Normalization of the electromyographic signals of masticatory muscles during non-habitual chewing activity

There is no consensus on the most appropriate method for normalizing electromyography (EMG) signals from masticatory muscles during isotonic activity. Aim: To analyze the best method for data processing of the EMG signal of the masticatory muscles during isotonic activity (non-habitual chewing), comparing raw data and different types of normalization. Methods: This is a cross-sectional study. Women aged between 18 and 45 years were selected. Anthropometric data were collected (age, height, body mass index ­ BMI, masticatory preference) as well as EMG signal (root mean square ­ RMS) data for the anterior temporal and masseter bilaterally, and for the suprahyoid muscles, during isotonic (non-habitual chewing) and isometric tasks. EMG data were processed offline using Matlab® Software. The normalization of the EMG signal was carried out using the 2nd masticatory cycle, chosen at random, of the 20 cycles collected, the maximum RMS value, and the maximum voluntary contraction (MVC). To analyze the best method of data processing for the isotonic data, the coefficient of variation (CV) was calculated. Descriptive data analysis was adopted, using the mean and standard deviation. ANOVA with repeated measures was used to detect significant differences between the methods of normalization. Statistical significance was set at 5% (α<0.05). Results: The final sample of this research was composed of 86 women. The volunteers presented an average age of 27.83±7.71 years and a mean BMI of 22.85±1.91 Kg/m2. Regarding masticatory preference, 73.25% reported the right side, and 26.75% the left side. Considering the comparison between the methods, the %CV measure of the 2nd cycle showed the lowest variation coefficient during biting for all the muscles from the raw data, RMS Max, and MVC (p=0.001, p=0.003, and p=0.001 respectively). Conclusion: In conclusion, for non-habitual chewing activity, the results of this study recommend data processing using normalization with the second cycle during chewing

Strength of scapular elevation in women with TMD and asymptomatic women - a cross-sectional study

Temporomandibular disorder (TMD) is recognized for its high prevalence, presenting characteristic signs and symptoms. Cervical spine pain is present in 70% of diagnosed TMD cases. Aim To verify if women with TMD present changes in isometric muscle strength in the scapula elevation. Methods This is an observational, cross-sectional study. Thirty-five women, aged 22.89±2.04 years, were divided into the TMD group (TMDG), diagnosed with TMD according to the DC/TMD, and control group (CG), with asymptomatic individuals. The volunteers accessed a online link by the smartphone in order to answer questions on personal data, the Fonseca Anamnestic Index (FAI), Neck Disability Index (NDI), and Masticatory preference. In all participants, evaluation of the force of the scapula elevation muscles was performed, using a load cell model MM-100 (Kratos® SP, Brazil). Data were analyzed descriptively using the maximum, mean, and standard deviation and a two-way ANCOVA test was applied for all variables. A significance level of 5% was considered. Results There were no statistically significant differences between the TMDG and CG for the maximal and mean muscle strength of scapular elevation. There were statistically significant differences in FAI (p <0.001*) between the CG and the TMDG. Conclusion Based on the results, it was not possible to confirm the hypothesis that women diagnosed with TMD present lower isometric strength during scapular elevation (right/left).

Efeitos da manipulação cervical alta sobre a atividade eletromiográfica dos músculos mastigatórios e amplitude de movimento de abertura da boca em mulheres com disfunção temporomandibular: ensaio clínico randomizado e cego / Los efectos de la manipulación cervical en la actividad electromiográfica de los músculos masticatorios y la amplitud del movimiento de apertura de la boca en mujeres con trastorno temporomandibular: un ensayo clínico aleatorizado y ciego / Effects of upper cervical manipulation on the electromyographic activity of the masticatory muscles and the opening range of motion of the mouth in women with temporomandibular disorder: randomized and blind clinical trial

RESUMO Avaliou-se os efeitos da manipulação cervical alta sobre a atividade eletromiográfica de superfície (sEMG) dos músculos mastigatórios e amplitude do movimento de abertura da boca em mulheres com disfunção temporomandibular (DTM). Foram avaliadas 10 mulheres com diagnóstico de DTM miogênica, segundo o Research Diagnostic Criteria for temporomandibular disorders (RDC/TMD), divididas, aleatoriamente, em grupo experimental (GE) n=5, que recebeu manipulação cervical alta e grupo placebo (GP) n=5, que recebeu manobra sem efeito terapêutico. Cinco intervenções foram aplicadas para ambos os grupos uma vez por semana, e avaliações de pré-intervenção, pós-imediato (após a 1ª intervenção) e pós-tardio (48 horas após a 5ª intervenção) foram realizadas. A atividade sEMG foi processada via raiz quadrada da média e normalizada pelo valor de pico (RMS EMGn). Utilizou-se para comparação os testes t de Student e ANOVA two-way (medidas repetidas), adotando-se como significância o valor de 5%, e o Cohen's d para tamanho de efeito de tratamento. Constatou-se a interação significativa grupo × tempo (p<0,05) no RMS EMGn dos músculos temporal direito e esquerdo, na condição de repouso, assim como para todos os músculos mastigatórios durante contração isométrica máxima de elevação e depressão da mandíbula. Os tamanhos de efeito de tratamento moderado a alto foram observados no GE, destacando-se na avaliação pós-tardia. Foi observado também um aumento significativo (p<0,05) e um alto efeito de tratamento na abertura da boca para o GE. A manipulação cervical alta demonstrou equilibrar o RMS EMGn dos músculos mastigatórios e aumentar a amplitude de movimento de abertura da boca em mulheres com DTM miogênica.

RESUMEN En este estudio se evaluaron los efectos de la manipulación cervical alta sobre la actividad electromiográfica de superficie (SEMG) de los músculos masticatorios y de amplitud del movimiento de apertura de la boca en mujeres con trastorno temporomandibular (TTM). Se evaluaron 10 mujeres con diagnóstico de TTM miogénico, con base en el Research Diagnostic Criteria for temporomandibular disorders (RDC/TMD), las que fueron aleatoriamente divididas en grupo experimental (GE) n=5, que recibió manipulación cervical alta, y grupo placebo (GP) n=5, que recibió maniobra sin efecto terapéutico. Se aplicaron cinco intervenciones para ambos grupos una vez por semana, y se realizaron evaluaciones preintervención, posintervención inmediata (después de la 1a. intervención) y posintervención tardía (48 horas después de la 5a. intervención). La actividad SEMG fue calculada mediante raíz cuadrada de la media y normalizada por el valor de pico (RMS EMGn). Se empleó para comparación los test t de Student y ANOVA two-way (medidas repetidas), y el nivel de significancia de 5%, y para el efecto del tratamiento el Cohen's d. Se encontró la interacción significativa grupo × tiempo (p<0,05) en el RMS EMGn de los músculos temporales derecho e izquierdo, en reposo, así como para todos los músculos masticatorios durante la contracción isométrica máxima de elevación y depresión de la mandíbula. Se observaron efectos de tratamiento moderado a alto en el GE, destacando en la etapa posevaluación tardía. También se observó un aumento significativo (p<0,05) y un alto resultado del tratamiento en la apertura de la boca en el GE. La manipulación cervical alta demostró equilibrar el RMS EMGn de los músculos masticatorios y aumentar la amplitud del movimiento de la apertura de la boca en mujeres con TTM miogénica.

ABSTRACT We evaluated the effects of upper cervical manipulation on the surface electromyographic activity (sEMG) of masticatory muscles and range of motion of the opening movement of the mouth in women with temporomandibular disorders (TMD). We evaluated 10 women with myogenic a TMD diagnosis, according to the Research Diagnostic Criteria for Temporomandibular Disorders (RDC/TMD) and divided randomly into an experimental group (EG) n=5, which received upper cervical manipulation, and a placebo group (PG) n=5, which received maneuvers without therapeutic effects. Five interventions were performed in both groups, once a week, with performance of pre-intervention assessments, post-immediate assessments (after 1st intervention) and post-delayed assessments (48 hours after the 5th intervention). The sEMG activity was processed using the root mean square and normalized by the peak value (RMS EMGn). We used for comparison the Student's t-test and ANOVA two-way repeated measures, adopting as significance the amount of 5%, and the Cohen d for treatment effect size. We found a significant interaction of group vs time (p<0.05) in the RMS EMGn of the left and right temporal muscles at rest, as well as for all masticatory muscles during maximal isometric contraction during jaw-elevation and jaw-depression. Treatment effect size, high to moderate, was observed in the EG, especially in the post-delayed assessment. We also observed a significant increase (p<0.05) and a high treatment effect during mouth opening in the EG. The upper cervical manipulation demonstrated a balance of the RMS EMGn of the masticatory muscles and increase the opening range of motion of the mouth in women with myogenic TMD.

Immediate effects of upper thoracic manipulation on the skin surface temperature of the vertebral region in healthy women / Efeitos imediatos da manipulação torácica alta sobre a temperatura superficial cutânea da região vertebral em mulheres saudáveis / Los efectos inmediatos de la alta manipulación torácica de la temperatura superficial de la piel en la región vertebral en mujeres sanas

Manipulation of the spinal column is a manual therapeutic resource characterized by passive thrust of a given joint at a high velocity and low amplitude within the limits of anatomic integrity. The objective of the present study was to assess the immediate effects of upper thoracic manipulation on skin temperature in the vertebral region in healthy women. Thus, a randomized controlled blind trial was realized in the university community. Twenty-six healthy women were randomly allocated into an experimental group (n=13) and a placebo group (n=13). A single session of upper thoracic spine manipulation (segment T3) was performed. Infrared thermography was used to determine changes in skin temperature in the vertebral region. Images were taken prior to, immediately after and both five and 10 minutes after manipulation. Two-way repeated measures analysis of variance with post hoc Bonferroni test was used for inter and intragroup comparisons. The level of significance was set to 5%. No significant differences were found between the different evaluation times in either group (p>0.05). In the intergroup analysis, no statistically significant differences were found in any of the comparisons (p>0.05). Based on the method employed, thoracic spine manipulation of the T3 vertebral segment does not promote changes in skin surface temperature in the region manipulated in asymptomatic individuals.

A manipulação da coluna vertebral é um recurso da terapia manual caracterizado por um impulso passivo de alta velocidade e baixa amplitude dentro dos limites de integridade anatômica de uma articulação (thrust). O objetivo do presente estudo foi avaliar os efeitos imediatos da manipulação torácica alta sobre a temperatura superficial cutânea da região vertebral em mulheres saudáveis. Para tal, foi realizado um estudo clínico randomizado cego na comunidade universitária. Vinte e seis voluntárias saudáveis foram alocadas de forma randomizada em um grupo experimental (n=13) e um grupo placebo (n=13). Uma sessão de manipulação torácica alta (segmento T3) foi realizada. Foi empregada a termografia infravermelha para determinar alterações na temperatura cutânea na região vertebral. Imagens foram capturadas antes, imediatamente após, cinco e dez minutos após a manipulação. Foi usada análise de variância com medidas repetidas (dois critérios) seguida do teste de Bonferroni para as comparações inter e intragrupos. Adotou-se um nível de significância de 5%. Não foi encontrada diferença significativa nas diferentes avaliações ao longo do tempo (p>0,05). Na análise intergrupos, não foi constatada diferença significativa nas comparações realizadas (p>0,05). Com base na metodologia empregada, a manipulação torácica do segmento vertebral T3 não promoveu alterações na temperatura superficial cutânea na região manipulada.

La manipulación de la espina dorsal es un recurso de terapia manual que se caracteriza por un impulso pasivo de alta velocidad y baja amplitud de los límites de integridad anatómica de una articulación (thrust). Esta investigación tuvo por objetivo evaluar los efectos inmediatos de la alta manipulación torácica de la temperatura superficial de la piel en la región vertebral en mujeres sanas. Para eso, se ha realizado un estudio clínico aleatorizado ciego en la comunidad universitaria. Veintiséis voluntarias han sido puestas de forma aleatorizada en un grupo experimental (n=13) y un grupo placebo (n=13). Ha sido realizada una sesión de manipulación torácica alta (segmento T3). Se ha empleado el término infrarrojo para determinar alteraciones en la temperatura de la piel en la región vertebral. Se han capturado imágenes antes, inmediatamente después, cinco y diez minutos tras la manipulación. Se ha hecho un análisis de los cambios con medidas repetidas (dos criterios) seguido de la prueba de Bonferroni para las comparaciones inter e intragrupal. Se ha adoptado un nivel de significancia de 5%. No ha sido encontrado diferencias significativas en las diferentes evaluaciones al largo del tiempo (p>0,05). En el análisis intergrupal, no ha sido constatado diferencias significativas en las comparaciones realizadas (p>0,05). Basándose en la metodología empleada, la manipulación torácica del segmento vertebral T3 no cambió la temperatura superficial de la piel en la región estudiada.

Intra and inter-rater reliability of infrared image analysis of masticatory and upper trapezius muscles in women with and without temporomandibular disorder / Confiabilidade intra e interexaminador da análise de imagens infravermelhas dos músculos mastigatórios e trapézio superior em mulheres com e sem disfunção temporomandibular

BACKGROUND: Infrared thermography is an aid tool that can be used to evaluate several pathologies given its efficiency in analyzing the distribution of skin surface temperature. OBJECTIVES: To propose two forms of infrared image analysis of the masticatory and upper trapezius muscles, and to determine the intra and inter-rater reliability of both forms of analysis. METHOD: Infrared images of masticatory and upper trapezius muscles of 64 female volunteers with and without temporomandibular disorder (TMD) were collected. Two raters performed the infrared image analysis, which occurred in two ways: temperature measurement of the muscle length and in central portion of the muscle. The Intraclass Correlation Coefficient (ICC) was used to determine the intra and inter-rater reliability. RESULTS: The ICC showed excellent intra and inter-rater values for both measurements: temperature measurement of the muscle length (TMD group, intra-rater, ICC ranged from 0.996 to 0.999, inter-rater, ICC ranged from 0.992 to 0.999; control group, intra-rater, ICC ranged from 0.993 to 0.998, inter-rater, ICC ranged from 0.990 to 0.998), and temperature measurement of the central portion of the muscle (TMD group, intra-rater, ICC ranged from 0.981 to 0.998, inter-rater, ICC ranged from 0.971 to 0.998; control group, intra-rater, ICC ranged from 0.887 to 0.996, inter-rater, ICC ranged from 0.852 to 0.996). CONCLUSION: The results indicated that temperature measurements of the masticatory and upper trapezius muscles carried out by the analysis of the muscle length and central portion yielded excellent intra and inter-rater reliability.

CONTEXTUALIZAÇÃO: A termografia infravermelha vem sendo utilizada como instrumento auxiliar na avaliação de patologias diversas, dada a sua eficiência na investigação da distribuição da temperatura superficial cutânea. OBJETIVOS: Propor duas formas de análise das imagens infravermelhas dos músculos mastigatórios e trapézio superior e determinar a confiabilidade intra e interexaminador dessas duas formas de análise. MÉTODO: Foram coletadas imagens infravermelhas dos músculos mastigatórios e trapézio superior de 64 voluntárias do gênero feminino, com e sem disfunção temporomandibular (DTM). A análise das imagens infravermelhas ocorreu de duas formas: mensuração da temperatura da extensão do músculo e do centro do músculo, sendo realizada por dois examinadores. A confiabilidade intra e interexaminador foi verificada por meio do Coeficiente de Correlação Intraclasse (CCI). RESULTADOS: Os valores do CCI intra e interexaminador foram considerados excelentes em ambas as avaliações: análises da extensão do músculo (grupo DTM, intraexaminador, CCI variou de 0,996 a 0,999, interexaminador, CCI variou de 0,992 a 0,999; grupo controle, intraexaminador, CCI variou de 0,993 a 0,998, interexaminador, CCI variou de 0,990 a 0,998) e análise do centro do músculo (grupo DTM, intraexaminador, CCI variou de 0,981 a 0,998, interexaminador, CCI variou de 0,971 a 0,998; grupo controle, intraexaminador, CCI variou de 0,887 a 0,996, interexaminador, CCI variou de 0,852 a 0,996). CONCLUSÃO: O estudo evidenciou que a mensuração da temperatura dos músculos mastigatórios e trapézio superior, realizada por meio da análise da extensão e do centro do músculo, apresentou excelente confiabilidade intra e interexaminador.

Does masticatory muscle hyperactivity occur in individuals presenting temporomandibular disorders?

Aim: To verify whether patients with temporomandibular disorders (TMD) present masticatory muscle hyperactivity with the mandible in the rest position. Method: Forty-six women were selected (18-33 years-old, mean age = 22.7 ± 3.52 years), 31 with TMD (experimental group) and 15 without TMD (control group). Electromyography (EMG) was performed in two situations: 1) with the mandible in the rest position and 2) in maximal dental clenching. RMS (root mean square) was used for EMG signal analysis. Data were analyzed statistically by the Mann Whitney U-test. Result: The experimental groups presented increased EMG activity of the muscles evaluated with the mandible in the rest position compared to the control. In maximal dental clenching, no differences were observed between the groups. Analyzing the percentage of EMG activity at rest, the control group presented EMG activity around 1 to 6% of maximal dental clenching and the experimental group, around 1 to 12% of the same activity. Conclusion: The experimental group presented an increase in EMG activity at rest in the studied muscles, mainly in the anterior portion of the temporal muscle, bilaterally. However, this increase should not be called muscular hyperactivity, but should rather be considered as an important sign of TMD.