Posturography measures in specific ballet stance position discriminate ballet dancers with different occurrences of musculoskeletal injuries.

BACKGROUND: This study aimed to identify the postural sway variables that can distinguish between ballet dancers with high and low occurrences of musculoskeletal injuries. METHODS: Fourteen professional ballet dancers were assigned to a high-occurrence group (N = 5, reports >2 injuries in the previous 6-months) or a low-occurrence group (N = 9, reports ≤1 injury). Center-of-pressure (COP) data were acquired using a force platform during the following tasks: single-leg stance with eyes open, single-leg stance with eyes closed, and demi-pointe stance with eyes open. The COP standard deviation (SD) and range (RA) in both the medial-lateral (ML) and anterior-posterior (AP) directions were estimated. Between-group comparisons were made through Welch's t-tests for unequal sample size along the effect size measure (Cohen's d). Spearman's rho was used to estimate the association between the number of injuries and the COP variables. The statistical threshold was set at 1%. RESULTS: A between-group effect was found only for the demi-pointe stance, with large effects for SDML (P = 0.006, d = 1.7), RAAP (P = 0.006, d = 1.7), and RAML (P = 0.005, d = 1.7). An inverse relationship was found between the number of injuries and the demi-pointe's COP range in both directions (Spearman's rho from -0.681 to -0.726, P = 0.007). CONCLUSIONS: COP measures taken in ballet-specific positions can distinguish between dancers with a high and low occurrence of musculoskeletal injuries. Suggestions are made to include ballet-specific tasks in the functional assessments of professional dancers.

Postural control in football players with vision impairment: Effect of sports adaptation or visual input restriction?

Abstract Aim: To assess the postural control performance of football 5-a-side (FFS) players, comparing them with sighted players. Methods: Eight FFS players and 7 sighted futsal players were included. Postural control tests included feet together stance (FTS) and single-leg stance (SLS) tasks, performed on rigid and foam surfaces. Sighted players performed the tests with open (EO) and closed (EC) eyes. Area of displacement (Area) and average velocity (Vavg) were calculated from the center of pressure time-series coordinates. Results: On both surfaces conditions, a significant difference between visually impaired football 5-a-side players and sighted EO players was observed during FTS (higher Vavg for visually impaired football 5-a-side players; p < 0.04) and SLS (higher Area and Vavg for visually impaired football 5-a-side players; p < 0.01). No differences between visually impaired football 5-a-side players and sighted EC players were found. Differences between sighted EO vs. sighted EC were observed during FTS on the foam surface, and in SLS on both surface conditions (p < 0.03). Conclusion: FFS players' postural control performance is similar to sighted players with EC but worse than sighted players with EO, suggesting their postural control performance can be simply explained in terms of visual restriction.

Biomechanical Analysis of the Closed Kinetic Chain Upper-Extremity Stability Test.

CONTEXT: The closed kinetic chain upper-extremity stability (CKCUES) test is a functional test for the upper extremity performed in the push-up position, where individuals support their body weight on 1 hand placed on the ground and swing the opposite hand until touching the hand on the ground, then switch hands and repeat the process as fast as possible for 15 s. OBJECTIVE: To study scapular kinematic and kinetic measures during the CKCUES test for 3 different distances between hands. DESIGN: Experimental. SETTING: Laboratory. PARTICIPANTS: 30 healthy individuals (15 male, 15 female). MAIN OUTCOME MEASURES: Participants performed 3 repetitions of the test at 3 distance conditions: original (36 in), interacromial, and 150% interacromial distance between hands. Participants completed a questionnaire on pain intensity and perceived exertion before and after the procedures. Scapular internal/external rotation, upward/downward rotation, and posterior/anterior tilting kinematics and kinetic data on maximum force and time to maximum force were measured bilaterally in all participants. Percentage of body weight on upper extremities was calculated. Data analyses were based on the total numbers of hand touches performed for each distance condition, and scapular kinematics and kinetic values were averaged over the 3 trials. Scapular kinematics, maximum force, and time to maximum force were compared for the 3 distance conditions within each gender. Significance level was set at α = .05. RESULTS: Scapular internal rotation, posterior tilting, and upward rotation were significantly greater in the dominant side for both genders. Scapular upward rotation was significantly greater in original distance than interacromial distance in swing phase. Time to maximum force in women was significantly greater in the dominant side. CONCLUSION: CKCUES test kinematic and kinetic measures were not different among 3 conditions based on distance between hands. However, the test might not be suitable for initial or mild-level rehabilitation due to its challenging requirements.

Muscular weakness represents the main limiting factor of walk, functional independence and quality of life of myelopathy patients associated to HTLV-1.

UNLABELLED: HTLV-1-associated myelopathy is a progressive disabling disease associated with gait abnormalities. OBJECTIVE: To identify and quantify the main muscles affected by weakness and spasticity, their impact on gait, functional capacity and on quality of life of HTLV-1-associated myelopathy patients. METHOD: We evaluated lower limbs muscular strength according to the Medical Research Council scale, spasticity according to the modified Ashworth scale, daily activities according to the Barthel Index and quality of life according to the Short-Form Health Survey-36 of 26 HTLV-1-associated myelopathy patients. RESULTS: The muscles most affected by weakness included the dorsal flexors and knee flexors. Spasticity predominated in the hip adductor muscles and in plantar flexors. Assistance for locomotion, minimal dependence in daily activities, limitations in functional capacity and physical aspects were the most common findings. CONCLUSION: The impairment of gait, functional dependence and quality of life were predominantly a consequence of intense muscle weakness in HTLV-1-associated myelopathy patients.

Muscular weakness represents the main limiting factor of walk, functional independence and quality of life of myelopathy patients associated to HTLV-1 / Fraqueza muscular representa o principal fator limitante da marcha, independência funcional e qualidade de vida de pacientes com mielopatia associada ao HTLV-1

ABSTRACT HTLV-1-associated myelopathy is a progressive disabling disease associated with gait abnormalities. Objective To identify and quantify the main muscles affected by weakness and spasticity, their impact on gait, functional capacity and on quality of life of HTLV-1-associated myelopathy patients. Method We evaluated lower limbs muscular strength according to the Medical Research Council scale, spasticity according to the modified Ashworth scale, daily activities according to the Barthel Index and quality of life according to the Short-Form Health Survey-36 of 26 HTLV-1-associated myelopathy patients. Results The muscles most affected by weakness included the dorsal flexors and knee flexors. Spasticity predominated in the hip adductor muscles and in plantar flexors. Assistance for locomotion, minimal dependence in daily activities, limitations in functional capacity and physical aspects were the most common findings. Conclusion The impairment of gait, functional dependence and quality of life were predominantly a consequence of intense muscle weakness in HTLV-1-associated myelopathy patients.

RESUMO Mielopatia associada ao HTLV-1 é uma doença inflamatória, incapacitante e progressiva que acomete o sistema nervoso central. Objetivo Identificar e quantificar os principais músculos comprometidos pela fraqueza e espasticidade, o impacto na capacidade funcional e na qualidade de vida dos pacientes com mielopatia associada ao HTLV-1. Método Força muscular ( Medical Research Council), espasticidade (escala Ashworth modificada), atividades de vida diária (Índice de Barthel) e qualidade de vida ( Short-Form Health Survey-36) foram avaliados em 26 pacientes . Resultados Os principais músculos comprometidos pela fraqueza incluíram os flexores dorsais e flexores do joelho. A espasticidade predominou nos músculos adutores do quadril e nos flexores plantares. Assistência para locomoção, dependência mínima nas atividades diárias, limitações na capacidade funcional e os aspectos físicos representaram os achados mais frequentes. Conclusão Dificuldade de deambulação, dependência funcional e prejuízo na qualidade de vida foram as principais consequências da intensa fraqueza muscular nos pacientes com mielopatia associada ao HTLV-1.

Characteristics and prevalence of musculoskeletal injury in professional and non-professional ballet dancers

BACKGROUND: Ballet is a high-performance activity that requires an advanced level of technical skills. Ballet places great stress on tendons, muscles, bones, and joints and may act directly as a trigger of injury by overuse. OBJECTIVES: 1) to describe the main types of injuries and affected areas related to classical ballet and 2) to compare the frequency of musculoskeletal injuries among professional and non-professional ballet dancers, considering possible gender differences among the professional dancers. METHOD: A total of 110 questionnaires were answered by professional and non-professional dancers. The questionnaire contained items related to the presence of injury, the regions involved, and the mechanism of the injury. RESULTS: We observed a high frequency of musculoskeletal injuries, with ankle sprains accounting for 69.8% of injuries in professional dancers and 42.1% in non-professional dancers. Pirouettes were the most frequent mechanism of injury in professional dancers, accounting for 67.9% of injuries, whereas in the non-professional dancers, repetitive movement was the most common mechanism (28.1%). Ankle sprains occurred in 90% of the women's injuries, and muscle sprains occurred in 54.5% of the men's injuries. The most frequent injury location was the ankle joint in both sexes among the professional dancers, with 67.6% in women and 40.9% in men. CONCLUSIONS: The identification of the mechanism of injury and time of practice may contribute to better therapeutic action aimed at the proper function of the dancers' bodies and improved performance by these athletes.

Characteristics and prevalence of musculoskeletal injury in professional and non-professional ballet dancers.

BACKGROUND: Ballet is a high-performance activity that requires an advanced level of technical skills. Ballet places great stress on tendons, muscles, bones, and joints and may act directly as a trigger of injury by overuse. OBJECTIVES: 1) to describe the main types of injuries and affected areas related to classical ballet and 2) to compare the frequency of musculoskeletal injuries among professional and non-professional ballet dancers, considering possible gender differences among the professional dancers. METHOD: A total of 110 questionnaires were answered by professional and non-professional dancers. The questionnaire contained items related to the presence of injury, the regions involved, and the mechanism of the injury. RESULTS: We observed a high frequency of musculoskeletal injuries, with ankle sprains accounting for 69.8% of injuries in professional dancers and 42.1% in non-professional dancers. Pirouettes were the most frequent mechanism of injury in professional dancers, accounting for 67.9% of injuries, whereas in the non-professional dancers, repetitive movement was the most common mechanism (28.1%). Ankle sprains occurred in 90% of the women's injuries, and muscle sprains occurred in 54.5% of the men's injuries. The most frequent injury location was the ankle joint in both sexes among the professional dancers, with 67.6% in women and 40.9% in men. CONCLUSIONS: The identification of the mechanism of injury and time of practice may contribute to better therapeutic action aimed at the proper function of the dancers' bodies and improved performance by these athletes.

Analysis of angular reading distortions of photographic images.

BACKGROUND: Although photogrammetry is a widespread technique in the health field, despite of the methodological efforts distortions in the angular readings of the images are common. OBJECTIVE: To measure the error of angular measurements in photo images with different digital resolutions in an object with pre-determined angles. METHODS: We used a rubber ball with 52 cm in circumference. The object was previously marked with angles of 10°, 30°, 60° and 90° degrees. The photographic records were performed with the focal axis of the camera perpendicular and three meters away from the object, without the use of optical zoom and a resolution of 3, 5 and 10 Megapixels (Mp). All photographic records were stored and a previously trained experimenter using the computer program ImageJ analyzed the angular values of each photo. The measurements were performed twice within a fifteen-days interval. Subsequently, we calculated the accuracy, relative error and error in degrees values, precision and the Intraclass Correlation Coefficient (ICC). RESULTS: When analyzing the angle of 10°, the average accuracy of measurements was higher for those records of 3 Mp resolution compared to 5 and 10 Mp resolutions. The ICC was considered excellent for all resolutions. With regards to the analyzed angles in photographic records, it was possible to verify that the 90-degree angle photographs were more accurate, had lower relative error and error in degrees, and were more precise, regardless of image resolution. CONCLUSION: The photographs records that were taken with a 3 Mp resolution provided great accuracy and precision measurements and lower errors values, suggesting to be the proper resolution to generate image of angles of 10º and 30º.

Analysis of angular reading distortions of photographic images / Análise das distorções em leituras angulares de imagens fotográficas

BACKGROUND: Although photogrammetry is a widespread technique in the health field, despite of the methodological efforts distortions in the angular readings of the images are common. OBJECTIVE: To measure the error of angular measurements in photo images with different digital resolutions in an object with pre-determined angles. METHODS: We used a rubber ball with 52 cm in circumference. The object was previously marked with angles of 10°, 30°, 60° and 90° degrees. The photographic records were performed with the focal axis of the camera perpendicular and three meters away from the object, without the use of optical zoom and a resolution of 3, 5 and 10 Megapixels (Mp). All photographic records were stored and a previously trained experimenter using the computer program ImageJ analyzed the angular values of each photo. The measurements were performed twice within a fifteen-days interval. Subsequently, we calculated the accuracy, relative error and error in degrees values, precision and the Intraclass Correlation Coefficient (ICC). RESULTS: When analyzing the angle of 10°, the average accuracy of measurements was higher for those records of 3 Mp resolution compared to 5 and 10 Mp resolutions. The ICC was considered excellent for all resolutions. With regards to the analyzed angles in photographic records, it was possible to verify that the 90-degree angle photographs were more accurate, had lower relative error and error in degrees, and were more precise, regardless of image resolution. CONCLUSION: The photographs records that were taken with a 3 Mp resolution provided great accuracy and precision measurements and lower errors values, suggesting to be the proper resolution to generate image of angles of 10º and 30º.

CONTEXTUALIZAÇÃO: A biofotogrametria é uma técnica difundida na área da saúde e, apesar dos cuidados metodológicos, há distorções nas leituras angulares das imagens fotográficas. OBJETIVO: Mensurar o erro das medidas angulares em imagens fotográficas com diferentes resoluções digitais em um objeto com ângulos pré-demarcados. MÉTODOS: Utilizou-se uma esfera de borracha com 52 cm de circunferência. O objeto foi previamente demarcado com ângulos de 10º, 30º, 60º e 90º, e os registros fotográficos foram realizados com o eixo focal da câmera a três metros de distância e perpendicular ao objeto, sem utilização de zoom óptico e com resolução de 3, 5 e 10 Megapixels (Mp). Todos os registros fotográficos foram armazenados, e os valores angulares foram analisados por um experimentador previamente treinado, utilizando o pro grama ImageJ. As aferições das medidas foram realizadas duas vezes, com intervalo de 15 dias entre elas. Posteriormente, foram calculados os valores de acurácia, erro relativo e em graus, precisão e Coeficiente de Correlação Intraclasse (ICC). RESULTADOS: Quando analisado o ângulo de 10º, a média da acurácia das medidas foi maior para os registros com resolução de 3 Mp em relação às resoluções de 5 e 10 Mp. O ICC foi considerado excelente para as três resoluções de imagem analisadas e, em relação aos ângulos analisados nos registros fotográficos, pôde-se verificar maior acurácia, menor erro relativo e em graus e maior precisão para o ângulo de 90º, independentemente da resolução da imagem. CONCLUSÃO: Os registros fotográficos realizados com a resolução de 3 Mp proporcionaram medidas de maiores valores de acurácia e precisão e menores valores de erro, sugerindo ser a resolução mais adequada para gerar imagem de ângulos de 10º e 30º.

Quantitative MRI of vastus medialis, vastus lateralis and gluteus medius muscle workload after squat exercise: comparison between squatting with hip adduction and hip abduction.

The aim of the present study was to evaluate the use MRI to quantify the workload of gluteus medius (GM), vastus medialis (VM) and vastus lateralis (VL) muscles in different types of squat exercises. Fourteen female volunteers were evaluated, average age of 22 ± 2 years, sedentary, without clinical symptoms, and without history of previous lower limb injuries. Quantitative MRI was used to analyze VM, VL and GM muscles before and after squat exercise, squat associated with isometric hip adduction and squat associated with isometric hip abduction. Multi echo images were acquired to calculate the transversal relaxation times (T2) before and after exercise. Mixed Effects Model statistical analysis was used to compare images before and after the exercise (ΔT2) to normalize the variability between subjects. Imaging post processing was performed in Matlab software. GM muscle was the least active during the squat associated with isometric hip adduction and VM the least active during the squat associated with isometric hip abduction, while VL was the most active during squat associated with isometric hip adduction. Our data suggests that isometric hip adduction during the squat does not increase the workload of VM, but decreases the GM muscle workload. Squat associated with isometric hip abduction does not increase VL workload.

Muscular activity of patella and hip stabilizers of healthy subjects during squat exercises.

BACKGROUND: Hip and knee muscle weaknesses have been associated with the onset of anterior knee pain (AKP). Therefore, the understanding of how squats exercises can be performed in order to optimize the electrical activity of these muscles is relevant for physical therapy treatments. OBJECTIVE: To compare the electromyographic activity of patella and pelvic stabilizers during traditional squat and squat associated with isometric hip adduction or abduction in subjects without AKP. METHODS: Electromyography signals were captured using double-differential electrodes at the vastus medialis obliquus (VMO), vastus lateralis obliquus (VLO), vastus lateralis longus (VLL) and gluteus medium (GMed) in 15 healthy and sedentary women during squats exercises: traditional and associated with hip adduction and hip abduction with load of 25% of body weight. Linear mixed models with significance level of 5% were used for data analysis. RESULTS: Squat associated with hip adduction and abduction produced electromyographic activity of GMed of 0.47 (0.2) and 0.59 (0.22) respectively, while conventional squat produced an electromyiographic activity of 0.33 (0.27). The higher VMO activity was 0.59 (0.27) during the isometric contraction in the squat associated with hip adduction. The higher VLO activity was 0.60 (0.32) during isometric contraction in the squat associated with hip abduction. CONCLUSION: Squat exercise associated with hip adduction increased VMO muscle activity as well as the activity of GMed activity.

Ativação muscular estabilizadora da patela e do quadril durante exercícios de agachamento em indivíduos saudáveis / Muscular activity of patella and hip stabilizers of healthy subjects during squat exercises

CONTEXTUALIZAÇÃO: Atualmente relaciona-se a fraqueza dos músculos do quadril e da coxa ao surgimento da dor anterior no joelho (DAJ). Dessa maneira, compreender como os agachamentos devem ser realizados para melhorar a ativação elétrica desses músculos é importante para o tratamento fisioterapêutico. OBJETIVO: Comparar a ativação mioelétrica de estabilizadores da patela e pelve entre as posições de agachamentos convencional e associado à contração isométrica em adução e abdução da coxa em indivíduos sem queixa de DAJ. MÉTODOS: O sinal eletromiográfico foi captado a partir de eletrodos duplo-diferenciais posicionados nos músculos vasto medial oblíquo (VMO), vasto lateral oblíquo (VLO), vasto lateral longo (VLL) e glúteo médio (GMed) em 15 mulheres sedentárias e clinicamente saudáveis, durante a contração de agachamentos convencional e associados à adução e à abdução isométrica da coxa com carga de 25 por cento do peso corporal. A análise estatística empregada foi o modelo linear de efeitos mistos, com significância de 5 por cento. RESULTADOS: A associação da adução e abdução isométrica da coxa no agachamento produziu cerca de 0,47 (0,2) e 0,59 (0,22), respectivamente, de atividade elétrica do músculo GMed, enquanto o agachamento convencional (AGA) produziu 0,33 (0,27) de atividade elétrica. A maior ativação do VMO aconteceu na contração de agachamento associado à adução da coxa e foi de 0,59 (0,27); já o músculo VLL apresentou uma maior atividade elétrica durante o agachamento associado à abdução, sendo de 0,60 (0,32). CONCLUSÃO: O exercício de agachamento associado à adução da coxa promoveu uma maior ativação muscular do VMO, além de aumentar a atividade muscular do GMed.

BACKGROUND: Hip and knee muscle weaknesses have been associated with the onset of anterior knee pain (AKP). Therefore, the understanding of how squats exercises can be performed in order to optimize the electrical activity of these muscles is relevant for physical therapy treatments. OBJECTIVE: To compare the electromyographic activity of patella and pelvic stabilizers during traditional squat and squat associated with isometric hip adduction or abduction in subjects without AKP. METHODS: Electromyography signals were captured using double-differential electrodes at the vastus medialis obliquus (VMO), vastus lateralis obliquus (VLO), vastus lateralis longus (VLL) and gluteus medium (GMed) in 15 healthy and sedentary women during squats exercises: traditional and associated with hip adduction and hip abduction with load of 25 percent of body weight. Linear mixed models with significance level of 5 percent were used for data analysis. RESULTS: Squat associated with hip adduction and abduction produced electromyographic activity of GMed of 0.47 (0.2) and 0.59 (0.22) respectively, while conventional squat produced an electromyiographic activity of 0.33 (0.27). The higher VMO activity was 0.59 (0.27) during the isometric contraction in the squat associated with hip adduction. The higher VLO activity was 0.60 (0.32) during isometric contraction in the squat associated with hip abduction. CONCLUSION: Squat exercise associated with hip adduction increased VMO muscle activity as well as the activity of GMed activity.