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Overactivity in Chronic Pain, the Role of Pain-related Endurance and Neuromuscular Activity: An Interdisciplinary, Narrative Review. Clin J Pain 2021; 36:162-171. [PMID: 31833914 DOI: 10.1097/ajp.0000000000000785] [Citation(s) in RCA: 20] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Abstract
OBJECTIVES Decades of research have convincingly shown that fear of pain and pain-related avoidance behavior are important precursors of disability in daily life. Reduced activity as a consequence of avoidance, however, cannot be blamed for chronic disability in all patients. A contrasting behavior, pain-related dysfunctional endurance in a task and overactivity has to be considered. Currently, there is a need to better understand the psychological determinants of overactivity, dysfunctional endurance, and neurobiomechanical consequences. METHODS This is a narrative review. RESULTS The first part of this review elucidates research on self-reported overactivity, showing associations with higher levels of pain and disability, especially in spinal load positions, for example, lifting, bending, or spending too long a time in specific positions. In addition, measures of habitual endurance-related pain responses, based on the avoidance-endurance model, are related to objective assessments of physical activity and, again, especially in positions known to cause high spinal load (part 2). The final part reveals findings from neuromuscular research on motor control indicating the possibility that, in particular, overactivity and dysfunctional endurance may result in a number of dysfunctional adaptations with repetitive strain injuries of muscles, ligaments, and vertebral segments as precursors of pain. DISCUSSION This narrative review brings together different research lines on overactivity, pain-related endurance, and supposed neuromuscular consequences. Clinicians should distinguish between patients who rest and escape from pain at low levels of pain, but who have high levels of fear of pain and those who predominantly persist in activities despite severely increasing pain until a break will be enforced by intolerable pain levels.
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Hessel AL, Monroy JA, Nishikawa KC. Non-cross Bridge Viscoelastic Elements Contribute to Muscle Force and Work During Stretch-Shortening Cycles: Evidence From Whole Muscles and Permeabilized Fibers. Front Physiol 2021; 12:648019. [PMID: 33854441 PMCID: PMC8039322 DOI: 10.3389/fphys.2021.648019] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/31/2020] [Accepted: 03/08/2021] [Indexed: 12/27/2022] Open
Abstract
The sliding filament-swinging cross bridge theory of skeletal muscle contraction provides a reasonable description of muscle properties during isometric contractions at or near maximum isometric force. However, it fails to predict muscle force during dynamic length changes, implying that the model is not complete. Mounting evidence suggests that, along with cross bridges, a Ca2+-sensitive viscoelastic element, likely the titin protein, contributes to muscle force and work. The purpose of this study was to develop a multi-level approach deploying stretch-shortening cycles (SSCs) to test the hypothesis that, along with cross bridges, Ca2+-sensitive viscoelastic elements in sarcomeres contribute to force and work. Using whole soleus muscles from wild type and mdm mice, which carry a small deletion in the N2A region of titin, we measured the activation- and phase-dependence of enhanced force and work during SSCs with and without doublet stimuli. In wild type muscles, a doublet stimulus led to an increase in peak force and work per cycle, with the largest effects occurring for stimulation during the lengthening phase of SSCs. In contrast, mdm muscles showed neither doublet potentiation features, nor phase-dependence of activation. To further distinguish the contributions of cross bridge and non-cross bridge elements, we performed SSCs on permeabilized psoas fiber bundles activated to different levels using either [Ca2+] or [Ca2+] plus the myosin inhibitor 2,3-butanedione monoxime (BDM). Across activation levels ranging from 15 to 100% of maximum isometric force, peak force, and work per cycle were enhanced for fibers in [Ca2+] plus BDM compared to [Ca2+] alone at a corresponding activation level, suggesting a contribution from Ca2+-sensitive, non-cross bridge, viscoelastic elements. Taken together, our results suggest that a tunable viscoelastic element such as titin contributes to: (1) persistence of force at low [Ca2+] in doublet potentiation; (2) phase- and length-dependence of doublet potentiation observed in wild type muscles and the absence of these effects in mdm muscles; and (3) increased peak force and work per cycle in SSCs. We conclude that non-cross bridge viscoelastic elements, likely titin, contribute substantially to muscle force and work, as well as the phase-dependence of these quantities, during dynamic length changes.
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Affiliation(s)
- Anthony L Hessel
- Institute of Physiology II, University of Muenster, Muenster, Germany
| | - Jenna A Monroy
- W.M. Keck Science Department, Claremont Colleges, Claremont, CA, United States
| | - Kiisa C Nishikawa
- Department of Biological Sciences, Northern Arizona University, Flagstaff, AZ, United States
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3
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Wernbom M, Aagaard P. Muscle fibre activation and fatigue with low-load blood flow restricted resistance exercise-An integrative physiology review. Acta Physiol (Oxf) 2020; 228:e13302. [PMID: 31108025 DOI: 10.1111/apha.13302] [Citation(s) in RCA: 45] [Impact Index Per Article: 11.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/10/2019] [Revised: 05/12/2019] [Accepted: 05/17/2019] [Indexed: 12/13/2022]
Abstract
Blood flow-restricted resistance exercise (BFRRE) has been shown to induce increases in muscle size and strength, and continues to generate interest from both clinical and basic research points of view. The low loads employed, typically 20%-50% of the one repetition maximum, make BFRRE an attractive training modality for individuals who may not tolerate high musculoskeletal forces (eg, selected clinical patient groups such as frail old adults and patients recovering from sports injury) and/or for highly trained athletes who have reached a plateau in muscle mass and strength. It has been proposed that achieving a high degree of muscle fibre recruitment is important for inducing muscle hypertrophy with BFRRE, and the available evidence suggest that fatiguing low-load exercise during ischemic conditions can recruit both slow (type I) and fast (type II) muscle fibres. Nevertheless, closer scrutiny reveals that type II fibre activation in BFRRE has to date largely been inferred using indirect methods such as electromyography and magnetic resonance spectroscopy, while only rarely addressed using more direct methods such as measurements of glycogen stores and phosphocreatine levels in muscle fibres. Hence, considerable uncertainity exists about the specific pattern of muscle fibre activation during BFRRE. Therefore, the purpose of this narrative review was (1) to summarize the evidence on muscle fibre recruitment during BFRRE as revealed by various methods employed for determining muscle fibre usage during exercise, and (2) to discuss reported findings in light of the specific advantages and limitations associated with these methods.
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Affiliation(s)
- Mathias Wernbom
- Center for Health and Performance, Department of Food and Nutrition and Sport Science University of Gothenburg Gothenburg Sweden
- Department of Health and Rehabilitation, Institute of Neuroscience and Physiology, Sahlgrenska Academy University of Gothenburg Gothenburg Sweden
| | - Per Aagaard
- Department of Sports Sciences and Clinical Biomechanics, SDU Muscle Research Cluster (SMRC) University of Southern Denmark Odense M Denmark
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4
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Witt A, Kristensen R, Fuglsang-Frederiksen A, Pedersen T, Finnerup N, Kasch H, Tankisi H. Muscle velocity recovery cycles in neurogenic muscles. Clin Neurophysiol 2019; 130:1520-1527. [DOI: 10.1016/j.clinph.2019.05.030] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/02/2019] [Revised: 04/17/2019] [Accepted: 05/19/2019] [Indexed: 12/01/2022]
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5
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Catania KC. The Astonishing Behavior of Electric Eels. Front Integr Neurosci 2019; 13:23. [PMID: 31379525 PMCID: PMC6646469 DOI: 10.3389/fnint.2019.00023] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2019] [Accepted: 06/24/2019] [Indexed: 11/29/2022] Open
Abstract
The remarkable physiology of the electric eel (Electrophorus electricus) made it one of the first model species in science. It was pivotal for understanding animal electricity in the 1700s, was investigated by Humboldt and Faraday in the 1800s, was leveraged to isolate the acetylcholine receptor in the 20th century, and has inspired the design of new power sources and provided insights to electric organ evolution in the 21st century. And yet few studies have investigated the electric eel’s behavior. This review focuses on a series of recently discovered behaviors that evolved alongside the eel’s extreme physiology. Eels use their high-voltage electric discharge to remotely control prey by transcutaneously activating motor neurons. Hunting eels use this behavior in two different ways. When prey have been detected, eels use high-voltage to cause immobility by inducing sustained, involuntary muscle contractions. On the other hand, when prey are hidden, eels often use brief pulses to induce prey twitch, which causes a water movement detected by the eel’s mechanoreceptors. Once grasped in the eel’s jaws, difficult prey are often subdued by sandwiching them between the two poles (head and tail) of the eel’s powerful electric organ. The resulting concentration of the high-voltage discharge, delivered at high-rates, causes involuntary fatigue in prey muscles. This novel strategy for inactivating muscles is functionally analogous to poisoning the neuromuscular junction with venom. For self-defense, electric eels leap from the water to directly electrify threats, efficiently activating nociceptors to deter their target. The latter behavior supports a legendary account by Alexander von Humboldt who described a battle between electric eels and horses in 1800. Finally, electric eels use high-voltage not only as a weapon, but also to efficiently track fast-moving prey with active electroreception. In conclusion, remarkable behaviors go hand in hand with remarkable physiology.
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Affiliation(s)
- Kenneth C Catania
- Department of Biological Sciences, Vanderbilt University, Nashville, TN, United States
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6
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Pedersen KK, Nielsen OB, Overgaard K. Contractile benefits of doublet-initiated low-frequency stimulation in rat extensor digitorum longus muscle exposed to high extracellular [K +] or fatiguing contractions. Am J Physiol Cell Physiol 2019; 317:C39-C47. [PMID: 30969780 DOI: 10.1152/ajpcell.00519.2018] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
During dynamic contractions, high-frequency muscle activation is needed to achieve optimal power. This must be balanced against an increased excitation-induced accumulation of extracellular K+, which can reduce excitability and ultimately may prevent adequate responses to high-frequency activation. Mean activation frequencies in vivo are often low (subtetanic), but activation patterns contain bursts of high (supratetanic) frequencies known as doublets, which enhance dynamic contraction in rested muscles at normal extracellular K+ concentration ([K+]o). Here, we examine how dynamic contractions in fast-twitch fibers stimulated by high frequency/doublets are affected during exposure to 11 mM [K+]o and during fatigue. Dynamic contractions were elicited by electrical stimulation in isolated rat extensor digitorum longus muscles incubated at 4 or 11 mM K+. When stimulation frequency was maintained constant, an increase from 150 to 300 Hz enhanced maximal power (Pmax), maximal velocity (Vmax), and rate of force development (RFD) at 4 mM K+ but only Vmax at 11 mM K+. With the use of subtetanic frequency trains (50 Hz) with or without an initiating doublet (300 Hz), the addition of a doublet increased maximal force, Pmax, Vmax, and RFD at both 4 and 11 mM K+. Furthermore, a work-matched fatiguing protocol was performed comparing a doublet-initiated subtetanic train (DT) of 60 Hz with a constant-frequency train (CFT) of 71 Hz during 100 dynamic contractions. We found that DT produced higher power, velocity, and RFD than CFT throughout the fatiguing protocol. The results indicate that doublets enhance dynamic contraction in fast-twitch muscles stimulated at subtetanic frequency during both normal and fatiguing conditions.
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Affiliation(s)
| | - Ole Bækgaard Nielsen
- Department of Public Health, Aarhus University , Aarhus , Denmark.,Department of Biomedicine, Aarhus University , Aarhus , Denmark
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7
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Bagni MA, Colombini B, Nocella M, Pregno C, S Cornachione A, Rassier DE. The effects of fatigue and oxidation on contractile function of intact muscle fibers and myofibrils isolated from the mouse diaphragm. Sci Rep 2019; 9:4422. [PMID: 30872655 PMCID: PMC6418105 DOI: 10.1038/s41598-019-39353-5] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/10/2018] [Accepted: 01/18/2019] [Indexed: 11/09/2022] Open
Abstract
The goal of this study was to investigate the effects of repetitive stimulation and the oxidant H2O2 on fatigue of diaphragm intact fibers and in myofibrils measured with different Ca2+ concentrations. Intact fibers were isolated from mice diaphragm, and twitch and tetanic contractions (500 ms duration) were performed at different frequencies of stimulation ranging from 15 Hz to 150 Hz to establish a force-frequency relation before and after a fatigue and recovery protocol, without or after a treatment with H2O2. Fatigue was induced with isometric contractions (500 ms, 40 Hz) evoked every 0.8 seconds, with a total of 625 tetani. After the fatigue, the force recovery was followed by invoking tetanic contractions (500 ms, 40 Hz) every 1 min, with a total duration of 30 min. Individual myofibrils were also isolated from the mouse diaphragm and were tested for isometric contractions before and after treatment with H2O2 and NAC. In a second series of experiments, myofibrils were activated at different pCa (pCa = -log10 [Ca2+]), before and after H2O2 treatment. After 15 minutes of H2O2 treatment, the myofibrillar force was decreased to 54 ± 12% of its control, maximal value, and a result that was reversed by NAC treatment. The force was also decreased after myofibrils were treated with H2O2 and activated in pCa ranging between 4.5 and 5.7. These results suggest that fatigue in diaphragm intact fibers and at the myofibrils level is caused partially by oxidation of the contractile proteins that may be responsible for changing the force in various levels of Ca2+ activation.
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Affiliation(s)
- M Angela Bagni
- Dept Experimental and Clinical Medicine, University of Firenze, Florence, Italy
| | - Barbara Colombini
- Dept Experimental and Clinical Medicine, University of Firenze, Florence, Italy
| | - Marta Nocella
- Dept Experimental and Clinical Medicine, University of Firenze, Florence, Italy
| | - Claudio Pregno
- Dept Experimental and Clinical Medicine, University of Firenze, Florence, Italy
| | - Anabelle S Cornachione
- Dept Kinesiology and Physical Education, Faculty of Education, McGill University, Montreal, Canada
| | - Dilson E Rassier
- Dept Kinesiology and Physical Education, Faculty of Education, McGill University, Montreal, Canada.
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8
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Surround inhibition can instantly be modulated by changing the attentional focus. Sci Rep 2018; 8:1085. [PMID: 29348536 PMCID: PMC5773585 DOI: 10.1038/s41598-017-19077-0] [Citation(s) in RCA: 31] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/04/2017] [Accepted: 12/20/2017] [Indexed: 12/05/2022] Open
Abstract
To further investigate the mechanism of surround inhibition (SI) and to determine whether adopting different attentional strategies might have an impact on the modulation of SI, the effects of adopting an external (EF) or internal focus of attention (IF) on SI and motor performance were investigated. While performing an index flexion with either an EF or IF, transcranial magnetic stimulation was applied at various time points in 14 healthy subjects. When adopting an EF compared to an IF, the results show an improved motor performance (+14.7% in MVC) and a reduced bEMG in the adjacent APB (−22.3%) during maximal index flexion. This was accompanied by an increased SI in the APB with an EF (+26.4%). Additionally, the decrease in bEMG correlated with the magnitude of SI in APB. The current results demonstrate an efficient way to modulate SI by changing the attentional focus in healthy subjects and might, at least in part, explain the better motor performance being associated with an EF. The present findings help to better understand the positive mechanisms of an EF on SI in the healthy motor system and may also points towards a treatment strategy in pathologies with disturbed SI such as focal hand dystonia.
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Rodríguez-Rosell D, Pareja-Blanco F, Aagaard P, González-Badillo JJ. Physiological and methodological aspects of rate of force development assessment in human skeletal muscle. Clin Physiol Funct Imaging 2017; 38:743-762. [DOI: 10.1111/cpf.12495] [Citation(s) in RCA: 76] [Impact Index Per Article: 10.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2017] [Accepted: 11/29/2017] [Indexed: 12/22/2022]
Affiliation(s)
- David Rodríguez-Rosell
- Centro de Investigación en Rendimiento Físico y Deportivo, Universidad Pablo de Olavide, Seville, Spain
| | - Fernando Pareja-Blanco
- Centro de Investigación en Rendimiento Físico y Deportivo, Universidad Pablo de Olavide, Seville, Spain
| | - Per Aagaard
- Department of Sports Science and Clinical Biomechanics, SDU Muscle Research Cluster (SMRC), University of Southern Denmark, Odense, Denmark
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Cheng AJ, Neyroud D, Kayser B, Westerblad H, Place N. Intramuscular Contributions to Low-Frequency Force Potentiation Induced by a High-Frequency Conditioning Stimulation. Front Physiol 2017; 8:712. [PMID: 28979214 PMCID: PMC5611669 DOI: 10.3389/fphys.2017.00712] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/26/2017] [Accepted: 09/04/2017] [Indexed: 11/13/2022] Open
Abstract
Electrically-evoked low-frequency (submaximal) force is increased immediately following high-frequency stimulation in human skeletal muscle. Although central mechanisms have been suggested to be the major cause of this low-frequency force potentiation, intramuscular factors might contribute. Thus, we hypothesized that two intramuscular Ca2+-dependent mechanisms can contribute to the low-frequency force potentiation: increased sarcoplasmic reticulum Ca2+ release and increased myofibrillar Ca2+ sensitivity. Experiments in humans were performed on the plantar flexor muscles at a shortened, intermediate, and long muscle length and electrically evoked contractile force and membrane excitability (i.e., M-wave amplitude) were recorded during a stimulation protocol. Low-frequency force potentiation was assessed by stimulating with a low-frequency tetanus (25 Hz, 2 s duration), followed by a high-frequency tetanus (100 Hz, 2 s duration), and finally followed by another low-frequency (25 Hz, 2 s duration) tetanus. Similar stimulation protocols were performed on intact mouse single fibers from flexor digitorum brevis muscle, whereby force and myoplasmic free [Ca2+] ([Ca2+]i) were assessed. Our data show a low-frequency force potentiation that was not muscle length-dependent in human muscle and it was not accompanied by any increase in M-wave amplitude. A length-independent low-frequency force potentiation could be replicated in mouse single fibers, supporting an intramuscular mechanism. We show that at physiological temperature (31°C) this low-frequency force potentiation in mouse fibers corresponded with an increase in sarcoplasmic reticulum (SR) Ca2+ release. When mimicking the slower contractile properties of human muscle by cooling mouse single fibers to 18°C, the low-frequency force potentiation was accompanied by minimally increased SR Ca2+ release and hence it could be explained by increased myofibrillar Ca2+ sensitivity. Finally, introducing a brief 200 ms pause between the high- and low-frequency tetanus in human and mouse muscle revealed that the low-frequency force potentiation is abolished, arguing that increased myofibrillar Ca2+ sensitivity is the main intramuscular mechanism underlying the low-frequency force potentiation in humans.
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Affiliation(s)
- Arthur J Cheng
- Department of Physiology and Pharmacology, Karolinska InstitutetStockholm, Sweden
| | - Daria Neyroud
- Faculty of Biology-Medicine, Institute of Sport Sciences, University of LausanneLausanne, Switzerland.,Department of Physical Therapy, University of Florida Health Science CenterGainesville, FL, United States
| | - Bengt Kayser
- Faculty of Biology-Medicine, Institute of Sport Sciences, University of LausanneLausanne, Switzerland
| | - Håkan Westerblad
- Department of Physiology and Pharmacology, Karolinska InstitutetStockholm, Sweden
| | - Nicolas Place
- Faculty of Biology-Medicine, Institute of Sport Sciences, University of LausanneLausanne, Switzerland
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11
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van Bremen T, Send T, Sasse P, Bruegmann T. Spot light on skeletal muscles: optogenetic stimulation to understand and restore skeletal muscle function. J Muscle Res Cell Motil 2017; 38:331-337. [PMID: 28918572 DOI: 10.1007/s10974-017-9481-9] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/11/2017] [Accepted: 09/07/2017] [Indexed: 02/04/2023]
Abstract
Damage of peripheral nerves results in paralysis of skeletal muscle. Currently, the only treatment option to restore proper function is electrical stimulation of the innervating nerve or of the skeletal muscles directly. However this approach has low spatial and temporal precision leading to co-activation of antagonistic muscles and lacks cell-type selectivity resulting in pain or discomfort by stimulation of sensible nerves. In contrast to electrical stimulation, optogenetic methods enable spatially confined and cell-type selective stimulation of cells expressing the light sensitive channel Channelrhodopsin-2 with precise temporal control over the membrane potential. Herein we summarize the current knowledge about the use of this technology to control skeletal muscle function with the focus on the direct, non-neuronal stimulation of muscle fibers. The high temporal flexibility of using light pulses allows new stimulation patterns to investigate skeletal muscle physiology. Furthermore, the high spatial precision of focused illumination was shown to be beneficial for selective stimulation of distinct nearby muscle groups. Finally, the cell-type specific expression of the light-sensitive effector proteins in muscle fibers will allow pain-free stimulation and open new options for clinical treatments. Therefore, we believe that direct optogenetic stimulation of skeletal muscles is a very potent method for basic scientists that also harbors several distinct advantages over electrical stimulation to be considered for clinical use in the future.
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Affiliation(s)
- Tobias van Bremen
- Department of Otorhinolaryngology/Head and Neck Surgery, University Hospital of Bonn, Sigmund-Freud-Strasse 25, 53127, Bonn, Germany
| | - Thorsten Send
- Department of Otorhinolaryngology/Head and Neck Surgery, University Hospital of Bonn, Sigmund-Freud-Strasse 25, 53127, Bonn, Germany
| | - Philipp Sasse
- Institute of Physiology I, Medical Faculty, University of Bonn, Sigmund-Freud-Strasse 25, 53127, Bonn, Germany.
| | - Tobias Bruegmann
- Institute of Physiology I, Medical Faculty, University of Bonn, Sigmund-Freud-Strasse 25, 53127, Bonn, Germany. .,Research Training Group 1873, University of Bonn, 53127, Bonn, Germany.
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12
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Søgaard K, Sjøgaard G. Physical Activity as Cause and Cure of Muscular Pain: Evidence of Underlying Mechanisms. Exerc Sport Sci Rev 2017; 45:136-145. [PMID: 28418998 PMCID: PMC5473374 DOI: 10.1249/jes.0000000000000112] [Citation(s) in RCA: 46] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 02/08/2017] [Indexed: 01/18/2023]
Abstract
Work-related physical activity (PA), in terms of peak loads and sustained and/or repetitive contractions, presents risk factors for the development of muscular pain and disorders. However, PA as a training tailored to the employee's work exposure, health, and physical capacity offers prevention and rehabilitation. We suggest the concept of "Intelligent Physical Exercise Training" relying on evidence-based sports science training principles.
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Affiliation(s)
- Karen Søgaard
- Department of Sports Science and Clinical Biomechanics, University of Southern Denmark, Odense M, Denmark
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13
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Bakker AJ, Cully TR, Wingate CD, Barclay CJ, Launikonis BS. Doublet stimulation increases Ca 2+ binding to troponin C to ensure rapid force development in skeletal muscle. J Gen Physiol 2017; 149:323-334. [PMID: 28209802 PMCID: PMC5339514 DOI: 10.1085/jgp.201611727] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/17/2016] [Revised: 01/08/2017] [Accepted: 01/09/2017] [Indexed: 01/24/2023] Open
Abstract
Fast-twitch skeletal muscle fibers are often exposed to motor neuron double discharges (≥200 Hz), which markedly increase both the rate of contraction and the magnitude of the resulting force responses. However, the mechanism responsible for these effects is poorly understood, likely because of technical limitations in previous studies. In this study, we measured cytosolic Ca2+ during doublet activation using the low-affinity indicator Mag-Fluo-4 at high temporal resolution and modeled the effects of doublet stimulation on sarcoplasmic reticulum (SR) Ca2+ release, binding of Ca2+ to cytosolic buffers, and force enhancement in fast-twitch fibers. Single isolated fibers respond to doublet pulses with two clear Ca2+ spikes, at doublet frequencies up to 1 KHz. A 200-Hz doublet at the start of a tetanic stimulation train (70 Hz) decreases the drop in free Ca2+ between the first three Ca2+ spikes of the transient, maintaining a higher overall free Ca2+ level during first 20-30 ms of the response. Doublet stimulation also increased the rate of force development in isolated fast-twitch muscles. We also modeled SR Ca2+ release rates during doublet stimulation and showed that Ca2+-dependent inactivation of ryanodine receptor activity is rapid, occurring ≤1ms after initial release. Furthermore, we modeled Ca2+ binding to the main intracellular Ca2+ buffers of troponin C (TnC), parvalbumin, and the SR Ca2+ pump during Ca2+ release and found that the main effect of the second response in the doublet is to more rapidly increase the occupation of the second Ca2+-binding site on TnC (TnC2), resulting in earlier activation of force. We conclude that doublet stimulation maintains high cytosolic Ca2+ levels for longer in the early phase of the Ca2+ response, resulting in faster saturation of TnC2 with Ca2+, faster initiation of cross-bridge cycling, and more rapid force development.
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Affiliation(s)
- Anthony J Bakker
- School of Anatomy, Physiology, and Human Biology, University of Western Australia, Perth, WA 6009, Australia
| | - Tanya R Cully
- School of Biomedical Sciences, University of Queensland, Brisbane, QLD 4072, Australia
| | - Catherine D Wingate
- School of Anatomy, Physiology, and Human Biology, University of Western Australia, Perth, WA 6009, Australia
| | - Christopher J Barclay
- School of Allied Health Sciences, Griffith University, Gold Coast, QLD 4222, Australia
| | - Bradley S Launikonis
- School of Biomedical Sciences, University of Queensland, Brisbane, QLD 4072, Australia
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14
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Moss RL, Lynch TL, Fitzsimons DP. Acting on an impulse (or two): Advantages of high-frequency tetanic onset in skeletal muscle. J Gen Physiol 2017; 149:297-300. [PMID: 28213459 PMCID: PMC5339515 DOI: 10.1085/jgp.201711763] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022] Open
Abstract
Moss et al. highlight why high-frequency bursts at the onset of tetany increase force development in fast-twitch skeletal muscle fibers.
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Affiliation(s)
- Richard L Moss
- Department of Cell and Regenerative Biology, University of Wisconsin School of Medicine and Public Health, Madison, WI 53705
| | - Thomas L Lynch
- Department of Cell and Regenerative Biology, University of Wisconsin School of Medicine and Public Health, Madison, WI 53705
| | - Daniel P Fitzsimons
- Department of Cell and Regenerative Biology, University of Wisconsin School of Medicine and Public Health, Madison, WI 53705
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15
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Leitch M, Macefield VG. Comparison of the ballistic contractile responses generated during microstimulation of single human motor axons with brief irregular and regular stimuli. Muscle Nerve 2016; 56:292-297. [PMID: 27862051 DOI: 10.1002/mus.25473] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/08/2016] [Revised: 11/02/2016] [Accepted: 11/10/2016] [Indexed: 11/10/2022]
Abstract
INTRODUCTION Ballistic contractions are induced by brief, high-frequency (60-100 Hz) trains of action potentials in motor axons. During ramp voluntary contractions, human motoneurons exhibit significant discharge variability of ∼20% and have been shown to be advantageous to the neuromuscular system. We hypothesized that ballistic contractions incorporating discharge variability would generate greater isometric forces than regular trains with zero variability. METHODS High-impedance tungsten microelectrodes were inserted into human fibular nerve, and single motor axons were stimulated with both irregular and constant-frequency stimuli at mean frequencies ranging from 57.8 to 68.9 Hz. RESULTS Irregular trains generated significantly greater isometric peak forces than regular trains over identical mean frequencies. CONCLUSIONS The high forces generated by ballistic contractions are not based solely on high frequencies, but rather a combination of high firing rates and discharge irregularity. It appears that irregular ballistic trains take advantage of the "catchlike property" of muscle, allowing augmentation of force. Muscle Nerve 56: 292-297, 2017.
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Affiliation(s)
- Michael Leitch
- School of Medicine, Western Sydney University, Locked Bag 1797, 183 Narellan Road, Penrith, New South Wales, 2751, Australia
| | - Vaughan G Macefield
- School of Medicine, Western Sydney University, Locked Bag 1797, 183 Narellan Road, Penrith, New South Wales, 2751, Australia
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Maffiuletti NA, Aagaard P, Blazevich AJ, Folland J, Tillin N, Duchateau J. Rate of force development: physiological and methodological considerations. Eur J Appl Physiol 2016; 116:1091-116. [PMID: 26941023 PMCID: PMC4875063 DOI: 10.1007/s00421-016-3346-6] [Citation(s) in RCA: 739] [Impact Index Per Article: 92.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/23/2015] [Accepted: 02/17/2016] [Indexed: 11/26/2022]
Abstract
The evaluation of rate of force development during rapid contractions has recently become quite popular for characterising explosive strength of athletes, elderly individuals and patients. The main aims of this narrative review are to describe the neuromuscular determinants of rate of force development and to discuss various methodological considerations inherent to its evaluation for research and clinical purposes. Rate of force development (1) seems to be mainly determined by the capacity to produce maximal voluntary activation in the early phase of an explosive contraction (first 50–75 ms), particularly as a result of increased motor unit discharge rate; (2) can be improved by both explosive-type and heavy-resistance strength training in different subject populations, mainly through an improvement in rapid muscle activation; (3) is quite difficult to evaluate in a valid and reliable way. Therefore, we provide evidence-based practical recommendations for rational quantification of rate of force development in both laboratory and clinical settings.
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Affiliation(s)
- Nicola A Maffiuletti
- Human Performance Lab, Schulthess Clinic, Lengghalde 6, 8008, Zurich, Switzerland.
| | - Per Aagaard
- Department of Sports Science and Clinical Biomechanics, SDU Muscle Research Cluster (SMRC), University of Southern Denmark, Odense, Denmark
| | - Anthony J Blazevich
- Centre for Exercise and Sports Science Research (CESSR), School of Medical and Health Sciences, Edith Cowan University, Joondalup, Australia
| | - Jonathan Folland
- School of Sport, Exercise and Health Sciences, Loughborough University, Loughborough, UK
| | - Neale Tillin
- Department of Life Sciences, University of Roehampton, London, UK
| | - Jacques Duchateau
- Laboratory of Applied Biology, ULB Neurosciences Institute, Université Libre de Bruxelles (ULB), Brussels, Belgium
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Mayfield DL, Lichtwark GA, Cronin NJ, Avela J, Cresswell AG. Doublet potentiation in the triceps surae is limited by series compliance and dynamic fascicle behavior. J Appl Physiol (1985) 2015; 119:807-16. [DOI: 10.1152/japplphysiol.00403.2015] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/26/2015] [Accepted: 08/03/2015] [Indexed: 11/22/2022] Open
Abstract
Activation of skeletal muscle twice in quick succession results in nonlinear force summation (i.e., doublet potentiation). The force contributed by a second activation is typically of augmented amplitude, longer in duration, and generated at a greater rate. The purpose of this study was to examine force summation in a muscle attached to a compliant tendon, where considerable internal shortening occurs during a fixed-end contraction. The triceps surae of 21 ( Experiment 1) and 9 ( Experiment 2) young adults were maximally activated with doublet stimulation of different interstimulus intervals (ISIs) (5-100 ms) at several muscle lengths. Ultrasound images acquired from lateral gastrocnemius and soleus muscles allowed quantification of dynamic fascicle behavior. Force summation was muscle length dependent. Force augmentation was limited to a short muscle length. Lateral gastrocnemius and soleus fascicles underwent large amounts of active shortening and achieved high velocities in response to doublet stimulation, dynamics unfavorable for force production. Summation amplitude and the sensitivity of summation to ISI were dramatically depressed in the triceps surae after comparison to muscles with less fixed-end compliance. We propose that the internal shortening permitted by high series compliance limited force augmentation by offsetting and/or interfering with activation and cross-bridge processes driving augmentation. High series compliance may also reduce the sensitivity of the summated response to ISI, an assertion supported by predictions from a Hill-type muscle model. These muscles may exhibit greater force augmentation during more accustomed stretch-shorten tasks (i.e., hopping), where the compliance of the Achilles tendon actually enables near-isometric fascicle behavior.
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Affiliation(s)
- Dean L. Mayfield
- School of Human Movement and Nutrition Sciences, The University of Queensland, Brisbane, Australia
| | - Glen A. Lichtwark
- School of Human Movement and Nutrition Sciences, The University of Queensland, Brisbane, Australia
| | - Neil J. Cronin
- Department of Biology of Physical Activity, University of Jyväskylä, Jyväskylä, Finland
| | - Janne Avela
- Department of Biology of Physical Activity, University of Jyväskylä, Jyväskylä, Finland
| | - Andrew G. Cresswell
- School of Human Movement and Nutrition Sciences, The University of Queensland, Brisbane, Australia
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Catania KC. An Optimized Biological Taser: Electric Eels Remotely Induce or Arrest Movement in Nearby Prey. BRAIN, BEHAVIOR AND EVOLUTION 2015; 86:38-47. [PMID: 26398438 DOI: 10.1159/000435945] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
Despite centuries of interest in electric eels, few studies have investigated the mechanism of the eel's attack. Here, I review and extend recent findings that show eel electric high-voltage discharges activate prey motor neuron efferents. This mechanism allows electric eels to remotely control their targets using two different strategies. When nearby prey have been detected, eels emit a high-voltage volley that causes whole-body tetanus in the target, freezing all voluntary movement and allowing the eel to capture the prey with a suction feeding strike. When hunting for cryptic prey, eels emit doublets and triplets, inducing whole-body twitch in prey, which in turn elicits an immediate eel attack with a full volley and suction feeding strike. Thus, by using their modified muscles (electrocytes) as amplifiers of their own motor efferents, eel's motor neurons remotely activate prey motor neurons to cause movement (twitch and escape) or immobilization (tetanus) facilitating prey detection and capture, respectively. These results explain reports that human movement is 'frozen' by eel discharges and shows the mechanism to resemble a law-enforcement Taser.
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Affiliation(s)
- Kenneth C Catania
- Department of Biological Sciences, Vanderbilt University, Nashville, Tenn., USA
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Kim H, Sandercock TG, Heckman CJ. An action potential-driven model of soleus muscle activation dynamics for locomotor-like movements. J Neural Eng 2015; 12:046025. [PMID: 26087477 PMCID: PMC4870066 DOI: 10.1088/1741-2560/12/4/046025] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
OBJECTIVE The goal of this study was to develop a physiologically plausible, computationally robust model for muscle activation dynamics (A(t)) under physiologically relevant excitation and movement. APPROACH The interaction of excitation and movement on A(t) was investigated comparing the force production between a cat soleus muscle and its Hill-type model. For capturing A(t) under excitation and movement variation, a modular modeling framework was proposed comprising of three compartments: (1) spikes-to-[Ca(2+)]; (2) [Ca(2+)]-to-A; and (3) A-to-force transformation. The individual signal transformations were modeled based on physiological factors so that the parameter values could be separately determined for individual modules directly based on experimental data. MAIN RESULTS The strong dependency of A(t) on excitation frequency and muscle length was found during both isometric and dynamically-moving contractions. The identified dependencies of A(t) under the static and dynamic conditions could be incorporated in the modular modeling framework by modulating the model parameters as a function of movement input. The new modeling approach was also applicable to cat soleus muscles producing waveforms independent of those used to set the model parameters. SIGNIFICANCE This study provides a modeling framework for spike-driven muscle responses during movement, that is suitable not only for insights into molecular mechanisms underlying muscle behaviors but also for large scale simulations.
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Affiliation(s)
- Hojeong Kim
- Division of Robotics Research, Daegu Gyeongbuk Institute of Science & Technology, Daegu 711-873, Korea
- Department of Physiology, Northwestern University Feinberg School of Medicine, Chicago 60611, USA
| | - Thomas G. Sandercock
- Department of Physiology, Northwestern University Feinberg School of Medicine, Chicago 60611, USA
| | - C. J. Heckman
- Department of Physiology, Northwestern University Feinberg School of Medicine, Chicago 60611, USA
- Department of Physical Medicine and Rehabilitation, and Physical Therapy and Human Movement Science, Northwestern University Feinberg School of Medicine, Chicago 60611, USA
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Mrówczyński W, Celichowski J, Raikova R, Krutki P. Physiological consequences of doublet discharges on motoneuronal firing and motor unit force. Front Cell Neurosci 2015; 9:81. [PMID: 25805972 PMCID: PMC4354388 DOI: 10.3389/fncel.2015.00081] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/28/2014] [Accepted: 02/23/2015] [Indexed: 11/13/2022] Open
Abstract
The double discharges are observed at the onset of contractions of mammalian motor units (MUs), especially during their recruitment to strong or fast movements. Doublets lead to MU force increase and improve ability of muscles to maintain high force during prolonged contractions. In this review we discuss an ability to produce doublets by fast and slow motoneurons (MNs), their influence on the course of action potential afterhyperpolarization (AHP) as well as its role in modulation of the initial stage of the firing pattern of MNs. In conclusion, a generation of doublets is an important strategy of motor control, responsible for fitting the motoneuronal firing rate to the optimal for MUs at the start of their contraction, necessary for increment of muscle force.
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Affiliation(s)
| | - Jan Celichowski
- Department of Neurobiology, University School of Physical Education Poznań, Poland
| | - Rositsa Raikova
- Institute of Biophysics and Biomedical Engineering, Bulgarian Academy of Sciences Sofia, Bulgaria
| | - Piotr Krutki
- Department of Neurobiology, University School of Physical Education Poznań, Poland
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Watanabe D, Kanzaki K, Kuratani M, Matsunaga S, Yanaka N, Wada M. Contribution of impaired myofibril and ryanodine receptor function to prolonged low-frequency force depression after in situ stimulation in rat skeletal muscle. J Muscle Res Cell Motil 2015; 36:275-86. [DOI: 10.1007/s10974-015-9409-1] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/06/2014] [Accepted: 02/12/2015] [Indexed: 01/21/2023]
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Abstract
Electric eels can incapacitate prey with an electric discharge, but the mechanism of the eel's attack is unknown. Through a series of experiments, I show that eel high-voltage discharges can activate prey motor neurons, and hence muscles, allowing eels to remotely control their target. Eels prevent escape in free-swimming prey using high-frequency volleys to induce immobilizing whole-body muscle contraction (tetanus). Further, when prey are hidden, eels can emit periodic volleys of two or three discharges that cause massive involuntary twitch, revealing the prey's location and eliciting the full, tetanus-inducing volley. The temporal patterns of eel electrical discharges resemble motor neuron activity that induces fast muscle contraction, suggesting that eel high-voltage volleys have been selected to most efficiently induce involuntary muscle contraction in nearby animals.
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Affiliation(s)
- Kenneth Catania
- Department of Biological Sciences, Vanderbilt University, VU Station B, Box 35-1634, Nashville, TN 37235, USA.E-mail:
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23
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Søgaard K, Olsen HB, Blangsted AK, Sjøgaard G. Single motor unit firing behavior in the right trapezius muscle during rapid movement of right or left index finger. Front Hum Neurosci 2014; 8:881. [PMID: 25404907 PMCID: PMC4217388 DOI: 10.3389/fnhum.2014.00881] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2014] [Accepted: 10/13/2014] [Indexed: 11/15/2022] Open
Abstract
Background: Computer work is associated with low level sustained activity in the trapezius muscle that may cause development of trapezius myalgia. Such a low level activity may be attention related or alternatively, be part of a general multi joint motor program providing stabilization of the shoulder joint as a biomechanical prerequisite for precise finger manipulation. This study examines single motor unit (MU) firing pattern in the right trapezius muscle during fast movements of ipsilateral or contralateral index finger. A modulation of the MU firing rate would support the existence of a general multi joint motor program, while a generally increased and continuous firing rate would support the attention related muscle activation. Method: Twelve healthy female subjects were seated at a computer work place with elbows and forearms supported. Ten double clicks (DC) were performed with right and left index finger on a computer mouse instrumented with a trigger. Surface electromyographic signals (EMG) was recorded from right and left trapezius muscle. Intramuscular EMG was recorded with a quadripolar wire electrode inserted into the right trapezius. Surface EMG was analyzed as RMS and presented as %MVE. The intramuscular EMG signals were decomposed into individual MU action potential trains using a computer algorithm based on signal shape recognition and manual editing. Instantaneous firing rate (IFR) was calculated as the inverse of each inter-spike interval (ISI). All ISI shorter than 20 ms were defined as doublets. For all MU IFR was spike triggered averaged across the 10 DC to show the modulation during DC as well as for calculation of the cross correlation coefficient (CCC). Results: All subjects showed surface EMG activity in both right and left trapezius ranging from 1.8 %MVE to 2.5 %MVE. Regarding intramuscular EMG during right hand DC a total of 32 MUs were identified. Four subjects showed no MU activity. Four showed MU activity with low mean firing rate (MFR) with weak or no variations related to the timing of DC. Four subjects showed firing patterns with large modulation in IFR with a clear temporal relation to the DC. During left hand DC 15 MUs were identified in four subjects, for two of the subjects with IFR modulations clearly related to DC. During both ipsi- and contralateral DC, doublets occurred sporadically as well as related to DC Conclusion: In conclusion, DC with ipsi- and contralateral fast movements of the index finger was found to evoke biomechanically as well as attention related activity pattern in the trapezius muscle. Doublets were for three of the subjects found as an integrated part of MU activation in the trapezius muscle and for one subject temporarily related to DC.
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Affiliation(s)
- Karen Søgaard
- Department of Sports Science and Clinical Biomechanics, University of Southern Denmark, Odense Denmark
| | - Henrik B Olsen
- Department of Sports Science and Clinical Biomechanics, University of Southern Denmark, Odense Denmark
| | | | - Gisela Sjøgaard
- Department of Sports Science and Clinical Biomechanics, University of Southern Denmark, Odense Denmark
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