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Journal of Bodywork and Movement... Jul 2015
Topics: Exercise; Humans; Muscle Contraction; Muscle Strength; Muscle, Skeletal
PubMed: 26118528
DOI: 10.1016/j.jbmt.2015.05.002 -
BioMed Research International 2015
Topics: Humans; Muscle Contraction; Muscle, Skeletal; Myosins
PubMed: 25961034
DOI: 10.1155/2015/694345 -
Journal of Applied Physiology... Apr 2024Whether eccentric exercise involves active fascicle stretch is unclear due to muscle-tendon unit (MTU) series compliance. Therefore, this study investigated the impact...
Whether eccentric exercise involves active fascicle stretch is unclear due to muscle-tendon unit (MTU) series compliance. Therefore, this study investigated the impact of changing the activation timing and level (i.e., preactivation) of the contraction on muscle fascicle kinematics and kinetics of the human tibialis anterior during dynamometer-controlled maximal voluntary MTU-stretch-hold contractions. B-mode ultrasound and surface electromyography were used to assess muscle fascicle kinematics and muscle activity levels, respectively. Although joint kinematics were similar among MTU-stretch-hold contractions (∼40° rotation amplitude), increasing preactivation increased fascicle shortening and stretch amplitudes (9.9-23.2 mm, ≤ 0.015). This led to increasing positive and negative fascicle work with increasing preactivation. Despite significantly different fascicle kinematics, similar peak fascicle forces during stretch occurred at similar fascicle lengths and joint angles regardless of preactivation. Similarly, residual force enhancement (rFE) following MTU stretch was not significantly affected (6.5-7.6%, = 0.559) by preactivation, but rFE was strongly correlated with peak fascicle force during stretch ( = 0.62, = 0.003). These findings highlight that apparent eccentric exercise causes shortening-stretch contractions at the fascicle level rather than isolated eccentric contractions. The constant rFE despite different fascicle kinematics and kinetics suggests that a passive element was engaged at a common muscle length among conditions (e.g., optimal fascicle length). Although it remains unclear whether different fascicle mechanics trigger different adaptations to eccentric exercise, this study emphasizes the need to consider MTU series compliance to better understand the mechanical drivers of adaptation to exercise. Apparent eccentric exercises do not result in isolated eccentric contractions, but shortening-stretch contractions at the fascicle level. The amount of fascicle shortening and stretch depends on the preactivation during the exercise and cannot be estimated from the muscle-tendon unit (MTU) or joint kinematics. As different fascicle mechanics might trigger different adaptations to eccentric exercise, muscle-tendon unit series compliance and muscle preactivation need to be considered when eccentric exercise protocols are designed.
Topics: Humans; Muscle, Skeletal; Tendons; Muscle Contraction; Electromyography; Exercise; Isometric Contraction
PubMed: 38482578
DOI: 10.1152/japplphysiol.00845.2023 -
Sports Medicine (Auckland, N.Z.) Aug 2017It is well known that prolonged passive muscle stretch reduces maximal muscle force production. There is a growing body of evidence suggesting that adaptations occurring... (Review)
Review
It is well known that prolonged passive muscle stretch reduces maximal muscle force production. There is a growing body of evidence suggesting that adaptations occurring within the nervous system play a major role in this stretch-induced force reduction. This article reviews the existing literature, and some new evidence, regarding acute neurophysiological changes in response to passive muscle stretching. We discuss the possible contribution of supra-spinal and spinal structures to the force reduction after passive muscle stretch. In summary, based on the recent evidence reviewed we propose a new hypothesis that a disfacilitation occurring at the motoneuronal level after passive muscle stretch is a major factor affecting the neural efferent drive to the muscle and, subsequently, its ability to produce maximal force.
Topics: Biomechanical Phenomena; Humans; Isometric Contraction; Motor Neurons; Muscle Contraction; Muscle Stretching Exercises; Muscle, Skeletal; Stress, Mechanical
PubMed: 28120238
DOI: 10.1007/s40279-017-0682-6 -
The Journal of Experimental Biology Jan 2016The relationship between muscle structure and function has been a matter of investigation since the Renaissance period. Extensive use of anatomical dissections and the... (Review)
Review
The relationship between muscle structure and function has been a matter of investigation since the Renaissance period. Extensive use of anatomical dissections and the introduction of the scientific method enabled early scholars to lay the foundations of muscle physiology and biomechanics. Progression of knowledge in these disciplines led to the current understanding that muscle architecture, together with muscle fibre contractile properties, has a major influence on muscle mechanical properties. Recently, advances in laser diffraction, optical microendoscopy and ultrasonography have enabled in vivo investigations into the behaviour of human muscle fascicles and sarcomeres with varying joint angle and muscle contraction intensity. With these technologies it has become possible to identify the length region over which fascicles and sarcomeres develop maximum isometric force in vivo as well as the operating ranges of fascicles and sarcomeres during real-life activities such as walking. Also, greater insights into the remodelling of muscle architecture in response to overloading and unloading, and in ageing, have been obtained by the use of ultrasonography; these have led to the identification of clinical biomarkers of disuse atrophy and sarcopenia. Recent evidence also shows that the pattern of muscle hypertrophy in response to chronic loading is contraction-mode dependent (eccentric versus concentric), as similar gains in muscle mass, but through differing addition of sarcomeres in series and in parallel (as indirectly inferred from changes in fascicle length and pennation angle), have been found. These innovative observations prompted a new set of investigations into the molecular mechanisms regulating this contraction-specific muscle growth.
Topics: Aging; Animals; Biomechanical Phenomena; Humans; Muscle Contraction; Muscle, Skeletal; Weight-Bearing
PubMed: 26792340
DOI: 10.1242/jeb.128017 -
Biochemical Pharmacology Feb 2024Extracellular nucleotides and nucleosides are crucial signalling molecules, eliciting diverse biological responses in almost all organs and tissues. These molecules... (Review)
Review
Extracellular nucleotides and nucleosides are crucial signalling molecules, eliciting diverse biological responses in almost all organs and tissues. These molecules exert their effects by activating specific nucleotide receptors, which are finely regulated by ectonucleotidases that break down their ligands. In this comprehensive review, we aim to elucidate the relevance of extracellular nucleotides as signalling molecules in the context of smooth muscle contraction, considering the modulatory influence of ectonucleotidases on this intricate process. Specifically, we provide a detailed examination of the involvement of extracellular nucleotides in the contraction of non-vascular smooth muscles, including those found in the urinary bladder, the airways, the reproductive system, and the gastrointestinal tract. Furthermore, we present a broader overview of the role of extracellular nucleotides in vascular smooth muscle contraction.
Topics: Nucleotides; Muscle Contraction; Urinary Bladder; Nucleosides; Signal Transduction
PubMed: 38142836
DOI: 10.1016/j.bcp.2023.116005 -
Pflugers Archiv : European Journal of... Mar 202214-3-3 proteins (14-3-3 s) are a family of highly conserved proteins that regulate many cellular processes in eukaryotes by interacting with a diverse array of client... (Review)
Review
14-3-3 proteins (14-3-3 s) are a family of highly conserved proteins that regulate many cellular processes in eukaryotes by interacting with a diverse array of client proteins. The 14-3-3 proteins have been implicated in several disease states and previous reviews have condensed the literature with respect to their structure, function, and the regulation of different cellular processes. This review focuses on the growing body of literature exploring the important role 14-3-3 proteins appear to play in regulating the biochemical and biophysical events associated with excitation-contraction coupling (ECC) in muscle. It presents both a timely and unique analysis that seeks to unite studies emphasizing the identification and diversity of 14-3-3 protein function and client protein interactions, as modulators of muscle contraction. It also highlights ideas within these two well-established but intersecting fields that support further investigation with respect to the mechanistic actions of 14-3-3 proteins in the modulation of force generation in muscle.
Topics: 14-3-3 Proteins; Calcium; Excitation Contraction Coupling; Humans; Muscle Contraction; Muscle, Skeletal
PubMed: 34820713
DOI: 10.1007/s00424-021-02635-x -
The Journal of Experimental Biology Jan 2016A number of studies over the last few decades have established that the control strategy employed by the nervous system during lengthening (eccentric) differs from those... (Review)
Review
A number of studies over the last few decades have established that the control strategy employed by the nervous system during lengthening (eccentric) differs from those used during shortening (concentric) and isometric contractions. The purpose of this review is to summarize current knowledge on the neural control of lengthening contractions. After a brief discussion of methodological issues that can confound the comparison between lengthening and shortening actions, the review provides evidence that untrained individuals are usually unable to fully activate their muscles during a maximal lengthening contraction and that motor unit activity during submaximal lengthening actions differs from that during shortening actions. Contrary to common knowledge, however, more recent studies have found that the recruitment order of motor units is similar during submaximal shortening and lengthening contractions, but that discharge rate is systematically lower during lengthening actions. Subsequently, the review examines the mechanisms responsible for the specific control of maximal and submaximal lengthening contractions as reported by recent studies on the modulation of cortical and spinal excitability. As similar modulation has been observed regardless of contraction intensity, it appears that spinal and corticospinal excitability are reduced during lengthening compared with shortening and isometric contractions. Nonetheless, the modulation observed during lengthening contractions is mainly attributable to inhibition at the spinal level.
Topics: Animals; Humans; Isometric Contraction; Models, Biological; Muscle Contraction; Muscles; Nervous System Physiological Phenomena
PubMed: 26792331
DOI: 10.1242/jeb.123158 -
Sensors (Basel, Switzerland) Mar 2022Complications related to neuromuscular blockade (NMB) could occur during anesthesia induction, maintenance, and emergency. It is recommended that neuromuscular... (Review)
Review
Complications related to neuromuscular blockade (NMB) could occur during anesthesia induction, maintenance, and emergency. It is recommended that neuromuscular monitoring techniques be utilized perioperatively to avoid adverse outcomes. However, current neuromuscular monitoring methods possess different shortcomings. They are cumbersome to use, susceptible to disturbances, and have limited alternative monitoring sites. Phonomyography (PMG) monitoring based on the acoustic signals yielded by skeletal muscle contraction is emerging as an interesting and innovative method. This technique is characterized by its convenience, stable signal quality, and multimuscle recording ability and shows great potential in the application field. This review summarizes the progression of PMG on perioperative neuromuscular monitoring chronologically and presents the merits, demerits, and challenges of PMG-based equipment, aiming at underscoring the potential of PMG-based apparatuses for neuromuscular monitoring.
Topics: Electric Stimulation; Muscle Contraction; Myography; Neuromuscular Blockade; Neuromuscular Monitoring
PubMed: 35408063
DOI: 10.3390/s22072448 -
Scandinavian Journal of Medicine &... Oct 2022During voluntary muscle contractions, force output is characterized by constant inherent fluctuations, which can be quantified either according to their magnitude or... (Review)
Review
During voluntary muscle contractions, force output is characterized by constant inherent fluctuations, which can be quantified either according to their magnitude or temporal structure, that is, complexity. The presence of such fluctuations when targeting a set force indicates that control of force is not perfectly accurate, which can have significant implications for task performance. Compared to young adults, older adults demonstrate a greater magnitude and lower complexity in force fluctuations, indicative of decreased steadiness, and adaptability of force output, respectively. The nature of this loss-of-force control depends not only on the age of the individual but also on the muscle group performing the task, the intensity and type of contraction and whether the task is performed with additional cognitive load. Importantly, this age-associated loss-of-force control is correlated with decreased performance in a range of activities of daily living and is speculated to be of greater importance for functional capacity than age-associated decreases in maximal strength. Fortunately, there is evidence that acute physical activity interventions can reverse the loss-of-force control in older individuals, though whether this translates to improved functional performance and whether lifelong physical activity can protect against the changes have yet to be established. A number of mechanisms, related to both motor unit properties and the behavior of motor unit populations, have been proposed for the age-associated changes in force fluctuations. It is likely, though, that age-associated changes in force control are related to increased common fluctuations in the discharge times of motor units.
Topics: Activities of Daily Living; Aged; Aging; Electromyography; Exercise; Humans; Isometric Contraction; Muscle Contraction; Muscle, Skeletal; Young Adult
PubMed: 35815914
DOI: 10.1111/sms.14207