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The hands are anatomically specialized for manipulative tasks with different physical objects, where they can cope with certain loads with different forces and intensity. During various physical and sports activities, the hands produce the appropriate muscular force for gripping, which manifests as the hand grip's force. For this reason, hand grip strength (HGS) is recognized as a limiting factor in all manipulative activities performed by the cranial part of the body. The current research included a sample of 22 subjects, 16 male Body Height (BH=180.28±4.65cm); Body Weight (BW=80.05±9.96kg), Body Mass Index (BMI=24.61±2.74kg/m²) and 6 female subjects Body Height (BH=167.42±11.11cm); Body Weight (BW=64.80±10.09kg); Body Mass Index (BMI=23.02±1.57kg/m²) on the third year of study at the Faculty of Physical Education and Sports. This study aimed to determine the maximum isometric muscle force of the handgrip and differences between the same gender of students. A t-test for small samples was applied for data processing, and the relevant statistical parameters were calculated. The obtained t-test results confirmed statistically significant differences between the so-called dominant and non-dominant hands in male subjects (t=4.158; p

Purpose There is growing evidence that vertebral column function and dysfunction play a vital role in neuromuscular control. This invited review summarises the evidence about how vertebral column dysfunction, known as a central segmental motor control (CSMC) problem, alters neuromuscular function and how spinal adjustments (high-velocity, low-amplitude or HVLA thrusts directed at a CSMC problem) and spinal manipulation (HVLA thrusts directed at segments of the vertebral column that may not have clinical indicators of a CSMC problem) alters neuromuscular function. Methods The current review elucidates the peripheral mechanisms by which CSMC problems, the spinal adjustment or spinal manipulation alter the afferent input from the paravertebral tissues. It summarises the contemporary model that provides a biologically plausible explanation for CSMC problems, the manipulable spinal lesion. This review also summarises the contemporary, biologically plausible understanding about how spinal adjustments enable more efficient production of muscular force. The evidence showing how spinal dysfunction, spinal manipulation and spinal adjustments alter central multimodal integration and motor control centres will be covered in a second invited review. Results Many studies have shown spinal adjustments increase voluntary force and prevent fatigue, which mainly occurs due to altered supraspinal excitability and multimodal integration. The literature suggests physical injury, pain, inflammation, and acute or chronic physiological or psychological stress can alter the vertebral column’s central neural motor control, leading to a CSMC problem. The many gaps in the literature have been identified, along with suggestions for future studies. Conclusion Spinal adjustments of CSMC problems impact motor control in a variety of ways. These include increasing muscle force and preventing fatigue. These changes in neuromuscular function most likely occur due to changes in supraspinal excitability. The current contemporary model of the CSMC problem, and our understanding of the mechanisms of spinal adjustments, provide a biologically plausible explanation for how the vertebral column’s central neural motor control can dysfunction, can lead to a self-perpetuating central segmental motor control problem, and how HVLA spinal adjustments can improve neuromuscular function.

Os hemangioblastomas do Sistema Nervoso Central (SNC) são tumores benignos raros, classificados como grau I pela Organização Mundial da Saúde. São bastante vascularizados e correspondem de 1 a 2% dos tumores primários do SNC. A tomografia computadorizada, ressonância magnética (RM) e angiografia são utilizadas no diagnóstico, sendo esta última principalmente indicada quando evidenciada ao exame de neuroimagem a lesão vascularizada. No presente relato, descrevemos o caso de uma mulher de 68 anos com quadro de dorsalgia, perda de força muscular progressiva grau III no membro inferior direito e grau II no membro inferior esquerdo, nível sensitivo em T8. À RM da coluna vertebral sugeriu como hipótese imagem compatível com meningioma. Realizado tratamento cirúrgico, no qual ficou documentada, durante a abordagem, a lesão puramente extradural e posteriormente comprovada ao exame histopatológico, verificou-se tratar de um hemangioblastoma. O pós-operatório apresentou boa evolução clínica.

The aim of the present study was to determine whether depression of maximal muscular force and neural drive subsequent to prolonged ( ≥ 60 s) passive muscle stretching is associated with altered corticospinal excitability or intracortical (GABAFourteen healthy adult males were tested before and after 5 min (5 × 60-s stretches) of intense, passive static stretching of the plantar flexor muscles. Two protocols (A and B) were conducted in a randomized order. Transcranial magnetic stimulation was delivered to the contralateral motor cortex at rest (Protocol A) and during maximal voluntary contractions (Protocol B). Changes in maximal voluntary isometric torque, voluntary surface electromyographic activity of triceps surae muscles (normalized to M-wave; EMG/M), motor-evoked potentials (MEP), and cortical silent period (cSP; Protocol B) in soleus elicited by transcranial magnetic stimulation were examined 10 min after stretch.In both protocols A and B, significant decreases were observed immediately after stretching in maximal voluntary plantar flexion torque ( - 20.1 ± 15.9%, P = 0.004; and - 17.2 ± 13.5%, P = 0.006) and EMG/M ( - 18.0 ± 18.2%, P = 0.023; and - 13.0 ± 9.3%, P = 0.003). Decreases in torque and EMG/M were highly correlated (r = 0.67-0.85, P 0.05). However, no changes were observed in MEP amplitudes during rest ( + 29.3 ± 50.0%) or maximum voluntary contraction ( + 1.9 ± 16.8%), or in cSP ( + 2.1 ± 15.1%).Impaired neural drive contributed to the stretch-induced force loss; however, changes in corticospinal excitability and intracortical inhibition could not explain the phenomenon.

Delayed-onset muscle soreness (DOMS) describes an entity of ultrastructural muscle damage. The manifestation of DOMS is caused by eccentric muscle contractions or unaccustomed forms of exercise. Clinical signs include impaired muscular force capacities, painful restriction of movement, stiffness, swelling, and altered biomechanics in adjacent joints. Although DOMS is categorised as a mild type of muscle damage, it is one of the most common reasons for compromised sportive performance. In the last decade, many hypotheses have been developed to explain the aetiology of DOMS, and there are a wide range of different interventions aiming to prevent or alleviate the symptoms. Many studies have evaluated various types of cold or heat therapy, compression, massage, physical therapy or nutritional interventions. Treatment considerations focus on the primary prevention of ultrastructural lesions during exercise, the treatment of the inflammatory response that leads to DOMS, and recovery strategies for manifest DOMS. This narrative review aims to present an overview of the current treatment and preventive strategies in the field of DOMS.Die Delayed Onset Muscle-Soreness (DOMS) oder auch „verzögert einsetzender Muskelkater" wird zu den ultrastrukturellen Muskelschädigungen gezählt. Als ursächlich werden vorausgegangene exzentrische Kontraktionsformen oder ungewohnte Muskelbelastungen angesehen. Klinische Symptome imponieren in Form einer reduzierten Kraftentfaltung, schmerzhafter Bewegungseinschränkungen, einer Erhöhung des Muskeltonus, Schwellungen sowie Funktionseinschränkungen angrenzender Gelenke. Obwohl die DOMS den milden Schädigungsformen zugeordnet wird, hat sie aufgrund der leistungseinschränkenden Auswirkungen eine große Bedeutung – insbesondere für den Leistungssport. Zur Behandlung und Prävention dieser Muskelverletzung ist bislang ein großes Spektrum an interventionellen Verfahren beschrieben worden. Gegenstand vieler Studien sind verschiedene Wärme- oder Kälteanwendungen, Kompressionstherapien, Massagen, physikalische Therapieformen oder Ernährungsinterventionen. Interventionelle Ansätze haben das Ziel, die Entstehung von ursächlichen Ultrastrukturschäden zu verhindern, die Inflammationsantwort zu limitieren oder eine Symptomlinderung und Regenerationsförderung im Falle einer manifesten DOMS zu erreichen. Die vorliegende Arbeit hat das Ziel, aktuelle Therapieverfahren und Präventionsstrategien zu beleuchten.

Objective. Passivity of the diaphragm during prolonged mechanical ventilation can lead to ventilation-induced diaphragmatic dysfunction reasoned by a reduction of diaphragmatic muscle strength. Electrical stimulation may be utilised to modulate diaphragm muscle strength. Therefore we intended to investigate diaphragmatic muscle strength based on stimulation with electric impulses. Approach. Diaphragms of Wistar rats were excised, embedded in various incubation solutions and placed in a diaphragm force measurement device. Pressure amplitudes generated by the diaphragm in dependency of the embedding solution, stimulation frequency and time (360 min) were determined. Furthermore, the diaphragms were histologically evaluated. Main results. The ex vivo diaphragms evoked no pressure if embedded in incubation solutions with high potassium concentrations and up to >20 cmH2O if embedded in incubation solutions with extracellular potassium concentrations. Although vitality was well maintained after 360 min (78%) cultivation, the diaphragm’s force dropped by 90.8% after 240 min. The decline in the diaphragm’s force progressed faster if stimulation was performed every 20 min compared to every 120 min. The size of Type I muscle fibres was largest in diaphragms stimulated every 120 min. The fibre size of Type 2b/x muscle cells was lower in diaphragms after electrical stimulation compared to non-stimulated diaphragms. Significance. The force that the diaphragm can develop in ex vivo conditions depends on the incubation solution and the conditions of activation. Activity-related changes in the diaphragm’s muscular force are accompanied by specific changes in muscle fibre size.

The study of falling, especially for the elderly, is a very critical problem in geriatric care and medicine. This study investigated the potential role of a surface-based electromyography (sEMG) and inertial measurement unit (IMU) sensor package for analyzing and detecting humans falling. Previous studies have only relied on motion sensors only, such as accelerometers and gyroscopes, detecting falling, which completely ignores the muscular force reaction of extremities during the precise moment before a person actually falls. This experiments conducted in this study show promising results of combining the sEMG and accelerometer signals to describe the muscular activity generated as the reflex reaction of the subjects in their arms as they grab onto something to prevent the fall. Further simulations of falling were conducted at a foam pit, specifically deliberate falling and surprised falling. Similar findings were obtained in this scenario where the subjects did not have anything to grab onto upon falling, which cancan be attributed to the fact that the subjects feel the same sensation of reflex and panic whether deliberately falling or surprised falling.

Assembly workers within for example the motor vehicle industry, are subject to physically demanding work tasks. One common type of load exposure for assembly workers, are reaction forces generated by tightening tools, such as nutrunners. The tool users counteract these forces through repetitive muscular force exertions, which in the long-term can pave the way for musculoskeletal disorders. As with other well-acknowledged load exposures commonly occurring in the assembly line environment, such as vibrations from tools, or adverse postures, reaction loads generated by nutrunners need thoroughly founded recommendations regarding acceptable exposure, in order to enable sustainable physical workloads for the tool users. The aim of this study was to lay a foundation for such recommendations. An experimental study was carried out in a simulated workstation, where assembly workers performed tightenings with an electric angle nutrunner, at different tool settings, joint stiffnesses and work-paces. Through a psychophysical approach, the participants judged the maximum amount of reaction load exposure which they perceived would enable a sustainable workload. The highly dynamic tool setting resulted in the highest chosen tightening torque levels, i.e. 35.0 and 37.7 Nm at five and eight tightenings per minute, respectively. This corresponded to a peak reaction force exposure of 71.6 and 69.8 N, respectively. Despite the statistically significant differences in impulse between the highly dynamic tightenings on hard joints and continuous drive tightenings on medium joints, no statistically significant difference between the chosen torque levels was found, suggesting that additional factors may contribute to the experience of reaction load exposure.

Extreme workplace heat exposures create eminent threats like heat stroke, and it confines the laborers’ aptitude to withstand physical activity. Cumulative heat waves predominantly in urban areas where construction work is more extensive. There is confined proof displayed on how these impacts reduce work efficiency; however, the quantitative relationship between heat stress and work efficiency is a crucial foundation for climate change impression evaluations. 124 male laborers from different construction sites of West Bengal were indiscriminately taken for this study. This investigation means to outline the impacts of heat stress and its impact on cardiac jeopardy among the construction laborers. This study consisted of HOTHAPS questionnaire study, environmental measurements of heat stress exposure in workplace surroundings, and different cardiac load assessment parameters like working and partial recovery heart rate, maximum heart rate, average working heart rate, maximum working heart rate, sum of recovery heart rate, percentage of recovery, percentage of recovery cardiac cost and net cardiac cost, etc., which were studied by using heart rate monitor. The study findings suggest that there are voluminous heat-allied symptoms in summer months. Most laborers reported exhaustion and pain during work on hot days. Heart rate recovered quickly at low heat, but more slowly at high heat, demonstrating cardiac jeopardy. From the study, it could be resolved that the construction-related jobs are exceptionally strenuous especially in hot environmental circumstances. It used to require extreme muscular force, which can upturn the cardiac burden.

Peak knee valgus has been shown to predict anterior cruciate ligament injury. The purpose of the current study was to compare peak rate of torque development (RTD) to peak isometric torque as a predictor of peak knee valgus during landing. Twenty-three healthy females participated. Hip abductor muscle performance was quantified using 2 types of isometric contractions: sustained and rapid. Peak isometric torque was calculated from the sustained isometric contraction. Peak RTD was calculated from the rapid isometric contraction (0–50 and 0–200 ms after force initiation). Kinematic data were collected during the deceleration phase of a double-leg drop jump task. Linear regression was used to assess the ability of hip abductor muscle performance variables to predict peak knee valgus. Increased peak RTD during the 0 to 50 milliseconds window after force initiation was found to significantly predict lower peak knee valgus (P = .011, R2 = .32). In contrast, neither peak RTD from 0 to 200 milliseconds after force initiation window (P = .45, R2 = .03) nor peak isometric torque (P = .49, R2 = .03) predicted peak knee valgus. The inability of the hip abductors to rapidly generate muscular force may be more indicative of “at-risk” movement behavior in females than measures of maximum strength.

Increasing muscular force occurs when motor units, comprised of the spinal motor neuron and innervating muscle fibers, increase firing rates, or when the number of motor units recruited within that muscle increases[1] [2]. It is known that the recruitment limb of increasing linear force generation can elicit nonlinear firing rate patterns, and that the firing rate at the point of recruitment of motor units is higher than the firing rate at de-recruitment.[3] To the best of our knowledge, the de-recruitment limb firing rates during decreasing torque generation have yet to be characterized. We sought to test whether over the course of a linearly increasing and decreasing torque generation, we would observe similar and linear behavior of firing rates. High density surface EMG (HD-EMG) recordings of a human subject were decomposed into motor units during contractions using blind source separation. 13 subjects were analyzed over 10s triangular torque contractions. Slopes of firing rates vs time over the course of isometric triangular torque generation were generated using a bilinear fit for both the recruitment and de-recruitment limbs. Residuals of raw firing rates for the lines of best fit before and after the breakpoint were calculated. Linear increases and decreases in torque are accompanied by nonlinear increases and decreases in firing rates. These results suggest important characteristic intrinsic mechanisms to the sustained and released firing activity of motor neurons.

Coaches and athletes in elite sports are constantly seeking to use innovative and advanced training strategies to efficiently improve strength/power performance in already highly-trained individuals. In this regard, high-intensity conditioning contractions have become a popular means to induce acute improvements primarily in muscle contractile properties, which are supposed to translate to subsequent power performances. This performance-enhancing physiological mechanism has previously been called postactivation potentiation (PAP). However, in contrast to the traditional mechanistic understanding of PAP that is based on electrically-evoked twitch properties, an increasing number of studies used the term PAP while referring to acute performance enhancements, even if physiological measures of PAP were not directly assessed. In this current opinion article, we compare the two main approaches (i.e., mechanistic vs. performance) used in the literature to describe PAP effects. We additionally discuss potential misconceptions in the general use of the term PAP. Studies showed that mechanistic and performance-related PAP approaches have different characteristics in terms of the applied research field (basic vs. applied), effective conditioning contractions (e.g., stimulated vs. voluntary), verification (lab-based vs. field tests), effects (twitch peak force vs. maximal voluntary strength), occurrence (consistent vs. inconsistent), and time course (largest effect immediately after vs. ~ 7 min after the conditioning contraction). Moreover, cross-sectional studies revealed inconsistent and trivial-to-large-sized associations between selected measures of mechanistic (e.g., twitch peak force) vs. performance-related PAP approaches (e.g., jump height). In an attempt to avoid misconceptions related to the two different PAP approaches, we propose to use two different terms. Postactivation potentiation should only be used to indicate the increase in muscular force/torque production during an electrically-evoked twitch. In contrast, postactivation performance enhancement (PAPE) should be used to refer to the enhancement of measures of maximal strength, power, and speed following conditioning contractions. The implementation of this terminology would help to better differentiate between mechanistic and performance-related PAP approaches. This is important from a physiological point of view, but also when it comes to aggregating findings from PAP studies, e.g., in the form of meta-analyses, and translating these findings to the field of strength and conditioning.

International audience; In biomechanics recent mathematical models allow to predict the muscular force response to functional electrical stimulations (in short, FES).The main concern of the present paper is to deal with the computation of optimized electrical pulses trains (for example in view of maximizing the final force response). Using the fact that FES are modeled as Dirac pulses, our problem is rewritten as an optimal sampled-data control problem where the control parameters are the pulses amplitudes and the pulses times. We establish the corresponding Pontryagin first-order necessary optimality conditionsand we show how they can be used in view of numerical simulations.

The agricultural industry in Thailand and many Southeast Asian countries relies heavily on manual labor with little utilization of advanced machinery. Prior investigation of the rice cultivation process indicated a high prevalence of musculoskeletal disorders and abnormal alignments in lower extremities (LEs) of Thai farmers. Since most tasks are typically performed with bare feet in heavy, muddy terrain, higher LE muscular force is required to compensate for mud viscosity. Consequently, this study investigated effects of muddy terrain on LEs of 30 experienced famers during simulated planting tasks of the rice cultivation process. Muscle activity and discomfort perception of LE joints were compared between rigid (“No-Force”) and muddy (“Mud-Force”) surface conditions, revealing significantly increased muscle activity and discomfort perception of knee and ankle in muddy work environments. The resulting high risk of knee and ankle injury for rice farmers should therefore be attenuated by development of appropriate protective equipment or assistive devices. Relevance to industry The working surface constitutes a physical workplace environments with potential direct impact on productivity and safety of the workforce. In the agricultural industry, workers typically perform tasks on muddy terrain where, besides common slips, trips and falls, mud viscosity might intensify the force and lead to potential injury to the lower limbs.

During eccentric contractions, muscular force production capacity is enhanced compared to isometric contractions. Although this is well accepted in terms of muscle mechanics, maximal voluntary eccentric contractions are associated with neural inhibition that prevents increased force production of in vivo human muscles. However, because it was shown that maximal voluntary eccentric forces can exceed maximum isometric forces by a factor of 1.2–1.4, this review focuses on the question of whether the absent eccentric force enhancement, as observed in many studies, can unambiguously be attributed to an inherent neural inhibition. First, we demonstrate that participant familiarization, preload, and fascicle behavior are crucial factors influencing maximal voluntary eccentric force production. Second, we show that muscle mechanics such as muscle length, lengthening velocity, and stretch amplitude interact when it comes to maximal voluntary eccentric force production. Finally, we discuss the diverging findings on neural inhibition during maximal voluntary eccentric contractions. Because there was no inhibition of the major motor pathways in the presence of enhanced maximal voluntary eccentric forces, further research is needed to test the concept of neural inhibition and to understand why maximal voluntary force production is reduced compared to the force capacity of isolated muscle preparations. Keywords: Active lengthening, Eccentric contraction, Inhibition, Muscle, Neural control

Every sport requires specific physical capacities to enable success and minimise injury risk. For instance, a competitive runner requires adequate muscular force production to counter ground reaction forces for a single step at a given speed ( local tissue capacity), and the muscular and cardiovascular endurance to tolerate the accumulation of steps for the time and distance of the event ( sport-specific capacity). Failing to adequately develop these physical qualities may result in underperformance and/or increased injury risk. In this editorial we explore how to optimally monitor and progress training loads to improve local tissue and sport-specific capacity. When referring to load capacity, sport-specific capacity is defined as the athlete’s ability to perform (and withstand) the demands of training and competition, whereas local tissue capacity is defined as a specific structure’s ability to withstand tissue-specific cumulative load.1 In healthy athletes, training load quantification focuses on the athlete’s sport-specific capacity and not on one’s specific local tissue capacity. Progressively applied sport-specific training load improves an athlete’s physical capacities (eg, strength, power and endurance) and performance.2 Conversely, injury risk increases if training loads grossly exceed the athlete’s current local tissue capacity.3 Thus, increasing local tissue capacity as a component of the training cycle can decrease injury risk. Loading for healthy athletes is designed to improve sport-specific …

espanolLa sarcopenia hace referencia a la disminucion de la masa y fuerza muscular relacionada con los mecanismos del envejecimiento y genera un compromiso funcional de alto costo, por lo tanto la presente revision describe su tratamiento actual. Metodologia de busqueda: se realizo una busqueda bibliografica en las bases de datos Pubmed, Cochrane, LILACS, SciELO y el motor de busqueda Google Scholar, seleccionandose 140 articulos para revision de los cuales 48 articulos originales y 50 revisiones fueron referenciados. Discusion: como tratamiento en las personas de edad, se recomienda la ingesta de al menos 1,2 g/kg de proteina al dia, acompanada de un aporte suficiente de micronutrientes y ocasionalmente de suplementos proteicos. Los programas de entrenamiento de fuerza en personas mayores es actualmente un metodo util para la misma. El uso de farmacos debe ser evaluado individualmente. Conclusiones: la adecuada alimentacion y el ejercicio de resistencia constituyen los pilares fundamentales del tratamiento y prevencion de la sarcopenia. MED.UIS. 2017;30(2):71-81. EnglishThe sarcopenia makes reference to the mass and muscular force’s decrease related with the mechanisms of the aging and generates a functional commitment of high cost, therefore the present revision describes its current treatment. Methodology: a bibliographic search was carried out in Pubmed, Cochrane, LILACS, SciELO and Google Scholar databases, selecting 140 articles to be reviewed of which 48 original articles and 50 reviews were referenced. Discussion: as a treatment for sarcopenia in elderly population, it is recommended to take at least 1.2 g/kg of protein per day, accompanied by a sufficient supply of micronutrients and occasional protein supplements. Strength training programs in older people is currently a useful method to combat this condition. The use of drugs should be evaluated individually. Conclusions: to prevent and treat sarcopenia, adequate nutrition and resistance exercise are the main pillars of treatment. MED.UIS. 2017;30(2):71-81.

Conservative treatment of diaphyseal humeral fractures is nowadays an effective option in terms of callogenesis and functional outcome: its selection is based on publications by Sarmiento and Rommers. However, the current trend is to provide a stable synthesis and early mobilization, leading to a quicker functional restore than that granted by conservative treatment. Therefore, endomedullary nailing (either anterograde or retrograde) and ORIF represent the gold standard. External fixation (EF) has absolute indications in case of open fractures, fractures with compromised soft tissue and multiple trauma, and represents an effective surgical option in case of closed fractures as well (both in adults and in children), thanks to its minimal invasiveness associated to good mechanical stability and functional restore. Patients’ quality of life is also very good during the first few weeks after surgery: the external fixator does not cause any trouble with shoulder and elbow mobility, allowing for a good restoration of muscular force. This method is even more indicated in elderly patients in overall poor medical conditions, where open invasive surgery would be contraindicated and conservative treatment would not be tolerated by the patients. Humeral external fixation can be considered a minimally invasive option that provides stable synthesis, with good fracture reduction and axial restoration: this leads to good results in terms of early mobilization, consolidation and low percentage of complications.