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Muscle force

Georg Bergmann, Ines Kutzner, Alwina Bender, Jörn Dymke, Adam Trepczynski, Georg N Duda, Dieter Felsenberg, Philipp Damm
During whole body vibrations, the total contact force in knee and hip joints consists of a static component plus the vibration-induced dynamic component. In two different cohorts, these forces were measured with instrumented joint implants at different vibration frequencies and amplitudes. For three standing positions on two platforms, the dynamic forces were compared to the static forces, and the total forces were related to the peak forces during walking. A biomechanical model served for estimating muscle force increases from contact force increases...
2018: PloS One
Rodrigo Pereira de Souza, Márcio Vinícius Fagundes Donadio, João Paulo Heinzmann-Filho, Rafael Reimann Baptista, Leonardo Araújo Pinto, Matias Epifanio, Paulo José Cauduro Marostica
OBJECTIVE: To compare muscle thickness and subcutaneous fat in cystic fibrosis (CF) patients and healthy controls using ultrasonography (US), and to correlate US findings with nutritional, clinical and functional variables. METHODS: Patients aged 6 to 18 years old with a diagnosis of CF and healthy controls were included. Participants underwent anthropometric measurements, an ultrasonographic evaluation of muscle thickness and subcutaneous fat in the triceps, quadriceps, and gastrocnemius regions, and skinfold thickness measurements...
October 2018: Revista Paulista de Pediatria: Orgão Oficial da Sociedade de Pediatria de São Paulo
G Manzanares, G Brito-da-Silva, P G Gandra
Exercise can prevent and improve the pathophysiology of diseases and promote healthy aging. Thus, understanding the mechanisms that regulate the beneficial effects of exercise may lead to the development of new strategies to enhance quality of life and to counteract chronic diseases. Voluntary wheel running is an interesting model to study the effects of exercise in mice. Compared to forced treadmill exercise, voluntary wheel running presents several advantages such as: 1) running pattern is similar to natural running behavior of mice; 2) it is performed under non-stressed conditions, according to the rhythmicity of the animal; 3) it does not require direct interference from the researcher, and can be easily applied in long-term studies...
December 10, 2018: Brazilian Journal of Medical and Biological Research, Revista Brasileira de Pesquisas Médicas e Biológicas
Dana Guy-Cherry, Ahmad Alanazi, Lauren Miller, Darrin Staloch, Alexis Ortiz-Rodriguez
The aim was to determine which three landing styles - stiff (ST), self-selected (SS), or soft (SF) - exhibit safer landing mechanics and greater jumping performance. Thirty participants (age: 26.5±5.1 years; height: 171.0±8.8 cm; weight: 69.7±10.1 kg) performed five trials of three randomized drop jump (40 cm) landing styles including SF (~60° knee flexion), ST (knees as straight as possible), and SS. Knee flexion and valgus angles and kinetics were measured. An electromyography system measured muscle activity of the gluteus maximus, quadriceps, hamstrings, tibialis anterior, and gastrocnemius...
April 2018: Sports Med Int Open
Ana Oliveira, Vera Afreixo, Alda Marques
Purpose: Acute exacerbations of COPD (AECOPD) are associated with pulmonary/systemic changes; however, quantification of those changes during AECOPD managed on an outpatient basis and factors influencing recovery are lacking. This study aimed to characterize patients' changes during AECOPD and identify factors influencing their recovery. Methods: Body mass index, the modified British Medical Research Council questionnaire, number of exacerbations in the previous year, and the Charlson comorbidity index (independent variables) were collected within 24-48 hours of hospital presentation (T0)...
2018: International Journal of Chronic Obstructive Pulmonary Disease
Andrew J Price, Anna-Lena Cost, Hanna Ungewiß, Jens Waschke, Alexander R Dunn, Carsten Grashoff
Desmosomes are intercellular adhesion complexes that connect the intermediate filament cytoskeletons of neighboring cells, and are essential for the mechanical integrity of mammalian tissues. Mutations in desmosomal proteins cause severe human pathologies including epithelial blistering and heart muscle dysfunction. However, direct evidence for their load-bearing nature is lacking. Here we develop Förster resonance energy transfer (FRET)-based tension sensors to measure the forces experienced by desmoplakin, an obligate desmosomal protein that links the desmosomal plaque to intermediate filaments...
December 11, 2018: Nature Communications
Thilo Hotfiel, Jürgen Freiwald, Matthias Wilhelm Hoppe, Christoph Lutter, Raimund Forst, Casper Grim, Wilhelm Bloch, Moritz Hüttel, Rafael Heiss
Delayed-onset muscle soreness (DOMS) is a type of ultrastructural muscle injury. The manifestation of DOMS is caused by eccentric or unfamiliar forms of exercise. Clinical signs include reduced force capacities, increased painful restriction of movement, stiffness, swelling, and dysfunction of adjacent joints. Although DOMS is considered a mild type of injury, it is one of the most common reasons for compromised sportive performance. In the past few decades, many hypotheses have been developed to explain the aetiology of DOMS...
December 2018: Sportverletzung Sportschaden: Organ der Gesellschaft Für Orthopädisch-Traumatologische Sportmedizin
Paul J Guelinckx
Background: Since 2004, microneurovascular platysma transfer has been used for dynamic eye closure in long-standing facial palsy. The idea was initially presented by Lee and Terzis in 1984 but abandoned owing to its transfer difficulty. This muscle transfer allows forceful closure and blink restoration. Methods: This study included 24 patients operated between 2004 and 2014 for long-standing facial palsy. In the first step of the procedure, a cross-facial nerve graft was employed to transfer the motor nerve fibers from the normal side to the paralyzed side responsible for eye closure...
October 2018: Plastic and Reconstructive Surgery. Global Open
Maddox L Reed, Rebecca L Begalle, Kevin G Laudner
Background: Posterior shoulder tightness (PST), defined as limited glenohumeral (GH) horizontal adduction and internal rotation motion, is a common occurrence in overhead athletes, particularly baseball and softball players, as a result of the extreme forces on the GH joint and the high number of throwing repetitions. Despite clinical evidence suggesting the use of joint mobilizations and muscle energy techniques (MET) for treating PST, there currently are no data examining the overall effectiveness of joint mobilizations and MET to determine optimal treatment for posterior shoulder tightness...
December 2018: International Journal of Sports Physical Therapy
Michael O Harris-Love, Kimberly Benson, Erin Leasure, Bernadette Adams, Valerie McIntosh
The optimal management of sarcopenia requires appropriate endpoint measures to determine intervention efficacy. While hand grip strength is a predictor of morbidity and mortality, lower extremity strength may be better associated with functional activities in comparison to hand grip strength. The purpose of our study was to examine the comparative association of upper and lower extremity strength with common measures of physical performance in older adults. Thirty community-dwelling men, aged 62.5 ± 9.2 years, completed body composition analysis, quantitative strength testing, and performance-based tests of functional status...
December 2018: Journal of Functional Morphology and Kinesiology
Amaleswaran Anbarasan, Nasrul Hanif Mohamad, Sureisen Mariapan
Open traumatic scapulothoracic dissociation is a rare and devastating injury. We are reporting a 21-year-old male factory worker who sustained a traumatic open scapulothoracic dissociation. His left arm was caught in conveyer belts resulting the arm, scapula, clavicle, and pectoral muscle torn from the body by tremendous traction force. He presented with pulseless, flail and cold limb and was promptly resuscitated and surgically managed with forequarter amputation.
December 2018: Trauma Case Reports
Norimichi Kamikawa, Hironobu Hamada, Kiyokazu Sekikawa, Hikaru Yamamoto, Yoshiya Fujika, Teruki Kajiwara, Fumiya Aizawa, Ippo Otoyama
Dysphagia is the major pathophysiologic mechanism leading to aspiration pneumonia in the elderly. Elderly people with dysphagia who show low levels of the cough peak flow (CPF) are at greater risk for aspiration pneumonia. It has been reported that CPF values were significantly lower in the "soft" versus "hard" mode of a pressure-relieving air mattress in healthy volunteers in a supine position. Parameters such as spinal curvature, however, were not evaluated in detail. In this study, we clarified whether the changes in posture associated with two different firmness levels of a pressure-relieving air mattress were associated with cough production and related factors in the elderly with dysphagia...
2018: PloS One
Alexander I Kostyukov, Tomasz Tomiak
The two-segment model of the human arm is considered; the shoulder and elbow joint torques (JTs) are simulated, providing a slow, steady rotation of the force vector at any end-point of the horizontal working space. The sinusoidal waves describe the JTs, their periods coincide with that of the rotation, and phases are defined by the slopes of the correspondent lines from the joint axes to the end-point. Analysis of the JTs includes an application of the same discrete changes in one joint angle under fixation of the other one and vice versa; the JT pairs are compared for the "shoulder" and "elbow" end-point traces that pass under fixation of the elbow and shoulder angles, respectively...
2018: Frontiers in Neurorobotics
Esther Kuperus, Jan C van der Meijden, Stijn L M In 't Groen, Marian A Kroos, Marianne Hoogeveen-Westerveld, Dimitris Rizopoulos, Monica Yasmin Nino Martinez, Michelle E Kruijshaar, Pieter A van Doorn, Nadine A M E van der Beek, Ans T van der Ploeg, W W M Pim Pijnappel
The majority of children and adults with Pompe disease in the population of European descent carry the leaky splicing GAA variant c.-32-13T>G (IVS1) in combination with a fully deleterious GAA variant on the second allele. The phenotypic spectrum of this patient group is exceptionally broad, with symptom onset ranging from early infancy to late adulthood. In addition, the response to enzyme replacement therapy (ERT) varies between patients. The insertion/deletion (I/D) polymorphism of the angiotensin I-converting enzyme (ACE) has been suggested to be a modifier of disease onset and/or response to ERT...
2018: PloS One
Wenjing Hu, Na Wei, Zong-Ming Li, Ke Li
Object manipulation requires well-coordinated force vectors involving both magnitudes and directions. Despite extensive studies about force magnitudes during manipulation, relatively little is known how the muscle fatigue could affect the directional coordination of fingertip forces. This study aims to examine the effects of muscle fatigue on inter-digit coordination of force directions during precision grip. Sixteen female subjects performed precision grip with their thumb and index finger before and after fatigue tasks, which required subjects to produce continuous submaximal pinch strength on the apparatus for a duration more than 200 s...
2018: PloS One
Antoine Falisse, Lynn Bar-On, Kaat Desloovere, Ilse Jonkers, Friedl De Groote
Muscle spasticity is characterized by exaggerated stretch reflexes and affects about 85% of the children with cerebral palsy. However, the mechanisms underlying spasticity and its influence on gait are not well understood. Here, we first aimed to model the response of spastic hamstrings and gastrocnemii in children with cerebral palsy to fast passive stretches. Then, we evaluated how the model applied to gait. We developed three models based on exaggerated proprioceptive feedback. The first model relied on feedback from muscle fiber length and velocity (velocity-related model), the second model relied on feedback from muscle fiber length, velocity, and acceleration (acceleration-related model), and the third model relied on feedback from muscle force and its first time derivative (force-related model)...
2018: PloS One
Derek D Ferley, Matthew D Vukovich
Ferley, DD and Vukovich, MD. Assessing the reliability of using a horizontal leg press equipped with a force plate to report on measures of positive and negative neuromuscular characteristics. J Strength Cond Res XX(X): 000-000, 2018-Individuals participating in sport or returning from a lower-extremity injury routinely perform assessments of lower-body anaerobic capacity and power to gauge fitness or readiness to return to competition. However, many commonly used assessments lack the specificity of movement and muscle contraction demonstrated in sprinting, jumping, and changing direction...
December 7, 2018: Journal of Strength and Conditioning Research
Jared W Skinner, Evangelos A Christou, Chris J Hass
BACKGROUND AND PURPOSE: Adequate lower limb strength and motor control are essential for mobility and quality of life. People with Parkinson disease (PD) experience a significant and progressive decline in motor capabilities as part of this neurodegenerative disease. The primary objective of this study was to examine the effect of PD on (1) muscular strength and (2) force steadiness in muscles that are primarily responsible for locomotion and stability. METHODS: Thirteen persons with PD and 13 healthy age-matched controls participated...
January 2019: Journal of Neurologic Physical Therapy: JNPT
K Kryściak, J Celichowski, P Krutki, R Raikova, H Drzymała-Celichowska
The sag phenomenon can be observed in fast motor units (MUs) as a transitional decline in force during unfused tetanic contractions; however, its mechanisms are poorly understood. The study aimed to identify in the rat muscle factors that contribute to sag in two types of fast MUs: fast fatigable (FF) and fast resistant to fatigue (FR). First, we performed mathematical decomposition of sagging tetanic contractions of FF and FR MUs into twitch-like responses to consecutive stimuli. This process indicated an increase in the amplitudes of a few initial responses (up to the 2nd-3rd for FF and up to the 2nd-7th for FR MUs), followed by a decrease in the amplitudes of later responses...
November 28, 2018: Journal of Electromyography and Kinesiology
S Ryan Oliver, Kyle J Anderson, Moriah M Hunstiger, Matthew T Andrews
Hibernation in mammals is a whole-body phenotype that involves profound reductions in oxygen consumption, metabolic reactions, core body temperature, neural activity and heart rate. An important aspect of mammalian hibernation is the ability to reverse this state of hypothermic torpor by rewarming and subsequent arousal. Brown adipose tissue (BAT) and skeletal muscle shivering have been characterized as the predominant driving forces for thermogenesis during arousal. Conversely, the thermogenic contribution of these organs needs to be minimized as hibernating mammals enter torpor...
December 5, 2018: Neuroscience Letters
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