Functional roles of abdominal and back muscles during isometric axial rotation of the trunk

Electromyographic (EMG) studies have shown that a large number of trunk muscles are recruited during axial rotation. The functional roles of these trunk muscles in axial rotation are multiple and have not been well investigated. In addition, there is no information on the coupling torque at different exertion levels during axial rotation. The aim of the study was to investigate the functional roles of rectus abdominis. external oblique. internal oblique, latissimus dorsi, iliocostalis lumborum and multifidus during isometric right and left axial rotation at 100%, 70%, 50% and 30% maximum voluntary contractions (MVC) in a standing position. The coupling torques in sagittal and coronal planes were measured during axial rotation to examine the coupling nature of torque at different levels of exertions. Results showed that the coupled sagittal torque switches from nil to flexion at maximum exertion of axial rotation. Generally, higher EMG activities were shown at higher exertion levels for all the trunk muscles. Significant differences in activity between the right and left axial rotation exertions were demonstrated in external oblique, internal oblique, latissimus dorsi and iliocostalis lumborum while no difference was shown in rectus abdominis and multifidus. These results demonstrated the different functional roles of trunk muscles during axial rotation. This is important considering that the abdominal and back muscles not only produce torque but also maintain the spinal posture and stability during axial rotation exertions. The changing coupling torque direction in the sagittal plane when submaximal to maximal exertions were compared may indicate the complex nature of the kinetic coupling of trunk muscles. (C) 2001 Orthopaedic Research Society. Published by Elsevier Science Ltd. All rights reserved.

Fatigue-related changes in torque output and electromyographic parameters of trunk muscles during isometric axial rotation exertion - An investigation in patients with back pain and in healthy subjects

Study Design. A cross-sectional case-control study. Objectives. To examine the effect of fatigue on torque output as well as electromyographic frequency and amplitude values of trunk muscles during isometric axial rotation exertion in back pain patients and to compare the results with a matched control group. Summary of Background Data. Back pain patients exhibited different activation strategies in trunk muscles during the axial rotation exertions. Fatigue changes of abdominal and back muscles during axial rotation exertion have not been examined in patients with back pain. Methods. Twelve back pain patients and 12 matched controls performed isometric fatiguing axial rotation to both sides at 80% maximum voluntary contraction in a standing position. During the fatiguing exertion, electromyographic changes of rectus abdominis, external oblique, internal oblique, latissimus dorsi, iliocostalis lumborum, and multifidus were recorded bilaterally. The primary torque in the transverse plane and the coupling torques in sagittal and coronal planes were also measured. Results. No difference in the endurance capacity was found between back pain and control groups. At the initial period of the exertion, back pain patients demonstrated a statistical trend (P = 0.058) of greater sagittal coupling torque as well as lower activity of rectus abdominis and multifidus and higher activity in external oblique. During the fatigue process similar changes of coupling torque were demonstrated in both sagittal and coronal planes, but a smaller fatigue rate for right external oblique, increase in median frequency for latissimus dorsi, and lesser increase in activity for back muscles were found in the back pain group compared with the control group. Conclusions. Alterations in electromyographic activation and fatigue rates of abdominal and back muscles demonstrated during the fatigue process provide insights into the muscle dysfunctions in back pain and may help clinicians to devise more rational treatment strategies.

On the effect of tracer density on axial dispersion in a batch oscillatory baffled column

In this paper, we report our modelling evaluation on the effect of tracer density on axial dispersion in a batch oscillatory baffled column (OBC). Tracer solution of potassium nitrite, its specific density ranged from 1.0 to 1.5, was used in the study, and was injected to the vertical column from either the top or bottom. Local concentration profiles are measured using conductivity probes at two locations along the height of the column. Using the experimental measured concentration profiles together with both 'Tank-in-Series' and 'Plug Flow with Axial Dispersion' models, axial dispersion coefficients were determined and used to describe the effect of specific tracer density on mixing in the OBC. The results showed that the axial dispersion coefficients evaluated by the two models are very similar in both magnitudes and trends, and the range of variations in such coefficients is generally larger for the bottom injection than for the top one. Empirical correlations linking the mechanical energy for mixing, the specific density of tracer and axial dispersion coefficient were established. Using these correlations, we identified the enhancements of up to 269% on axial dispersion for various specific tracer densities. (C) 2002 Elsevier Science B.V. All rights reserved.

Axial mixing in rotating drums using magnetic resonance imaging using bran as a model for solid state fermentations

Magnetic resonance imaging (MRI) is an easily automated, reliable technique to investigate axial mixing within rotating drums. Moist bran can be clearly differentiated from dry bran using MRI allowing a non-segregating tracer for axial mixing. For a 20-cm diameter drum, the axial dispersion coefficient in the particle bed was 0.51 cm s(-2). Axial dispersion is scale-dependent.

EMG activity of trunk muscles and torque output during isometric axial rotation exertion: a comparison between back pain patients and matched controls

Abnormal patterns of trunk muscle activity could affect the biomechanics of spinal movements and result in back pain. The present study aimed to examine electromyographic (EMG) activity of abdominal and back muscles as well as triaxial torque output during isometric axial rotation at different exertion levels in back pain patients and matched controls. Twelve back pain patients and 12 matched controls performed isometric right and left axial rotation at 100%, 70%, 50%, and 30% maximum voluntary contractions in a standing position. Surface EMG activity of rectus abdominis, external oblique, internal oblique, latissimus dorsi, iliocostalis lumborum and multifidus were recorded bilaterally. The primary torque in the transverse plane and the coupling torques in sagittal and coronal planes were measured. Results showed that there was a trend (P = 0.08) of higher flexion coupling torque during left axial rotation exertion in back pain patients. Higher activity for external oblique and lower activity for multifidus was shown during left axial rotation exertion in back pain group when compared to the control group. In right axial rotation, back pain patients exhibited lesser activity of rectus abdominis at higher levels of exertion when compared with matched controls. These findings demonstrated that decreased activation of one muscle may be compensated by overactivity in other muscles. The reduced levels of activity of the multifidus muscle during axial rotation exertion in back pain patients may indicate that spinal stability could be compromised. Future studies should consider these alternations in recruitment patterns in terms of spinal stability and internal loading. The findings also indicate the importance of training for coordination besides the strengthening of trunk muscles during rehabilitation process. (C) 2002 Orthopaedic Research Society. Published by Elsevier Science Ltd. All rights reserved.

Effect of fatigue on torque output and electromyographic measures of trunk muscles during isometric axial rotation

Objectives: To examine the changes in torque output resulting from fatigue, as well as changes in electromyographic measures of trunk muscles during isometric axial rotation and to compare these changes between directions of axial rotation. Design: Subjects performed fatiguing right and left isometric axial rotation of the trunk at 80% of maximum voluntary contraction while standing upright. Setting: A rehabilitation center. Participants: Twenty-three men with no history of back pain. Interventions: Not applicable. Main Outcome Measures: Surface electromyographic Signals were recorded from 6 trunk muscles bilaterally. The primary torque in the transverse plane and the coupling torques in sagittal and coronal planes were also measured. Results: During the fatiguing axial rotation contraction, coupling torques of both sagittal and coronal planes were slightly decreased and no difference was found between directions of axial rotation. Decreasing median frequency and an increase in electromyographic amplitude were also found in trunk muscles with different degrees of changes in individual muscles. There were significant differences (P

Reliability of electromyographic and torque measures during isometric axial rotation exertions of the trunk

Objective: The aim of the present study was to investigate the between-days reliability of electromyographic (EMG) measurement of 6 bilateral trunk muscles and also the torque output in 3 planes during isometric right and left axial rotation at different exertion levels. Methods: Ten healthy subjects performed isometric right and left axial rotation at 100, 70, 50 and 30% maximum voluntary contractions in two testing sessions at least 7 days apart. EMG amplitude and frequency analyses of the recorded surface EMG signals were performed for rectus abdominis, external oblique, internal oblique, latissimus dorsi, iliocostalis lumborum and multifidus bilaterally. The primary torque in the transverse plane and the coupling torques in sagittal and coronal planes were measured. Results: For both EMG amplitude and frequency values, good (intraclass correlation coefficient, ICC = 0.75-0.89) to excellent (ICC greater than or equal to 0.90) reliability was found in the 6 trunk muscles at different exertion levels during axial rotation. The reliability of both maximal isometric axial rotation torque and coupling torques in sagittal and coronal planes were found to be excellent (ICC greater than or equal to 0.93). Conclusions: Good to excellent reliability of EMG measures of trunk muscles and torque measurements during isometric axial rotation was demonstrated. This provides further confidence of using EMG and triaxial torque assessment as outcome measures in rehabilitation and in the evaluation of the human performance in the work place. (C) 2003 International Federation of Clinical Neurophysiology. Published by Elsevier Ireland Ltd. All rights reserved.

Estudo comparativo da eminectomia e do uso de miniplaca na eminência articular para tratamento da luxação recidivante da articulação temporomandibular

AA luxação da articulação temporomandibular ocorre quando o côndilo mandibular move-se para fora da cavidade glenóide e permanece travado anteriormente à eminência articular, sendo sua ocorrência repetitiva (luxação recidivante) geralmente associada a hipermobilidade mandibular e a inclinação da eminência articular. OBJETIVO: Neste estudo avaliou-se, clínica e radiograficamente, a técnica de eminectomia e do uso de miniplaca na eminência articular para tratamento da luxação recidivante da articulação temporomandibular de pacientes operados no Hospital Universitário Osvaldo Cruz (HUOC/UPE), no período de janeiro de 2001 a setembro de 2003. FORMA DE ESTUDO: Retrospectivo. MATERIAL E MÉTODO: A amostra foi composta por 11 pacientes. A cirurgia de eminectomia foi realizada em nove articulações de cinco pacientes, enquanto a cirurgia para colocação de miniplaca na eminência articular em 11 articulações de seis pacientes. A obtenção dos dados foi efetuada através da análise de prontuários e de nova consulta pós-operatória. RESULTADOS: Os resultados mostraram não haver maiores complicações pós-operatórias para as duas técnicas. A abertura bucal máxima foi maior nos pacientes operados pela técnica de eminectomia e nenhum dos pacientes apresentou recorrência da luxação. CONCLUSÃO: Concluiu-se que as duas técnicas mostraram-se eficientes para o tratamento da luxação recidivante da articulação temporomandibular.

Presença de desconforto na articulação temporomandibular relacionada ao uso da chupeta

OBJETIVO: O presente estudo teve por objetivo analisar se o tempo de uso da chupeta influenciava no aparelho estomatognático em crianças que não apresentavam outros hábitos parafuncionais. FORMA DE ESTUDO: Estudo de coorte transversal. MATERIAL E MÉTODO: Para coletar os dados, mães de 90 crianças de três a sete anos responderam a um questionário. As crianças foram divididas em três grupos: não usaram chupeta; usaram até dois anos; usaram até mais de dois anos. RESULTADO: Entre as crianças que não usaram chupeta e naquelas que fizeram uso desta por mais de dois anos, notou-se maior prevalência de dor ou desconforto no aparelho estomatognático. Já as crianças que fizeram uso da chupeta até dois anos, essa prevalência foi menor. CONCLUSÃO: Conclui-se, então, que a chupeta é importante por fazer com que a criança realize movimentos de sucção, preparando-a para a introdução de alimentos sólidos. Porém, se usada por tempo prolongado, pode prejudicar a articulação e, conseqüentemente, a qualidade de vida da criança.

Análise anátomo-radiográfica da persistência do Forame de Huschke

OBJETIVO: o objetivo neste trabalho é avaliar e localizar o Forame de Huschke. FORMA DE ESTUDO: anatômico. MATERIAL E MÉTODO: utilizando materiais de contraste como a Guta percha e o sulfato de bário, através de técnicas radiográficas extrabucais, como a panorâmica, submentovértex e a tomografia linear lateral corrigida para a Articulação Têmporo-mandibular, em quatro crânios, onde foi verificada clinicamente a presença do Forame de Huschke. RESULTADO: Os resultados obtidos mostraram que o Forame de Huschke pôde ser observado em crânios secos após a sua evidenciação por meio de material de contraste nestas técnicas radiográficas.

Artrocentese da articulação temporomandibular: avaliação de resultados e revisão da literatura

OBJETIVO: Avaliar o efeito da artrocentese em relação à sintomatologia e movimentação mandibular em uma serie de pacientes com deslocamento anterior de disco e travamento mandibular. MATERIAIS E MÉTODOS: O estudo foi baseado nos dados pré e pós-operatório de pacientes através de exame clínico e radiográfico. A Escala Analógica Visual (EAV) foi usada para quantificar a dor no pré e pós-operatório. Foram avaliados 6 pacientes (12 articulações) tratados no Hospital Universitário Oswaldo Cruz (HUOC) com travamento mandibular (2 casos) e desarranjo interno (4 casos). O período médio de acompanhamento foi de 11,5 meses. RESULTADOS: A média de abertura bucal pré-operatória foi de 31,83mm e no pós-operatório foi de 36,50mm. A média de dor articular segundo a escala visual analógica encontrada foi de 7 e no pós-operatório foi de 4,3. CONCLUSÃO: A artrocentese mostrou-se efetiva na melhora da dor articular e na movimentação mandibular nesta série de casos.

Anquilose da articulação têmporo-mandibular

A anquilose pode ser definida como sendo a fusão das superfícies articulares e seu tratamento é um verdadeiro desafio devido à alta taxa de recorrência. OBJETIVO: Descrever seis casos clínicos tratados pela técnica da reconstrução articular, avaliar os resultados dessas cirurgias e fazer uma revisão da literatura. METODOLOGIA: A população estudada neste estudo retrospectivo foi obtida dos prontuários do hospital universitário e tinha que ter sido submetida a cirurgia para tratamento de anquilose por reconstrução aloplástica ou autógena entre os períodos de março de 2001 e outubro de 2005. Dados como a máxima abertura de boca (MAB), etiologia, tipo de anquilose e tratamento, e ocorrência de recidiva e lesão do nervo facial foram coletados no pré-operatório, através dos prontuários, e no pós-operatório, através de entrevista. RESULTADOS: A média da MAB no pré-operatório foi de 9,6mm (0 a 17mm) e no pós-operatório foi de 31,33mm (14mm a 41mm), não houve lesão do nervo facial e apenas em um caso houve recidiva da anquilose. CONCLUSÃO: A reconstrução da articulação com material autógeno ou alógeno, para o tratamento da anquilose da ATM se mostrou eficaz em relação à MAB pós-operatória, recidiva e função da articulação.

A síntese imperfeita: articulação entre política externa e política de defesa na era Cardoso

Esse artigo tem por objetivo gerar hipóteses sobre a articulação entre política externa e política de defesa na gestão Cardoso. Partiu-se de estudo de caso sobre a formulação da Política de Defesa Nacional (PDN) e as conseqüências dessa para a institucionalização do Ministério da Defesa (MD). Constatou-se a baixa prioridade atribuída pela diplomacia ao poder militar como ferramenta de política externa. Finalmente, explicitou-se a inexistência de mecanismos efetivos de articulação.