the contribution ratios among different muscles, there is not too big difference and SO algorithm is recommended for its simplicity and efficiency. For horizontal comparison of muscle forces and muscle activations estimated by SO and CMC algorithms in different studies, the differences between the two algorithms should be considered.

Analysis on Muscle Mechanical Properties of Stroke Patients’ Hand Grasping Training Based on AnyBody / 医用生物力学

Objective To establish the biomechanical model of skeletal muscle during hand grasping for reverse dynamics simulation, so as to obtain the maximum muscle force of each muscle involved in the process of hand grasping under different forces. Methods CT scanning was performed on a volunteer’s hand, and CT data of his hand were imported into Mimics software for 3D reconstruction, so as to obtain the bone models of each segment. After adjusting the model coordinates by Geomagic Studio, the model was imported in AnyBody software for establishing the kinematics model of the hand skeleton. The related muscles involved in the flexion of each finger were added, to establish the skeletal muscle model of the hand. The model was then used to simulate the reverse dynamics of hand grasping. ResultsThe maximum muscle force of each muscle in the whole process of finger movement was obtained after the 5-30 N external force was applied to each distal phalanx. With the increase of force, the maximum muscle force of each muscle showed a linear trend. For example, the maximum muscle force of flexor pollicis longus increased from 18.49 N to 110.93 N; when the external force was 5 N, the maximum muscle force of flexor pollicis brevis, flexor pollicis longus, adductor pollicis and flexor digiti minimi brevis during hand grasping was 7.70, 18.49, 9.49, 8.39 N, respectively. The muscle force of superficial and deep flexors was greater than that of other muscles in the process of finger movement, which played a major role in grasping the hand. Conclusions The maximum muscle force of the muscles involved in hand grasping under different resistance, and the relationship between muscle force of main muscles and joint angles, can provide guidance and references for the evaluation of hand rehabilitation effect of stroke patients, as well as certain theoretical basis for the manufacture of rehabilitation equipment.

Muscle force response characteristics of the slipping leg after an unexpected slip / 中国组织工程研究

BACKGROUND: Surface electromyogram signal is often used for qualitative analysis of muscles in the process of autonomic balance recovery after unexpected slips, but there is little research on the response characteristics of muscle force. OBJECTIVE: By the combination of gait analysis and simulation technology to study the muscle force response characteristics of the slipping leg when an unexpected slip of the heel occurs during walking straightly. METHODS: Five healthy subjects were recruited, wearing shoes uniformly, and asked to walk normally on two different straight footpaths (dry oil-free and oil-coated paths). The Vicon motion system and AMTI force measuring platform were used to collect the motion data. Based on the AnyBody Modeling System, a human musculoskeletal model matching with the subjects was established. The model was driven by the motion data, and the data of muscle force were collected and analyzed. RESULTS AND CONCLUSION: The recovery time after an unexpected slip was 15%-45% of a gait cycle and the single support phase was shortened. In the course of autonomic recovery, the muscle strength of the semitendinosus was increased by 25.6% (P < 0.05), and the muscle strength of the short head of biceps femoris increased by 14%. The maximum muscle strength of the medial gastrocnemius increased from 8.4 N/kg to 13.6 N/kg, and that of the lateral gastrocnemius increased by 17.4%. These findings indicate that: in the process of recovering the balance after unexpected slips, the semitendinosus, biceps femoris, gastrocnemius and gastrocnemius produce great muscle force, and meanwhile, the time of single support phase is shortened, so as to quickly transfer the gravity of human body from the sliding leg to the dragging leg and keep the body balance. After the balance recovery from the slip, the human body will make a prediction in the later period of the swing phase to prevent the slip again.

Acute effect of elastic bandage technique on middle deltoid muscle force and activation in healthy men / Efeito agudo da técnica de bandagem elástica sobre a força e ativação muscular do deltoide médio em homens saudáveis / Efecto agudo de la técnica de bandaje elástica sobre la fuerza y activación muscular del deltóide medio en hombres sanos

Abstract Introduction: Elastic bandages (EB), such as Kinesio taping, have been widely used in sports or daily life activities with the aim of preventing or reducing musculoskeletal injuries. It has been suggested that Kinesio Taping is capable of altering muscle activation through neurophysiological mechanisms, but the evidences about this are controversial. Objective: To verify the acute effect of EB on maximum voluntary isometric force (MVIF) and muscle activation of the middle deltoid muscle during muscle contraction. Method: Twenty-four healthy male (24 ± 4 years, 73.2 ± 13.9kg, 1.80 ± 0.10m) were randomly assigned to a group with elastic bandage activated at 100% (AEB n = 8); with tensionless elastic bandage (NEB n = 8), and the control group (CG n = 9). The volunteers were instructed to perform 5s of maximal isometric contraction at 90° of shoulder abduction while the MIVF and EMGrms records were registered. Results: One-way ANOVA was unable to identify significant difference (α = 0.05) in MIVF and EMGrms of the middle deltoid at 90° of shoulder abduction. Conclusion: The application of elastic bandage was not able to alter the production of maximal isometric voluntary contraction and activation of the middle deltoid muscle of healthy individuals and, therefore, its use is not justified for these purposes.

Resumo Introdução: Bandagens elásticas (BE), como a Kinesio taping, têm sido amplamente utilizadas em atividades esportivas ou da vida cotidiana com o objetivo de prevenir ou reduzir as lesões musculoesqueléticas. Tem sido sugerido que a Kinesio Taping é capaz de alterar a ativação muscular por meio de mecanismos neurofisiológicos, mas as evidências são controversas. Objetivo: verificar o efeito agudo da BE sobre a força isométrica voluntária máxima (FIVM) e ativação muscular do músculo deltoide médio durante a contração muscular. Método: Vinte e quatro participantes saudáveis, do sexo masculino (24 ± 4 anos; 73,2 ± 13,9kg; 1,80 ± 0,1m) foram distribuídos aleatoriamente em grupo com a bandagem elástica ativada a 100% (BEA n = 8) e com bandagem elástica sem tensão (BEN n = 8), ambas posicionadas no ombro; além do grupo controle (GC = 9). Os voluntários foram orientados a realizar 5s de contração isométrica máxima a 90° de abdução da articulação do ombro enquanto os registros de FIVM e EMGrms eram captados. Resultados: A ANOVA de uma entrada não foi capaz de identificar diferença significativa (α = 0,05) na FIVM e na EMGrms do deltoide médio a 90° de abdução da articulação do ombro. Conclusão: A aplicação da bandagem elástica não foi capaz de alterar a produção da força isométrica voluntária máxima e a ativação do músculo deltoide médio de indivíduos saudáveis e, portanto, seu uso não se justifica para esses fins.

Resumen Introducción: Vendaje elásticos (VE), como la Kinesio taping, han sido ampliamente utilizadas en actividades deportivas o de la vida cotidiana con el objetivo de prevenir o reducir las lesiones musculoesqueléticas. Se ha sugerido que la Kinesio Taping es capaz de alterar la activación muscular por medio de mecanismos neurofisiológicos, pero las evidencias son controvertidas. Objetivo: verificar el efecto agudo de los VE sobre la fuerza isométrica voluntaria máxima (FIVM) y activación muscular del músculo deltoide medio durante la contracción muscular. Método: Veinticuatro participantes sanos, del sexo masculino (24 ± 4 años, 73,2 ± 13,9kg, 1,80 ± 0,1m) fueron distribuidos aleatoriamente en grupo con el vendage elástico activado al 100% (VEA n = 8); con el vendaje elástico sin tensión (VEN n = 8; y el grupo de control (GC = 9). Los voluntarios fueron orientados a realizar 5s de contracción isométrica máxima a 90° de abducción de la articulación del hombro mientras los registros de FIVM y EMGrms eran captados. Resultados: La ANOVA de una entrada no fue capaz de identificar diferencia significativa (α = 0,05) en la FIVM y en la EMGrms del deltoide medio a 90° de abducción de la articulación del hombro. Conclusión: La aplicación de el vendaje elástico no fue capaz de alterar la producción de fuerza isométrica voluntaria máxima y la activación del músculo deltoide medio de individuos sanos y, por lo tanto, su uso no está justificado para esos propósitos.

OpenSim-Based Biomechanical Analysis of Lumbar Musculoskeletal System under Forward Flexion / 医用生物力学

Objective Based on OpenSim platform, an improved musculoskeletal model was developed to analyze the force of lumbar muscle groups under forward flexion. Methods The existing lumbar musculoskeletal model was improved via modifying constraints of lumbar vertebrae to restore them into 6 degrees of freedom (DOF). The 30 year-old and 70 year-old muscle models were established respectively by adjusting muscle parameters according to Thelen’s model, adding stiffness matrixes and abdominal pressure (AP) characterized by concentrated force to investigate the effects of arm swing, movement velocity, varying AP and muscle aging on the force distribution of 9 lumbar muscle groups during forward flexion. Results A multi-body musculoskeletal model with 9 lumbar muscle groups was developed. Based on the computations of 0°-70° flexion, the results showed that arm swing reduced the force of psoas and external oblique abdominis, while under the movement of forward flexing to 70° and returning up-right, the force of psoas, erector spinae, rectus and external oblique abdominis obviously increased, when the time of flexing-returning process was reduced from 5 s to 2.5 s, and in the 5 s case, increasing AP reduced the force of psoas but increased the force of transversus, internal and external oblique abdominis. In the 2.5 s case, there was no obvious difference between the 30 year-old and 70 year-old muscle models under different conditions. Conclusions The developed model provides an effective method to analyze the force of lumbar spine and muscles, and it certainly shows a potential application in the fields of kinematic mechanics and rehabilitation engineering with further development of basic theory.

Dynamic simulation and experimental verification of human body turning over in supine position / 生物医学工程学杂志

The tilted supine position has been evaluated to be one of the significantly effective approaches to prevent bedsore of the patients in the bedridden state. Thus, it has deeply positive influences that in view of dynamics this study explores how the position works. Based on the anatomical theories, this study formulates the human dynamic model. Furthermore, the dynamic simulation of three usual postures in tilted supine position including lying on back, lying with one knee bent and lying with the upper and lower limb on one side lifted is carried out. Therefore, the changes of the three driving forces named as chest force, waist force and thigh force in the tilted supine position can be observed. In order to verify the validity of this simulation, this study obtains the electromyogram measurements of ectopectoralis, external obliques and thigh muscles which are respectively close to the chest, waist and thigh by conducting the human force measurements experiment. The result revealed that in terms of range and trend, the experimental data and simulation's data were consistent. In conclusion, the changes of these muscles in the supine position movements are researched efficiently by both this experiment and the dynamic simulation. Besides, the result is crucially key to find the mechanism of human's tilted supine position movements.

Biomechanical properties of cervical traction under neck muscle force / 医用生物力学

Objective To establish a three-dimensional(3D) finite element model of cervical vertebrae (C1-7),and study its biomechanical properties under muscle force by cervical traction,so as to provide references for clinical treatment.Methods On the basis of nonlinear finite element model of normal cervical vertebrae and combined with clinical traction methods,cervical traction at the extension angle of 0°,10°,20°,30°,40° under the same traction weight,was simulated by finite element analysis (FEA) software to obtain and select the joint force and muscle force that were appropriate for FEA on the model.Results In the process of cervical extension by traction,under the muscle force,the average maximum equivalent stress of cervical vertebrae,intervertebral disc and uncovertebral joints increased by 4.86,1.79,0.69 MPa,respectively,and the average maximum relative displacement of cervical vertebrae in sagittal and vertical axis direction increased by 1 1.1,1.26 mm,respectively.The biomechanical properties of cervical traction were similar to the FEA results reported in the literature.Conclusions Neck muscles play an active role in promoting the stress and displacement of cervical vertebrae,intervertebral discs and uncovertebral joints and it should be taken into consideration when performing cervical traction in clinic.In addition,the traction angle should not be too large:0.-20. is generally recommended as a relatively safe angle range at the initial stage.

Biomechanical properties of cervical traction under neck muscle force / 医用生物力学

Objective To establish a three-dimensional(3D) finite element model of cervical vertebrae (C1-7), and study its biomechanical properties under muscle force by cervical traction, so as to provide references for clinical treatment. Methods On the basis of nonlinear finite element model of normal cervical vertebrae and combined with clinical traction methods, cervical traction at the extension angle of 0°, 10°, 20°, 30°, 40° under the same traction weight, was simulated by finite element analysis (FEA) software to obtain and select the joint force and muscle force that were appropriate for FEA on the model. Results In the process of cervical extension by traction, under the muscle force, the average maximum equivalent stress of cervical vertebrae, intervertebral disc and uncovertebral joints increased by 4.86, 1.79, 0.69 MPa, respectively, and the average maximum relative displacement of cervical vertebrae in sagittal and vertical axis direction increased by 11.1, 1.26 mm, respectively. The biomechanical properties of cervical traction were similar to the FEA results reported in the literature. Conclusions Neck muscles play an active role in promoting the stress and displacement of cervical vertebrae, intervertebral discs and uncovertebral joints and it should be taken into consideration when performing cervical traction in clinic. In addition, the traction angle should not be too large: 0°-20° is generally recommended as a relatively safe angle range at the initial stage.

Biomechanical properties of cervical traction under neck muscle force / 医用生物力学

Objective To establish a three-dimensional(3D) finite element model of cervical vertebrae (C1-7),and study its biomechanical properties under muscle force by cervical traction,so as to provide references for clinical treatment.Methods On the basis of nonlinear finite element model of normal cervical vertebrae and combined with clinical traction methods,cervical traction at the extension angle of 0°,10°,20°,30°,40° under the same traction weight,was simulated by finite element analysis (FEA) software to obtain and select the joint force and muscle force that were appropriate for FEA on the model.Results In the process of cervical extension by traction,under the muscle force,the average maximum equivalent stress of cervical vertebrae,intervertebral disc and uncovertebral joints increased by 4.86,1.79,0.69 MPa,respectively,and the average maximum relative displacement of cervical vertebrae in sagittal and vertical axis direction increased by 1 1.1,1.26 mm,respectively.The biomechanical properties of cervical traction were similar to the FEA results reported in the literature.Conclusions Neck muscles play an active role in promoting the stress and displacement of cervical vertebrae,intervertebral discs and uncovertebral joints and it should be taken into consideration when performing cervical traction in clinic.In addition,the traction angle should not be too large:0.-20. is generally recommended as a relatively safe angle range at the initial stage.

Biomechanical properties of cervical traction under neck muscle force / 医用生物力学

Objective To establish a three-dimensional(3D) finite element model of cervical vertebrae (C1-7),and study its biomechanical properties under muscle force by cervical traction,so as to provide references for clinical treatment.Methods On the basis of nonlinear finite element model of normal cervical vertebrae and combined with clinical traction methods,cervical traction at the extension angle of 0°,10°,20°,30°,40° under the same traction weight,was simulated by finite element analysis (FEA) software to obtain and select the joint force and muscle force that were appropriate for FEA on the model.Results In the process of cervical extension by traction,under the muscle force,the average maximum equivalent stress of cervical vertebrae,intervertebral disc and uncovertebral joints increased by 4.86,1.79,0.69 MPa,respectively,and the average maximum relative displacement of cervical vertebrae in sagittal and vertical axis direction increased by 1 1.1,1.26 mm,respectively.The biomechanical properties of cervical traction were similar to the FEA results reported in the literature.Conclusions Neck muscles play an active role in promoting the stress and displacement of cervical vertebrae,intervertebral discs and uncovertebral joints and it should be taken into consideration when performing cervical traction in clinic.In addition,the traction angle should not be too large:0.-20. is generally recommended as a relatively safe angle range at the initial stage.

Observe and Analyze the Rehabilitation of Multiparous Pelvic Floor Muscles in Postpartum / 实用妇产科杂志

Objective:To analyze the effects of mutiparity on the pelvic floor muscle and the best time of postpartum for pelvic floor rehabilitation intervention.Methods:By questionnaire survey and pelvic floor functional checking on women with 42 days postpartum clinic routine health checking,and following up pelvic floor muscles force exam in postpartum 3 months,6 months and 1 year,426 cases were included in the puerpera group,including primipara 325 cases as primiparous group,two birth multipara 101 cases as multiparous group,the damage of pelvic floor muscles(≤level Ⅱ) was compared between the two groups,the difference between multiparity and primiparity were compared.Results:①In postpartum 42 days,type Ⅰ muscle fiber damage rate was lower in multiparous group than that in primiparous group(P ＜0.05),there was no significant difference on the muscle fiber damage ratio (muscles force below Ⅲ) between the two groups (P ＞ 0.05).②)In postpartum 3 months,6 months,1 year there was no significant difference in proportion of muscle damage between the two groups (P ＞ 0.05).③Multiparous group pelvic floor muscle damage ratio decreased slowly and gradually in the four periods,there was no statistical difference between adjacent period (P ＞ 0.05),the pelvic muscle damage ratio appeared significant statistical difference between postpartum 6 months and postpartum 42 days(P ＜ 0.01).④In primiparous group,pelvic floor muscle damage ratio decreased significantly in postpartum 6 months,postpartum 42 days、3 months,6 months,the differces were statistically significant among the three times(P ＜ 0.05),there was no statistical difference between postpartum 6 months and 1 year(P＞0.05).Conclusions:Type Ⅰ muscle fibers suffer injury more in Primipara than that in multipara,multiparous pelvic floor muscle recovery process is more slowly than primipara's,we should pay attention to pelvic muscle recovery within 6 months after delivery.

Ocorrência de lesões de punho e mão e análise álgica em praticantes de Jiu-jítsu / Wrist and hand lesions and algic analysis in jiu-jitsu practitioners

No jiu-jítsu predominam técnicas de luta sobre a imposição da força bruta e, juntamente com os princípios biomecânicos, otimiza a força muscular do lutador, anula a do oponente e utiliza as valências físicas deste contra ele próprio. Desse modo, buscou-se identificar a ocorrência de lesões de punho e mão e análise da dor em praticantes de jiu-jítsu. Esta é uma pesquisa de campo, descritiva, de análise quali-quantitativa, com 6 participantes avaliados em sua preensão palmar, goniometria de punho, além dos testes de Phalen e Finkelstein e aplicação da Escala Visual Analógica, diagrama corporal e questionário de McGill (Br-MPQ). Foram identificados 4 testes de Phalen positivos, 2 positivos para Finkelstein e 2 praticantes não apresentaram lesão. Ao analisar a força de preensão palmar da amostra, observou-se uma média de 54,83 ± 6,85 para a mão direita, e de 52,83 ± 6,01 para a esquerda. Já na goniometria 100% dos praticantes apresentaram alterações em um ou mais movimentos avaliados da articulação de punho. Ao avaliar a classificação da dor, verificou-se que os praticantes de jiu-jítsu referiram dor em duas ou mais regiões do corpo.

Jiu-jitsu fighting techniques are characterized by the imposition of brute force which, coupled to bio-mechanical principles, optimizes the fighter´s muscular strength, vanquishes the opponent and uses the physical valences of the former against himself. Current analysis identifies the occurrence of wrist and hand lesions and analyzes pain in jiu-jitsu practitioners. Current field, descriptive and qualitative-quantitative research was undertaken with 6 participants evaluated through hand pressure, wrist goniometry, Phalen and Finkelstein test and the application of the Analogic Visual Scale, body diagram and McGill questionnaire (Br-MPQ). Four Phalen tests were positive; two Finkelstein tests were positive and two practitioners did not manifest any lesion. The sample´s hand-palm pressure force revealed an average of 54.83±6.85 for the right hand and 52.83±6.01 for the left hand. All practitioners had alterations in one or more movements of the wrist articulations. Assessment of pain showed that jiu-jitsu practitioners indicated pain in two or more body regions.

Associação entre força muscular e sensibilidade plantar em pacientes diabéticos: um estudo transversal / Association bet ween muscle force and foot sensitiveness in patients with diabetes: a transversal study

Diabetes Mellitus, distúrbio metabólico crônico dos carboidratos com elevadas taxas de morbi-mortalidade, tem a neuropatia diabética periférica (alterações sensitivas, motoras e autonômicas) como complicação mais prevalente. Em estudo transversal, 18 pacientes, verificou-se se há associação entre sensibilidade plantar e força muscular do tornozelo em pacientes diabéticos, avaliados quanto à sensibilidade tátil com monofilamentos (Semmes-Weisntein) em três pontos da região plantar nos dois pés, e força muscular de tornozelo, com teste de força manual, graduada de 0 a 5. Análise realizada no SPSS 20.0, testes qui quadrado e exato de Fisher, e p<0,05. Observou-se que 44,5% dos pacientes tinham perda da sensibilidade tátil e 38,8% da sensibilidade dolorosa; 38,8% e 33,3% tiveram diminuição da força de dorso-flexão direita e esquerda respectivamente, no entanto a correlação dessas variáveis, não foi estatisticamente significante. Diante dos resultados, não foi possível correlacionar a perda de sensibilidade plantar com a diminuição da força muscular nesse grupo de pacientes diabéticos.

Diabetes mellitus, a chronic carbohydrate metabolic disorder with high morbo-mortality rates, also includes peripheral diabetic neuropathy as a predominant complication. Current analysis verifies the association between foot sensitiveness and muscle force of the ankle in patients with diabetes. A transversal study involving 18 patients revealed that there is an association between foot sensitiveness and muscle force at the ankle in patients who were evaluated with regard to tactile sensitiveness with monofilaments (Semmes-Weistein) at three sites of the sole the foot and the muscular force of the ankle, with tests for hand strength, graduated from 0 to 5. Analysis SPSS 20.0, chi-square tests and Fisher´s exact test (p<0.05) were performed. Further, 44.5% of patients suffered loss of tactile sensitiveness; 38.8% had loss of pain sensitiveness; 38.8% and 33.3% had a decrease in the lateral dorsal-flexor force even though the co-relationship of variables was not statistically significant. Loss of sole sensitiveness could not be associated with decrease in muscle force in patients with diabetes.

Isokinetic dynamometry on the internal rotator and adductor muscles of the swimmers' shoulders: no differences between asymmetrical and symmetrical swimming strokes / Dinamometria isocinética dos músculos rotadores internos e adutores dos ombros de nadadores: sem diferenças entre braçadas de nados assimétricos e simétricos

OBJECTIVE: In this study, we compare muscular strength of the internal rotators and adductors of the shoulder between asymmetrical (backstroke and freestyle) and symmetrical (breaststroke and butterfly) swimming strokes. METHOD: We evaluated: shoulders of (a) asymmetrical swimmers (aged 21.8 ± 3.8 years), (b) symmetrical swimmers (aged 20.3 ± 4.5 years), (c) recreational swimmers (aged 24.5 ± 4.5 years), and (d) control individuals (aged 25.8 ± 3.5 years). All evaluations were performed on a Biodex® isokinetic dynamometer at velocities of 60° and 300°/second. Adduction and internal rotation movements were evaluated. The variables studied were peak torque corrected for body weight (PTQ/BW), total work (TW) and the agonist/antagonist relationship. RESULTS: There were no differences in adductor strength between the symmetrical and asymmetrical swimmers regarding PTQ/BW (symmetrical: 114.4 Newto-meter vs. asymmetrical: 109.4 Newton-meter) and TW (symmetrical: 642.9 Joules; asymmetrical: 641.5 Joules). There was no difference in the abduction/adduction relationship between the symmetrical (67.4%) and asymmetrical (68.3%) swimmers. There was no difference in the internal rotator musculature between the symmetrical and asymmetrical swimmers regarding the variables PTQ/BW (symmetrical = 66.4 Newton-meter and asymmetrical = 63.4 Newton-meterm) and TW (symmetrical = 517.4 J and asymmetrical 526.7 J). There was no difference in the ratio of external to internal rotation of the shoulder between the symmetrical (65.7%) and asymmetrical (61.5%) swimmers. CONCLUSIONS: There were no differences in muscular strength in the adductor and internal rotator muscles of the shoulder between symmetrical and asymmetrical swimming strokes.

RESUMO OBJETIVO: Neste estudo, comparamos a força muscular dos músculos rotadores internos e dos adutores do ombro entre nadadores especializados em estilos assimétricos (costas e nado livre) e simétricos (nado peito e borboleta). MÉTODO: Foram avaliados: ombros de (a) nadadores assimétricos (com idade 21,8 ± 3,8 anos), (b) nadadores simétricas (com idade de 20,3 ± 4,5 anos), (c) nadadores recreativos (com idade de 24,5 ± 4,5 anos), e (d) indivíduos do grupo controle (idade 25,8 ± 3,5 anos). As avaliações foram realizadas em um dinamômetro isocinético Biodex® nas velocidades de 60° e 300° / segundo. Foram avaliados adução e movimentos de rotação interna. As variáveis estudadas foram o pico de torque corrigido para peso corporal (PTQ/BW), trabalho total (TT) e a relação agonista/antagonista. RESULTADOS: Não houve diferenças na força adutora entre os nadadores simétricos e assimétricos em relação PTQ/BW (simétricos: 114,4 newton-metro vs. assimétricos: 109,4 newton-metro) e TW (simétrica: 642,9 Joules; assimétrica: 641,5 Joules). Não houve diferença na relação abdução/adução entre nadadores simétricos (67,4%) e assimétricos (68,3%). Não houve diferença na musculatura rotadora interna entre o nadadores simétricos vs. assimétricos em relação às variáveis PTQ/BW (simétricos = 66,4 Newton-metro e assimétricos = 63,4 Newton-metro) e TW (simétricos = 517,4 J e assimétricos 526,7 J). Não houve diferença na relação de rotação externo para interno do ombro entre nadadores simétricos (65,7%) e assimétricos (61,5%). CONCLUSÕES: Não houve diferenças na força muscular dos músculos adutores e rotadores internos do ombro entre estilos de natação simétricos e assimétricos.

Efeito do laser vs LED na região do infravermelho próximo sobre a atividade muscular esquelética: estudo clínico / Effect of laser vs LED in the near infrared region on the skeletal muscle activity: clinical study

INTRODUÇÃO: Estudos têm demonstrado a efetividade do laser no infravermelho (IV) sobre a atividade musculoesquelética. Contudo, não foram observados estudos sobre os efeitos da radiação emitida por um LED (Light Emitting Diode) no IV sobre a atividade do músculo masseter (MM, importante músculo da mastigação), sendo este o objetivo do presente estudo. MÉTODOS: Participaram do estudo 10 voluntários, os quais foram analisados por eletromiografia (atividade muscular, força e tempo de fadiga) e nível de lactato sanguíneo (mmol/L) após terapia placebo, laser (GaAlAs, 780 nm) e LED (GaAlAs, 880 nm). Os sinais obtidos previamente antes de realizadas as terapias foram tidos como controle. Os parâmetros de irradiação (laser ou LED) foram: potência de saída de 0,02 W, densidade de energia de 4 J/cm², área do feixe de 0,2 cm². Foram irradiados 8 pontos sobre o MM, de forma perpendicular e transcutânea, com distância de 1 cm entre os pontos. RESULTADOS: A atividade muscular foi significativamente maior pós-terapia laser e LED em relação aos valores controle. Não foram encontradas diferenças significativas nos valores de força, tempos de fadiga e níveis de lactato sanguíneo pós-terapia placebo, laser ou LED, quando comparados aos valores controle. CONCLUSÃO: Os resultados obtidos no presente estudo sugerem a otimização da atividade muscular com uso de terapia laser ou LED, sem causar efeitos colaterais, como a elevação de força e aumento dos níveis de lactato.

INTRODUCTION: Studies have demonstrated the effectiveness of the infrared laser (IR) on the skelet al muscle activity. However, it was not found studies on the effects of radiation emitted by IR LED (Light Emitting Diode) on the activity of masseter muscle (MM, important muscle of mastication), the aim of the present study. METHODS: Ten volunteers were involved and their electromyography (muscle activity, strength and fatigue time) and blood lactate levels (mmol/L) were analyzed after placebo, laser (GaAlAs, 780 nm) and LED (GaAlAs, 880 nm) therapies. The signals obtained previously conducted before the therapies were taken as control. The irradiation parameters (laser or LED) were: output power of 0.02 W, energy density of 4 J/cm² and beam area of 0.2 cm². Eight points on the MM were irradiated in a perpendicular and transcutaneous form with a 1-cm distance between the points. RESULTS: Muscle activity was significantly higher after laser and LED therapies when compared to control. No significant differences were found in force, fatigue time and blood lactate levels after placebo therapy, laser or LED, when compared to control. CONCLUSION: The results suggest the optimization of muscle activity with the use of laser or LED therapy, without causing side effects such as the increase in the force and levels of lactate.

Influência de parâmetros da estimulação elétrica funcional na contração concêntrica do quadríceps / Influence of functional electrical stimulation parameters in quadriceps concentric contraction

INTRODUÇÃO: Sistemas de estimulacão elétrica funcional (FES) são usados na pràtica clínica para o fortalecimento muscular, assim como para a recuperacão e preservacão funcional dos músculos enfraquecidos. Porém, uma das dificuldades encontradas na sua aplicacão é a falta de padrões adequados para a realizacão de um movimento pré-estabelecido, uma vez que os parâmetros da estimulacão (frequência, intensidade de corrente e duracão do pulso) são variados heuristicamente. O presente trabalho investigou a influência dos paraêmetros da FES usada no estabelecimento da posicão angular e forca produzida na extensão de joelho. MÉTODOS: O procedimento experimental foi dividido em duas fases chamadas Fase I e Fase II. A amostra total do estudo foi composta por 41 voluntàrios saudàveis de ambos os sexos (27 na Fase I e 14 na Fase II). Durante a Fase I cada voluntàrio foi estimulado com 18 combinacões diferentes de parâmetros para a FES, com o objetivo de determinar um modelo capaz de prever o movimento realizado para cada padrão de estimulacão. RESULTADOS: As diferentes duracões de pulso aplicadas não resultaram em alteracões significativas nos movimentos produzidos. Dentre os valores de frequência investigados, 50 Hz foi escolhida para a Fase II, por ter apresentado maior diferenca estatisticamente significativa para os valores de intensidade de corrente avaliados. Durante a Fase II, a intensidade de corrente da FES foi ajustada segundo um modelo linear estabelecido durante a primeira fase e que considerou características antropométricas dos sujeitos; encontrando-se um coeficiente de correlação r = 0,798 entre o ângulo pré-estabelecido e o ângulo alcancado. CONCLUSÃO: Este trabalho apresenta um modelo para a determinação de parâmetros de FES que permitem estabelecer variações angulares da articulação do joelho associadas à eletroestimulação. Considerando a frequência e a duração de pulsos constantes, se estima, usando uma equação de primeira ordem ...

INTRODUCTION: Functional electrical stimulation (FES) is used in clinical practice for muscle strengthening, as well as for functional recovery and preservation of weakened muscles. However, one of the problems in clinical application is the lack of adequate standards for determining the attainment of a predetermined movement, since the stimulation parameters are often adjusted heuristically. The present study investigated the influence of some parameters (frequency, current intensity and pulse duration) of the FES used to establish the joint angle and force produced in knee extension. METHODS: The experimental procedure was divided in two phases (Phase I and Phase II). The total sample included 41 healthy volunteers of both sexes (27 and 14 in Phase I and Phase II). During Phase I 18 profiles of FES were applied in the quadriceps muscle of subjects, changing the above-mentioned FES parameters. RESULTS: It was observed that the pulse duration of the electrical stimulation pulse did not exhibit significant relevance in the evoked movements. Among the discrete values of frequency investigated, the stimulation at 50 Hz was selected because it showed higher statistical significant difference considering the values of current intensity measured. During the Phase II, devoted to place the knee joint angle in a pre-determined value, the current intensity of the FES was adjusted according to the linear model established during the Phase I, which considered anthropometric characteristics of the subjects. In this Phase we found a correlation coefficient r = 0,798 between the pre-determined angle and the reached one. CONCLUSION: This paper presents a model for the determination of FES parameters for establishing angular variations of the knee associated with electrical stimulation. Considering frequency and pulse duration constants we estimate, using a first order equation and correlation coefficient of 0.72, the current intensity dependent of desired angle variation.

Kinematics and dynamics characteristics of index finger after cold stimulation / 医用生物力学

Objective To investigate effects of cold water stimulation on kinematic and dynamic characteristics of index finger. Method In order to reduce the influence on its flexion and extension, the index finger movement was recorded by a high speed camera. Then a self developed MATLAB program was developed to obtain the trajectory with the help of the black speckles on index finger joints. Finally, a dynamic calculating model with FDS and FDP was set up to describe the relationship between the trajectory and muscle forces changed along with the time. Results After the cold water stimulation, the average angular velocity of the second joint in the index finger decreased in the process of fisting and stretching. Before and after the cold water stimulation, the force of FDP muscle changed little while the force of FDS muscle approximately doubled at the end of the fisting. Conclusions An optical method for obtaining the trajectory of index finger was applied, and a dynamic calculating model was developed to calculate the muscle forces during the finger movement. Therefore, the characteristics of the index finger before and after the cold stimulation could be further discussed.

The Effect of Physical Performance and Physical Activity on Quality of Life in Old People: The Korean Longitudinal Study on Health and Aging

BACKGROUND: To investigate the physical function of elderly people in Korea using quantitative and objective tools and to assess the impact of declined physical function on their quality of life. METHODS: The Korean Longitudinal Study on Health and Aging was designed as a population-based prospective cohort study on the health and aging of the elderly people in Korea aged 65 years and older. Within one city's central metropolitan area, 1,000 subjects including a simple random sample and an oldest-old subpopulation participated in a baseline study for one year. We evaluated the isokinetic peak torque of the knee extensors and flexors, grip force, and Short Physical Performance Battery (SPPB) and surveyed their daily physical activities and quality of life using the 36-Item Short Form Health Survey (SF-36). RESULTS: Overall, 676 subjects completed the evaluations of physical function and activity. The isokinetic torque of the knee extensors and flexors declined with age in both men and women. The women in the old-old (75-84 years) group showed lower SPPB and physical activity than women in the young-old (65-74 years) group, but these measures were maintained till age 85 in the men. SPPB and physical activity were significantly associated with the physical component scale (PCS) of the SF-36 in both men and women, while isokinetic torque was associated with PCS in women only. CONCLUSION: Physical performance and activity declined differently in Korean elderly men and women. Both these measures showed to be the main factors associated with quality of life.

Força de mordida em crianças com mantenedor de espaço funcional na fase da dentadura mista inicial / Bite force in children with functional space maintainer in early mixed dentition

OBJETIVO: verificar a influência do mantenedor de espaço funcional (MEF) na força muscular em crianças com perda prematura de molares decíduos na fase inicial da dentadura mista (5,5 a 6,5 anos de idade) com oclusão normal, considerando-se o padrão facial. MÉTODOS: a amostra foi constituída por dois grupos: Grupo MEF (n = 15), com perda precoce de pelo menos um molar decíduo; e Grupo Controle (n = 16). Determinou-se a força de mordida máxima (FM) com um tubo transmissor pressurizado, conectado a um circuito eletrônico analógico/digital antes (t0), um mês (t1) e 6 meses (t6) após a instalação do mantenedor. O padrão facial foi determinado pelo índice de Jarabak (FHR). Os dados foram analisados pela estatística descritiva, análise de variância para medidas repetidas, teste t e correlação de Pearson. RESULTADOS:a FM foi significativamente menor em t0 e t1 para o Grupo MEF em relação ao Controle. Em t6 não houve diferença. Os dois grupos apresentaram a FM significativamente maior em t6, em relação a t0, mas o percentual de variação para o Grupo MEF foi significativamente maior. Os valores de FHR não se correlacionaram com a FM, não ocorrendo diferença entre os tipos faciais intragrupos. Os dolicofaciais do Grupo MEF apresentaram a FM significativamente menor que os do Grupo Controle, em t0 e t1, mas não em t6. CONCLUSÃO: o maior aumento na FM para o Grupo MEF após 6 meses foi favorecido pelo maior número de contatos oclusais, devido aos dentes artificiais, melhorando a função e recuperando a força muscular.

AIM: To verify the influence of a functional space maintainer (FSM) in muscle strength in children with premature loss of primary molars in early mixed dentition (5.5-6.5 years old) with normal occlusion, considering the facial pattern. METHODS: The sample was distributed in: FSM Group (n = 15), with premature loss of at least one primary molar and a Control Group (n = 16). It was determined the maximal bite force (BF) with a pressurized transmitter tube, connected to a analogic/digital electronic circuit, before (t0), 1 month (t1) and 6 months (t6) after the maintainer installation. The facial pattern was determined by the Jarabak's index (FHR). Data was analyzed by descriptive statistics, variance analysis with repeated measures, t test and Pearson's correlation. RESULTS: The BF was significantly lower in t0 and t6 for FSM Group than Control Group. There was no difference in t6. Both groups presented significantly higher BF at t6 in relation to t0, but the percentage of variation was higher for FSM Group. FHR values did not correlated with the BF, and there was no difference among facial pattern intragroups. The dolichofacial children in FSM Group had values significantly lower than their matched controls in t0 and t1, but not in t6. CONCLUSION: It was concluded that the higher increase in the FM values for SFM Group after 6 month was due to the number of occlusal contacts allowed by the artificial teeth, improving the function and catching up the muscle strength.

Effects of combined training programs on force-velocity relation and power output in human muscle / 体力科学

The effects of different training programs on the force-velocity relation and the maximum power output from the elbow flexor muscles were examined in eighteen male adults. The subjects were divided into three equal groups (G 30, G 30+0, G 30+ 100) . Training for G 30 was performed with ten repetitions at 30% P<SUB>o</SUB> (P<SUB>o</SUB>: maximum strength), for G30+0 with five repetitions at 30% P<SUB>o</SUB> and five contractions with no load (0 % P<SUB>o</SUB>), and for G 30+100 with five repetitions at 30% P<SUB>o</SUB> and five isometric contractions (100% P<SUB>o</SUB>) .<BR>Maximum power was increased significantly in all groups after training. The amounts of power increase tended to be greatest for G 30+ 100, followed by G 30+0 and G 30. A significant difference was observed between G 30 + 100 and G 30 + 0. Maximum strength increased most in G 30 + 100, followed by G30 and G 30+0. The strength gain in G 30+100 was significantly greater than that in G 30. Maximum velocity increased significantly in all groups. No significant difference in velocity gain was observed between any pair of groups.<BR>These results suggest that isometric training at maximum strength (100% P<SUB>o</SUB>) appears to be a more effective form of supplementary training to increase power production than would no load training at maximum velocity.