18 resultados para fadiga muscular


Relevância:

20.00% 20.00%

Publicador:

Resumo:

Background: The adult central nervous system (CNS) contains different populations of immature cells that could possibly be used to repair brain and spinal cord lesions. The diversity and the properties of these cells in the human adult CNS remain to be fully explored. We previously isolated Nestin(+) Sox2(+) neural multipotential cells from the adult human spinal cord using the neurosphere method (i.e. non adherent conditions and defined medium). -- Results: Here we report the isolation and long term propagation of another population of Nestin(+) cells from this tissue using adherent culture conditions and serum. QPCR and immunofluorescence indicated that these cells had mesenchymal features as evidenced by the expression of Snai2 and Twist1 and lack of expression of neural markers such as Sox2, Olig2 or GFAP. Indeed, these cells expressed markers typical of smooth muscle vascular cells such as Calponin, Caldesmone and Acta2 (Smooth muscle actin). These cells could not differentiate into chondrocytes, adipocytes, neuronal and glial cells, however they readily mineralized when placed in osteogenic conditions. Further characterization allowed us to identify the Nkx6.1 transcription factor as a marker for these cells. Nkx6.1 was expressed in vivo by CNS vascular muscular cells located in the parenchyma and the meninges. -- Conclusion: Smooth muscle cells expressing Nestin and Nkx6.1 is the main cell population derived from culturing human spinal cord cells in adherent conditions with serum. Mineralization of these cells in vitro could represent a valuable model for studying calcifications of CNS vessels which are observed in pathological situations or as part of the normal aging. In addition, long term propagation of these cells will allow the study of their interaction with other CNS cells and their implication in scar formation during spinal cord injury.

Relevância:

10.00% 10.00%

Publicador:

Resumo:

[EN]In an attempt to predict intramuscular fatty acid composition using easily accessible fat depots, between-tissue correlations were studied in 75 Asturiana de los Valles bulls with different levels of muscular hypertrophy, and 25 Asturiana de la Montan˜ a bulls. Trans-18:1 in intramuscular fat was highly and positively correlated with levels in subcutaneous and intermuscular fats, while levels of total n-3 were not correlated. Predicting intramuscular fatty acid composition using easily accessible depots is thus possible for some fatty acids exhibiting high between-tissue correlations (e.g., trans-18:1) but breed and tissue specific deposition may limit this for others (e.g., n-3 fatty acids).

Relevância:

10.00% 10.00%

Publicador:

Resumo:

294 p. : il.

Relevância:

10.00% 10.00%

Publicador:

Resumo:

225 p. : il. Texto en español con conclusiones en inglés

Relevância:

10.00% 10.00%

Publicador:

Resumo:

Los objetivos de este estudio fueron analizar las diferencias en las características antropométricas, resistencia aeróbica, temperatura corporal y percepción subjetiva del esfuerzo en futbolistas de distintas categorías (cadete y juvenil), y examinar la relación existente entre las distintas variables analizadas. Para ello participaron 37 jóvenes futbolistas, 20 de ellos cadetes (15,12 ± 0,69 años) y 17 juveniles (16,94 ± 0,89 años). A los futbolistas se les midió la talla y la masa corporal, calculándose el índice de masa corporal (IMC). A su vez, para determinar su resistencia aeróbica, los jugadores realizaron el Yo-Yo Intermittent Recovery Level 1, registrándose la distancia total recorrida, la temperatura pre y post-test y la percepción subjetiva del esfuerzo (RPE). Los futbolistas de categoría juvenil obtuvieron mayores valores de masa corporal e IMC, obteniendo además mejores valores en el test de resistencia que los cadetes. Asimismo, se registraron diferencias en el RPEmus y RPEmus-TL, siendo mayor el de los juveniles en ambos casos. Para acabar, se observaron correlaciones altas entre los resultados del test de resistencia y el RPEres-TL, así como con el RPEmus-TL en los juveniles, mientras que en el caso de los cadetes solo correlacionó con el RPEres-TL. Se cree que dichas diferencias pueden ser debidas al mayor desarrollo muscular de los juveniles respecto a los cadetes, aunque se necesitan más estudios.

Relevância:

10.00% 10.00%

Publicador:

Resumo:

Lan honen helburua eskuzko pilotarien eta atleten autoefikazia neurtu eta hauen arteko ezberdintasunak zein diren aztertzea zen autematen zuten abilezia fisikoaren inguruan. Honetarako, ???Perceived Physical Ability??? (PPA) eskala erabili zen. Lagina kategoria ezberdineko (kadete, jubenil eta senior) 37 kirolariz osatuta zegoen (24 pilotari eta 13 atleta) beraien bataz besteko adina, pilotariena 19,41 eta atletena 20,53 izanik. Lortutako emaitzek adierazten dute atletek balore altuagoak izan dituztela abiadura, azkartasuna, bizitasuna eta trebeziari erlazionatutako galderetan batez ere eta baita ere masa muskular tonuari dagokion galdera batean. Konklusiotzat, eskala honen bidez pilotari eta atleten arteko ezberdintasun orokorrak zein diren ikusi dira hautematen duten autoefikazia mailari dagokionez. Ezberdintasunak adierazgarriak aurkitu ziren abiadura, azkartasuna, trebezia, zalutasuna eta muskular tonuari zegozkien itemetan.

Relevância:

10.00% 10.00%

Publicador:

Resumo:

La pr??ctica competitiva del f??tbol expone a sus practicantes a un riesgo elevado de sufrir lesiones. De hecho, se trata de uno de los deportes con mayor ??ndice lesional. Por ello, existe la necesidad de investigar las formas de reducir este riesgo. Las lesiones musculares suponen un gran volumen del total de las lesiones de los futbolistas (31%), y de ellas las lesiones de la zona isquiotibial son las m??s comunes en deportes que requieren sprints, cambios de direcci??n y saltos, que son las acciones m??s comunes en el f??tbol. Este art??culo de revisi??n, realiza una propuesta metodol??gica de prevenci??n para dichas lesiones bas??ndose en los principales factores de riesgo de esta lesi??n muscular y en dos grandes pilares de trabajo: la fuerza y la propiocepci??n.

Relevância:

10.00% 10.00%

Publicador:

Resumo:

[EN] Some authors have suggested that body weight dissatisfaction may be high in students majoring in dietetics. Therefore, this study was conducted to examine the extent of body weight and image dissatisfaction in a sample of women in dietetics major. Additionally, predictors of magnitude of body weight dissatisfaction were analyzed. Participants were 62 volunteers with normalweight whose mean age was 21.87±1.89 years old (nonrandom sample). The assessment instruments included anthropometric measurements, a somatomorphic matrix test and an eating disorders inventory (EDI-2). Data were analyzed using SPSS vs. 15.0. A larger proportion of students chose an ideal body weight lower than actual weight (67.7%) and body image with less body fat and more muscle mass than actual values (56.4%). The magnitude of body weight dissatisfaction was associated with muscle mass and body fat dissatisfaction, and with the subscale of EDI-2 “body dissatisfaction”. So, from a public health standpoint, we consider important to continue working in this line of research with the aim of better understanding the extent of body weight dissatisfaction in women dietitians, and how this dissatisfaction could interfere with their professional practice.

Relevância:

10.00% 10.00%

Publicador:

Resumo:

Este trabajo se encuentra bajo la licencia Creative Commons Attribution 3.0.

Relevância:

10.00% 10.00%

Publicador:

Resumo:

In this study we employed a dynamic recurrent neural network (DRNN) in a novel fashion to reveal characteristics of control modules underlying the generation of muscle activations when drawing figures with the outstretched arm. We asked healthy human subjects to perform four different figure-eight movements in each of two workspaces (frontal plane and sagittal plane). We then trained a DRNN to predict the movement of the wrist from information in the EMG signals from seven different muscles. We trained different instances of the same network on a single movement direction, on all four movement directions in a single movement plane, or on all eight possible movement patterns and looked at the ability of the DRNN to generalize and predict movements for trials that were not included in the training set. Within a single movement plane, a DRNN trained on one movement direction was not able to predict movements of the hand for trials in the other three directions, but a DRNN trained simultaneously on all four movement directions could generalize across movement directions within the same plane. Similarly, the DRNN was able to reproduce the kinematics of the hand for both movement planes, but only if it was trained on examples performed in each one. As we will discuss, these results indicate that there are important dynamical constraints on the mapping of EMG to hand movement that depend on both the time sequence of the movement and on the anatomical constraints of the musculoskeletal system. In a second step, we injected EMG signals constructed from different synergies derived by the PCA in order to identify the mechanical significance of each of these components. From these results, one can surmise that discrete-rhythmic movements may be constructed from three different fundamental modules, one regulating the co-activation of all muscles over the time span of the movement and two others elliciting patterns of reciprocal activation operating in orthogonal directions.

Relevância:

10.00% 10.00%

Publicador:

Resumo:

A central question in Neuroscience is that of how the nervous system generates the spatiotemporal commands needed to realize complex gestures, such as handwriting. A key postulate is that the central nervous system (CNS) builds up complex movements from a set of simpler motor primitives or control modules. In this study we examined the control modules underlying the generation of muscle activations when performing different types of movement: discrete, point-to-point movements in eight different directions and continuous figure-eight movements in both the normal, upright orientation and rotated 90 degrees. To test for the effects of biomechanical constraints, movements were performed in the frontal-parallel or sagittal planes, corresponding to two different nominal flexion/abduction postures of the shoulder. In all cases we measured limb kinematics and surface electromyographic activity (EMB) signals for seven different muscles acting around the shoulder. We first performed principal component analysis (PCA) of the EMG signals on a movement-by-movement basis. We found a surprisingly consistent pattern of muscle groupings across movement types and movement planes, although we could detect systematic differences between the PCs derived from movements performed in each sholder posture and between the principal components associated with the different orientations of the figure. Unexpectedly we found no systematic differences between the figute eights and the point-to-point movements. The first three principal components could be associated with a general co-contraction of all seven muscles plus two patterns of reciprocal activatoin. From these results, we surmise that both "discrete-rhythmic movements" such as the figure eight, and discrete point-to-point movement may be constructed from three different fundamental modules, one regulating the impedance of the limb over the time span of the movement and two others operating to generate movement, one aligned with the vertical and the other aligned with the horizontal.

Relevância:

10.00% 10.00%

Publicador:

Resumo:

Hoy en día y con el objetivo de conseguir el mayor rendimiento posible en la mayoría de los deportes profesionales, la suplementación deportiva está adquiriendo un protagonismo vital, siendo conscientes de que la suplementación deportiva por sí sola no sea el principal factor responsable del aumento del rendimiento deportivo. Sin embargo, ha quedado demostrado que estos suplementos pueden ayudar a dar el salto de calidad en deportistas profesionales y últimamente salen a la luz investigaciones de nuevos suplementos que empiezan a ser habituales en algunos deportistas, como es el caso de la Beta-Alanina. El principal efecto de la ingesta exógena de b-alanina en el organismo radica en el aumento de la carnosina muscular debido a su rol como factor limitante en la síntesis de la misma, un dipéptido citoplasmático que tiene la capacidad de secuestrar los protones inducidos por el ejercicio de alta intensidad, retrasando la disminución del pH intramuscular y en consecuencia, retrasando la fatiga. La mayoría de los estudios hasta el momento que han investigado el efecto de la b-alanina y el rendimiento deportivo se centran en los deportes cíclicos, especialmente en aquellos deportes anaeróbicos donde la disminución del pH es limitante del rendimiento deportivo. Por ello, mediante una revisión bibliográfica el objetivo de este artículo será identificar y resumir los efectos principales de la suplementación exógena de Beta-alanina relacionados con el aumento del rendimiento deportivo y complementariamente, se realizar también un análisis sobre los factores fisiológicos del fútbol con el fin de conocer si este suplemento podría aumentar el rendimiento en los futbolistas de alto nivel.