TRPV4 Activation during Guinea Pig Airway Smooth Muscle Contraction Promotes Ca2+ and Na+ Influx.

Airway smooth muscle (ASM) contraction is determined by the increase in intracellular Ca2+ concentration ([Ca2+]i) caused by its release from the sarcoplasmic reticulum (SR) or by extracellular Ca2+ influx. Major channels involved in Ca2+ influx in ASM cells are L-type voltage-dependent Ca2+ channels (L-VDCCs) and nonselective cation channels (NSCCs). Transient receptor potential vanilloid 4 (TRPV4) is an NSCC recently studied in ASM. Mechanical stimuli, such as contraction, can activate TRPV4. We investigated the possible activation of TRPV4 by histamine (His)- or carbachol (CCh)-induced contraction in guinea pig ASM. In single myocytes, the TRPV4 agonist (GSK101) evoked an increase in [Ca2+]i, characterized by a slow onset and a plateau phase. The TRPV4 antagonist (GSK219) decreased channel activity by 94%, whereas the Ca2+-free medium abolished the Ca2+ response induced by GSK101. Moreover, GSK101 caused Na+ influx in tracheal myocytes. GSK219 reduced the Ca2+ peak and the Ca2+ plateau triggered by His or CCh. TRPV4 blockade shifted the concentration-response curve relating to His and CCh to the right in tracheal rings and reduced the maximal contraction. Finally, the activation of TRPV4 in single myocytes increased the Ca2+ refilling of the SR. We conclude that contraction of ASM cells after stimulation with His or CCh promotes TRPV4 activation, the subsequent influx of Ca2+ and Na+, and the opening of L-VDCCs. The entry of Ca2+ into ASM cells via TRPV4 and L-VDCCs contributes to optimal smooth muscle contraction.

A low-cost 2-D sarcomere model to demonstrate titin-related mechanisms for force production.

Given the recently proposed three-filament theory of muscle contraction, we present a low-cost physical sarcomere model aimed at illustrating the role of titin in the production of active force in skeletal muscle. With inexpensive materials, it is possible to illustrate actin-myosin cross-bridge interactions between the thick and thin filaments and demonstrate the two different mechanisms by which titin is thought to contribute to active and passive muscle force. Specifically, the model illustrates how titin, a molecule with springlike properties, may increase its stiffness by binding free calcium upon muscle activation and reducing its extensible length by attaching itself to actin, resulting in the greater force-generating capacity after an active than a passive elongation that has been observed experimentally. The model is simple to build and manipulate, and demonstration to high school students was shown to result in positive perception and improved understanding of the otherwise complex titin-related mechanisms of force production in skeletal and cardiac muscles.NEW & NOTEWORTHY Our physical sarcomere model illustrates not only the classic view of muscle contraction, the sliding filament and cross-bridge theories, but also the newly discovered role of titin in force regulation, called the three-filament theory. The model allows for easy visualization of the role of titin in muscle contraction and aids in explaining complex muscle properties that are not captured by the traditional cross-bridge theory.

Glutamine supplementation accelerates functional recovery of EDL muscles after injury by modulating the expression of S100 calcium-binding proteins.

The aim of the current study was to investigate the effect of glutamine supplementation on the expression of HSP70 and the calcium-binding proteins from the S100 superfamily in the recovering extensor digitorum longus (EDL) muscle after injury. Two-month-old Wistar rats were subjected to cryolesion of the EDL muscle and then randomly divided into two groups (with or without glutamine supplementation). Starting immediately after the injury, the supplemented group received daily doses of glutamine (1 g/kg/day, via gavage) for 3 and 10 days orally. Then, muscles were subjected to histological, molecular, and functional analysis. Glutamine supplementation induced an increase in myofiber size of regenerating EDL muscles and prevented the decline in maximum tetanic strength of these muscles evaluated 10 days after injury. An accelerated upregulation of myogenin mRNA levels was detected in glutamine-supplemented injured muscles on day 3 post-cryolesion. The HSP70 expression increased only in the injured group supplemented with glutamine for 3 days. The increase in mRNA levels of NF-κB, the pro-inflammatory cytokines IL-1ß and TNF-α, and the calcium-binding proteins S100A8 and S100A9 on day 3 post-cryolesion in EDL muscles was attenuated by glutamine supplementation. In contrast, the decrease in S100A1 mRNA levels in the 3-day-injured EDL muscles was minimized by glutamine supplementation. Overall, our results suggest that glutamine supplementation accelerates the recovery of myofiber size and contractile function after injury by modulating the expression of myogenin, HSP70, NF-κB, pro-inflammatory cytokines, and S100 calcium-binding proteins.

Electromagnetic field for supramaximal muscle stimulation: A retrospective study of safety, efficacy, and patient satisfaction in Brazil.

BACKGROUND: Currently, even individuals who do physical activity regularly have some degree of dissatisfaction with their own bodies. The electromagnetic field for supramaximal muscle contraction has been the subject of research. High-intensity supramaximal muscle stimulation (HI-SMS) is a non-invasive technology used to strengthen, firm, and tone the abdominal muscles, arms, buttocks, and thighs and has been indicated for aesthetic purposes. AIMS: The present study aimed to examine the safety and efficacy of HI-SMS used in the abdominal muscles of patients through the analysis of clinical evaluation, biochemical serum profile, and patient satisfaction with the procedure. PATIENTS/METHODS: This is retrospective non-randomized and non-controlled study collected in a private clinic; all data from healthy participants (n = 25), aged between 18 and 55 years, were compiled and analyzed. All received eight 30 min sessions of electromagnetic field ONIX HI-SMS (intensity of the 90%-100%) located in abdominal, twice a week with intervals of 2-3 days. RESULTS: The results show that BMI, fat thickness, and waist circumference improved the body contour after the treatment. There was no statistical difference in the data referring to the values of AST, ALT, ALP, creatinine, cholesterol, LDL-C, VLDL-C, HDL-C, glycemia, LDH, CK, and IL-6. However, there was a reduction of "non-esterified" free fatty acids when compared to baseline. This treatment provided high levels of tolerance, comfort, and high level of satisfaction. CONCLUSIONS: Thus, it can be suggested that the treatment with HI-SMS in abdominal muscles proves to be a safe technology with potential for non-invasive therapy for aesthetic purposes.

Effect of exercise on female pelvic floor morphology and muscle function: a systematic review.

INTRODUCTION AND HYPOTHESIS: The objective was to synthesize the scientific evidence on the relationship of exercise with morphology and muscle function parameters of the female pelvic floor. The design was a systematic review. METHODS: Searches were performed in MEDLINE, PubMed, CINAHL, Web of Science, SCOPUS, SportDiscuss, and Google Scholar up to April 2021. Observational and experimental studies evaluating the morphology and/or function of the pelvic floor muscles (PFMs) in women were eligible. Studies reporting exercise or sports disciplines as exposure/intervention were included. RESULTS: Twenty-five studies were included. Compared with the control group, women performing vigorous and high-impact exercises exhibited lower maximum voluntary contraction of the PFM and those performing moderate exercise had better maximum voluntary contraction. Exercise practitioners had a larger hiatal area at rest, during contraction, and during Valsalva, and greater bladder neck descent than the control group. CONCLUSIONS: The results of this review demonstrate an inverse relationship of PFM maximum voluntary contraction with exercise intensity. Qualitative synthesis showed that the studies found favorable outcomes for the control group in terms of hiatal area during contraction and Valsalva and bladder neck displacement.

The role of muscle relaxation in badminton players / O papel do relaxamento muscular em jogadores de badminton / El papel de la relajación muscular en jugadores de bádminton

ABSTRACT Introduction: In training, fatigue and recovery are antagonistic factors. Physical rehabilitation of athletes and elimination of sports fatigue have gradually become essential factors in improving competitiveness. Muscle relaxation exercises can reduce badminton players' physical effort, allowing them to recover quickly. Objective: Analyze muscle relaxation's effect on fatigue relief until the normalization of physical strength in badminton players. Methods: Twelve badminton players were grouped in cross-sectional tests. During the three weeks of physical training, players performed two training methods: muscle relaxation and complete rest. Laboratory analysis encompassed blood biomarkers such as urea and creatine kinase. Data were collected before and after the interventions, confronted, and studied mathematically and statistically. Results: The proportions of leukocytes and lymphocytes in the muscle relaxation group after resistance exercise were lower than before. The decrease of morning leukocytes in the muscle relaxation group on the second day was less than in the resting group. The recovery effect of the lymphocyte ratio was also better. After special strength training, the value of creatine kinase was significantly higher than before exercise in both the muscle relaxation group and the complete rest group. Conclusion: Muscle relaxation can reduce exercise fatigue in badminton players. Level of evidence II; Therapeutic studies - investigation of treatment outcomes.

RESUMO Introdução: No treinamento, fadiga e recuperação são fatores antagônicos. A reabilitação física dos atletas e a eliminação da fadiga esportiva tornaram-se gradualmente fatores essenciais para melhorar a competitividade. O exercício de relaxamento muscular pode reduzir o esforço físico dos jogadores de badminton, permitindo ao jogador recuperar-se rapidamente. Objetivo: Analisar o efeito do relaxamento muscular sobre o alívio da fadiga até a normalização da força física nos jogadores de badminton. Métodos: Foram agrupados 12 jogadores de badminton em testes transversais. Durante as três semanas de treinamento físico, os jogadores realizaram dois métodos de treinamento: relaxamento muscular e repouso completo. A análise laboratorial englobou biomarcadores sanguíneos, como ureia e creatina cinase. Os dados foram coletados antes e após as intervenções, confrontados e estudados de forma matemática e estatística. Resultados: As proporções de leucócitos e linfócitos no grupo de relaxamento muscular após o exercício de resistência foram menores do que antes. A diminuição dos leucócitos matinais no grupo de relaxamento muscular no segundo dia foi menor do que no grupo de repouso, e o efeito de recuperação da relação de linfócitos também foi melhor. Após o treinamento especial de força, o valor da creatina quinase foi significativamente maior do que antes do exercício tanto no grupo de relaxamento muscular quanto no grupo de repouso completo. Conclusão: O relaxamento muscular pode reduzir a fadiga do exercício nos jogadores de badminton. Nível de evidência II; Estudos terapêuticos - investigação dos resultados do tratamento.

RESUMEN Introducción: En el entrenamiento, la fatiga y la recuperación son factores antagónicos. La rehabilitación física de los atletas y la eliminación de la fatiga deportiva se han convertido gradualmente en factores esenciales para mejorar la competitividad. El ejercicio de relajación muscular puede reducir el esfuerzo físico de los jugadores de bádminton, permitiendo que el jugador se recupere rápidamente. Objetivo: Analizar el efecto de la relajación muscular en el alivio de la fatiga hasta la normalización de la fuerza física en jugadores de bádminton. Métodos: Se agruparon doce jugadores de bádminton en pruebas transversales. Durante las tres semanas de entrenamiento físico, los jugadores realizaron dos métodos de entrenamiento: la relajación muscular y el descanso completo. Los análisis de laboratorio incluían biomarcadores sanguíneos como la urea y la creatina quinasa. Los datos se recogieron antes y después de las intervenciones, se confrontaron y se estudiaron matemática y estadísticamente. Resultados: Las proporciones de leucocitos y linfocitos en el grupo de relajación muscular tras el ejercicio de resistencia fueron menores que antes. La disminución de los leucocitos matinales en el grupo de relajación muscular en el segundo día fue menor que en el grupo de reposo, y el efecto de recuperación de la proporción de linfocitos también fue mejor. Después del entrenamiento especial de fuerza, el valor de la creatina quinasa fue significativamente mayor que antes del ejercicio tanto en el grupo de relajación muscular como en el de reposo completo. Conclusión: La relajación muscular puede reducir la fatiga del ejercicio en los jugadores de bádminton. Nivel de evidencia II; Estudios terapéuticos - investigación de los resultados del tratamiento.

Phytochemicals and modulation of exercise-induced oxidative stress: a novel overview of antioxidants.

The practice of physical exercise induces a series of physiological changes in the body at different levels, either acutely or chronically. During exercise, the increase in oxygen consumption promotes the production of reactive oxygen species (ROS) and reactive nitrogen species (RNS), which are necessary to maintain homeostasis. ROS/RNS activate cellular signaling pathways, such as the antioxidant cytoprotective systems, inflammation, and cell proliferation, which are crucial for cell survival. However, in exhaustive-extended physical exercise, workloads can exceed the endogenous antioxidant defenses, which may be related to impairment of muscle contraction, fatigue, and a decrease in athletic performance. This review addresses the role of some antioxidants from plant-derived extracts called phytochemicals that can mediate the response to oxidative stress induced by physical exercise by activating signaling pathways, such as Nrf2/Keap1/ARE, responsible for the endogenous antioxidant response and possibly having an impact on sports performance.

Exercise fatigue injury under sport resistance / Lesão de fadiga causada por exercício sob resistência esportiva / Lesión por fatiga causada por ejercicio bajo resistencia deportiva

ABSTRACT Introduction Athletes are prone to local muscle fatigue due to high-intensity training and to long-term accumulation of musculoskeletal injuries. Musculoskeletal complications represent a large proportion of occupational health problems and, for this reason, have received increased attention from the sports industry. In this sense, studies on muscle fatigue should be intensified. Objective Verify muscle fatigue and injury involving the strain characteristics of lower limb joints in the eccentric and centripetal contraction of the jump. Methods A total of 691 individuals aged 20 to 40 years were selected. Fatigue was caused by active muscle contraction. The characteristic curves of active muscle contraction in different isometric, isotonic, and isokinetic training were analyzed. The degree of fatigue caused by three different sports states was tested by experimentation. The corresponding active muscle contraction characteristics were also analyzed. The potential for homeostasis at different ages was compared. Results The delay in recovery to fatigue is directly proportional to the athlete's age. The return to post-exercise relief proportion from fatigue gradually decreases. Conclusion The experimental results showed that active muscle contraction could reduce exercise fatigue to some extent. This beneficial biochemical property of active muscle contraction is not found in people with advanced age. The findings have a guiding potential for the relief of sports fatigue. Evidence Level II; Therapeutic Studies - Investigating the result.

RESUMO Introdução Os esportistas estão propensos à fadiga muscular local devido ao treinamento de alta intensidade, e ao acúmulo de lesões musculoesqueléticas a longo prazo. As complicações musculoesqueléticas representam uma grande fatia dos problemas de saúde ocupacional e por isso têm recebido maior atenção da indústria esportiva. Nesse sentido, os estudos sobre a fadiga muscular devem ser aprofundados. Objetivo Verificar a fadiga e lesão muscular envolvendo as características de esforço das articulações dos membros inferiores na contração excêntrica e contração centrípeta do salto. Métodos Foram selecionados 691 indivíduos com idade entre 20 a 40 anos. A fadiga foi ocasionada por contração muscular ativa. Foram analisadas as curvas características da contração muscular ativa em diferentes estados nos treinos isométrico, isotônico e isocinético. O grau de fadiga causado por três estados esportivos diferentes foi testado através de experimentos. Também foram analisadas as características de contração muscular ativa correspondentes. O potencial de homeostase em diferentes idades foi comparado. Resultados O retardo na recuperação à fadiga é diretamente proporcional a idade do esportista. A proporção de retorno ao alívio pós-exercício sobre a fadiga diminui gradualmente. Conclusão Os resultados experimentais mostram que a contração muscular ativa pode reduzir até certo ponto a fadiga ao exercício. Os efeitos dessas propriedades bioquímicas benéficas da contração muscular ativa não são encontrados em pessoas com idade avançada. Os achados tem um potencial orientador para o alívio da fadiga esportiva. Nível de evidência II; Estudos Terapêuticos - Investigação de Resultados.

RESUMEN Introducción Los deportistas son propensos a la fatiga muscular local debido al entrenamiento de alta intensidad, y a la acumulación de lesiones musculoesqueléticas a largo plazo. Las complicaciones musculoesqueléticas representan una gran parte de los problemas de salud laboral y por ello han recibido una mayor atención por parte de la industria del deporte. En este sentido, hay que profundizar en los estudios sobre la fatiga muscular. Objetivo Verificar la fatiga muscular y las lesiones que implican las características de esfuerzo de las articulaciones de los miembros inferiores en la contracción excéntrica y centrípeta del salto. Métodos Se seleccionaron 691 individuos de entre 20 y 40 años. La fatiga fue causada por la contracción muscular activa. Fueron analizadas las curvas características de la contracción muscular activa en diferentes estados en el entrenamiento isométrico, isotónico e isocinético. El grado de fatiga provocado por tres estados deportivos diferentes se comprobó mediante experimentos. También se analizaron las correspondientes características de la contracción muscular activa. Se comparó el potencial de homeostasis a diferentes edades. Resultados El retraso en la recuperación a la fatiga es directamente proporcional a la edad del deportista. La proporción de retorno al alivio de la fatiga después del ejercicio disminuye gradualmente. Conclusión Los resultados experimentales muestran que la contracción muscular activa puede reducir la fatiga del ejercicio en cierta medida. Los efectos de estas propiedades bioquímicas beneficiosas de la contracción muscular activa no se encuentran en las personas mayores. Los hallazgos tienen un potencial orientador para el alivio de la fatiga deportiva. Nivel de evidencia II; Estudios terapéuticos - Investigación de resultados.

Perspectives on the Therapeutic Effects of Pelvic Floor Electrical Stimulation: A Systematic Review.

Pelvic, perineal, and nervous lesions, which derive principally from pregnancy and childbirth, may lead to pelvic floor dysfunctions, such as organ prolapses and lesions in the nerves and muscles due to muscle expansion and physiology. It is estimated that 70% of women affected by this clinical picture have symptoms that do not respond to the classical treatments with antimuscarinic and anticholinergic drugs. Therefore, resorting to efficient alternatives and less invasive methods is necessary to assist this public health problem that predominantly affects the female population, which is more susceptible to the risk factors. This study aimed to perform an updated and comprehensive literature review focused on the effects of pelvic floor electrical stimulation, considering new perspectives such as a correlation between electric current and site of intervention and other molecular aspects, different from the present reviews that predominantly evaluate urodynamic aspects. For that purpose, PubMed and ScienceDirect databases were used to perform the search, and the Methodi ordinatio method was applied. With well-researched therapeutic effects, electrical stimulation induced promising results in histological, nervous, and molecular evaluations and spinal processes, which showed beneficial results and revealed new perspectives on ways to evoke responses in the lower urinary tract in a non-invasive way. Thus, it is possible to conclude that this type of intervention may be a non-invasive alternative to treat pelvic and perineal dysfunctions.

Two devices to facilitate the perception of pelvic floor muscle contraction in the sitting position in women with urinary incontinence: comparative analysis / Dois dispositivos facilitadores de percepção da contração do assoalho pélvico na posição sentada em mulheres com incontinência urinária: análise comparativa / Dos herramientas que facilitan la percepción de la contracción del suelo pélvico en posición sentada de mujeres con incontinencia urinaria: un análisis comparativo

ABSTRACT The use of support devices may facilitate the perception of pelvic floor muscle (PFM) contraction, which is difficult to be performed. Therefore, this study aimed to compare the perception of PFM contraction in the sitting position during the use of two different support devices on women with PFM dysfunction. This is a cross-sectional study performed with 37 women with stress or mixed urinary incontinence (UI). All women performed three free PFM contractions sitting on a chair, followed by three contractions using each support device (sand pads and a cylindrical foam, which provide sciatic and perineal support, respectively). Women scored the perception of PFM contraction from 1 to 5, as well as the perception of facilitation of contraction (higher grades show better results) and discomfort (higher grades show more discomfort) when compared with free contraction. The cylindrical foam presented similar results to sand pads for the perception of PFM contraction (2.84±1.61 vs. 3.19±1.43; p=0.34) and facilitation of contraction (3.38±1.34 vs. 3.19±1.54; p=0.61), as well as for their discomfort (1.83±1.23 vs. 1.5±1.16; p=0.20). Of all women, 57% preferred sand pads. Thus, both sand pads (sciatic support) and the cylindrical foam (perineal support) improved the perception of PFM contraction and facilitation of contraction in the sitting position of women with PFM dysfunction when compared with sitting with no device. The two devices presented no difference between them.

RESUMO O uso de dispositivos de suporte pode auxiliar na percepção da contração dos músculos do assoalho pélvico (AP). O objetivo deste estudo foi, comparar na posição sentada, a percepção da contração dos músculos do AP durante o uso de dois tipos diferentes de dispositivos, em mulheres com disfunção dos músculos do AP. Para tanto, foi realizado um estudo transversal com 37 mulheres com incontinência urinária (IU) de esforço ou mista. Primeiro as participantes faziam três contrações livres dos músculos do AP sem o uso de dispositivos, sentadas em uma cadeira. Em seguida, faziam três contrações utilizando cada um dos dois dispositivos: almofadas de areia e uma espuma cilíndrica, que forneciam apoio isquiático e perineal, respectivamente. As pacientes atribuíram nota de 1 a 5 para a percepção que tiveram da contração dos músculos do AP, da facilitação da contração (quanto maior a nota, melhor o resultado) e do desconforto com o dispositivo (quanto maior a nota, maior o desconforto) em comparação às contrações livres. Como resultados principais, verificou-se que o uso da almofada cilíndrica foi similar ao das almofadas de areia para a percepção da contração dos músculos do AP (2,84±1,61 vs. 3,19±1,43; p=0,34), e da facilitação da contração (3,38±1,34 vs. 3,19±1,54; p=0,61), assim como do desconforto (1,83±1,23 vs. 1,5±1,16; p=0,20). Entre as participantes, 57% relataram preferir as almofadas de areia. Concluiu-se que em mulheres com incontinência urinária, tanto as almofadas de areia (apoio isquiático) quanto a espuma cilíndrica (apoio perineal) melhoraram a percepção da contração e facilitaram a contração dos músculos do assoalho pélvico na posição sentada, não havendo, no entanto, diferença entre os dispositivos.

RESUMEN Las herramientas de apoyo pueden ayudar en la percepción de la contracción de los músculos del suelo pélvico (SP), que no siempre es fácil de obtener su medición. El objetivo de este estudio fue comparar si dos tipos diferentes de herramientas ayudan a las mujeres con disfunción muscular del SP a contraer estos músculos en posición sentada. Para ello, se realizó un estudio transversal con 37 mujeres con incontinencia urinaria (IU) de esfuerzo o mixta. Primero, las participantes realizaron tres contracciones libres de los músculos del SP sentadas en una silla, sin el uso de herramientas de apoyo. Luego, realizaron tres contracciones utilizando cada uno de los dos dispositivos de apoyo: almohadillas de arena y espuma cilíndrica, que brindan apoyo isquiático y perineal, respectivamente. Las participantes deberían asignar una puntuación de 1 a 5 cuanto a su percepción de la contracción muscular del SP, de la facilitación de la contracción (cuanto mayor sea la puntuación, mejor será el resultado) y la incomodidad con la herramienta (cuanto mayor sea la puntuación, mayor será la incomodidad) en comparación con las contracciones libres. Los principales resultados encontrados apuntan que el uso de la almohadilla cilíndrica fue similar al de las almohadillas de arena en cuanto a su percepción de la contracción de los músculos del SP (2,84±1,61 vs. 3,19±1,43; p=0,34), y la facilitación de la contracción (3,38±1,34 vs. 3,19±1,54; p=0,61), así como la incomodidad (1,83±1,23 vs. 1,5±1,16; p=0,20). El 57% de las participantes informó preferir las almohadillas de arena. Se concluyó que tanto las almohadillas de arena (apoyo isquiático) como la espuma cilíndrica (apoyo perineal) mejoraron la percepción y la facilitación de la contracción muscular del SP en posición sentada de mujeres con disfunción muscular del SP en comparación con la ausencia de la herramienta, sin embargo, hay no hubo diferencia entre las herramientas.

Variability in Normalization Methods of Surface Electromyography Signals in Eccentric Hamstring Contraction.

CONTEXT: In human movement analysis, normalization of a surface electromyography signal is a crucial step; therefore, parameter selection for this procedure must be adequately justified. The aim of this research was to determine the variability of electromyography signals in eccentric hamstring contraction under different normalization parameters. DESIGN: Cross-sectional study. METHODS: Nine university rugby players (age 21.50 [3.61] y; body mass index 21.50 [4.95]) and no history of recent hamstring injury. Values from maximum voluntary isometric contraction protocol and task related (ie, Nordic hamstring exercise) were used for surface electromyography signal normalization. Intersubject and intrasubject variation coefficients were used for normalization method variability and for signal reproducibility, respectively. RESULTS: Intrasubject variation coefficient value indicates acceptable reproducibility of surface electromyography (less than 12%) for all normalization procedures. Lower values of intersubject variation coefficient value were achieved for normalization procedures using task-related values. CONCLUSION: Parameters extracted from task execution provided less variability for surface electromyography amplitude normalization in eccentric hamstring muscle contractions.

Isometric strength of upper limb muscles in youth using hand-held and hand-grip dynamometry.

The present study aimed to determine the isometric strength profile of the upper limb muscles of children and adolescents between 7-15 years of age. Furthermore, to (a) identify the age at which differences in strength are observed between sexes; to (b) determine the age range at which significant progression of strength could be observed; and (c) identify the role of each muscle on the total upper limb strength. Cross-sectional study that evaluated the isometric strength of nine muscle groups of the upper limb of 243 Chilean children, split into 9 age groups, separated by 1-year intervals. For this, hand-held dynamometry and hand-grip dynamometry were used. A two-factor analysis of variance for the maximum isometric strength and a stepwise multiple linear regression analysis were performed. From 11 years of age, wrist flexors were the first muscle group that revealed a significant difference in isometric strength in favor of boys (P=0.0143). In boys, the narrowest and earliest age range in the progression of isometric strength was 10 to 12 years for wrist flexors (P=0.0392). Shoulder flexors was the main factor that explained the performance of the total upper limb strength (R 2=0.742; P<0.001). The most progressive isometric strength development occurred from age 10 years in the ventral and distal muscles of the upper limb; and from this age the boys begin to present a greater isometric strength than girls. In addition, the isometric strength of shoulder flexors explained the higher total upper limb strength performance.

Efectos de un protocolo de entrenamiento excéntrico sobre el rendimiento de velocidad en adolescentes de Chile / Effects of an Eccentric Training Protocol on Speed Performance in Chilean Adolescents

Resumen Introducción: Los beneficios del entrenamiento de fuerza sobre la velocidad de carrera han sido descritos en la bibliografía especializada, sin embargo, la evidencia sobre la influencia de estímulos específicos, basados en contracciones excéntricas sobre la musculatura extensora de cadera, no han sido demostrados. Objetivo: Determinar los efectos de un protocolo de entrenamiento basado en contracciones excéntricas (curl nórdico) sobre la velocidad de carrera en 20 metros en adolescentes de la región de Ñuble, Chile. Metodología: 42 individuos escolares fueron divididos en grupo experimental (n=22) y grupo control (n=20). El entrenamiento se desarrolló durante 6 semanas, con una frecuencia de 2 sesiones/semana, pasando de un volumen de 8 a 32 repeticiones de curl nórdico por sesión para el grupo experimental. El rendimiento de velocidad fue evaluado en 20 metros. La prueba T de Student fue utilizada para comparar los resultados pre y post intervención y se calculó el tamaño del efecto (TE). Resultados: Se encontraron diferencias estadísticamente significativas (p<0,05) a partir de la intervención en el grupo experimental (pre= 3,43 s. vs post= 3,15 s.), y un TE grande (1,04). Conclusión: Se concluye que el entrenamiento excéntrico basado en la aplicación de Curl nórdico, mejora el rendimiento de la velocidad de carrera.

Abstract Introduction: The specialized literature has described the benefits of strength training on running speed. In the same way, stimulation of training based on eccentric contractions has been shown to be effective in improving this quality. Objective: To determine the effects of a training protocol based on the stretch-shortening cycle (SSC) and another on eccentric contractions (Nordic curl) on the running speed in 20 meters in adolescents from the Ñuble Region, Chile. Methodology: 42 school subjects were divided into experimental group (n = 22) and control group (n = 20). The training was developed for 6 weeks, with a frequency of 2 sessions/week, going from a volume of 8 to 32 repetitions of Nordic curl per session for the experimental group. The speed performance was evaluated in 20 meters. With photocells, the T Student's was applied to compare the pre- and post-intervention results, and the effect size (ES) was calculated. Results: Statistically significant differences were found (p <0.05) from the intervention in the experimental group (pre= 3,43 s. vs post= 3,15 s.), and a large ES (1,04). Conclusion: It is concluded that the eccentric training based on the application of Nordic Curl improves the performance of the running speed.

Resumo Introdução: Os benefícios do treinamento de força na velocidade de corrida foram descritos na literatura especializada, no entanto, não foram demonstradas evidências sobre a influência de estímulos específicos, baseados em contrações excêntricas na musculatura extensora do quadril. Objetivo: Determinar os efeitos de um protocolo de treinamento baseado em contrações excêntricas (cacho nórdico) em velocidade de corrida de 20 m em adolescentes da região do Ñuble, Chile. Metodologia: 42 escolares foram divididos em um grupo experimental (n=22) e um grupo controle (n=20). O treino foi desenvolvido durante 6 semanas, com uma frequência de 2 sessões/semana, passando de um volume de 8 para 32 repetições de ondulação nórdica por sessão para o grupo experimental. O desempenho da velocidade foi avaliado acima de 20 metros. O teste T de Student foi usado para comparar os resultados pré e pós-intervenção e o tamanho do efeito (TE) foi calculado. Resultados: Foram encontradas diferenças estatisticamente significativas (p<0,05) da intervenção no grupo experimental (pré= 3,43 s. vs pós= 3,15 s.), e um TE grande (1,04). Conclusão: Conclui-se que o treinamento excêntrico baseado na aplicação do Curl nórdico melhora o desempenho da velocidade de corrida.

Pelvic floor muscle dysfunction at 3D transperineal ultrasound in maternal exposure to gestational diabetes mellitus: A prospective cohort study during pregnancy.

AIM: This study aimed to assess, for the first time, the dynamic morphometry of pelvic floor muscles (PFM) using three-dimensional transperineal ultrasound (3D-TPUS) and its progression at two-time points of gestation between women with and without gestational diabetes mellitus (GDM), and whether the PFM dysfunction is connected to GDM. METHODS: The study comprised 83 consecutive pregnant women with (n = 38) and without (n = 45) GDM screened at 24-30 and 38-40 weeks of gestation. 3D-TPUS and a mobility test were used to quantify PFM dynamic morphometry during maximum contraction and the Valsalva maneuver. RESULTS: When compared to the control group, GDM women had no significant variations in all levator hiatal dimensions at 24-30 weeks of gestation. Meanwhile, women with GDM experienced an increase in levator hiatal area (LHa) (p < 0.000) during PFM contraction and enlargement in LHa (p < 0.001) during Valsalva maneuver (p = 0.010) at 38-40 weeks of gestation. As a result, the mobility index among GDM women had a lower value (p = 0.000). The dynamic morphometry development of PFM in GDM women at two stages during pregnancy revealed a substantial decrease (p = 0.000) in all LHa dimensions of contraction, distension, and mobility. CONCLUSIONS: Using 3D-TPUS, we found that GDM women had a specific pattern of PFM functional changes in the third trimester of pregnancy. These initial findings revealed alterations in PFM functionality, such as decreased contractility, distensibility, or mobility. This dysfunctional PFM could contribute to the long-term development of pelvic floor dysfunction years after a GDM pregnancy.

Efecto contráctil del extracto acuoso de Artemisia absinthium (ajenjo) frente a oxitocina en útero aislado de ratas / Contractile effect of aqueous extract of Artemisia absinthium (ajenjo) against oxytocin in isolated uterus of rats

RESUMEN Introducción. El uso de Artemisia absinthium (ajenjo) en el trabajo de parto es ampliamente empleado en países de la región; sin embargo, no hay evidencia científica suficiente de su eficacia y seguridad, lo que representa un alto riesgo maternofetal. Objetivo. El propósito fue evaluar el efecto contractil de la Artemisia absinthium (ajenjo) en comparación a la oxitocina en útero aislado de ratas. Métodos. Se separaron 8 ratas Holtzman en i) Grupo experimental: Artemisia dosis 5, 10, 20, 30, 40 y 50 mg y ii) Grupo control: oxitocina 10-6 M. Se montaron los úteros en un baño de órganos aislados y se registraron contracciones por 5 minutos. Resultados. La frecuencia de contracciones con ajenjo 40 y 50 mg fueron comparables con oxitocina (p>0,05). Asimismo, dosis de 20 y 30 mg de Artemisia provocaron contracciones significativamente más duraderas que la oxitocina. La intensidad resultó ser comparable con oxitocina con dosis de 20, 40 y 50 mg de Artemisia. Conclusión. El extracto acuoso de Artemisia absinthium presentó efecto contráctil similar a la oxitocina y dependiente de la dosis en útero aislado de ratas.

ABSTRACT Introduction. The use of Artemisia absinthium (wormwood) in labour is widely used in countries in the region; however, there is no enough scientific evidence of its efficacy and safety, which represents a high maternalfetal risk. Objective. The purpose was to assess the contractile effect of Artemisia absinthium (wormwood) compared to oxytocin in utero isolated from rats. Methods. Eight Holtzman rats were separated into i) Experimental group: Artemisia dose 5, 10, 20, 30, 40, and 50 mg and ii) Control group: oxytocin 10-6 M. The uteruses were mounted in an isolated organ bath, and contractions were recorded for 5 minutes. Results. The frequency of contractions with wormwood 40 and 50 mg were comparable with oxytocin (p>0.05). Likewise, doses of 20 and 30 mg of Artemisia caused significantly longer-lasting contractions than oxytocin. The intensity was found to be comparable with oxytocin at doses of 20, 40, and 50 mg of Artemisia. Conclusion. The aqueous extract of Artemisia absinthium has a contractile effect similar to oxytocin and is dose dependent in utero isolated from rats.

Glutamine supplementation improves contractile function of regenerating soleus muscles from rats.

This study evaluated the effects of glutamine supplementation immediately after freezing injury on morphological and contractile function of regenerating soleus muscles from rats. Young male Wistar rats were subjected to cryolesion of soleus muscles, and immediately after received a daily supplementation of glutamine (1 g/kg/day). The muscles were evaluated on post-injury days 3 and 10. Glutamine-supplemented injured muscles had a lower number of CD11b positive immune cells and higher mRNA levels of IL-4 compared to those from the cryolesioned muscles analyzed on post-injury day 3. The mRNA and protein expression levels of the myogenic transcription factor MyoD were also higher in glutamine-supplemented injured muscles than in injured muscles examined on post-cryolesion day 3. In addition, glutamine-supplemented injured muscles had a higher size of their regenerating myofibers, attenuated decline in maximum tetanic strength and improved fatigue resistance compared to those from injured muscles evaluated on post-cryolesion day 10. No effect was observed in uninjured muscles supplemented with glutamine. Our results suggest that glutamine supplementation improves the resolution of inflammation, as well as the size and functional recovery of regenerating myofibers from soleus muscles by accelerating the up-regulation of IL-4 and MyoD expression. Future non-pharmacological rehabilitation studies are warranted to investigate the effect of glutamine supplementation on the outcome of injured skeletal muscles.

Blood glucose kinetics during concentric and eccentric muscle contractions

Studies comparing the two classes of stimuli (concentric and eccentric) have shown differences in the improvement of cardiovascular, metabolic, and muscle strength gain. This is an experimental, quantitative, and prospective study that aimed to verify the effect of eccentric exercise on glycolytic consumption and kinetics. The blood glucose kinetics of 17 male subjects was evaluated during a treadmill exercise with a 10% declined floor and velocity that required a 60% metabolic activity of VO2max, for 30 minutes. Seventy-two hours later, the same subjects exercised on the treadmill with a 10% inclined floor and 60% VO2max, for 30 minutes. To quantify glucose, blood samples were collected before the exercise, every three minutes along the 30 minutes of physical activity, and five and 10 minutes after finishing the exercise. For the downward slope, there was a homogeneous group behavior for blood glucose dynamics during the exercise, which was characterized by a monotonic decrease of glucose levels until reaching a minimum value at experimental times between 20 and 30 min, followed by a progressive recovery toward initial values. For the acclivity condition, blood glucose dynamics did not follow such a homogeneous behavior. A set of different types of dynamics could be identified. Experimental data showed that the type of dynamics could be predicted, to some extent, by the basal blood glucose level of subjects. The type of floor slope (upward or downward) directly affected glycolytic consumption and kinetics for the individuals analyzed.

Padrões de contração muscular e suas associações no terço superior da face: um estudo clínico e epidemiológico / Muscle contraction patterns and their associations in the upper third of the face: a clinical and epidemiological study

Introdução: o uso da toxina botulínica tornou-se um dos procedimentos cosméticos mais importantes realizados no mundo. Objetivo: identificar padrões de contração muscular da fronte, complexo glabelar e músculo orbicular dos olhos em pacientes do sul do Brasil, estabelecendo sua epidemiologia e possíveis associações entre eles. Métodos: foram incluídos 101 pacientes que buscaram tratamento com toxina botulínica para fronte, glabela e linhas perioculares entre 2012 e 2016. Análises foram feitas por meio de fotografias digitais tiradas durante consulta médica, antes da aplicação dos produtos. Os pacientes foram tratados com diferentes marcas de toxina botulínica, de acordo com suas preferências ou com as do médico. Resultados: os padrões de contração mais comuns foram frontal completo, glabelar em setas convergentes e periocular completo. Mulheres representaram 94,1% dos pacientes. A maioria tinha idade entre 31 e 50 anos, com média de 44,57 anos. Padrões mais frequentes em cada área individual foram mais frequentemente associados. Conclusões: o estudo mostra os principais padrões de contração muscular do terço superior da face em 101 pacientes, bem como suas características clínicas, e os compara com artigos publicados anteriormente. Estudos sobre padrões de contração muscular podem auxiliar no uso mais seguro e racional dos produtos disponíveis, evitando desperdícios e complicações.

Introduction: The use of botulinum toxin has become one the essential cosmetic procedures performed in the world. Objective: To identify patterns of muscle contraction of the forehead, glabellar complex, and orbicularis oculi muscle in patients from southern Brazil, establishing their epidemiology and possible associations between them. Methods: One hundred and one patients who sought treatment with botulinum toxin for the forehead, glabella, and periocular lines between 2012 and 2016 were included. Analyzes were made using digital photographs taken during a medical consultation before applying the products., The subjects received with different brands of botulinum toxin, according to the patients' or the doctors' preference Results: The most common contraction patterns were complete frontal, glabellar in converging arrows, and complete periocular. Women represented 94.1% of patients. Most patients were between 31 and 50 years old, with an average of 44.57 years. More frequent patterns in each area were more frequently associated. Conclusions: The study shows the main muscle contraction patterns of the upper third of the face in 101 patients, as well as their clinical characteristics, comparing them with previously published articles. Studies on muscle contraction patterns can assist in the safer and more rational use of the products available, avoiding waste and complications.

FAT/CD36 Participation in Human Skeletal Muscle Lipid Metabolism: A Systematic Review.

Fatty acid translocase/cluster of differentiation 36 (FAT/CD36) is a multifunctional membrane protein activated by a high-fat diet, physical exercise, fatty acids (FAs), leptin, and insulin. The principal function of FAT/CD36 is to facilitate the transport of long-chain fatty acids through cell membranes such as myocytes, adipocytes, heart, and liver. Under high-energy expenditure, the different isoforms of FAT/CD36 in the plasma membrane and mitochondria bind to the mobilization and oxidation of FAs. Furthermore, FAT/CD36 is released in its soluble form and becomes a marker of metabolic dysfunction. Studies with healthy animals and humans show that physical exercise and a high-lipid diet increase FAT/CD36 expression and caloric expenditure. However, several aspects such as obesity, diabetes, Single Nucleotide polymorphisms (SNPs), and oxidative stress affect the normal FAs metabolism and function of FAT/CD36, inducing metabolic disease. Through a comprehensive systematic review of primary studies, this work aimed to document molecular mechanisms related to FAT/CD36 in FAs oxidation and trafficking in skeletal muscle under basal conditions, physical exercise, and diet in healthy individuals.