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1.
PLoS One ; 15(5): e0232397, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32365096

RESUMO

Biometric ratios of the relative length of the rays in the hand have been analyzed between primate species in the light of their hand function or phylogeny. However, how relative lengths among phalanges are mechanically linked to the grasping function of primates with different locomotor behaviors remains unclear. To clarify this, we calculated cross and triple-ratios, which are related to the torque distribution, and the torque generation mode at different joint angles using the lengths of the phalanges and metacarpal bones in 52 primates belonging to 25 species. The torque exerted on the finger joint and traction force of the flexor tendons necessary for a cylindrical grip and a suspensory hand posture were calculated using the moment arm of flexor tendons measured on magnetic resonance images, and were compared among Hylobates spp., Ateles sp., and Papio hamadryas. Finally, the torques calculated from the model were validated by a mechanical study detecting the force exerted on the phalanx by pulling the digital flexor muscles during suspension in these three species. Canonical discriminant analysis of cross and triple-ratios classified primates almost in accordance with their current classification based on locomotor behavior. The traction force was markedly reduced with flexion of the MCP joint parallel to the torque in brachiating primates; this was notably lower in the terrestrial quadrupedal primates than in the arboreal primates at mild flexion. Our mechanical study supported these features in the torque and traction force generation efficiencies. Our results suggest that suspensory or terrestrial quadrupedal primates have hand structures that can exert more torque at a suspensory posture, or palmigrade and digitigrade locomotion, respectively. Furthermore, our study suggests availability of the cross and triple-ratios as one of the indicators to estimate the hand function from the skeletal structure.


Assuntos
Mãos/anatomia & histologia , Mãos/fisiologia , Locomoção/fisiologia , Primatas/anatomia & histologia , Primatas/fisiologia , Animais , Atelinae/anatomia & histologia , Atelinae/fisiologia , Fenômenos Biomecânicos , Falanges dos Dedos da Mão/anatomia & histologia , Falanges dos Dedos da Mão/diagnóstico por imagem , Falanges dos Dedos da Mão/fisiologia , Análise de Elementos Finitos , Mãos/diagnóstico por imagem , Força da Mão/fisiologia , Humanos , Hylobates/anatomia & histologia , Hylobates/fisiologia , Imagem por Ressonância Magnética , Ossos Metacarpais/anatomia & histologia , Ossos Metacarpais/diagnóstico por imagem , Ossos Metacarpais/fisiologia , Fenômenos Fisiológicos Musculoesqueléticos , Sistema Musculoesquelético/anatomia & histologia , Papio hamadryas/anatomia & histologia , Papio hamadryas/fisiologia , Especificidade da Espécie , Tomografia Computadorizada por Raios X , Torque
2.
PLoS One ; 15(4): e0226789, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32240174

RESUMO

Exploration in reward-based motor learning is observable in experimental data as increased variability. In order to quantify exploration, we compare three methods for estimating other sources of variability: sensorimotor noise. We use a task in which participants could receive stochastic binary reward feedback following a target-directed weight shift. Participants first performed six baseline blocks without feedback, and next twenty blocks alternating with and without feedback. Variability was assessed based on trial-to-trial changes in movement endpoint. We estimated sensorimotor noise by the median squared trial-to-trial change in movement endpoint for trials in which no exploration is expected. We identified three types of such trials: trials in baseline blocks, trials in the blocks without feedback, and rewarded trials in the blocks with feedback. We estimated exploration by the median squared trial-to-trial change following non-rewarded trials minus sensorimotor noise. As expected, variability was larger following non-rewarded trials than following rewarded trials. This indicates that our reward-based weight-shifting task successfully induced exploration. Most importantly, our three estimates of sensorimotor noise differed: the estimate based on rewarded trials was significantly lower than the estimates based on the two types of trials without feedback. Consequently, the estimates of exploration also differed. We conclude that the quantification of exploration depends critically on the type of trials used to estimate sensorimotor noise. We recommend the use of variability following rewarded trials.


Assuntos
Aprendizagem/fisiologia , Atividade Motora/fisiologia , Desempenho Psicomotor/fisiologia , Adolescente , Adulto , Comportamento/fisiologia , Biorretroalimentação Psicológica , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Fenômenos Fisiológicos Musculoesqueléticos , Tempo de Reação/fisiologia , Projetos de Pesquisa , Recompensa , Distribuições Estatísticas , Adulto Jovem
3.
J Sports Sci ; 38(5): 568-575, 2020 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-32019482

RESUMO

This study aimed to assess the effect of playing surface (Natural [NT] and Artificial [AT] Turf) on the fatigue response to a soccer-specific exercise protocol (SSEP). Eighteen male soccer players completed the SSEP on NT and AT with pre-, post-, and 48 h post-assessments of eccentric knee flexor (eccKF) and concentric knee extensor peak torque (PT), peak countermovement (CMJ) and squat jump (SJ) height, and Nordic hamstring break angle. No significant main effects for surface or any surface and time interactions were observed for any of the outcome measures, except for eccKF PT recorded at 3.14 rad·s-1, which was significantly lower 48 h post-trial in the AT condition (AT = 146.3 ± 20.4 Nm; NT = 158.8 ± 24.7 Nm). Main effects for time were observed between pre- and post-trial measures for eccKF PT at all angular velocities, Nordic break angle, CMJ and SJ height. Nordic break angle, and both CMJ and SJ height were significantly impaired 48 h post-trial when compared to pre-trial. The findings of the current study suggest surface dependent changes in eccKF PT which may have implications for recovery and subsequent performance after competition on AT.


Assuntos
Planejamento Ambiental , Exercício Físico/fisiologia , Articulação do Joelho/fisiologia , Fadiga Muscular/fisiologia , Músculo Esquelético/fisiologia , Futebol/fisiologia , Adulto , Desempenho Atlético/fisiologia , Estudos Cross-Over , Músculos Isquiossurais/fisiologia , Humanos , Masculino , Fenômenos Fisiológicos Musculoesqueléticos , Desempenho Físico Funcional , Amplitude de Movimento Articular , Futebol/lesões , Torque , Adulto Jovem
4.
J Sports Sci ; 38(5): 534-541, 2020 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-31952463

RESUMO

This study examined the associations between socioeconomic status (SES) and musculoskeletal (MSF) and cardiorespiratory fitness (CRF) in youth.  The sample consisted of boys and girls between 3-15 years.  SES was categorized utilizing family-income-to-poverty ratio (FIPR).  All analyses were standardized for age and sex.  For each test of physical fitness, SES was used to estimate mean fitness test percentile and 95% confidence intervals, controlling for race/ethnicity and physical activity.  Odds ratios were calculated for the likelihood of having low fitness by SES category.  In general, the high SES group had a better composite MSF, body composition, and CRF profiles than low and moderate SES groups.  Statistically significant differences were identified for relative grip strength, plank, body mass index, and cardiovascular endurance time (all p < 0.05).  Additionally, the odds of low/poor MSF fitness were 1.7 and 1.6 times higher in the low and moderate SES groups (respectively) compared to the children from high SES families.  The moderate SES group had an odds of poor CRF 1.6 times higher than the high SES group as well.  Children and adolescents from high SES families tend to have higher mean fitness and were less likely to have low/poor fitness.


Assuntos
Aptidão Física , Classe Social , Adolescente , Composição Corporal , Aptidão Cardiorrespiratória , Criança , Pré-Escolar , Intervalos de Confiança , Exercício Físico , Feminino , Força da Mão , Humanos , Masculino , Fenômenos Fisiológicos Musculoesqueléticos , Inquéritos Nutricionais , Razão de Chances
5.
PLoS One ; 15(1): e0218977, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-31978115

RESUMO

Tying the hands behind the back has detrimental effects on sensorimotor perceptual tasks. Here we provide evidence that beta band oscillatory activity in a resting state condition might play a crucial role in such detrimental effects. EEG activity at rest was measured from thirty young participants (mean age = 24.03) in two different body posture conditions. In one condition participants were required to keep their hands freely resting on the table. In the other condition, participants' hands were tied behind their back. Increased beta power was observed in the left inferior frontal gyrus during the tied hands condition compared to the free hands condition. A control experiment ruled out alternative explanations for observed change in beta power, including muscle tension. Our findings provide new insights on how body postural manipulations impact on perceptual tasks and brain activity.


Assuntos
Encéfalo/fisiologia , Fenômenos Fisiológicos Musculoesqueléticos , Equilíbrio Postural/fisiologia , Córtex Sensório-Motor/fisiologia , Adulto , Mapeamento Encefálico , Eletroencefalografia , Feminino , Mãos/fisiologia , Humanos , Masculino , Contração Muscular/fisiologia , Descanso/fisiologia , Couro Cabeludo/fisiologia , Visão Ocular/fisiologia , Adulto Jovem
6.
PLoS One ; 14(12): e0225925, 2019.
Artigo em Inglês | MEDLINE | ID: mdl-31821334

RESUMO

The present study addresses how task constraints and aging influence isometric force control. We used two tasks requiring either force maintenance (straight line target force) or force modulation (sine-wave target force) around different force levels and at different modulation frequencies. Force levels were defined relative the individual maximum voluntary contraction. A group of young adults (mean age ± SD = 25 ± 3.6 years) and a group of elderly (mean age = 77 ± 6.4 years) took part in the study. Age- and task-related effects were assessed through differences in: (i) force control accuracy, (ii) time-structure of force fluctuations, and (iii) the contribution of deterministic (predictable) and stochastic (noise-like) dynamic components to the expressed behavior. Performance-wise, the elderly showed a pervasive lower accuracy and higher variability than the young participants. The analysis of fluctuations showed that the elderly produced force signals that were less complex than those of the young adults during the maintenance task, but the reverse was observed in the modulation task. Behavioral complexity results suggest a reduced adaptability to task-constraints with advanced age. Regarding the dynamics, we found comparable generating mechanisms in both age groups for both tasks and in all conditions, namely a fixed-point for force maintenance and a limit-cycle for force modulation. However, aging increased the stochasticity (noise-driven fluctuations) of force fluctuations in the cyclic force modulation, which could be related to the increased complexity found in elderly for this same task. To our knowledge this is the first time that these different perspectives to motor control are used simultaneously to characterize force control capacities. Our findings show their complementarity in revealing distinct aspects of sensorimotor adaptation to task constraints and age-related declines. Although further research is still needed to identify the physiological underpinnings, the used task and methodology are shown to have both fundamental and clinical applications.


Assuntos
Contração Isométrica , Fenômenos Fisiológicos Musculoesqueléticos , Adulto , Idoso , Algoritmos , Análise de Variância , Feminino , Humanos , Masculino , Modelos Biológicos , Adulto Jovem
8.
Arch. med. deporte ; 36(194): 376-385, nov.-dic. 2019. tab, graf
Artigo em Espanhol | IBECS | ID: ibc-187297

RESUMO

INTRODUCCIÓN: El aumento de la masa muscular es uno de los principales retos de los entrenadores deportivos, ya sea para optimizar el rendimiento, por razones estéticas o para la mejora de la salud. Por ello, el objetivo de este trabajo fue analizar los métodos de entrenamiento y aspectos nutricionales de mayor importancia para el aumento de la masa muscular. MATERIAL Y MÉTODO: Se realizó una búsqueda bibliográfica en las bases de datos PubMed y Google Scholar usando los siguien-tes términos: "hypertrophy", "skeletal muscle", "strength" y "training", y, por otro lado, "hypertrophy", "skeletal muscle" y "nutrition". RESULTADOS: Tras aplicar las estrategias de búsqueda, se obtuvieron un total de 322 artículos sobre métodos de entrenamiento y 269 respecto a estrategias nutricionales. Tras la lectura de título y resumen se eliminaron 238 y 212 artículos respectivamente. Finalmente, se seleccionaron 26 artículos sobre métodos de entrenamiento y 11 sobre estrategias nutricionales, los cuales cumplieron los criterios de inclusión, y fueron incluidos en esta revisión. CONCLUSIONES: Los resultados de este estudio sugieren la realización de un entrenamiento con cargas con las siguientes características: 3-5 series de 6-12 repeticiones realizadas en el rango de movimiento completo, con una intensidad cercana al fallo muscular (repeticiones en reserva de 0 a 2), con un volumen de entrenamiento semanal alto, y una frecuencia semanal de 3 días por grupo muscular, empleando varios ejercicios diferentes, combinando contracciones concéntricas y excéntricas, utilizando un foco atencional interno y con un descanso entre series de 2-3 minutos es el método más efectivo para el aumento de la masa muscular. Las estrategias nutricionales juegan un papel fundamental sobre el aumento de la masa muscular, siendo imprescindible un sobre aporte energético para que se produzca hipertrofia. Además, la ingesta de nutrientes como la proteína de suero de leche, la leucina y los ácidos grasos omega-3 favorecen la acreción proteica muscular


INTRODUCTION: The increase of the muscle mass is one of the main challenges of the athletic trainers, either to optimize the performance, for esthetical reasons or for the health improvement. Therefore, the aim of this study was to analyse the training methods and nutritional aspects for the increase of muscle mass. MATERIAL AND METHOD: A data search were conducted in PubMed and Google Scholar databases using the terms: "hypertro-phy", "skeletal muscle", "strength" and "training", on the other hand, "hypertrophy", "skeletal muscle" and "nutrition". RESULTS: After applying the search strategies, a total of 322 articles on training methods and 269 regarding nutritional strategies were obtained. After reading the title and abstract, 238 and 212 articles were eliminated, respectively. Finally, 26 articles on trai-ning methods and 11 on nutritional strategies were selected, which met the inclusion criteria and were included in this review. CONCLUSIONS: The results of this study suggest carrying out a training with external loads with the following characteristics: 3-5 series of 6-12 repetitions, with an intensity close to muscle failure (repetitions in reserve of 0 to 2), with a high weekly training volume, and a weekly frequency of 3 days per muscle group, at full range of several different exercises, combining concentric and eccentric contractions, using an internal attentional focus, and with a rest between sets of 2-3 minutes. The nutritional strategies play a fundamental role on the increase of the muscular mass, being essential a high energetic contribution so that hypertrophy occurs. In addition, the intake of nutrients such as whey protein, leucine and omega-3 fatty acids favour muscle protein accretion


Assuntos
Humanos , Exercício Físico/fisiologia , Treinamento de Resistência/métodos , Desenvolvimento Muscular/fisiologia , Força Muscular/fisiologia , Fenômenos Fisiológicos Musculoesqueléticos , Músculos/fisiologia
10.
Nat Commun ; 10(1): 4825, 2019 10 23.
Artigo em Inglês | MEDLINE | ID: mdl-31645555

RESUMO

Natural creatures, from fish and cephalopods to snakes and birds, combine neural control, sensory feedback and compliant mechanics to effectively operate across dynamic, uncertain environments. In order to facilitate the understanding of the biophysical mechanisms at play and to streamline their potential use in engineering applications, we present here a versatile numerical approach to the simulation of musculoskeletal architectures. It relies on the assembly of heterogenous, active and passive Cosserat rods into dynamic structures that model bones, tendons, ligaments, fibers and muscle connectivity. We demonstrate its utility in a range of problems involving biological and soft robotic scenarios across scales and environments: from the engineering of millimeter-long bio-hybrid robots to the synthesis and reconstruction of complex musculoskeletal systems. The versatility of this methodology offers a framework to aid forward and inverse bioengineering designs as well as fundamental discovery in the functioning of living organisms.


Assuntos
Bioengenharia , Simulação por Computador , Articulação do Cotovelo/fisiologia , Plumas/fisiologia , Fenômenos Fisiológicos Musculoesqueléticos , Asas de Animais/fisiologia , Animais , Osso e Ossos/fisiologia , Humanos , Ligamentos/fisiologia , Músculo Esquelético/fisiologia , Sistema Musculoesquelético , Amplitude de Movimento Articular/fisiologia , Robótica , Tendões/fisiologia
11.
PLoS Comput Biol ; 15(9): e1006883, 2019 09.
Artigo em Inglês | MEDLINE | ID: mdl-31487282

RESUMO

How muscles are used is a key to understanding the internal driving of fish swimming. However, the underlying mechanisms of some features of the muscle activation patterns and their differential appearance in different species are still obscure. In this study, we explain the muscle activation patterns by using 3D computational fluid dynamics models coupled to the motion of fish with prescribed deformation and examining the torque and power required along the fish body with two primary swimming modes. We find that the torque required by the hydrodynamic forces and body inertia exhibits a wave pattern that travels faster than the curvature wave in both anguilliform and carangiform swimmers, which can explain the traveling wave speeds of the muscle activations. Notably, intermittent negative power (i.e., power delivered by the fluid to the body) on the posterior part, along with a timely transfer of torque and energy by tendons, explains the decrease in the duration of muscle activation towards the tail. The torque contribution from the body elasticity further clarifies the wave speed increase or the reverse of the wave direction of the muscle activation on the posterior part of a carangiform swimmer. For anguilliform swimmers, the absence of the aforementioned changes in the muscle activation on the posterior part is consistent with our torque prediction and the absence of long tendons from experimental observations. These results provide novel insights into the functions of muscles and tendons as an integral part of the internal driving system, especially from an energy perspective, and they highlight the differences in the internal driving systems between the two primary swimming modes.


Assuntos
Peixes , Modelos Biológicos , Músculo Esquelético , Natação/fisiologia , Animais , Fenômenos Biomecânicos/fisiologia , Biologia Computacional , Simulação por Computador , Peixes/anatomia & histologia , Peixes/fisiologia , Músculo Esquelético/anatomia & histologia , Músculo Esquelético/fisiologia , Fenômenos Fisiológicos Musculoesqueléticos
12.
BMC Pregnancy Childbirth ; 19(1): 251, 2019 Jul 19.
Artigo em Inglês | MEDLINE | ID: mdl-31324160

RESUMO

BACKGROUND: The squatting birth position is widely used for "natural" birth or in countries where childbirth occurs in non-medical facilities. Squatting birth positions, like others, are roughly defined so a biomechanical assessment is required with the availability of noninvasive technology in pregnant women. In practice, we can observe spontaneously two kinds of squatting birth position: on tiptoes and with feet flat. OBJECTIVE: To compare the impact of foot posture on biomechanical parameters considered essential in obstetrical biomechanics during a squatting birth position: on tiptoes versus with feet flat on the floor. STUDY DESIGN: Thirteen pregnant women beyond 32 weeks of gestational age who were not in labor were assessed during squatting birth position firstly spontaneously and secondly with the foot posture that was not taken spontaneously (on the tiptoes vs with feet flat). For each position, ANGle of flexion on the spine of the plane of the pelvis external conjugate (ANGec), hip flexion and abduction, and lumbar curve were assessed using an optoelectronic motion capture system and a biomechanical model adapted from the conventional gait model as well as a measuring system of the lumbar curve. RESULTS: Spontaneously, 11 out of 13 women squatted on tiptoe at the first test. On tiptoes the hip flexion was lower than with feet flat (p < 0.02), whereas hip abduction was not significantly different (p = 0.28). A lower ANGec angle (p = 0.003) was noticed for the tiptoe position than feet flat. The lumbar curve (lordosis) was more marked for the squatting position on tiptoes than for the position with feet flat (p < 0.001). On tiptoes no woman had a pelvic inlet plane perpendicular to the spine and none had a flat back or kyphosis. No woman on tiptoes fulfilled the two conditions necessary for the position that we consider optimal. CONCLUSION: In squatting birth position, foot posture has a biomechanical impact on lumbar curve and pelvic orientation. When comparing squatting positions (on tiptoes vs feet flat), feet flat on the ground is closer to optimal birth conditions than on tiptoes.


Assuntos
Feto/fisiologia , Apresentação no Trabalho de Parto , Fenômenos Fisiológicos Musculoesqueléticos , Parto , Fenômenos Biomecânicos , Feminino , Humanos , Extremidade Inferior/fisiologia , Projetos Piloto , Postura , Gravidez , Diagnóstico Pré-Natal/métodos , Amplitude de Movimento Articular
13.
J Strength Cond Res ; 33(8): 2145-2152, 2019 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-31344011

RESUMO

Hintzy, F, Gregoire, N, Samozino, P, Chiementin, X, Bertucci, W, and Rossi, J. Effect of thigh-compression shorts on muscle activity and soft-tissue vibration during cycling. J Strength Cond Res 33(8): 2145-2152, 2019-This study examined the effects of different levels of thigh compression (0, 2, 6, and 15 mm Hg) in shorts on both vibration and muscle activity of the thigh during cycling with superimposed vibrations. Twelve healthy males performed a 18-minute rectangular cycling test per shorts condition (randomized cross-over design) on a specifically designed vibrating cycloergometer. Each test was composed of 2 intensity levels (moderate then high) and 3 vibration frequencies of 18.3, 22.4, and 26.3 Hz, corresponding to cadences of 70, 85, and 100 rpm, respectively. Muscle vibrations were measured with 2 triaxial accelerometers located before and on the lower-body compression garment, to quantify, respectively, the input and output vibrations, and vastus lateralis muscle activity was measured using surface electromyography. Both vibration and electromyography signals were measured throughout the tests and quantified using root-mean-square analyses. The study showed that the use of a thigh-compression shorts at 6-15 mm Hg significantly reduced both the vibration transmissibility to the thigh and the muscle activity, with higher effect size at higher superimposed vibrations. The thigh-compression shorts garment therefore seems to be 1 way to dampen vibrations transmitted to the cyclists and then to reduce the negative consequences of these vibrations on muscles.


Assuntos
Ciclismo/fisiologia , Bandagens Compressivas , Músculo Esquelético/fisiologia , Coxa da Perna/fisiologia , Vibração , Adulto , Eletromiografia , Humanos , Masculino , Fenômenos Fisiológicos Musculoesqueléticos , Modalidades de Fisioterapia , Músculo Quadríceps/fisiologia , Adulto Jovem
14.
PLoS One ; 14(7): e0218959, 2019.
Artigo em Inglês | MEDLINE | ID: mdl-31287814

RESUMO

Lunge motion is one of the fundamental attacks used in modern fencing, asking for a high level of coordination, speed and accuracy to be efficient. The aim of the current paper was the assessment of fencer's performance and response time in lunge attacks under uncertain conditions. For this study, an innovative fencing lunge simulator was designed. The performance of 11 regional to national-level fencers performing lunges in Fixed, Moving and Uncertain conditions was assessed. The results highlighted notably that i) Accuracy and success decreased significantly in Moving and Uncertain conditions with regard to Fixed ones ii) Movement and Reaction times were also affected by the experimental conditions iii) Different fencer profiles were distinguishable among subjects. In conclusion, the hypothesis that fencers may privilege an adaptation to the attack conditions and preserve accuracy instead of privileging quickness was supported by the results. Such simulators may be further used to analyze in more detail the motor control strategies of fencers through the measure and processing of biomechanical quantities and a wider range of fencing levels. It has also a great potential to be used as training device to improve fencer's performance to adapt his attack to controlled opponent's motion.


Assuntos
Movimento/fisiologia , Fenômenos Fisiológicos Musculoesqueléticos , Tempo de Reação/fisiologia , Esportes/fisiologia , Braço/fisiologia , Fenômenos Biomecânicos/fisiologia , Peso Corporal , Feminino , Humanos , Luz , Masculino , Desempenho Psicomotor/fisiologia , Software
15.
Int J Mol Sci ; 20(12)2019 Jun 24.
Artigo em Inglês | MEDLINE | ID: mdl-31238505

RESUMO

The relation between the force (load) and the velocity of shortening (V) in contracting skeletal muscle is part of a rectangular hyperbola: (P + a) V = b(Po - P); where Po is the maximum isometric force and a and b are constants. The force-velocity (P-V) relation suggests that muscle can regulate its energy output depending on the load imposed on it (Hill, 1938). After the establishment of the sliding filament mechanism (H.E. Huxley and Hanson, 1954), the P-V relation has been regarded to reflect the cyclic interaction between myosin heads in myosin filaments and the corresponding myosin-binding sites in actin filaments, coupled with ATP hydrolysis (A.F. Huxley, 1957). In single skeletal muscle fibers, however, the P-V relation deviates from the hyperbola at the high force region, indicating complicated characteristics of the cyclic actin-myosin interaction. To correlate the P-V relation with kinetics of actin-myosin interaction, skinned muscle fibers have been developed, in which the surface membrane is removed to control chemical and ionic conditions around the 3D lattice of actin and myosin filaments. This article also deals with experimental methods with which the structural instability of skinned fibers can be overcome by applying parabolic decreases in fiber length.


Assuntos
Contração Muscular/fisiologia , Fibras Musculares Esqueléticas/fisiologia , Músculo Esquelético/fisiologia , Animais , Humanos , Contração Isotônica , Cinética , Modelos Biológicos , Fibras Musculares Esqueléticas/ultraestrutura , Proteínas Musculares/química , Proteínas Musculares/metabolismo , Força Muscular , Músculo Esquelético/ultraestrutura , Fenômenos Fisiológicos Musculoesqueléticos , Miosinas/química , Miosinas/metabolismo , Relação Estrutura-Atividade
16.
J Orthop Res ; 37(10): 2231-2240, 2019 10.
Artigo em Inglês | MEDLINE | ID: mdl-31206865

RESUMO

Multi-segment foot models (MFMs) are becoming a common tool in musculoskeletal research on the ankle-foot complex. The purpose of this study was to compare ankle joint kinematics as well as ligament and muscle strains that result from MFM with a different number of segments during vertical hopping. Ten participants were recruited and performed double-limb vertical hops. Marker positions and ground reaction forces were collected. Two-segment (2MFM), three-segment (3MFM), and five-segment MFM (5MFM) were used to calculate ankle kinematics and the strains of the anterior talofibular and calcaneofibular ligaments and of the soleus and gastrocnemius muscles. Ranges of motion and peak strains were analyzed with Kruskal-Wallis and post hoc tests, whereas the time-series of the ankle kinematics and ligament and muscle strains were analyzed with statistical parametric mapping. There were significant main effects for MFM in the talocrural joint range of motion and peak strains of ligaments and muscles. In addition, there were significant main effects for MFM in time-series data of the talocrural joint angle as well as for ligament and muscle strains. In all cases, the post hoc analyses showed that the 2MFM consistently overestimated the range of motion and tissue strains compared to the 3MFM and 5MFM, while 3MFM and 5MFM did not differ from each other in the most variables. This study showed that the number of segments in MFM significantly affects the biomechanical estimates of joint kinematics and tissue strains during hopping. Clinical significance: MFM that combine all foot structures beyond the talus into one segment likely overestimate ankle joint biomechanics. © 2019 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 37:2231-2240, 2019.


Assuntos
Articulação do Tornozelo/fisiologia , Pé/fisiologia , Ligamentos Articulares/fisiologia , Modelos Biológicos , Músculo Esquelético/fisiologia , Fenômenos Biomecânicos , Fenômenos Fisiológicos Musculoesqueléticos
17.
PLoS One ; 14(6): e0217690, 2019.
Artigo em Inglês | MEDLINE | ID: mdl-31194764

RESUMO

INTRODUCTION: Long-term head-down bed rest (HDBR) results in musculoskeletal losses similar to those observed during long-term space flight. Agents such as testosterone, in addition to regular exercise, are effective countermeasures for reducing loss of skeletal muscle mass and function. OBJECTIVE: We investigated the skeletal muscle proteome of healthy men in response to long term HDBR alone (CON) and to HDBR with exercise (PEX) or exercise plus testosterone (TEX) countermeasures. METHOD: Biopsies were performed on the vastus lateralis before (pre) HDBR and on HDBR days 32 (mid) and 64 (post). Extracted proteins from these skeletal muscle biopsies were subjected to 2-dimensional gel electrophoresis (2DE), stained for phosphoproteins (Pro-Q Diamond dye) and total proteins (Sypro Ruby dye). Proteins showing significant fold differences (t-test p ≤ 0.05) in abundance or phosphorylation state at mid or post were identified by mass spectroscopy (MS). RESULTS: From a total of 932 protein spots, 130 spots were identified as potentially altered in terms of total protein or phosphoprotein levels due to HDBR and/or countermeasures, and 59 unique molecules emerged from MS analysis. Top canonical pathways identified through IPA included calcium signaling, actin cytoskeleton signaling, integrin linked kinase (ILK) signaling, and epithelial adherens junction signaling. Data from the pre-HDBR proteome supported the potential for predicting physiological post-HDBR responses such as the individual's potential for loss vs. maintenance of muscle mass and strength. CONCLUSIONS: HDBR resulted in alterations to skeletal muscle abundances and phosphorylation of several structural and metabolic proteins. Inclusion of exercise alone or in combination with testosterone treatment modulated the proteomic responses towards cellular reorganization and hypertrophy, respectively. Finally, the baseline proteome may aid in the development of personalized countermeasures to mitigate health risks in astronauts as related to loss of muscle mass and function.


Assuntos
Repouso em Cama/efeitos adversos , Decúbito Inclinado com Rebaixamento da Cabeça/efeitos adversos , Músculo Esquelético/fisiopatologia , Adulto , Atrofia/tratamento farmacológico , Exercício Físico/fisiologia , Terapia por Exercício/métodos , Decúbito Inclinado com Rebaixamento da Cabeça/fisiologia , Voluntários Saudáveis , Humanos , Masculino , Fenômenos Fisiológicos Musculoesqueléticos/efeitos dos fármacos , Proteômica/métodos , Músculo Quadríceps/metabolismo , Testosterona/uso terapêutico , Simulação de Ausência de Peso
18.
IEEE Trans Neural Syst Rehabil Eng ; 27(7): 1426-1435, 2019 07.
Artigo em Inglês | MEDLINE | ID: mdl-31199264

RESUMO

Predictive simulation based on dynamic optimization using musculoskeletal models is a powerful approach for studying human gait. Predictive musculoskeletal simulation may be used for a variety of applications from designing assistive devices to testing theories of motor control. However, the underlying cost function for the predictive optimization is unknown and is generally assumed a priori. Alternatively, the underlying cost function can be determined from among a family of possible cost functions, representing an inverse optimal control problem that may be solved using a bilevel optimization approach. In this study, a nested evolutionary approach is proposed to solve the bilevel optimization problem. The lower level optimization is solved by a direct collocation method, and the upper level is solved by a genetic algorithm. We demonstrate our approach to solve different bilevel optimization problems, including finding the weights among three common performance criteria in the cost function for normal human walking. The proposed approach was found to be effective at solving the bilevel optimization problems. This approach should provide practical utility in designing assistive devices to aid mobility, and could yield insights about the control of human walking.


Assuntos
Metabolismo Energético/fisiologia , Marcha/fisiologia , Adulto , Algoritmos , Fenômenos Biomecânicos , Simulação por Computador , Desenho de Equipamento , Feminino , Humanos , Masculino , Modelos Biológicos , Músculo Esquelético/fisiologia , Fenômenos Fisiológicos Musculoesqueléticos , Equipamentos de Autoajuda , Caminhada , Adulto Jovem
19.
Neurol India ; 67(Supplement): S176-S181, 2019.
Artigo em Inglês | MEDLINE | ID: mdl-31134907

RESUMO

This article reviews current challenges to health in space and has a secondary intention to set the tone for this special supplement on 'Extra-Terrestrial Neurosciences'. The effects of microgravity, radiation, isolation, disturbance in circadian rhythms and the hostile environment on the cardiovascular, neurological, immunological and various biological human systems are discussed here. Alterations in physiology, environmental hazards, and mitigative safety measures are briefly discussed along with challenges encountered in providing remote diagnoses and health care during space missions.


Assuntos
Meio Ambiente Extraterreno , Neurologia/tendências , Voo Espacial , Astronautas , Encéfalo/fisiologia , Humanos , Índia , Fenômenos Fisiológicos Musculoesqueléticos , Ausência de Peso
20.
PLoS One ; 14(5): e0216663, 2019.
Artigo em Inglês | MEDLINE | ID: mdl-31071162

RESUMO

Head collisions in sport can result in catastrophic injuries to the cervical spine. Musculoskeletal modelling can help analyse the relationship between motion, external forces and internal loads that lead to injury. However, impact specific musculoskeletal models are lacking as current viscoelastic values used to describe cervical spine joint dynamics have been obtained from unrepresentative quasi-static or static experiments. The aim of this study was to develop and validate a cervical spine musculoskeletal model for use in axial impacts. Cervical spine specimens (C2-C6) were tested under measured sub-catastrophic loads and the resulting 3D motion of the vertebrae was measured. Specimen specific musculoskeletal models were then created and used to estimate the axial and shear viscoelastic (stiffness and damping) properties of the joints through an optimisation algorithm that minimised tracking errors between measured and simulated kinematics. A five-fold cross validation and a Monte Carlo sensitivity analysis were conducted to assess the performance of the newly estimated parameters. The impact-specific parameters were integrated in a population specific musculoskeletal model and used to assess cervical spine loads measured from Rugby union impacts compared to available models. Results of the optimisation showed a larger increase of axial joint stiffness compared to axial damping and shear viscoelastic parameters for all models. The sensitivity analysis revealed that lower values of axial stiffness and shear damping reduced the models performance considerably compared to other degrees of freedom. The impact-specific parameters integrated in the population specific model estimated more appropriate joint displacements for axial head impacts compared to available models and are therefore more suited for injury mechanism analysis.


Assuntos
Vértebras Cervicais/lesões , Modelos Biológicos , Traumatismos da Coluna Vertebral/fisiopatologia , Algoritmos , Animais , Fenômenos Biomecânicos , Vértebras Cervicais/diagnóstico por imagem , Vértebras Cervicais/fisiopatologia , Simulação por Computador , Elasticidade , Futebol Americano/lesões , Futebol Americano/fisiologia , Humanos , Imageamento Tridimensional , Técnicas In Vitro , Masculino , Modelos Animais , Fenômenos Fisiológicos Musculoesqueléticos , Traumatismos da Coluna Vertebral/diagnóstico por imagem , Traumatismos da Coluna Vertebral/etiologia , Sus scrofa , Viscosidade , Microtomografia por Raio-X
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