-
European Journal of Applied Physiology Oct 2022Declines in muscle force, power, and contractile function can be observed in older adults, clinical populations, inactive individuals, and injured athletes. Passive... (Review)
Review
Declines in muscle force, power, and contractile function can be observed in older adults, clinical populations, inactive individuals, and injured athletes. Passive heating exposure (e.g., hot baths, sauna, or heated garments) has been used for health purposes, including skeletal muscle treatment. An acute increase in muscle temperature by passive heating can increase the voluntary rate of force development and electrically evoked contraction properties (i.e., time to peak twitch torque, half-relation time, and electromechanical delay). The improvements in the rate of force development and evoked contraction assessments with increased muscle temperature after passive heating reveal peripheral mechanisms' potential role in enhancing muscle contraction. This review aimed to summarise, discuss, and highlight the potential role of an acute passive heating stimulus on skeletal muscle cells to improve contractile function. These mechanisms include increased calcium kinetics (release/reuptake), calcium sensitivity, and increased intramuscular fluid.
Topics: Aged; Calcium; Humans; Isometric Contraction; Muscle Contraction; Muscle, Skeletal; Temperature; Torque
PubMed: 35771296
DOI: 10.1007/s00421-022-04991-7 -
Journal of Biomechanics Jul 2023Muscle energetics encompasses the relationships between mechanical performance and the biochemical and thermal changes that occur during muscular activity. The... (Review)
Review
Muscle energetics encompasses the relationships between mechanical performance and the biochemical and thermal changes that occur during muscular activity. The biochemical reactions that underpin contraction are described and the way in which these are manifest in experimental recordings, as initial and recovery heat, is illustrated. Energy use during contraction can be partitioned into that related to cross-bridge force generation and that associated with activation by Ca. Activation processes account for 25-45% of ATP turnover in an isometric contraction, varying amongst muscles. Muscle energy use during contraction depends on the nature of the contraction. When shortening muscles produce less force than when contracting isometrically but use energy at a greater rate. These characteristics reflect more rapid cross-bridge cycling when shortening. When lengthening, muscles produce more force than in an isometric contraction but use energy at a lower rate. In that case, cross-bridges cycle but via a pathway in which ATP splitting is not completed. Shortening muscles convert part of the free energy available from ATP hydrolysis into work with the remainder appearing as heat. In the most efficient muscle studied, that of a tortoise, cross-bridges convert a maximum of 47% of the available energy into work. In most other muscles, only 20-30% of the free energy from ATP hydrolysis is converted into work.
Topics: Energy Metabolism; Adenosine Triphosphate; Muscle Contraction; Muscles; Isometric Contraction
PubMed: 37302165
DOI: 10.1016/j.jbiomech.2023.111669 -
Pflugers Archiv : European Journal of... Dec 2023Cell contraction plays an important role in many physiological and pathophysiological processes. This includes functions in skeletal, heart, and smooth muscle cells,... (Review)
Review
Cell contraction plays an important role in many physiological and pathophysiological processes. This includes functions in skeletal, heart, and smooth muscle cells, which lead to highly coordinated contractions of multicellular assemblies, and functions in non-muscle cells, which are often highly localized in subcellular regions and transient in time. While the regulatory processes that control cell contraction in muscle cells are well understood, much less is known about cell contraction in non-muscle cells. In this review, we focus on the mechanisms that control cell contraction in space and time in non-muscle cells, and how they can be investigated by light-based methods. The review particularly focusses on signal networks and cytoskeletal components that together control subcellular contraction patterns to perform functions on the level of cells and tissues, such as directional migration and multicellular rearrangements during development. Key features of light-based methods that enable highly local and fast perturbations are highlighted, and how experimental strategies can capitalize on these features to uncover causal relationships in the complex signal networks that control cell contraction.
Topics: Muscle, Smooth; Muscle Contraction; Myocytes, Smooth Muscle; Phosphorylation
PubMed: 37851146
DOI: 10.1007/s00424-023-02864-2 -
Naunyn-Schmiedeberg's Archives of... Jul 2018The epithelial inner layer of the lower urinary tract, i.e., the urothelium, and other parts of the mucosa are not just a passive barrier but play an active role in the... (Review)
Review
The epithelial inner layer of the lower urinary tract, i.e., the urothelium, and other parts of the mucosa are not just a passive barrier but play an active role in the sensing of stretching, neurotransmitters, paracrine mediators, hormones, and growth factors and of changes in the extracellular environment. We review the molecular and cellular mechanisms enabling the urothelium to sense such inputs and how this leads to modulation of smooth muscle contraction and relaxation. The urothelium releases various mediators including ATP, acetylcholine, prostaglandins, nitric oxide, and nerve growth factor. These may affect function and growth of smooth muscle cells and afferent nerves. However, the molecular identity of the urothelium-derived mediator directly modulating contractile and relaxant responses of isolated bladder strips has remained elusive. The morphology and function of the urothelium undergo changes with aging and in many pathophysiological conditions. Therefore, the urothelium may contribute to the therapeutic effects of established drugs to treat lower urinary tract dysfunction and may also serve as a target for novel therapeutics. However, therapeutics may also change urothelial function, and it is not always easy to determine whether such changes are part of the therapeutic response or reflect secondary alterations.
Topics: Animals; Humans; Muscle Contraction; Muscle Relaxation; Muscle, Smooth; Urinary Tract Physiological Phenomena; Urothelium
PubMed: 29808232
DOI: 10.1007/s00210-018-1510-8 -
Exercise and Sport Sciences Reviews Jan 2021Understanding the physiological/mechanical mechanisms leading to skeletal muscle damage remains one of the challenges in muscle physiology. This review presents the... (Review)
Review
Understanding the physiological/mechanical mechanisms leading to skeletal muscle damage remains one of the challenges in muscle physiology. This review presents the functional, structural, and cellular consequences of electrically evoked submaximal isometric contractions that can elicit severe and localized skeletal muscle damage. Hypotheses related to underlying physiological and mechanical processes involved in severe and localized muscle damage also are discussed.
Topics: Electric Stimulation; Humans; Isometric Contraction; Muscle Contraction; Muscle, Skeletal
PubMed: 33122596
DOI: 10.1249/JES.0000000000000239 -
Journal of Bodywork and Movement... Jan 2020
Topics: Adaptation, Physiological; Biomechanical Phenomena; Biomedical Research; Elasticity; Humans; Muscle Contraction; Muscle Fibers, Skeletal; Muscle Relaxation; Osteopathic Medicine; Range of Motion, Articular
PubMed: 31987532
DOI: 10.1016/j.jbmt.2019.12.001 -
Physiological Reports May 2022Muscle co-contraction between the agonist and antagonist muscles often causes low energy efficiency or movement disturbances. Surface electromyography biofeedback...
Muscle co-contraction between the agonist and antagonist muscles often causes low energy efficiency or movement disturbances. Surface electromyography biofeedback (sEMG-BF) has been used to train muscle activation or relaxation but it is unknown whether sEMG-BF reduces muscle co-contraction. We hypothesized that auditory sEMG-BF improves muscle co-contraction. Our purpose was to investigate whether auditory sEMG-BF is effective in improving muscle co-contraction. Thirteen participants pedaled on a road bike using four different auditory sEMG-BF conditions. We measured the surface electromyography at the lower limb muscles. The vastus lateralis (VL) and the semitendinosus (ST) activities were individually transformed into different beep sounds. Four feedback conditions were no-feedback, VL feedback, ST feedback, and both VL and ST feedback. We compared the co-contraction index (COI) of the knee extensor-flexor muscles and the hip flexor-extensor muscles among the conditions. There were no significant differences in COIs among the conditions (p = 0.83 for the COI of the knee extensor-flexor; p = 0.32 for the COI of the hip flexor-extensor). To improve the muscle co-contraction by sEMG-BF, it may be necessary to convert muscle activation into a muscle co-contraction. We concluded that individual sEMG-BF does not immediately improve muscle co-contraction during pedaling.
Topics: Biofeedback, Psychology; Electromyography; Humans; Knee Joint; Muscle Contraction; Muscle, Skeletal
PubMed: 35611763
DOI: 10.14814/phy2.15288 -
Aesthetic Surgery Journal Feb 2024Addressing neck contouring with surgical and nonsurgical aesthetic procedures includes understanding the origin of platysmal banding. A theory was postulated to explain...
BACKGROUND
Addressing neck contouring with surgical and nonsurgical aesthetic procedures includes understanding the origin of platysmal banding. A theory was postulated to explain this phenomenon by isometric vs isotonic muscular contraction patterns. However, no scientific proof had been provided to date for its correctness.
OBJECTIVES
The aim of this study was to confirm the correctness of the platysmal banding theory based on isometric vs isotonic muscular contractions.
METHODS
Eighty platysma muscles from 40 volunteers (15 males and 25 females) were investigated (mean age 41.8; SD 15.2 years; mean BMI of 22.2; SD 2.3 kg/m2). Real-time ultrasound imaging was utilized to measure the increase in local muscle thickness inside and outside of a platysmal band as well as platysma mobility.
RESULTS
Within a platysmal band, the local thickness of the muscle increases during muscular contractions by 0.33 mm (37.9%; P < .001). Outside of a platysmal band the thickness of the platysma muscle decreased by 0.13 mm (20.3%; P < .001). It was identified that within a platysmal band no gliding was detectable, whereas outside of a band an average muscle gliding of 2.76 mm was observed.
CONCLUSIONS
The results confirm the correctness of the isometric vs isotonic platysma muscle contraction pattern theory: isotonic muscle contraction (gliding without increase in tension and therefore in muscle thickness) vs isometric muscle contraction (no gliding but increase in tension and therefore in muscle thickness). These 2 types of contraction patterns occur within the platysma simultaneously and are an indicator for zones of adhesion in the neck to guide surgical and nonsurgical aesthetic procedures.
Topics: Male; Female; Humans; Adult; Superficial Musculoaponeurotic System; Muscle Contraction; Neck; Ultrasonography
PubMed: 37418617
DOI: 10.1093/asj/sjad216 -
Neuroscience Letters Apr 2020Endocannabinoids play important roles in regulating CNS synaptic function and peripheral metabolism, but cannabinoids can also act acutely to modulate contraction... (Review)
Review
Endocannabinoids play important roles in regulating CNS synaptic function and peripheral metabolism, but cannabinoids can also act acutely to modulate contraction strength in skeletal muscle. Nerve terminals and the skeletal muscle sarcolemma express components of the cannabinoid signaling system. Endocannabinoids, N-arachidonylethanolamine (anandamide, AEA) and 2-arachidonoyl-glycerol (2-AG), are produced by skeletal muscle. They may be involved in the acute regulation of neuromuscular transmission, by adjusting the parameters for quantal acetylcholine release from the motor nerve terminal. Downstream of neuromuscular transmission, cannabinoids may also act to limit the efficiency of excitation-contraction coupling. Improved understanding of the distinct signaling actions of particular cannabinoid compounds and their receptor/transduction systems will help advance our understanding of the role of endocannabinoids in skeletal muscle physiology. Cannabinoids might also offer the potential to develop new pharmacotherapeutics to treat neuromuscular disorders that affect muscle strength.
Topics: Animals; Cannabinoids; Humans; Motor Neurons; Muscle Contraction; Muscle, Skeletal; Signal Transduction; Synaptic Transmission
PubMed: 32156612
DOI: 10.1016/j.neulet.2020.134900 -
Journal of Muscle Research and Cell... Mar 2020The heart is an extraordinarily versatile pump, finely tuned to respond to a multitude of demands. Given the heart pumps without rest for decades its efficiency is... (Review)
Review
The heart is an extraordinarily versatile pump, finely tuned to respond to a multitude of demands. Given the heart pumps without rest for decades its efficiency is particularly relevant. Although many proteins in the heart are essential for viability, the non-essential components can attract numerous mutations which can cause disease, possibly through alterations in pumping efficiency. Of these, myosin binding protein C is strongly over-represented with ~ 40% of all known mutations in hypertrophic cardiomyopathy. Therefore, a complete understanding of its molecular function in the cardiac sarcomere is warranted. In this review, we revisit contemporary and classical literature to clarify both the current standing of this fast-moving field and frame future unresolved questions. To date, much effort has been directed at understanding MyBP-C function on either thick or thin filaments. Here we aim to focus questions on how MyBP-C functions at a molecular level in the context of both the thick and thin filaments together. A concept that emerges is MyBP-C acts to govern interactions on two levels; controlling myosin access to the thin filament by sequestration on the thick filament, and controlling the activation state and access of myosin to its binding sites on the thin filament. Such affects are achieved through directed interactions mediated by phosphorylation (of MyBP-C and other sarcomeric components) and calcium.
Topics: Carrier Proteins; Humans; Muscle Contraction
PubMed: 31960266
DOI: 10.1007/s10974-019-09567-1