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Lanfranchi C, Rodriguez-Falces J, Place N. The first and second phases of the muscle compound action potential in the thumb are differently affected by electrical stimulation trains. J Appl Physiol (1985) 2024; 136:1122-1128. [PMID: 38511213 DOI: 10.1152/japplphysiol.00861.2023] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/29/2023] [Revised: 03/11/2024] [Accepted: 03/14/2024] [Indexed: 03/22/2024] Open
Abstract
Sarcolemmal membrane excitability is often evaluated by considering the peak-to-peak amplitude of the compound muscle action potential (M wave). However, the first and second M-wave phases represent distinct properties of the muscle action potential, which are differentially affected by sarcolemma properties and other factors such as muscle architecture. Contrasting with previous studies in which voluntary contractions have been used to induce muscle fatigue, we used repeated electrically induced tetanic contractions of the adductor pollicis muscle and assessed the kinetics of M-wave properties during the course of the contractions. Eighteen participants (24 ± 6 yr; means ± SD) underwent 30 electrically evoked tetanic contractions delivered at 30 Hz, each lasting 3 s with 1 s intervals. We recorded the amplitudes of the first and second M-wave phases for each stimulation. During the initial stimulation train, the first and second M-wave phases exhibited distinct kinetics. The first phase amplitude showed a rapid decrease to reach ∼59% of its initial value (P < 0.001), whereas the second phase amplitude displayed an initial transient increase of ∼19% (P = 0.007). Within subsequent trains, both the first and second phase amplitudes consistently decreased as fatigue developed with a reduction during the last train reaching ∼47% of its initial value (P < 0.001). Analyzing the first M wave of each stimulation train unveiled different kinetics for the first and second phases during the initial trains, but these distinctions disappeared as fatigue progressed. These findings underscore the interplay of factors affecting the M wave and emphasize the significance of separately scrutinizing its first and second phases when assessing membrane excitability adjustments during muscle contractions.NEW & NOTEWORTHY Our understanding of how the first and second phases of the compound muscle action potential (M wave) behave during fatigue remains incomplete. Using electrically evoked repeated tetanic contractions of the adductor pollicis, we showed that the first and second phases of the M wave followed distinct kinetics only during the early stages of fatigue development. This suggests that the factors affecting the M-wave first and second phases may change as fatigue develops.
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Affiliation(s)
- Clément Lanfranchi
- Institute of Sport Sciences, University of Lausanne, Lausanne, Switzerland
| | - Javier Rodriguez-Falces
- Department of Electrical and Electronical Engineering, Public University of Navarra, Pamplona, Spain
| | - Nicolas Place
- Institute of Sport Sciences, University of Lausanne, Lausanne, Switzerland
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Barbi C, Temesi J, Giuriato G, Laginestra FG, Martignon C, Moro T, Schena F, Venturelli M, Vernillo G. Skeletal muscle fiber type and TMS-induced muscle relaxation in unfatigued and fatigued knee-extensor muscles. Am J Physiol Regul Integr Comp Physiol 2024; 326:R438-R447. [PMID: 38525536 DOI: 10.1152/ajpregu.00174.2023] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/14/2023] [Revised: 03/14/2024] [Accepted: 03/15/2024] [Indexed: 03/26/2024]
Abstract
The force drop after transcranial magnetic stimulation (TMS) delivered to the motor cortex during voluntary muscle contractions could inform about muscle relaxation properties. Because of the physiological relation between skeletal muscle fiber-type distribution and size and muscle relaxation, TMS could be a noninvasive index of muscle relaxation in humans. By combining a noninvasive technique to record muscle relaxation in vivo (TMS) with the gold standard technique for muscle tissue sampling (muscle biopsy), we investigated the relation between TMS-induced muscle relaxation in unfatigued and fatigued states, and muscle fiber-type distribution and size. Sixteen participants (7F/9M) volunteered to participate. Maximal knee-extensor voluntary isometric contractions were performed with TMS before and after a 2-min sustained maximal voluntary isometric contraction. Vastus lateralis muscle tissue was obtained separately from the participants' dominant limb. Fiber type I distribution and relative cross-sectional area of fiber type I correlated with TMS-induced muscle relaxation at baseline (r = 0.67, adjusted P = 0.01; r = 0.74, adjusted P = 0.004, respectively) and normalized TMS-induced muscle relaxation as a percentage of baseline (r = 0.50, adjusted P = 0.049; r = 0.56, adjusted P = 0.031, respectively). The variance in the normalized peak relaxation rate at baseline (59.8%, P < 0.001) and in the fatigue resistance (23.0%, P = 0.035) were explained by the relative cross-sectional area of fiber type I to total fiber area. Fiber type I proportional area influences TMS-induced muscle relaxation, suggesting TMS as an alternative method to noninvasively inform about skeletal muscle relaxation properties.NEW & NOTEWORTHY Transcranial magnetic stimulation (TMS)-induced muscle relaxation reflects intrinsic muscle contractile properties by interrupting the drive from the central nervous system during voluntary muscle contractions. We showed that fiber type I proportional area influences the TMS-induced muscle relaxation, suggesting that TMS could be used for the noninvasive estimation of muscle relaxation in unfatigued and fatigued human muscles when the feasibility of more direct method to study relaxation properties (i.e., muscle biopsy) is restricted.
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Affiliation(s)
- Chiara Barbi
- Department of Neurosciences, Biomedicine and Movement Sciences, University of Verona, Verona, Italy
| | - John Temesi
- Faculty of Health and Life Sciences, Northumbria University, Newcastle upon Tyne, United Kingdom
| | - Gaia Giuriato
- Department of Neurosciences, Biomedicine and Movement Sciences, University of Verona, Verona, Italy
- Surgical, Medical and Dental Department of Morphological Sciences Related to Transplant, Oncology and Regenerative Medicine, University of Modena and Reggio Emilia, Modena, Italy
| | | | - Camilla Martignon
- Department of Neurosciences, Biomedicine and Movement Sciences, University of Verona, Verona, Italy
| | - Tatiana Moro
- Department of Biomedical Sciences, University of Padua, Padua, Italy
| | - Federico Schena
- Department of Neurosciences, Biomedicine and Movement Sciences, University of Verona, Verona, Italy
| | - Massimo Venturelli
- Department of Neurosciences, Biomedicine and Movement Sciences, University of Verona, Verona, Italy
- Department of Internal Medicine, University of Utah, Salt Lake City, Utah, United States
| | - Gianluca Vernillo
- Department of Biomedical Sciences for Health, Università degli Studi di Milano, Milan, Italy
- Department of Social Sciences, University of Alberta, Camrose, Alberta, Canada
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Farina D, Gandevia S. The neural control of movement: a century of in vivo motor unit recordings is the legacy of Adrian and Bronk. J Physiol 2024; 602:281-295. [PMID: 38059891 PMCID: PMC10952757 DOI: 10.1113/jp285319] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/18/2023] [Accepted: 11/24/2023] [Indexed: 12/08/2023] Open
Abstract
In two papers dated 1928 to 1929 in The Journal of Physiology, Edgar Adrian and Detlev Bronk described recordings from motor nerve and muscle fibres. The recordings from motor nerve fibres required progressive dissection of the nerve until a few fibres remained, from which isolated single fibre activity could be detected. The muscle fibre recordings were performed in humans during voluntary contractions with an intramuscular electrode - the concentric needle electrode - that they describe for the first time in the second paper. They recognised that muscle fibres would respond to each impulse sent by the innervating motor neurone and that therefore muscle fibre recordings provided information on the times of activation of the motor nerve fibres which were as accurate as a direct record from the nerve. These observations and the description of the concentric needle electrode opened the era of motor unit recordings in humans, which have continued for almost a century and have provided a comprehensive view of the neural control of movement at the motor unit level. Despite important advances in technology, many of the principles of motor unit behaviour that would be investigated in the subsequent decades were canvassed in the two papers by Adrian and Bronk. For example, they described the concomitant motor neurones' recruitment and rate coding for force modulation, synchronisation of motor unit discharges, and the dependence of discharge rate on motor unit recruitment threshold. Here, we summarise their observations and discuss the impact of their work. We highlight the advent of the concentric needle, and its subsequent influence on motor control research.
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Affiliation(s)
- Dario Farina
- Department of BioengineeringImperial College LondonLondonUK
| | - Simon Gandevia
- Neuroscience Research AustraliaSydney and University of New South WalesSydneyAustralia
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Zero AM, Fanous J, Rice CL. Acute and prolonged competing effects of activation history on human motor unit firing rates during contractile impairment and recovery. J Physiol 2023; 601:5689-5703. [PMID: 37962903 DOI: 10.1113/jp285189] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/22/2023] [Accepted: 10/26/2023] [Indexed: 11/15/2023] Open
Abstract
The purpose of this study was to investigate the effect of inducing post-activation potentiation (PAP) during prolonged low-frequency force depression (PLFFD) on motor unit (MU) firing rates. In 10 participants, grouped firing rates of 3027 MUs from the tibialis anterior were recorded with tungsten microelectrodes. Baseline MU firing rates at 25% isometric maximal voluntary contraction (MVC) were ∼14 Hz. A 1 min dorsiflexion MVC reduced torque and maximal MU firing rates (36 Hz) by 49% and 52%, respectively. Following task completion, firing rates at 25% of baseline MVC torque and torque in response to electrically evoked (single twitch, 10 Hz and 50 Hz) stimulation were assessed before and after a 5 s MVC (to induce PAP) every 10 min for 60 min. From 10 to 60 min after task completion, the torque ratios (twitch:50 Hz and 10:50 Hz) were depressed (∼30%) relative to baseline (P < 0.001), indicating PLFFD; and firing rates were higher by ∼15% relative to baseline (P < 0.001). This occurred despite recovery of MVC rates (∼99%) and torque (∼95%) by 10 min (P > 0.3). Inducing PAP during PLFFD increased both low to high torque ratios (twitch and 10:50 Hz) by ∼200% and ∼135%, respectively (P < 0.001) and firing rates were ∼18% lower relative to PLFFD rates (P < 0.001), despite a speeding of evoked contractile properties (P = 0.001). Thus, firing rates appear strongly matched to alterations in torque, rather than contractile speed when modified by contractile history, and lower rates during PAP may be a mechanism to mitigate effects of PLFFD. The effect of activation history on contractile function demonstrates acute compensatory responses of motoneuron output. KEY POINTS: Prolonged low frequency force depression (PLFFD) following a sustained 1 min isometric maximal voluntary contraction causes an increase in submaximal mean motor unit (MU) firing rates. Inducing post-activation potentiation (PAP) during PLFFD, however, causes a reduction in mean submaximal MU firing rates to a level below those at baseline. The mean firing rate reduction during PAP occurs despite a speeding of evoked contractile properties and thus firing rates are more strongly matched to alterations in torque, rather than contractile speed when modified by various contractile histories. The reductions in firing rates during PAP may mitigate the effects of PLFFD during voluntary contractions. These results demonstrate that firing rates are highly responsive to opposing influences on the contractile state and can make rapid compensatory rate adjustments dependent on the active state of the muscle.
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Affiliation(s)
- Alexander M Zero
- School of Kinesiology, Faculty of Health Sciences, University of Western Ontario, London, Ontario, Canada
| | - Jacob Fanous
- School of Kinesiology, Faculty of Health Sciences, University of Western Ontario, London, Ontario, Canada
| | - Charles L Rice
- School of Kinesiology, Faculty of Health Sciences, University of Western Ontario, London, Ontario, Canada
- Department of Anatomy and Cell Biology, Schulich School of Medicine, and Dentistry, University of Western Ontario, London, Ontario, Canada
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Lowe TW, Tenan MS, Shah K, Griffin L. Low-load blood flow restriction reduces time-to-minimum single motor unit discharge rate. Exp Brain Res 2023; 241:2795-2805. [PMID: 37874365 DOI: 10.1007/s00221-023-06720-8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/16/2023] [Accepted: 10/04/2023] [Indexed: 10/25/2023]
Abstract
Resistance training with low loads in combination with blood flow restriction (BFR) facilitates increases in muscle size and strength comparable with high-intensity exercise. We investigated the effects of BFR on single motor unit discharge behavior throughout a sustained low-intensity isometric contraction. Ten healthy individuals attended two experimental sessions: one with, the other without, BFR. Motor unit discharge rates from the tibialis anterior (TA) were recorded with intramuscular fine-wire electrodes throughout the duration of a sustained fatigue task. Three 5-s dorsiflexion maximal voluntary contractions (MVC) were performed before and after the fatigue task. Each participant held a target force of 20% MVC until endurance limit. A significant decrease in motor unit discharge rate was observed in both the non-BFR condition (from 13.13 ± 0.87 Hz to 11.95 ± 0.43 Hz, P = 0.03) and the BFR condition (from 12.95 ± 0.71 Hz to 10.9 ± 0.75 Hz, P = 0.03). BFR resulted in significantly shorter endurance time and time-to-minimum discharge rates and greater end-stage motor unit variability. Thus, low-load BFR causes an immediate steep decline in motor unit discharge rate that is greater than during contractions performed without BFR. This shortened neuromuscular response of time-to-minimum discharge rate likely contributes to the rapid rate of neuromuscular fatigue observed during BFR.
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Affiliation(s)
- Timothy W Lowe
- Paul M. Rady Department of Mechanical Engineering, University of Colorado Boulder, Boulder, CO, USA
| | - Matthew S Tenan
- The Blanchette Rockefeller Neuroscience Institute, West Virginia University, Morgantown, WV, USA
| | - Kena Shah
- Select Physical Therapy, Spring, TX, USA
| | - Lisa Griffin
- Department of Kinesiology and Health Education, The University of Texas at Austin, 1University Station, D3700, Austin, TX, 78712, USA.
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Renaud JM, Ørtenblad N, McKenna MJ, Overgaard K. Exercise and fatigue: integrating the role of K +, Na + and Cl - in the regulation of sarcolemmal excitability of skeletal muscle. Eur J Appl Physiol 2023; 123:2345-2378. [PMID: 37584745 PMCID: PMC10615939 DOI: 10.1007/s00421-023-05270-9] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/07/2023] [Accepted: 06/29/2023] [Indexed: 08/17/2023]
Abstract
Perturbations in K+ have long been considered a key factor in skeletal muscle fatigue. However, the exercise-induced changes in K+ intra-to-extracellular gradient is by itself insufficiently large to be a major cause for the force decrease during fatigue unless combined to other ion gradient changes such as for Na+. Whilst several studies described K+-induced force depression at high extracellular [K+] ([K+]e), others reported that small increases in [K+]e induced potentiation during submaximal activation frequencies, a finding that has mostly been ignored. There is evidence for decreased Cl- ClC-1 channel activity at muscle activity onset, which may limit K+-induced force depression, and large increases in ClC-1 channel activity during metabolic stress that may enhance K+ induced force depression. The ATP-sensitive K+ channel (KATP channel) is also activated during metabolic stress to lower sarcolemmal excitability. Taking into account all these findings, we propose a revised concept in which K+ has two physiological roles: (1) K+-induced potentiation and (2) K+-induced force depression. During low-moderate intensity muscle contractions, the K+-induced force depression associated with increased [K+]e is prevented by concomitant decreased ClC-1 channel activity, allowing K+-induced potentiation of sub-maximal tetanic contractions to dominate, thereby optimizing muscle performance. When ATP demand exceeds supply, creating metabolic stress, both KATP and ClC-1 channels are activated. KATP channels contribute to force reductions by lowering sarcolemmal generation of action potentials, whilst ClC-1 channel enhances the force-depressing effects of K+, thereby triggering fatigue. The ultimate function of these changes is to preserve the remaining ATP to prevent damaging ATP depletion.
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Affiliation(s)
- Jean-Marc Renaud
- Faculty of Medicine, Department of Cellular and Molecular Medicine, University of Ottawa, 451 Smyth Rd., Ottawa, ON, K1H 8M5, Canada.
| | - Niels Ørtenblad
- Department of Sports Science and Clinical Biomechanics, University of Southern Denmark, Odense, Denmark
| | - Michael J McKenna
- Institute for Health and Sport, Victoria University, Melbourne, VIC, 8001, Australia
- College of Physical Education, Southwest University, Chongqing, China
- College of Sport Science, Zhuhai College of Science and Technology, Zhuhai, China
| | - Kristian Overgaard
- Exercise Biology, Department of Public Health, Aarhus University, Aarhus, Denmark
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Silva G, Goethel M, Machado L, Sousa F, Costa MJ, Magalhães P, Silva C, Midão M, Leite A, Couto S, Silva R, Vilas-Boas JP, Fernandes RJ. Acute Recovery after a Fatigue Protocol Using a Recovery Sports Legging: An Experimental Study. SENSORS (BASEL, SWITZERLAND) 2023; 23:7634. [PMID: 37688089 PMCID: PMC10490679 DOI: 10.3390/s23177634] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/06/2023] [Revised: 08/18/2023] [Accepted: 08/31/2023] [Indexed: 09/10/2023]
Abstract
Enhancing recovery is a fundamental component of high-performance sports training since it enables practitioners to potentiate physical performance and minimise the risk of injuries. Using a new sports legging embedded with an intelligent system for electrostimulation, localised heating and compression (completely embodied into the textile structures), we aimed to analyse acute recovery following a fatigue protocol. Surface electromyography- and torque-related variables were recorded on eight recreational athletes. A fatigue protocol conducted in an isokinetic dynamometer allowed us to examine isometric torque and consequent post-exercise acute recovery after using the sports legging. Regarding peak torque, no differences were found between post-fatigue and post-recovery assessments in any variable; however, pre-fatigue registered a 16% greater peak torque when compared with post-fatigue for localised heating and compression recovery methods. Our data are supported by recent meta-analyses indicating that individual recovery methods, such as localised heating, electrostimulation and compression, are not effective to recover from a fatiguing exercise. In fact, none of the recovery methods available through the sports legging tested was effective in acutely recovering the torque values produced isometrically.
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Affiliation(s)
- Gonçalo Silva
- Porto Biomechanics Laboratory (LABIOMEP-UP), University of Porto, 4200-450 Porto, Portugal; (G.S.)
- Faculty of Sport (CIFI2D), University of Porto, 4099-002 Porto, Portugal
| | - Márcio Goethel
- Porto Biomechanics Laboratory (LABIOMEP-UP), University of Porto, 4200-450 Porto, Portugal; (G.S.)
- Faculty of Sport (CIFI2D), University of Porto, 4099-002 Porto, Portugal
| | - Leandro Machado
- Porto Biomechanics Laboratory (LABIOMEP-UP), University of Porto, 4200-450 Porto, Portugal; (G.S.)
- Faculty of Sport (CIFI2D), University of Porto, 4099-002 Porto, Portugal
| | - Filipa Sousa
- Porto Biomechanics Laboratory (LABIOMEP-UP), University of Porto, 4200-450 Porto, Portugal; (G.S.)
- Faculty of Sport (CIFI2D), University of Porto, 4099-002 Porto, Portugal
| | - Mário Jorge Costa
- Porto Biomechanics Laboratory (LABIOMEP-UP), University of Porto, 4200-450 Porto, Portugal; (G.S.)
- Faculty of Sport (CIFI2D), University of Porto, 4099-002 Porto, Portugal
| | - Pedro Magalhães
- Tintex Textiles S.A., 4924-909 Viana do Castelo, Portugal; (P.M.); (C.S.)
| | - Carlos Silva
- Tintex Textiles S.A., 4924-909 Viana do Castelo, Portugal; (P.M.); (C.S.)
| | - Marta Midão
- Centre of Nanotechnology and Smart Materials, 4760-034 Vila Nova de Famalicão, Portugal
| | - André Leite
- Centre of Nanotechnology and Smart Materials, 4760-034 Vila Nova de Famalicão, Portugal
| | | | | | - João Paulo Vilas-Boas
- Porto Biomechanics Laboratory (LABIOMEP-UP), University of Porto, 4200-450 Porto, Portugal; (G.S.)
- Faculty of Sport (CIFI2D), University of Porto, 4099-002 Porto, Portugal
| | - Ricardo Jorge Fernandes
- Porto Biomechanics Laboratory (LABIOMEP-UP), University of Porto, 4200-450 Porto, Portugal; (G.S.)
- Faculty of Sport (CIFI2D), University of Porto, 4099-002 Porto, Portugal
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Laidlaw R, Vandenboom R. Posttetanic potentiation improves neuromuscular efficiency of mouse muscle in vitro. Physiol Rep 2022; 10:e15529. [PMID: 36461650 PMCID: PMC9718938 DOI: 10.14814/phy2.15529] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/23/2022] [Revised: 10/31/2022] [Accepted: 11/11/2022] [Indexed: 12/04/2022] Open
Abstract
Neuromuscular efficiency is defined as the ratio of work output to stimulation rate. The purpose of these experiments was to test the hypothesis that neuromuscular efficiency would be increased in proportion to posttetanic potentiation, that is, the stimulation-induced increase in work output displayed by rodent fast-twitch muscle. To this end, extensor digitorum longus muscles from wild-type and skeletal myosin light chain kinase knockout (skMLCK-/- ) mice were surgically isolated and suspended in vitro (25°C). Concentric force development during shortening at 70% of maximal unloaded shortening velocity was tested at stimulus frequencies between 10 and 80 Hz both before and after a potentiating tetanus. A strong genotype-dependent difference in the potentiation of concentric work output was observed; concentric work output of wild-type muscles was increased by 51%-88% while that of skMLCK-/- muscles was increased by only 20%-34% across the frequencies tested. As a result, comparison of work - frequency plots revealed that the frequency required for peak and 50% peak unpotentiated work of wild-type muscles was decreased from ~80 to 52 Hz and from ~48 to 21 Hz, respectively. By contrast, the frequency required for peak and 50% peak unpotentiated work of skMLCK-/- muscles was decreased from ~80 to 68 Hz and from ~51 to 41 Hz, respectively. Thus, wild-type muscles with the ability to phosphorylate myosin displayed larger increases in neuromuscular efficiency than skMLCK-/- muscles (25-30 vs 10-15 Hz, respectively). This suggests that the presence of myosin phosphorylation may ameliorate or mitigate fatigue mechanisms associated with high-frequency stimulation rates.
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Affiliation(s)
- Ryan Laidlaw
- Department of KinesiologyFaculty of Applied Health Sciences, Center of Bone and Muscle HealthSt. Catharine'sOntarioCanada
| | - Rene Vandenboom
- Department of KinesiologyFaculty of Applied Health Sciences, Center of Bone and Muscle HealthSt. Catharine'sOntarioCanada
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Lulic-Kuryllo T, Greig Inglis J. Sex differences in motor unit behaviour: A review. J Electromyogr Kinesiol 2022; 66:102689. [DOI: 10.1016/j.jelekin.2022.102689] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/14/2021] [Revised: 07/28/2022] [Accepted: 07/29/2022] [Indexed: 10/15/2022] Open
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10
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Beltran Martinez K, Nazarahari M, Rouhani H. K-score: A novel scoring system to quantify fatigue-related ergonomic risk based on joint angle measurements via wearable inertial measurement units. APPLIED ERGONOMICS 2022; 102:103757. [PMID: 35378482 DOI: 10.1016/j.apergo.2022.103757] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/21/2021] [Revised: 02/21/2022] [Accepted: 03/27/2022] [Indexed: 06/14/2023]
Abstract
Work-related musculoskeletal disorders have been recognized as a global problem that affects millions of people annually. Fatigue is one of the main contributors to musculoskeletal disorders. Thus, this study investigated fatigue detection based on the measured body motion by wearable inertial measurement units. We quantified the body motion during manual handling tasks using a novel kinematic score (i.e., K-score), and the Rapid Entire Body Assessment (REBA). K-score and REBA were calculated using joint angles. Nevertheless, unlike REBA, K-score showed a significant correlation (Spearman's correlation coefficient of ρ(302) = 0.21, p < 0.05) with electromyography (EMG) signal amplitude, which was affected by muscle fatigue. Therefore, in-field measurement of K-score using inertial measurement units could detect the fatigue-induced change of body motion in long-duration manual handling tasks. Our proposed K-score can be used to assess fatigue-related ergonomic risk in long-term and real-world working conditions without the need for tedious EMG recording at workplaces.
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Affiliation(s)
- Karla Beltran Martinez
- Department of Mechanical Engineering, University of Alberta, Donadeo Innovation Centre for Engineering, Edmonton, Alberta, T6G 1H9, Canada.
| | - Milad Nazarahari
- Department of Mechanical Engineering, University of Alberta, Donadeo Innovation Centre for Engineering, Edmonton, Alberta, T6G 1H9, Canada; Department of Mechanical and Mechatronics Engineering, University of Waterloo, Waterloo, Ontario, N2L 3G1, Canada.
| | - Hossein Rouhani
- Department of Mechanical Engineering, University of Alberta, Donadeo Innovation Centre for Engineering, Edmonton, Alberta, T6G 1H9, Canada.
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11
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Watanabe K, Yoshimura A, Holobar A, Yamashita D, Kunugi S, Hirono T. Neuromuscular characteristics of front and back legs in junior fencers. Exp Brain Res 2022; 240:2085-2096. [PMID: 35771284 PMCID: PMC9288367 DOI: 10.1007/s00221-022-06403-w] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/20/2022] [Accepted: 06/16/2022] [Indexed: 11/19/2022]
Abstract
In elite fencers, muscle strength and muscle mass of the front leg (FL) are greater than those of the back leg (BL) due to characteristic physiological and biomechanical demands placed on each leg during fencing. However, the development of laterality in their neural and muscular components is not well-understood. The present study investigated neuromuscular characteristics of FL and BL in junior fencers. Nineteen junior fencers performed neuromuscular performance tests for FL and BL, separately. There were no significant differences in the isometric knee extension strength (MVC), unilateral vertical jump (UVJ), vastus lateralis muscle thickness (MT), or motor unit firing rate of the vastus lateralis muscle (MUFR) between FL and BL (p > 0.05). In subgroup analyses, a significantly greater MUFR in FL than BL was noted only in fencers with > 3 years of fencing experience, and significantly greater UVJ in FL than BL was observed solely in fencers with < 3 years of fencing experience (p < 0.05). Strong positive correlations between FL and BL were identified in MVC, MT, and MUFR in fencers with > 3 years of fencing experience, but not in those with < 3 years of experience. These findings suggest that in junior fencers, laterality in neuromuscular performance has not manifested, whereas longer fencing experience induces fencing-dependent laterality in neural components, and laterality in dynamic muscle strength is decreased with fencing experience.
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Affiliation(s)
- Kohei Watanabe
- Laboratory of Neuromuscular Biomechanics, School of Health and Sport Sciences, Chukyo University, Tokodachi, Kaizu-cho, Toyota, 470-0093, Japan.
| | - Akane Yoshimura
- Laboratory of Neuromuscular Biomechanics, School of Health and Sport Sciences, Chukyo University, Tokodachi, Kaizu-cho, Toyota, 470-0093, Japan. .,Faculty of Education and Integrated Arts and Sciences, Waseda University, Tokyo, Japan.
| | - Aleš Holobar
- Faculty of Electrical Engineering and Computer Science, University of Maribor, Maribor, Slovenia
| | - Daichi Yamashita
- Department of Sport Science, Japan Institute of Sport Sciences, Kita-ku, Tokyo, Japan
| | - Shun Kunugi
- Laboratory of Neuromuscular Biomechanics, School of Health and Sport Sciences, Chukyo University, Tokodachi, Kaizu-cho, Toyota, 470-0093, Japan.,Center for General Education, Aichi Institute of Technology, Toyota, Japan
| | - Tetsuya Hirono
- Laboratory of Neuromuscular Biomechanics, School of Health and Sport Sciences, Chukyo University, Tokodachi, Kaizu-cho, Toyota, 470-0093, Japan.,Research Fellow of Japan Society for the Promotion of Science, Tokyo, Japan
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12
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Electrical Properties of Adult Mammalian Motoneurons. ADVANCES IN NEUROBIOLOGY 2022; 28:191-232. [PMID: 36066827 DOI: 10.1007/978-3-031-07167-6_9] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/14/2022]
Abstract
Motoneurons are the 'final common path' between the central nervous system (that intends, selects, commands, and organises movement) and muscles (that produce the behaviour). Motoneurons are not passive relays, but rather integrate synaptic activity to appropriately tune output (spike trains) and therefore the production of muscle force. In this chapter, we focus on studies of mammalian motoneurons, describing their heterogeneity whilst providing a brief historical account of motoneuron recording techniques. Next, we describe adult motoneurons in terms of their passive, transition, and active (repetitive firing) properties. We then discuss modulation of these properties by somatic (C-boutons) and dendritic (persistent inward currents) mechanisms. Finally, we briefly describe select studies of human motor unit physiology and relate them to findings from animal preparations discussed earlier in the chapter. This interphyletic approach to the study of motoneuron physiology is crucial to progress understanding of how these diverse neurons translate intention into behaviour.
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McKeown DJ, McNeil CJ, Brotherton EJ, Simmonds MJ, Kavanagh JJ. Severe acute hypoxia impairs recovery of voluntary muscle activation after sustained submaximal elbow flexion. J Physiol 2021; 599:5379-5395. [PMID: 34761807 DOI: 10.1113/jp281897] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/09/2021] [Accepted: 11/04/2021] [Indexed: 11/08/2022] Open
Abstract
The purpose of this study was to determine how severe acute hypoxia alters neural mechanisms during, and following, a sustained fatiguing contraction. Fifteen participants (25 ± 3.2 years, six female) were exposed to a sham condition and a hypoxia condition where they performed a 10 min elbow flexor contraction at 20% of maximal torque. For hypoxia, peripheral blood oxygen saturation ( S p O 2 ) was titrated to 80% over a 15 min period and maintained for 2 h. Maximal voluntary contraction torque, EMG root mean square, voluntary activation, rating of perceived muscle fatigue, and corticospinal excitability (motor-evoked potential) and inhibition (silent period duration) were then assessed before, during and for 6 min after the fatiguing contraction. No hypoxia-related effects were identified for neuromuscular variables during the fatigue task. However, for recovery, voluntary activation assessed by motor point stimulation of biceps brachii was lower for hypoxia than sham at 4 min (sham: 89% ± 7%; hypoxia: 80% ± 12%; P = 0.023) and 6 min (sham: 90% ± 7%; hypoxia: 78% ± 11%; P = 0.040). Similarly, voluntary activation (P = 0.01) and motor-evoked potential area (P = 0.002) in response to transcranial magnetic stimulation of the motor cortex were 10% and 11% lower during recovery for hypoxia compared to sham, respectively. Although an S p O 2 of 80% did not affect neural activity during the fatiguing task, motor cortical output and corticospinal excitability were reduced during recovery in the hypoxic environment. This was probably due to hypoxia-related mechanisms involving supraspinal motor circuits. KEY POINTS: Acute hypoxia has been shown to impair voluntary activation of muscle and alter the excitability of the corticospinal motor pathway during exercise. However, little is known about how hypoxia alters the recovery of the motor system after performing fatiguing exercise. Here we assessed hypoxia-related responses of motor pathways both during active contractions and during recovery from active contractions, with transcranial magnetic stimulation and motor point stimulation of the biceps brachii. Fatiguing exercise caused reductions in voluntary activation, which was exacerbated during recovery from a 10 min sustained elbow flexion in a hypoxic environment. These results suggest that reductions in blood oxygen concentration impair the ability of motor pathways in the CNS to recover from fatiguing exercise, which is probably due to hypoxia-induced mechanisms that reduce output from the motor cortex.
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Affiliation(s)
- Daniel J McKeown
- Neural Control of Movement Laboratory, Menzies Health Institute Queensland, Griffith University, Gold Coast, Queensland, Australia
| | - Chris J McNeil
- Integrated Neuromuscular Physiology Laboratory, Centre for Heart, Lung, and Vascular Health, School of Health and Exercise Sciences, University of British Columbia, Kelowna, British Columbia, Canada
| | - Emily J Brotherton
- Neural Control of Movement Laboratory, Menzies Health Institute Queensland, Griffith University, Gold Coast, Queensland, Australia
| | - Michael J Simmonds
- Biorheology Research Laboratory, Menzies Health Institute Queensland, Griffith University, Gold Coast, Queensland, Australia
| | - Justin J Kavanagh
- Neural Control of Movement Laboratory, Menzies Health Institute Queensland, Griffith University, Gold Coast, Queensland, Australia
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Petrie MA, Taylor EB, Suneja M, Shields RK. Genomic and Epigenomic Evaluation of Electrically Induced Exercise in People With Spinal Cord Injury: Application to Precision Rehabilitation. Phys Ther 2021; 102:6413907. [PMID: 34718779 PMCID: PMC8754383 DOI: 10.1093/ptj/pzab243] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/26/2021] [Revised: 08/06/2021] [Accepted: 09/23/2021] [Indexed: 11/13/2022]
Abstract
OBJECTIVE Physical therapists develop patient-centered exercise prescriptions to help overcome the physical, emotional, psychosocial, and environmental stressors that undermine a person's health. Optimally prescribing muscle activity for people with disability, such as a spinal cord injury, is challenging because of their loss of volitional movement control and the deterioration of their underlying skeletal systems. This report summarizes spinal cord injury-specific factors that should be considered in patient-centered, precision prescription of muscle activity for people with spinal cord injury. This report also presents a muscle genomic and epigenomic analysis to examine the regulation of the proliferator-activated receptor γ coactivator 1α (PGC-1α) (oxidative) and myostatin (hypertrophy) signaling pathways in skeletal muscle during low-frequency (lower-force) electrically induced exercise versus higher-frequency (higher-force) electrically induced exercise under constant muscle recruitment (intensity). METHODS Seventeen people with spinal cord injury participated in 1 or more unilateral electrically induced exercise sessions using a lower-force (1-, 3-, or 5-Hz) or higher-force (20-Hz) protocol. Three hours after the exercise session, percutaneous muscle biopsies were performed on exercised and nonexercised muscles for genomic and epigenomic analysis. RESULTS We found that low-frequency (low-force) electrically induced exercise significantly increased the expression of PGC-1α and decreased the expression of myostatin, consistent with the expression changes observed with high-frequency (higher-force) electrically induced exercise. Further, we found that low-frequency (lower-force) electrically induced exercise significantly demethylated, or epigenetically promoted, the PGC-1α signaling pathway. A global epigenetic analysis showed that >70 pathways were regulated with low-frequency (lower-force) electrically induced exercise. CONCLUSION These novel results support the notion that low-frequency (low-force) electrically induced exercise may offer a more precise rehabilitation strategy for people with chronic paralysis and severe osteoporosis. Future clinical trials are warranted to explore whether low-frequency (lower-force) electrically induced exercise training affects the overall health of people with chronic spinal cord injury.
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Affiliation(s)
- Michael A Petrie
- Department of Physical Therapy and Rehabilitation Science, Carver College of Medicine, The University of Iowa, Iowa City, Iowa, USA
| | - Eric B Taylor
- Department of Biochemistry, Carver College of Medicine, The University of Iowa, Iowa City, Iowa, USA
| | - Manish Suneja
- Department of Internal Medicine, Carver College of Medicine, The University of Iowa, Iowa City, Iowa, USA
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Inglis JG, Gabriel DA. Sex differences in the modulation of the motor unit discharge rate leads to reduced force steadiness. Appl Physiol Nutr Metab 2021; 46:1065-1072. [PMID: 33667116 DOI: 10.1139/apnm-2020-0953] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
The purpose of this study was to evaluate the relationship between the variability in the motor unit inter-pulse interval and force steadiness at submaximal and maximal force outputs between the sexes. Twenty-four male and 24 female participants were recruited to perform isometric dorsiflexion contractions at 20, 40, 60, 80, and 100% maximum voluntary contraction. Tibialis anterior myoelectric signal was recorded by an intramuscular electrode. Females had lower force steadiness (coefficient of variation of force (CoV-Force), 27.3%, p < 0.01) and a greater coefficient of variation of motor unit action potential inter-pulse interval (CoV-IPI), compared with males (9.6%, p < 0.01). There was no significant correlation between the normalized CoV-IPI and CoV-Force (r = 0.19, p > 0.01), but there was a significant repeated measures correlation between the raw scores for root-mean-square force error and the standard deviation of motor unit discharge rate (r = 0.65, p < 0.01). Females also had a greater incidence of doublet discharges on average across force levels (p < 0.01). The sex differences may result from motor unit behaviours (i.e., doublet and rapid discharges, synchronization, rate coding or recruitment), leading to lower force steadiness and greater CoV-IPI in females. Novelty: Sex differences in force steadiness may be due to neural strategies. Females have lower force steadiness compared with males. Greater incidence of doublet discharges in females may result in lesser force steadiness.
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Affiliation(s)
- J Greig Inglis
- Electromyographic Kinesiology Laboratory, Department of Kinesiology, Brock University, St. Catharines, ON L2S 3A1, Canada.,Electromyographic Kinesiology Laboratory, Department of Kinesiology, Brock University, St. Catharines, ON L2S 3A1, Canada
| | - David A Gabriel
- Electromyographic Kinesiology Laboratory, Department of Kinesiology, Brock University, St. Catharines, ON L2S 3A1, Canada.,Electromyographic Kinesiology Laboratory, Department of Kinesiology, Brock University, St. Catharines, ON L2S 3A1, Canada
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Zarrouk N, Mtibaa K, Hammouda O, Chtourou H, Chaabouni K, Ayadi-Makni F, Rebai H. Assessment of acute neuromuscular fatigue manifestations and functional performances after heavy resistance exercise. J Sports Med Phys Fitness 2021; 61:1596-1604. [PMID: 33586932 DOI: 10.23736/s0022-4707.21.12015-8] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
BACKGROUND This study aimed to assess neuromuscular fatigue after heavy resistance exercise in rugby players. METHODS Twelve male rugby players performed five sets of knee extension exercise lifting 80% of their one repetition maximum until failure, with 3min of rest in-between. Maximal voluntary contraction (MVC) and surface electromyographic activity from quadriceps muscles, as well as ions (i.e., Na+, K+, and Cl-) and metabolic responses (i.e., blood lactate and ammonia concentrations) were measured before and after exercise. Maximum repetitions performance and both peripheral (RPEp) and overall body (RPEo) rating of perceived exertion were recorded following each set. RESULTS The number of maximum repetitions decreased significantly across sets (P<0.001). Both RPEp and RPEo increased significantly across sets (P<0.001) with higher RPEp values after each set (P<0.001). Both RPEp (r=-0.98, P<0.01) and RPEo (r=-0.99, P<0.001) were negatively correlated with the changes in the number of maximum repetitions. MVC (P<0.001), root mean square (P<0.05), and neuromuscular efficiency (P<0.01) as well as Na+ (P<0.01), Cl- (P<0.001) and blood concentrations of lactate (P<0.001) and ammonia (P<0.001) decreased significantly after the exercise. However, K+ (P<0.001) increased after the resistance exercise. CONCLUSIONS Heavy resistance exercise affected both objective (i.e., neuromuscular and biochemical parameters) and subjective (i.e., RPE) aspects of neuromuscular fatigue.
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Affiliation(s)
- Nidhal Zarrouk
- Research Laboratory: Education, Motricité, Sport et Santé (EM2S), LR 19JS01, High Institute of Sport and Physical Education of Sfax, University of Sfax, Sfax, Tunisia -
| | - Khouloud Mtibaa
- Qatar University, Sports Science Program, College of Arts and Sciences, Doha, Qatar
| | - Omar Hammouda
- Research Laboratory: Molecular Bases of Human Pathology, LR 19ES13, Faculty of Medicine, University of Sfax, Sfax, Tunisia.,Interdisciplinary Laboratory in Neurosciences, Physiology and Psychology: Physical Activity, Health and Learning (LINP2), UFR STAPS, UPL, Paris Nanterre University, Nanterre, France
| | - Hamdi Chtourou
- Research Unit: Physical Activity, Sport and Health, UR 18JS01, National Sport Observatory, Tunis, Tunisia
| | - Khansa Chaabouni
- Research Laboratory: Molecular Bases of Human Pathology, LR 19ES13, Faculty of Medicine, University of Sfax, Sfax, Tunisia.,Laboratory of Biochemistry, Habib Bourguiba University Hospital, Sfax, Tunisia
| | - Fatma Ayadi-Makni
- Research Laboratory: Molecular Bases of Human Pathology, LR 19ES13, Faculty of Medicine, University of Sfax, Sfax, Tunisia.,Laboratory of Biochemistry, Habib Bourguiba University Hospital, Sfax, Tunisia
| | - Haithem Rebai
- Research Laboratory: Education, Motricité, Sport et Santé (EM2S), LR 19JS01, High Institute of Sport and Physical Education of Sfax, University of Sfax, Sfax, Tunisia
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Beretta-Piccoli M, Cescon C, D’Antona G. Evaluation of performance fatigability through surface EMG in health and muscle disease: state of the art. ARAB JOURNAL OF BASIC AND APPLIED SCIENCES 2020. [DOI: 10.1080/25765299.2020.1862985] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022] Open
Affiliation(s)
- Matteo Beretta-Piccoli
- Criams-Sport Medicine Centre Voghera, University of Pavia, Pavia, Italy
- Rehabilitation Research Laboratory 2rLab, Department of Business Economics, Health and Social Care, University of Applied, Sciences and Arts of Southern Switzerland, Manno, Switzerland
| | - Corrado Cescon
- Rehabilitation Research Laboratory 2rLab, Department of Business Economics, Health and Social Care, University of Applied, Sciences and Arts of Southern Switzerland, Manno, Switzerland
| | - Giuseppe D’Antona
- Criams-Sport Medicine Centre Voghera, University of Pavia, Pavia, Italy
- Department of Public Health, Experimental and Forensic Medicine, University of Pavia, Pavia, Italy
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18
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Inglis JG, Gabriel DA. Sex differences in motor unit discharge rates at maximal and submaximal levels of force output. Appl Physiol Nutr Metab 2020; 45:1197-1207. [DOI: 10.1139/apnm-2019-0958] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
This study evaluated potential sex differences in motor unit (MU) behaviour at maximal and submaximal force outputs. Forty-eight participants, 24 females and 24 males, performed isometric dorsiflexion contractions at 20%, 40%, 60%, 80%, and 100% of a maximum voluntary contraction (MVC). Tibialis anterior electromyography was recorded both by surface and intramuscular electrodes. Compared with males, females had a greater MU discharge rate (MUDR) averaged across all submaximal intensities (Δ 0.45 pps, 2.56%). Males exhibited greater increases in MUDR above 40% MVC, surpassing females at 100% MVC (p’s < 0.01). Averaged across all force outputs, females had a greater incidence of doublet and rapid discharges and a greater percentage of MU trains with doublet and rapid (5–10 ms) discharges (Δ 75.55% and 61.48%, respectively; p’s < 0.01). A subset of males (n = 8) and females (n = 8), matched for maximum force output, revealed that females had even greater MUDR (Δ 1.38 pps, 7.47%) and percentage of MU trains with doublet and rapid discharges (Δ 51.62%, 56.68%, respectively; p’s < 0.01) compared with males at each force output, including 100% MVC. Analysis of the subset of strength-matched males and females suggest that sex differences in MU behaviour may be a result of females needing to generate greater neural drive to achieve fused tetanus. Novelty Females had higher MUDRs and greater percentage of MU trains with doublets across submaximal force outputs (20%–80% MVC). Differences were even greater for a strength matched subset. Differences in motor unit behaviour may arise from musculoskeletal differences, requiring greater neural drive in females.
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Affiliation(s)
- J. Greig Inglis
- Electromyographic Kinesiology Laboratory, Kinesiology Department, Brock University, St. Catharines, ON L2S 3A1, Canada
- Electromyographic Kinesiology Laboratory, Kinesiology Department, Brock University, St. Catharines, ON L2S 3A1, Canada
| | - David A. Gabriel
- Electromyographic Kinesiology Laboratory, Kinesiology Department, Brock University, St. Catharines, ON L2S 3A1, Canada
- Electromyographic Kinesiology Laboratory, Kinesiology Department, Brock University, St. Catharines, ON L2S 3A1, Canada
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Martinez-Valdes E, Negro F, Falla D, Dideriksen JL, Heckman CJ, Farina D. Inability to increase the neural drive to muscle is associated with task failure during submaximal contractions. J Neurophysiol 2020; 124:1110-1121. [DOI: 10.1152/jn.00447.2020] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Motor unit firing and contractile properties during a submaximal contraction until failure were assessed with a new tracking technique. Two distinct phases in firing behavior were observed, which compensated for changes in twitch area and predicted time to failure. However, the late increase in firing rate was below the rates attained in the absence of fatigue, which points to an inability of the central nervous system to sufficiently increase the neural drive to muscle with fatigue.
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Affiliation(s)
- Eduardo Martinez-Valdes
- Centre of Precision Rehabilitation for Spinal Pain (CPR Spine), School of Sport, Exercise and Rehabilitation Sciences, College of Life and Environmental Sciences, University of Birmingham, Birmingham, United Kingdom
| | - Francesco Negro
- Department of Clinical and Experimental Sciences, Research Centre for Neuromuscular Function and Adapted Physical Activity “Teresa Camplani,” Università degli Studi di Brescia, Brescia, Italy
| | - Deborah Falla
- Centre of Precision Rehabilitation for Spinal Pain (CPR Spine), School of Sport, Exercise and Rehabilitation Sciences, College of Life and Environmental Sciences, University of Birmingham, Birmingham, United Kingdom
| | - Jakob Lund Dideriksen
- Center for Sensory-Motor Interaction, Department of Health Science and Technology, Aalborg University, Aalborg, Denmark
| | - C. J. Heckman
- Department of Physiology, Northwestern University, Chicago, Illinois
| | - Dario Farina
- Department of Bioengineering, Imperial College London, Royal School of Mines, London, United Kingdom
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20
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Vernillo G, Temesi J, Martin M, Krüger RL, Millet GY. Spinal contribution to neuromuscular recovery differs between elbow-flexor and knee-extensor muscles after a maximal sustained fatiguing task. J Neurophysiol 2020; 124:763-773. [PMID: 32755359 DOI: 10.1152/jn.00273.2020] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Data from studies of elbow-flexor (EF) or knee-extensor (KE) muscles suggest that a fatigue-related decrease in motoneuron excitability only occurs in EF. It is unknown how motoneuron excitability changes after sustained fatiguing maximal voluntary isometric contractions (MVICs) in EF and KE in the same participants. In two sessions, eight healthy men performed a 2-min MVIC of EF or KE to induce fatigue with brief MVICs before and six times after the 2-min MVIC. Electromyographic responses elicited by corticospinal tract stimulation at the transmastoid [cervicomedullary motor-evoked potential (CMEP)] or thoracic [thoracic motor-evoked potential (TMEP)] level were recorded from EF and KE, respectively. To account for muscle excitability, CMEPs and TMEPs were normalized to maximal M-wave (Mmax) elicited by peripheral nerve stimulation during each brief MVIC. Immediately after the 2-min MVIC, biceps brachii and brachioradialis CMEP/Mmax were 88% (SD 11%) (P = 0.026) and 87% (SD 12%) (P = 0.029) of pre-MVIC (PRE) values, respectively, and remained lower than PRE after 5 s of recovery [91% (SD 8%), P = 0.036 and 87% (SD 13%), P = 0.046, respectively]. No subsequent time points differed from PRE (all P ≥ 0.253). TMEP/Mmax for rectus femoris and vastus lateralis were not different from PRE at any time during the recovery period (all P > 0.050). A different recovery pattern in motoneuron excitability occurred in EF as it recovered by 60 s whereas KE motoneurons were unaffected by the fatiguing task. The present findings may contribute to better understand muscle-specific neurophysiological differences in spinal excitability.NEW & NOTEWORTHY By comparing the changes in motoneuron excitability in elbow-flexor and knee-extensor muscles after sustained fatiguing maximal voluntary contractions, this study shows that motoneuron recovery behavior depends on the muscle performing the exercise. A different recovery pattern in motoneuron excitability occurs in elbow flexors as it recovered by 60 s whereas knee extensors were unaffected by fatigue. This finding can help to increase understanding of the effect of a fatigue and subsequent recovery on neural processes.
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Affiliation(s)
- Gianluca Vernillo
- Human Performance Laboratory, Faculty of Kinesiology, University of Calgary, Calgary, Alberta, Canada.,Department of Biomedical Sciences for Health, Università degli Studi di Milano, Milan, Italy
| | - John Temesi
- Human Performance Laboratory, Faculty of Kinesiology, University of Calgary, Calgary, Alberta, Canada.,Faculty of Health & Life Sciences, Northumbria University, Newcastle upon Tyne, United Kingdom
| | - Matthieu Martin
- Human Performance Laboratory, Faculty of Kinesiology, University of Calgary, Calgary, Alberta, Canada
| | - Renata L Krüger
- Human Performance Laboratory, Faculty of Kinesiology, University of Calgary, Calgary, Alberta, Canada
| | - Guillaume Y Millet
- Human Performance Laboratory, Faculty of Kinesiology, University of Calgary, Calgary, Alberta, Canada.,Univ Lyon, UJM-Saint-Etienne, Inter-university Laboratory of Human Movement Biology, EA 7424, F-42023, Saint-Etienne, France.,Institut Universitaire de France (IUF)
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21
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Williams SE, Koch KC, Disselhorst-Klug C. Non-invasive assessment of motor unit activation in relation to motor neuron level and lesion location in stroke and spinal muscular atrophy. Clin Biomech (Bristol, Avon) 2020; 78:105053. [PMID: 32563725 DOI: 10.1016/j.clinbiomech.2020.105053] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/13/2019] [Revised: 05/06/2020] [Accepted: 05/19/2020] [Indexed: 02/07/2023]
Abstract
BACKGROUND Neuromuscular disorders e.g. spinal muscular atrophy and stroke have a negative impact on functional movement capability. These disorders affect lower and upper motor neurons respectively. METHODS In this study high spatial resolution electromyography was used to record the motor unit activity in 3 groups: healthy subjects, a spinal muscular atrophy group and a stroke group. 7 clinically sensitive parameters were used to analyze the activation patterns of a few motor units. FINDINGS In the case of spinal muscular atrophy there was no effect on motor unit activation but on their number. Stroke was characterized by fewer active motor units and a significantly reduced firing rate with low variability. INTERPRETATION The results suggest, that for stroke, information from the brain is modified thereby resulting in motor units firing at their natural frequency. Thus, high spatial resolution electromyography and the chosen parameters facilitate non-invasive, objective differentiation and analysis of the activation patterns of motor units in neuromuscular disorders.
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Affiliation(s)
- Sybele E Williams
- Department of Rehabilitation and Prevention Engineering, Institute of Applied Medical Engineering, RWTH Aachen University, 52074 Aachen, Germany.
| | - Kathrin C Koch
- Department of Rehabilitation and Prevention Engineering, Institute of Applied Medical Engineering, RWTH Aachen University, 52074 Aachen, Germany
| | - Catherine Disselhorst-Klug
- Department of Rehabilitation and Prevention Engineering, Institute of Applied Medical Engineering, RWTH Aachen University, 52074 Aachen, Germany
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Forman DA, Forman GN, Murphy BA, Holmes MWR. Sustained Isometric Wrist Flexion and Extension Maximal Voluntary Contractions on Corticospinal Excitability to Forearm Muscles during Low-Intensity Hand-Gripping. Brain Sci 2020; 10:E445. [PMID: 32668568 PMCID: PMC7408559 DOI: 10.3390/brainsci10070445] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/12/2020] [Revised: 07/06/2020] [Accepted: 07/07/2020] [Indexed: 02/02/2023] Open
Abstract
The wrist extensors demonstrate an earlier fatigue onset than the wrist flexors. However, it is currently unclear whether fatigue induces unique changes in muscle activity or corticospinal excitability between these muscle groups. The purpose of this study was to examine how sustained isometric wrist extension/flexion maximal voluntary contractions (MVCs) influence muscle activity and corticospinal excitability of the forearm. Corticospinal excitability to three wrist flexors and three wrist extensors were measured using motor evoked potentials (MEPs) elicited via transcranial magnetic stimulation. Responses were elicited while participants exerted 10% of their maximal handgrip force, before and after a sustained wrist flexion or extension MVC (performed on separate sessions). Post-fatigue measures were collected up to 10-min post-fatigue. Immediately post-fatigue, extensor muscle activity was significantly greater following the wrist flexion fatigue session, although corticospinal excitability (normalized to muscle activity) was greater on the wrist extension day. Responses were largely unchanged in the wrist flexors. However, for the flexor carpi ulnaris, normalized MEP amplitudes were significantly larger following wrist extension fatigue. These findings demonstrate that sustained isometric flexion/extension MVCs result in a complex reorganization of forearm muscle recruitment strategies during hand-gripping. Based on these findings, previously observed corticospinal behaviour following fatigue may not apply when the fatiguing task and measurement task are different.
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Affiliation(s)
- Davis A. Forman
- Faculty of Science, Ontario Tech University, Oshawa, ON L1G 0C5, Canada;
| | - Garrick N. Forman
- Faculty of Applied Health Sciences, Brock University, St. Catharines, ON L2S 3A1, Canada;
| | - Bernadette A. Murphy
- Faculty of Health Sciences, Ontario Tech University, Oshawa, ON L1G 0C5, Canada;
| | - Michael W. R. Holmes
- Faculty of Applied Health Sciences, Brock University, St. Catharines, ON L2S 3A1, Canada;
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23
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Forman DA, Forman GN, Mugnosso M, Zenzeri J, Murphy B, Holmes MWR. Sustained Isometric Wrist Flexion and Extension Maximal Voluntary Contractions Similarly Impair Hand-Tracking Accuracy in Young Adults Using a Wrist Robot. Front Sports Act Living 2020; 2:53. [PMID: 33345044 PMCID: PMC7739644 DOI: 10.3389/fspor.2020.00053] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/08/2020] [Accepted: 04/16/2020] [Indexed: 11/13/2022] Open
Abstract
Due to their stabilizing role, the wrist extensor muscles demonstrate an earlier onset of performance fatigability and may impair movement accuracy more than the wrist flexors. However, minimal fatigue research has been conducted at the wrist. Thus, the purpose of this study was to examine how sustained isometric contractions of the wrist extensors/flexors influence hand-tracking accuracy. While gripping the handle of a three-degrees-of-freedom wrist manipulandum, 12 male participants tracked a 2:3 Lissajous curve (±32° wrist flexion/extension; ±18° radial/ulnar deviation). A blue, circular target moved about the trajectory and participants tracked the target with a yellow circle (corresponding to the handle's position). Five baseline tracking trials were performed prior to the fatiguing task. Participants then exerted either maximal wrist extension or flexion force (performed on separate days) against a force transducer until they were unable to maintain 25% of their pre-fatigue maximal voluntary contraction (MVC). Participants then performed 7 tracking trials from immediately post-fatigue to 10 min after. Performance fatigability was assessed using various metrics to account for errors in position-tracking, error tendencies, and movement smoothness. While there were no differences in tracking error between flexion/extension sessions, tracking error significantly increased immediately post-fatigue (Baseline: 1.40 ± 0.54°, Post-fatigue: 2.02 ± 0.51°, P < 0.05). However, error rapidly recovered, with no differences in error from baseline after 1-min post-fatigue. These findings demonstrate that sustained isometric extension/flexion contractions similarly impair tracking accuracy of the hand. This work serves as an important step to future research into workplace health and preventing injuries of the distal upper-limb.
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Affiliation(s)
- Davis A Forman
- Faculty of Science, Ontario Tech University, Oshawa, ON, Canada
| | - Garrick N Forman
- Faculty of Applied Health Sciences, Brock University, St. Catharines, ON, Canada
| | - Maddalena Mugnosso
- Robotics, Brain and Cognitive Sciences, Istituto Italiano di Tecnologia, Genoa, Italy
| | - Jacopo Zenzeri
- Robotics, Brain and Cognitive Sciences, Istituto Italiano di Tecnologia, Genoa, Italy
| | - Bernadette Murphy
- Faculty of Health Sciences, Ontario Tech University, Oshawa, ON, Canada
| | - Michael W R Holmes
- Faculty of Applied Health Sciences, Brock University, St. Catharines, ON, Canada
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D'Amico JM, Rouffet DM, Gandevia SC, Taylor JL. Unlike voluntary contractions, stimulated contractions of a hand muscle do not reduce voluntary activation or motoneuronal excitability. J Appl Physiol (1985) 2020; 128:1412-1422. [PMID: 32324475 DOI: 10.1152/japplphysiol.00553.2019] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023] Open
Abstract
Voluntary force declines during sustained, maximal voluntary contractions (MVC) due to changes in muscle and central nervous system properties. Central fatigue, an exercise-induced reduction in voluntary activation, is influenced by multiple processes. Some may occur independently of descending voluntary drive. To differentiate the effects associated with voluntary drive from other central and peripheral influences, we measured voluntary activation and motoneuron excitability following fatiguing contractions produced voluntarily or by electrical stimulation. On two separate days, participants performed either a 2-min MVC of adductor pollicis muscle or received 2-min continuous supramaximal electrical stimulation of the ulnar nerve. In study 1 (n = 14), the superimposed twitch elicited by ulnar nerve stimulation during brief MVCs was increased, and, hence, voluntary activation was reduced, up to 240 s after the 2-min MVC [-20 ± 12% (SD), P = 0.002] but not the 2-min stimulated contraction (-4 ± 7%), despite large reductions in MVC force (voluntary, -54 ± 18%; stimulated, -46 ± 16%). In study 2 (n = 12), F-waves recorded from the adductor pollicis were reduced in area for 150 s following the 2-min MVC (-21 ± 16%, P = 0.007) but not after the stimulated contraction (5 ± 27%). Therefore, voluntary activation and motoneuron excitability decreased only when descending voluntary drive was present during the fatiguing task. The findings do not exclude a cortical or brain stem contribution to the reduced voluntary activation but suggest that neither sensory feedback from the fatigued muscle nor repetitive activation of motoneurons underlie the changes, whereas they are consistent with motoneuronal inhibition by released factors linked to voluntary drive.NEW & NOTEWORTHY We demonstrate that reductions in voluntary activation and motoneuron excitability following 2-min isometric maximal contractions in humans occur only when fatigue is produced through voluntary contractions and not through electrically stimulated contractions. This is contrary to studies that suggest that changes in the superimposed twitch and therefore voluntary activation are explained by changes in peripheral factors alone. Thus, the interpolated twitch technique remains a viable tool to assess voluntary activation and central fatigue.
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Affiliation(s)
- J M D'Amico
- Neuroscience Research Australia, Randwick, New South Wales, Australia.,Kentucky Spinal Cord Injury Research Center, Department of Neurological Surgery, University of Louisville, Louisville, Kentucky
| | - D M Rouffet
- Kentucky Spinal Cord Injury Research Center, Department of Health and Sport Sciences, University of Louisville, Louisville, Kentucky.,Institute for Health and Sport, Victoria University, Melbourne, Victoria, Australia
| | - S C Gandevia
- Neuroscience Research Australia, Randwick, New South Wales, Australia.,University of New South Wales, Sydney, New South Wales, Australia
| | - J L Taylor
- Neuroscience Research Australia, Randwick, New South Wales, Australia.,School of Medical and Health Sciences, Edith Cowan University, Perth, Western Australia, Australia
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Validating the Capability for Measuring Age-Related Changes in Grip-Force Strength Using a Digital Hand-Held Dynamometer in Healthy Young and Elderly Adults. BIOMED RESEARCH INTERNATIONAL 2020; 2020:6936879. [PMID: 32382565 PMCID: PMC7191369 DOI: 10.1155/2020/6936879] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 12/10/2019] [Revised: 03/29/2020] [Accepted: 04/04/2020] [Indexed: 12/25/2022]
Abstract
Background Grip-force performance can be affected by aging, and hand-grip weakness is associated with functional limitations of dasily living. However, using an appropriate digital hand-held dynamometer with continuous hand-grip force data collection shows age-related changes in the quality of hand-grip force control may provide more valuable information for clinical diagnoses rather than merely recording instantaneous maximal hand-grip force in frail elderly adults or people with a disability. Therefore, the purpose of this study was to indicate the construct validity of the digital MicroFET3 dynamometer with Jamar values for maximal grip-force assessments in elderly and young adults and confirmed age-related changes in the maximal and the quality of grip-force performance using the MicroFET3 dynamometer in elderly people. Methods Sixty-five healthy young (23.3 ± 4.5 years) and 50 elderly (69.5 ± 5.8 years) adults were recruited and asked to perform a validity test of the grip-force maximum voluntary contraction (MVC) using both the dominant and nondominant hands with a Jamar dynamometer and a MicroFET3 dynamometer. Results A strong correlation of maximal grip-force measurements was found between the MicroFET3 dynamometer and Jamar standard dynamometer for both hands in all participants (p < 0.05). Although, the results showed that a lower grip force was measured in both hands by the MicroFET3 dynamometer than with the Jamar dynamometer by 49.9%~57% (p < 0.05), but confidently conversion formulae were also developed to convert MicroFET3 dynamometer values to equivalent Jamar values for both hands. Both dynamometers indicated age-related declines in the maximum grip-force performance by 36.7%~44.3% (p < 0.05). We also found that the maximal hand-grip force values generated in both hand by the elderly adults were slower and more inconsistent than those of the young adults when using the MicroFET3 dynamometer. Conclusions This study demonstrated that the digital MicroFET3 dynamometer has good validity when used to measure the maximal grip force of both hands, and conversion formulae were also developed to convert MicroFET3 dynamometer force values to Jamar values in both hands. Comparing with the Jamar dynamometer for measuring grip force, the MicroFET3 dynamometer not only indicated age-related declines in the maximum grip-force performance but also showed slower and more inconsistent maximal hand-grip strength generation by the elderly.
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26
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Carr JC, Ye X. Strength and Electromyographic Responses of Upper and Lower Limbs During Maximal Intermittent Contractions in Males and Females. J Strength Cond Res 2020; 36:2403-2409. [PMID: 32304518 DOI: 10.1519/jsc.0000000000003580] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
Carr, JC and Ye, X. Strength and electromyographic responses of upper and lower limbs during maximal intermittent contractions in males and females. J Strength Cond Res XX(X): 000-000, 2020-This study examined the strength and electromyographic (EMG) responses of upper vs. lower limb muscles during intermittent maximal contractions in both sexes. Twenty subjects (n = 7 women) performed a fatiguing protocol (6, 30-second intermittent maximal isometric contractions with a 50% duty cycle) with either the elbow flexors or the knee extensors on separate visits. Bipolar surface EMG signals were detected from the biceps brachii and vastus lateralis muscles (n = 5 women retained). Women maintained more of their maximal force than men (Δforce: men vs. women = -55.0 ± 12.8% vs. -43.3 ± 9.9%, p = 0.042). Although force loss was similar between the elbow flexors and knee extensors, the EMG responses showed greater reductions for the biceps brachii than those for the vastus lateralis (Δamplitude: biceps brachii vs. vastus lateralis: -32.0 ± 22.3% vs. -18.9 ± 28.9%; Δmedian frequency: biceps brachii vs. vastus lateralis: -31.1 ± 14.5% vs. -10.3 ± 17.0%). During a series of maximal intermittent isometric contractions with 30 seconds of recovery between work bouts, women are more fatigue resistant than men. In addition, the greater electrophysiological fatigue exhibited by the biceps brachii than that by the vastus lateralis suggests that high-intensity contractions involving elbow flexion will have a greater rate of fatigue progression than those involving knee extension.
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Affiliation(s)
- Joshua C Carr
- Department of Kinesiology and Outdoor Recreation, Southern Utah University, Cedar City, Utah
| | - Xin Ye
- Department of Health, Exercise Science, and Recreation Management, The University of Mississippi, University, Mississippi
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Recovery of the first and second phases of the M wave after prolonged maximal voluntary contractions. J Electromyogr Kinesiol 2020; 50:102385. [DOI: 10.1016/j.jelekin.2019.102385] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/13/2019] [Revised: 11/18/2019] [Accepted: 12/23/2019] [Indexed: 11/24/2022] Open
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28
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Ma S, Chen C, Lv B, Sheng X, Zhu X. Estimation of Motor Unit Global Firing Rate by Maximum Power Amplitude. ANNUAL INTERNATIONAL CONFERENCE OF THE IEEE ENGINEERING IN MEDICINE AND BIOLOGY SOCIETY. IEEE ENGINEERING IN MEDICINE AND BIOLOGY SOCIETY. ANNUAL INTERNATIONAL CONFERENCE 2020; 2019:6607-6610. [PMID: 31947356 DOI: 10.1109/embc.2019.8857676] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
Motor unit (MU) global firing rate is widely applied in physiological and clinical investigation. Currently it still remains difficult to measure the MU global firing rate from sEMG. In this study, we propose a new feature of maximum power amplitude (MPA) from sEMG power spectrum. Based on an analysis of mathematical model and simulated signals, MPA was demonstrated to be highly correlated with the MU global firing rate. The performance of MPA was comparable with features based on sEMG amplitude in the time domain. Moreover, the simulation results showed that the square of MPA changed accordingly with the output force, indicating potential application estimating force using MPA2.
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29
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Sasada S, Endoh T, Ishii T, Kawashima K, Sato S, Hayashi A, Komiyama T. Differential effects of transcranial direct current stimulation on sprint and endurance cycling. TRANSLATIONAL SPORTS MEDICINE 2020. [DOI: 10.1002/tsm2.129] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Affiliation(s)
- Syusaku Sasada
- Department of Food and Nutrition Science Sagami Women's University Kanagawa Japan
| | - Takashi Endoh
- Faculty of Development and Education Uekusa Gakuen University Chiba Japan
| | - Tomoya Ishii
- Division of Health and Sport Education United of Graduate School of Education Tokyo Gakugei University Tokyo Japan
| | | | - Shuta Sato
- Graduate School of Education Chiba University Chiba Japan
| | | | - Tomoyoshi Komiyama
- Division of Health and Sport Education United of Graduate School of Education Tokyo Gakugei University Tokyo Japan
- Graduate School of Education Chiba University Chiba Japan
- Faculty of Education Chiba University Chiba Japan
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30
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McKeown DJ, Simmonds MJ, Kavanagh JJ. Reduced blood oxygen levels induce changes in low-threshold motor unit firing that align with the individual’s tolerance to hypoxia. J Neurophysiol 2019; 121:1664-1671. [DOI: 10.1152/jn.00071.2019] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
This study aimed to quantify how acute hypoxia impacts firing characteristics of biceps brachii motor units (MUs) during sustained isometric elbow flexions. MU data were extracted from surface electromyography (EMG) during 25% maximal voluntary contractions (MVC) in 10 healthy subjects (age 22 ± 1 yr). Blood oxygen saturation (SpO2) was then stabilized at 80% by reducing 1% of the fraction of inspired oxygen every 3 min for 35 min. MU data were once again collected 1 h and 2 h following the 35-min desaturation phase. Although MVC remained unaffected during 2 h of 80% SpO2, subject-specific changes in MU firing rate were observed. Four of 10 subjects exhibited a decrease in firing rate 1 h postdesaturation (12 ± 11%) and 2 h postdesaturation (16 ± 12%), whereas 6 of 10 subjects exhibited an increase in firing rate 1 h (9 ± 6%) and 2 h (9 ± 4%) postdesaturation. These bidirectional changes in firing rate were strongly correlated to the desaturation phase and the subjects’ SpO2 sensitivity to oxygen availability, where subjects who had decreased firing rates reached the target SpO2 20 min into the desaturation phase ( R2 = 0.90–0.98) and those who had increased firing rates reached the target SpO2 35 min into the desaturation phase ( R2 = 0.87–0.98). It is unlikely that a single mechanism accounted for these subject-specific changes in firing rate. Instead, differences in intrinsic properties of the neurons, afferent input to the motoneurons, neuromodulators, and sympathetic nerve activity may exist between groups. NEW & NOTEWORTHY The mechanisms of compromised motor control when exposed to hypoxia are largely unknown. The current study examined how severe acute hypoxia affects motor unit firing rate during sustained isometric contractions of the bicep brachii. The response to hypoxia was different across subjects, where motor unit firing rate increased for some individuals and decreased for others. This bidirectional change in firing rate was associated with how fast subjects desaturated during hypoxic exposure.
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Affiliation(s)
- Daniel J. McKeown
- School of Allied Health Sciences, Menzies Health Institute Queensland, Griffith University, Gold Coast Campus, Queensland, Australia
| | - Michael J. Simmonds
- School of Allied Health Sciences, Menzies Health Institute Queensland, Griffith University, Gold Coast Campus, Queensland, Australia
| | - Justin J. Kavanagh
- School of Allied Health Sciences, Menzies Health Institute Queensland, Griffith University, Gold Coast Campus, Queensland, Australia
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31
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Enoka RM. Physiological validation of the decomposition of surface EMG signals. J Electromyogr Kinesiol 2019; 46:70-83. [PMID: 31003192 DOI: 10.1016/j.jelekin.2019.03.010] [Citation(s) in RCA: 44] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/04/2018] [Revised: 02/15/2019] [Accepted: 03/20/2019] [Indexed: 11/30/2022] Open
Abstract
Advances in technology have ushered in a new era in the measurement and interpretation of surface-recorded electromyographic (EMG) signals. These developments have included improvements in detection systems, the algorithms used to decompose the interference signals, and the strategies used to edit the identified waveforms. To evaluate the validity of the results obtained with this new technology, the purpose of this review was to compare the results achieved by decomposing surface-recorded EMG signals into the discharge times of single motor units with what is known about the rate coding characteristics of single motor units based on recordings obtained with intramuscular electrodes. The characteristics compared were peak discharge rate, saturation of discharge rate during submaximal contractions, rate coding during fast contractions, the association between oscillations in force and discharge rate, and adjustments during fatiguing contractions. The comparison indicates that some decomposition methods are able to replicate many of the findings derived from intramuscular recordings, but additional improvements in the methods are required. Critically, more effort needs to be focused on editing the waveforms identified by the decomposition algorithms. With adequate attention to detail, this technology has the potential to augment our knowledge on motor unit physiology and to provide useful approaches that are being translated into clinical practice.
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Affiliation(s)
- Roger M Enoka
- Department of Integrative Physiology, University of Colorado, Boulder, CO, USA.
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32
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Relation between the ankle joint angle and the maximum isometric force of the toe flexor muscles. J Biomech 2019; 85:1-5. [DOI: 10.1016/j.jbiomech.2018.12.010] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/04/2018] [Revised: 11/30/2018] [Accepted: 12/06/2018] [Indexed: 11/16/2022]
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Spatial Reorganization of Myoelectric Activities in Extensor Digitorum for Sustained Finger Force Production. SENSORS 2019; 19:s19030555. [PMID: 30699981 PMCID: PMC6386817 DOI: 10.3390/s19030555] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 12/15/2018] [Revised: 01/23/2019] [Accepted: 01/28/2019] [Indexed: 11/16/2022]
Abstract
The study aims to explore the spatial distribution of multi-tendinous muscle modulated by central nervous system (CNS) during sustained contraction. Nine subjects were recruited to trace constant target forces with right index finger extension. Surface electromyography (sEMG) of extensor digitorum (ED) were recorded with a 32-channel electrode array. Nine successive topographic maps (TM) were obtained. Pixel wise analysis was utilized to extract subtracted topographic maps (STM), which exhibited inhomogeneous distribution. STMs were characterized into hot, warm, and cool regions corresponding to higher, moderate, and lower change ranges, respectively. The relative normalized area (normalized to the first phase) of these regions demonstrated different changing trends as rising, plateauing, and falling over time, respectively. Moreover, the duration of these trends were found to be affected by force level. The rising/falling periods were longer at lower force levels, while the plateau can be achieved from the initial phase for higher force output (45% maximal voluntary contraction). The results suggested muscle activity reorganization in ED plays a role to maintain sustained contraction. Furthermore, the decreased dynamical regulation ability to spatial reorganization may be prone to induce fatigue. This finding implied that spatial reorganization of muscle activity as a regulation mechanism contribute to maintain constant force production.
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34
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Abstract
Sex differences in common sports injuries to the lower extremity have been reported. Biomechanical factors of the hip have been investigated between sexes with regard to running-related injury. This study investigates gluteal muscle forces between sexes to aid in our understanding of sex-related biomechanical factors in running. Twenty-one healthy male and female runners were participants. Each ran at a controlled speed of 3.52-3.89 m/s down a 20-m runway. Kinetic and kinematic data were utilised to estimate muscle forces. Multivariate analysis of variance tests were utilised to detect differences in gluteal and hamstring muscle forces, hip and pelvic kinematics, and hip kinetic variables between sexes. Males produced greater peak gluteus maximus force, but lesser peak gluteus medius, minimus, and hamstring force than females during running. Males also demonstrated less hip adduction and greater hip flexion and anterior pelvic tilt than females. Finally, males produced lesser peak hip abduction and external rotation moments than females. Males and females demonstrate differences in gluteal muscle forces and hip kinetics and kinematics during running. Further understanding of underlying muscle forces may offer further insight into biomechanical differences in running between males and females.
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Affiliation(s)
- C Nathan Vannatta
- Sports Physical Therapy Department, Gundersen Health System , Onalaska, WI, USA.,Department of Health Professions, Physical Therapy Program, La Crosse Institute for Movement Science, University of Wisconsin - La Crosse , La Crosse, WI, USA
| | - Thomas W Kernozek
- Department of Health Professions, Physical Therapy Program, La Crosse Institute for Movement Science, University of Wisconsin - La Crosse , La Crosse, WI, USA.,Department of Health Professions, Physical Therapy Program, University of Wisconsin, La Crosse , La Crosse, WI, USA
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35
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Murphy SA, Negro F, Farina D, Onushko T, Durand M, Hunter SK, Schmit BD, Hyngstrom A. Stroke increases ischemia-related decreases in motor unit discharge rates. J Neurophysiol 2018; 120:3246-3256. [PMID: 30379629 DOI: 10.1152/jn.00923.2017] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Following stroke, hyperexcitable sensory pathways, such as the group III/IV afferents that are sensitive to ischemia, may inhibit paretic motor neurons during exercise. We quantified the effects of whole leg ischemia on paretic vastus lateralis motor unit firing rates during submaximal isometric contractions. Ten chronic stroke survivors (>1 yr poststroke) and 10 controls participated. During conditions of whole leg occlusion, the discharge timings of motor units were identified from decomposition of high-density surface electromyography signals during repeated submaximal knee extensor contractions. Quadriceps resting twitch responses and near-infrared spectroscopy measurements of oxygen saturation as an indirect measure of blood flow were made. There was a greater decrease in paretic motor unit discharge rates during the occlusion compared with the controls (average decrease for stroke and controls, 12.3 ± 10.0% and 0.1 ± 12.4%, respectively; P < 0.001). The motor unit recruitment thresholds did not change with the occlusion (stroke: without occlusion, 11.68 ± 5.83%MVC vs. with occlusion, 11.11 ± 5.26%MVC; control: 11.87 ± 5.63 vs. 11.28 ± 5.29%MVC). Resting twitch amplitudes declined similarly for both groups in response to whole leg occlusion (stroke: 29.16 ± 6.88 vs. 25.75 ± 6.78 Nm; control: 38.80 ± 13.23 vs 30.14 ± 9.64 Nm). Controls had a greater exponential decline (lower time constant) in oxygen saturation compared with the stroke group (stroke time constant, 22.90 ± 10.26 min vs. control time constant, 5.46 ± 4.09 min; P < 0.001). Ischemia of the muscle resulted in greater neural inhibition of paretic motor units compared with controls and may contribute to deficient muscle activation poststroke. NEW & NOTEWORTHY Hyperexcitable inhibitory sensory pathways sensitive to ischemia may play a role in deficient motor unit activation post stroke. Using high-density surface electromyography recordings to detect motor unit firing instances, we show that ischemia of the exercising muscle results in greater inhibition of paretic motor unit firing rates compared with controls. These findings are impactful to neurophysiologists and clinicians because they implicate a novel mechanism of force-generating impairment poststroke that likely exacerbates baseline weakness.
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Affiliation(s)
- Spencer A Murphy
- Department of Biomedical Engineering, Marquette University and the Medical College of Wisconsin , Milwaukee, Wisconsin
| | - Francesco Negro
- Department of Clinical and Experimental Sciences, University of Brescia , Brescia , Italy
| | - Dario Farina
- Department of Bioengineering, Imperial College of London , London , United Kingdom
| | - Tanya Onushko
- Department of Biomedical Engineering, Marquette University and the Medical College of Wisconsin , Milwaukee, Wisconsin
| | - Matthew Durand
- Department of Physical Medicine and Rehabilitation, Medical College of Wisconsin , Milwaukee, Wisconsin
| | - Sandra K Hunter
- Department of Physical Therapy, Marquette University , Milwaukee, Wisconsin
| | - Brian D Schmit
- Department of Biomedical Engineering, Marquette University and the Medical College of Wisconsin , Milwaukee, Wisconsin
| | - Allison Hyngstrom
- Department of Physical Therapy, Marquette University , Milwaukee, Wisconsin
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36
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Smith BW, Rowe JB, Reinkensmeyer DJ. Real-time slacking as a default mode of grip force control: implications for force minimization and personal grip force variation. J Neurophysiol 2018; 120:2107-2120. [PMID: 30089024 DOI: 10.1152/jn.00700.2017] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
During trial-to-trial movement adaptation, the motor system systematically reduces extraneous muscle forces when kinematic errors experienced on previous movements are small, a phenomenon termed "slacking." There is also growing evidence that the motor system slacks continuously (i.e., in real-time) during arm movement or grip force control, but the initiation of this slacking is not well-characterized, obfuscating its physiological cause. Here, we addressed this issue by asking participants ( n = 32) to track discrete force targets presented visually using isometric grip force, then applying a brief, subtle error-clamp to that visual feedback on random trials. Participants reduced their force in an exponential fashion, on these error-clamp trials, except when the target force was <10% maximum voluntary contraction (MVC). This force drift began <250 ms after the onset of the error-clamp, consistent with slacking being an ongoing process unmasked immediately after the motor system finished reacting to the last veridical feedback. Above 10% MVC, the slacking rate increased linearly with grip force magnitude. Grip force variation was approximately 50-100% higher with veridical feedback, largely due to heightened signal power at ~1 Hz, the band of visuomotor feedback control. Finally, the slacking rate measured for each participant during error-clamp trials correlated with their force variation during control trials. That is, participants who slacked more had greater force variation. These results suggest that real-time slacking continuously reduces grip force until visual error prompts correction. Whereas such slacking is suited for force minimization, it may also account for ~30% of the variability in personal grip force variation. NEW & NOTEWORTHY We provide evidence that a form of slacking continuously conditions real-time grip force production. This slacking is well-suited to promote efficiency but is expected to increase force variation by triggering additional feedback corrections. Moreover, we show that the rate at which a person slacks is substantially correlated with the variation of their grip force. In combination, at the neurophysiological level, our results suggest slacking is caused by one or more relatively smooth neural adaptations.
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Affiliation(s)
- Brendan W Smith
- Department of Mechanical Engineering, Loyola Marymount University , Los Angeles, California
| | - Justin B Rowe
- Department of Biomedical Engineering, University of California , Irvine, California
| | - David J Reinkensmeyer
- Department of Biomedical Engineering, University of California , Irvine, California.,Departments of Anatomy and Neurobiology, Mechanical and Aerospace Engineering, and Physical Medicine and Rehabilitation, University of California , Irvine, California
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Abstract
Performance fatigability is characterized as an acute decline in motor performance caused by an exercise-induced reduction in force or power of the involved muscles. Multiple mechanisms contribute to performance fatigability and originate from neural and muscular processes, with the task demands dictating the mechanisms. This review highlights that (1) inadequate activation of the motoneuron pool can contribute to performance fatigability, and (2) the demands of the task and the physiological characteristics of the population assessed, dictate fatigability and the involved mechanisms. Examples of task and population differences in fatigability highlighted in this review include contraction intensity and velocity, stability and support provided to the fatiguing limb, sex differences, and aging. A future challenge is to define specific mechanisms of fatigability and to translate these findings to real-world performance and exercise training in healthy and clinical populations across the life span.
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Affiliation(s)
- Sandra K Hunter
- Exercise Science Program, Department of Physical Therapy, Marquette University, Milwaukee, Wisconsin 53201
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38
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Doix ACM, Wachholz F, Marterer N, Immler L, Insam K, Federolf PA. Is the cross-over effect of a unilateral high-intensity leg extension influenced by the sex of the participants? Biol Sex Differ 2018; 9:29. [PMID: 29954447 PMCID: PMC6022493 DOI: 10.1186/s13293-018-0188-4] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/28/2018] [Accepted: 06/13/2018] [Indexed: 12/02/2022] Open
Abstract
Background While performing a unilateral muscle contraction, electrical muscle activity also arises in the contralateral homologous muscle, muscle group, or limb. When the muscle contraction induces muscle fatigue, females show not only a greater resistance than males but also a reduced contralateral muscle activation. The study aimed at investigating whether, during a high-intensity 30-s unilateral maximal effort isometric leg extension exercise, the contralateral non-exercising limb (NEL) knee extensor muscle activation would differ between females and males. Methods Twenty participants, 11 females (23.80 ± 2.15 years old) and 9 males (26.50 ± 2.45 years old), performed a unilateral 30-s exercise while surface electromyography (sEMG) was measured from the vastus lateralis (VL), vastus medialis (VM), and rectus femoris (RF) on both limbs. The maximal voluntary contraction (MVC) was measured for both the exercising limb (EL) and the NEL before (MVC PRE) and after (MVC POST) the 30-s exercise to assess muscle fatigue. Results While both females and males exhibited muscle fatigue in the EL (p = 0.015), females exhibited a lower MVC reduction than males (p = 0.042), suggesting that females were less fatigued than males. Although no muscle fatigue, i.e., no MVC force reduction was found in the NEL for either group before and after the 30-s exercise, the muscle activity of the VL was found to be of greater magnitude during the MVC POST only for females (p = 0.047) while it remained unchanged for males. During the 30-s exercise, the force output of the EL decreased only for males (p = 0.029) while females showed a preservation of the force output (p > 0.05). The sEMG activity of the NEL during the 30-s unilateral exercise increased for both groups in all measured muscles (all p-values < 0.03). Conclusions Likely, different underlying muscle fatigue mechanisms occurred in the EL between females and males. Yet, our findings suggest that the cross-over effect to the NEL during the 30-s exercise occurred in a similar fashion in both groups. The current study suggests that the contralateral muscle activation seen with a unilateral exercise is independent of the sex of individuals. Therefore, unilateral training or rehabilitation-based protocols would similarly impact females and males.
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Affiliation(s)
- Aude-Clémence M Doix
- Department of Sport Science, University of Innsbruck, Fürstenweg 185, 6020, Innsbruck, Austria.
| | - Felix Wachholz
- Department of Sport Science, University of Innsbruck, Fürstenweg 185, 6020, Innsbruck, Austria
| | - Natalie Marterer
- Department of Sport Science, University of Innsbruck, Fürstenweg 185, 6020, Innsbruck, Austria
| | - Lorenz Immler
- Department of Sport Science, University of Innsbruck, Fürstenweg 185, 6020, Innsbruck, Austria
| | - Kathrin Insam
- Department of Sport Science, University of Innsbruck, Fürstenweg 185, 6020, Innsbruck, Austria
| | - Peter A Federolf
- Department of Sport Science, University of Innsbruck, Fürstenweg 185, 6020, Innsbruck, Austria
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39
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Yacyshyn AF, Nettleton J, Power GA, Jakobi JM, McNeil CJ. The effect of muscle length on transcranial magnetic stimulation-induced relaxation rate in the plantar flexors. Physiol Rep 2018; 5:5/18/e13442. [PMID: 28947595 PMCID: PMC5617929 DOI: 10.14814/phy2.13442] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/13/2017] [Accepted: 08/17/2017] [Indexed: 11/24/2022] Open
Abstract
Transcranial magnetic stimulation (TMS) of the motor cortex during a maximal voluntary contraction (MVC) permits functionally relevant measurements of muscle group relaxation rate (i.e., when muscles are actively contracting under voluntary control). This study's purpose was twofold: (1) to explore the impact of muscle length on TMS‐induced plantar flexor relaxation rate; and (2) to incorporate ultrasonography to measure relaxation‐induced lengthening of medial gastrocnemius (MG) fascicles and displacement of the muscle–tendon junction (MTJ). Eleven males (24.8 ± 7.0 years) performed 21 brief isometric plantar flexor MVCs. Trials were block‐randomized every three MVCs among 20° dorsiflexion (DF), a neutral ankle position, and 30° plantar flexion (PF). During each MVC, TMS was delivered and ultrasound video recordings captured MG fascicles or MTJ length changes. Peak relaxation rate was calculated as the steepest slope of the TMS‐induced drop in plantar flexor torque or the rate of length change for MG fascicles and MTJ. Torque relaxation rate was slower for PF (−804 ± 162 Nm·s−1) than neutral and DF (−1896 ± 298 and −2008 ± 692 Nm·s−1, respectively). Similarly, MG fascicle relaxation rate was slower for PF (−2.80 ± 1.10 cm·s−1) than neutral and DF (−5.35 ± 1.10 and −4.81 ± 1.87 cm·s−1, respectively). MTJ displacement rate showed a similar trend (P = 0.06), with 3.89 ± 1.93 cm·s−1 for PF compared to rates of 6.87 ± 1.55 and 6.36 ± 2.97 cm·s−1 for neutral and DF, respectively. These findings indicate muscle length affects the torque relaxation rate recorded after TMS during an MVC. Comparable results were obtained from muscle fascicles, indicating ultrasound imaging is suitable for measuring evoked contractile properties during voluntary contraction.
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Affiliation(s)
- Alexandra F Yacyshyn
- School of Health and Exercise Sciences, University of British Columbia, Kelowna, British Columbia, Canada.,Centre for Heart, Lung and Vascular Health, Faculty of Health and Social Development, University of British Columbia, Kelowna, British Columbia, Canada
| | - Jane Nettleton
- School of Health and Exercise Sciences, University of British Columbia, Kelowna, British Columbia, Canada
| | - Geoffrey A Power
- Department of Human Health & Nutritional Sciences, College of Biological Sciences, University of Guelph, Guelph, Ontario, Canada
| | - Jennifer M Jakobi
- School of Health and Exercise Sciences, University of British Columbia, Kelowna, British Columbia, Canada.,Healthy Exercise and Aging Laboratory Group, Faculty of Health and Social Development, University of British Columbia, Kelowna, British Columbia, Canada
| | - Chris J McNeil
- School of Health and Exercise Sciences, University of British Columbia, Kelowna, British Columbia, Canada .,Centre for Heart, Lung and Vascular Health, Faculty of Health and Social Development, University of British Columbia, Kelowna, British Columbia, Canada
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Scheidegger O, Kamber N, Rösler KM. Estimation of voluntary elicited motor neuron discharge using a peripheral nerve collision technique at different contraction strengths. Clin Neurophysiol 2018; 129:1579-1587. [PMID: 29885647 DOI: 10.1016/j.clinph.2018.04.751] [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: 02/02/2018] [Revised: 03/24/2018] [Accepted: 04/25/2018] [Indexed: 11/26/2022]
Abstract
OBJECTIVE To estimate non-invasively the amount, recruitment pattern and discharge frequency of spinal motor neurons (MN) at contraction strength >20% of maximal voluntary contraction (MVC) of small hand muscles. METHODS A peripheral collision technique was used and consisted of supramaximal electrical stimuli at Erb's point and at the wrist, synchronizing descending volleys of action potential during voluntary isometric contractions of the abductor digiti minimi muscle at 20-80% of MVC strength and 1-8 s of contraction duration. Responses of 13 healthy volunteers were quantified and analysed using a recently described model of MN behaviour. RESULTS A linear relationship between MN discharge and force generation was noticed with R2 = 0.996, and was confirmed using the simulation results (R2 = 0.997) for contraction durations up to 8 s. For each investigated force level, discharge frequency and recruitment pattern were calculated for individual MN. CONCLUSIONS Using this method, MN discharge properties during voluntary activity can be estimated non-invasively. SIGNIFICANCE This method provides new opportunities for the non-invasive study of MN behaviour, and could be expanded to patients with conduction failure and during fatigue.
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Affiliation(s)
- Olivier Scheidegger
- Department of Neurology, Inselspital, Bern University Hospital, and University of Bern, Switzerland.
| | - Nicole Kamber
- Department of Neurology, Inselspital, Bern University Hospital, and University of Bern, Switzerland
| | - Kai Michael Rösler
- Department of Neurology, Inselspital, Bern University Hospital, and University of Bern, Switzerland
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Hageman S, Kovalchuk MO, Sleutjes BTHM, van Schelven LJ, van den Berg LH, Franssen H. Sodium-potassium pump assessment by submaximal electrical nerve stimulation. Clin Neurophysiol 2018; 129:809-814. [PMID: 29477980 DOI: 10.1016/j.clinph.2018.01.016] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/07/2017] [Revised: 12/15/2017] [Accepted: 01/07/2018] [Indexed: 12/14/2022]
Abstract
OBJECTIVE Sodium-potassium pump dysfunction in peripheral nerve is usually assessed by determining axonal hyperpolarization following maximal voluntary contraction (MVC) or maximal electrical nerve stimulation. As MVC may be unreliable and maximal electrical stimulation too painful, we assessed if hyperpolarization can also be induced by submaximal electrical nerve stimulation. METHODS In 8 healthy volunteers different submaximal electrical stimulus trains were given to the median nerve at the wrist, followed by 5 min assessment of thresholds for compound muscle action potentials of 20%, 40% or 60% of maximal. RESULTS Threshold increase after submaximal electrical nerve stimulation was most prominent after an 8 Hz train of at least 5 min duration evoking submaximal CMAPs of 60%. It induced minimal discomfort and was not painful. Threshold increase after MVC was not significantly higher than this stimulus train. CONCLUSIONS Submaximal electrical stimulation evokes activity dependent hyperpolarization in healthy test subjects without causing significant discomfort. SIGNIFICANCE Sodium-potassium pump function may be assessed using submaximal electrical stimulation.
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Affiliation(s)
- Steven Hageman
- Brain Centre Rudolf Magnus, Department of Neurology and Neurosurgery, University Medical Centre Utrecht, The Netherlands
| | - Maria O Kovalchuk
- Brain Centre Rudolf Magnus, Department of Neurology and Neurosurgery, University Medical Centre Utrecht, The Netherlands
| | - Boudewijn T H M Sleutjes
- Brain Centre Rudolf Magnus, Department of Neurology and Neurosurgery, University Medical Centre Utrecht, The Netherlands
| | - Leonard J van Schelven
- Department of Medical Technology & Clinical Physics, University Medical Centre Utrecht, The Netherlands
| | - Leonard H van den Berg
- Brain Centre Rudolf Magnus, Department of Neurology and Neurosurgery, University Medical Centre Utrecht, The Netherlands
| | - Hessel Franssen
- Brain Centre Rudolf Magnus, Department of Neurology and Neurosurgery, University Medical Centre Utrecht, The Netherlands.
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Vera-Ibáñez A, Romero-Arenas S, Marín-Pagán C, Márquez G. Concurrencia de fatiga y potenciación tras una contracción voluntaria máxima sostenida / Concurrence Of Fatigue And Potentiation After A Sustained Maximal Voluntary Contraction. REVISTA INTERNACIONAL DE MEDICINA Y CIENCIAS DE LA ACTIVIDAD FÍSICA Y DEL DEPORTE 2018. [DOI: 10.15366/rimcafd2018.69.004] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
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Polarity-dependent improvement of maximal-effort sprint cycling performance by direct current stimulation of the central nervous system. Neurosci Lett 2017; 657:97-101. [PMID: 28778807 DOI: 10.1016/j.neulet.2017.07.056] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/14/2016] [Revised: 07/24/2017] [Accepted: 07/30/2017] [Indexed: 01/26/2023]
Abstract
Sprint motor performance, such as in short-distance running or cycling, gradually decreases after reaching a maximum speed or cadence. This may be attributed to the central nervous system. Brain stimulation studies have recently revealed the plastic nature of the human brain and spinal cord, but it is unclear how direct current stimulation (DCS) affects sprint motor performance. To address this issue, we investigated DCS's effect on healthy volunteers' sprint cycling performance. DCS was applied to the lumbar spinal cord (3mA) or the leg area of the motor cortex (2mA) for 15min with 3 different polarities: anodal, cathodal, and sham. After DCS, the subjects performed maximal-effort sprint cycling for 30s under a constant load. Pooled mean power during the 30s was significantly greater after cathodal transcutaneous spinal DCS to the lumbar spinal cord (tsDCS) than anodal or sham tsDCS. The improvement with cathodal stimulation was notable both 0-5 and 20-25s after the performance onset. There were no significant inter-conditional differences in peak power. Pooled mean power was significantly greater after anodal transcranial DCS to the motor cortex (tDCS) than after cathodal tDCS, although mean powers of anodal and sham tDCS were not significantly different. The increase in mean power after cathodal tsDCS could result from a reduction in central fatigue. This stimulus method might improve sprint performance.
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Mira J, Lapole T, Souron R, Messonnier L, Millet GY, Rupp T. Cortical voluntary activation testing methodology impacts central fatigue. Eur J Appl Physiol 2017; 117:1845-1857. [DOI: 10.1007/s00421-017-3678-x] [Citation(s) in RCA: 31] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/03/2017] [Accepted: 06/30/2017] [Indexed: 10/19/2022]
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45
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Collins BW, Gale LH, Buckle NCM, Button DC. Corticospinal excitability to the biceps brachii and its relationship to postactivation potentiation of the elbow flexors. Physiol Rep 2017; 5:5/8/e13265. [PMID: 28455452 PMCID: PMC5408290 DOI: 10.14814/phy2.13265] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/21/2017] [Revised: 03/30/2017] [Accepted: 04/05/2017] [Indexed: 11/24/2022] Open
Abstract
We examined the effects of a submaximal voluntary elbow flexor contraction protocol on measures of corticospinal excitability and postactivation potentiation of evoked muscle forces and if these measures were state‐dependent (rest vs. voluntary muscle contraction). Participants completed four experimental sessions where they rested or performed a 5% maximum voluntary contraction (MVC) of the elbow flexors prior to, immediately, and 5 min following a submaximal contraction protocol. During rest or 5% MVC, transcranial magnetic stimulation, transmastoid electrical stimulation, electrical stimulation of biceps brachii motor point and Erb's point were elicited to induce motor‐evoked potentials (MEPs), cervicomedullary MEPs (CMEPs), potentiated twitch (PT) force, and maximal muscle compound action potential (Mmax), respectively prior to, immediately, and 5 min postcontraction protocol. MEP amplitudes increased (215 and 165%Mmax, P ≤ 0.03) only at 1 and 6s postcontraction protocol, respectively during rest but not 5% MVC. CMEP amplitudes decreased during rest and 5% MVC (range:21–58%Mmax, P ≤ 0.04) for up to 81 sec postcontraction protocol. Peak twitch force increased immediately postcontraction protocol and remained elevated for 90 sec (range:122–147% increase, P < 0.05). There was a significant positive correlation between MEP and PT force during rest (r = 0.88, P = 0.01) and a negative correlation between CMEP and PT force during rest (r = −0.85, P < 0.02 and 5% MVC (r = −0.96, P < 0.01) immediately postcontraction protocol. In conclusion, the change in corticospinal and spinal excitability was state‐ and time‐dependent whereas spinal excitability and postactivation potentiation were time‐dependent following the contraction protocol. Changes in corticospinal excitability and postactivation potentiation correlated and were also state‐dependent.
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Affiliation(s)
- Brandon W Collins
- Human Neurophysiology Laboratory, School of Human Kinetics and Recreation, Newfoundland and Labrador Canada
| | - Laura H Gale
- Human Neurophysiology Laboratory, School of Human Kinetics and Recreation, Newfoundland and Labrador Canada
| | - Natasha C M Buckle
- Human Neurophysiology Laboratory, School of Human Kinetics and Recreation, Newfoundland and Labrador Canada
| | - Duane C Button
- Human Neurophysiology Laboratory, School of Human Kinetics and Recreation, Newfoundland and Labrador Canada .,BioMedical Sciences, Faculty of Medicine Memorial University St. John's, Newfoundland and Labrador, Canada
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46
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Beretta-Piccoli M, D’Antona G, Zampella C, Barbero M, Clijsen R, Cescon C. Test-retest reliability of muscle fiber conduction velocity and fractal dimension of surface EMG during isometric contractions. Physiol Meas 2017; 38:616-630. [DOI: 10.1088/1361-6579/aa614c] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
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Piotrkiewicz M, Türker KS. Onion Skin or Common Drive? Front Cell Neurosci 2017; 11:2. [PMID: 28154526 PMCID: PMC5243795 DOI: 10.3389/fncel.2017.00002] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/08/2016] [Accepted: 01/05/2017] [Indexed: 11/13/2022] Open
Affiliation(s)
- Maria Piotrkiewicz
- Department of Engineering of Nervous and Muscular System, Nalecz Institute of Biocybernetics and Biomedical Engineering, Polish Academy of Sciences Warsaw, Poland
| | - Kemal S Türker
- Laboratory of Neuromuscular Research, Koç University School of Medicine Istanbul, Turkey
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Rodriguez-Falces J, Place N. Muscle excitability during sustained maximal voluntary contractions by a separate analysis of the M-wave phases. Scand J Med Sci Sports 2016; 27:1761-1775. [DOI: 10.1111/sms.12819] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 11/17/2016] [Indexed: 11/29/2022]
Affiliation(s)
- J. Rodriguez-Falces
- Department of Electrical and Electronical Engineering; Public University of Navarra; Pamplona Spain
| | - N. Place
- Institute of Sport Sciences and Department of Physiology; University of Lausanne; Lausanne Switzerland
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D'Amico JM, Butler AA, Héroux ME, Cotel F, Perrier JFM, Butler JE, Gandevia SC, Taylor JL. Human motoneurone excitability is depressed by activation of serotonin 1A receptors with buspirone. J Physiol 2016; 595:1763-1773. [PMID: 27859267 DOI: 10.1113/jp273200] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/26/2016] [Accepted: 11/14/2016] [Indexed: 11/08/2022] Open
Abstract
KEY POINTS In the adult turtle spinal cord, action potential generation in motoneurones is inhibited by spillover of serotonin to extrasynaptic serotonin 1A (5-HT1A ) receptors at the axon initial segment. We explored whether ingestion of the 5-HT1A receptor partial agonist, buspirone, decreases motoneurone excitability in humans. Following ingestion of buspirone, two tests of motoneurone excitability showed decreases. F-wave areas and persistence in an intrinsic muscle of the hand were reduced, as was the area of cervicomedullary motor evoked potentials in biceps brachii. Our findings suggest that activation of 5-HT1A receptors depresses human motoneurone excitability. Such a depression could contribute to decreased motoneurone output during fatiguing exercise if there is high serotonergic drive to the motoneurones. ABSTRACT Intense serotonergic drive in the turtle spinal cord results in serotonin spillover to the axon initial segment of the motoneurones where it activates serotonin 1A (5-HT1A ) receptors and inhibits generation of action potentials. We examined whether activation of 5-HT1A receptors decreases motoneurone excitability in humans by determining the effects of a 5-HT1A receptor partial agonist, buspirone, on F waves and cervicomedullary motor evoked potentials (CMEPs). In a placebo-controlled double-blind study, 10 participants were tested on two occasions where either placebo or 20 mg of buspirone was administered orally. The ulnar nerve was stimulated supramaximally to evoke F waves in abductor digiti minimi (ADM). CMEPs and the maximal M wave were elicited in biceps brachii by cervicomedullary stimulation and brachial plexus stimulation, respectively. Following buspirone intake, F-wave area and persistence, as well as CMEP area, were significantly decreased. The mean post-pill difference in normalized F-wave areas and persistence between buspirone and placebo days was -27% (-42, -12; 95% confidence interval) and -9% (-16, -2), respectively. The mean post-pill difference in normalized CMEP area between buspirone and placebo days showed greater variation and was -31% (-60, -2). In conclusion, buspirone reduces motoneurone excitability in humans probably via activation of 5-HT1A receptors at the axon initial segment. This has implications for motor output during high drive to the motoneurones when serotonin may spill over to these inhibitory receptors and consequently inhibit motoneurone output. Such a mechanism could potentially contribute to fatigue with exercise.
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Affiliation(s)
- Jessica M D'Amico
- Neuroscience Research Australia, Barker Street, Randwick, NSW, Australia
| | - Annie A Butler
- Neuroscience Research Australia, Barker Street, Randwick, NSW, Australia.,University of New South Wales, Sydney, NSW, Australia
| | - Martin E Héroux
- Neuroscience Research Australia, Barker Street, Randwick, NSW, Australia.,University of New South Wales, Sydney, NSW, Australia
| | | | | | - Jane E Butler
- Neuroscience Research Australia, Barker Street, Randwick, NSW, Australia.,University of New South Wales, Sydney, NSW, Australia
| | - Simon C Gandevia
- Neuroscience Research Australia, Barker Street, Randwick, NSW, Australia.,University of New South Wales, Sydney, NSW, Australia
| | - Janet L Taylor
- Neuroscience Research Australia, Barker Street, Randwick, NSW, Australia.,University of New South Wales, Sydney, NSW, Australia
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Effect of Training Leading to Repetition Failure on Muscular Strength: A Systematic Review and Meta-Analysis. Sports Med 2016; 46:487-502. [PMID: 26666744 DOI: 10.1007/s40279-015-0451-3] [Citation(s) in RCA: 67] [Impact Index Per Article: 8.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022]
Abstract
BACKGROUND It remains unclear whether repetitions leading to failure (failure training) or not leading to failure (non-failure training) lead to superior muscular strength gains during resistance exercise. Failure training may provide the stimulus needed to enhance muscular strength development. However, it is argued that non-failure training leads to similar increases in muscular strength without the need for high levels of discomfort and physical effort, which are associated with failure training. OBJECTIVE We conducted a systematic review and meta-analysis to examine the effect of failure versus non-failure training on muscular strength. METHODS Five electronic databases were searched using terms related to failure and non-failure training. Studies were deemed eligible for inclusion if they met the following criteria: (1) randomised and non-randomised studies; (2) resistance training intervention where repetitions were performed to failure; (3) a non-failure comparison group; (4) resistance training interventions with a total of ≥3 exercise sessions; and (5) muscular strength assessment pre- and post-training. Random-effects meta-analyses were performed to pool the results of the included studies and generate a weighted mean effect size (ES). RESULTS Eight studies were included in the meta-analysis (combined studies). Training volume was controlled in four studies (volume controlled), while the remaining four studies did not control for training volume (volume uncontrolled). Non-failure training resulted in a 0.6-1.3% greater strength increase than failure training. A small pooled effect favouring non-failure training was found (ES = 0.34; p = 0.02). Significant small pooled effects on muscular strength were also found for non-failure versus failure training with compound exercises (ES = 0.37-0.38; p = 0.03) and trained participants (ES = 0.37; p = 0.049). A slightly larger pooled effect favouring non-failure training was observed when volume-uncontrolled studies were included (ES = 0.41; p = 0.047). No significant effect was found for the volume-controlled studies, although there was a trend favouring non-failure training. The methodological quality of the included studies in the review was found to be moderate. Exercise compliance was high for the studies where this was reported (n = 5), although limited information on adverse events was provided. CONCLUSION Overall, the results suggest that despite statistically significant effects on muscular strength being found for non-failure compared with failure training, the small percentage of improvement shown for non-failure training is unlikely to be meaningful. Therefore, it appears that similar increases in muscular strength can be achieved with failure and non-failure training. Furthermore, it seems unnecessary to perform failure training to maximise muscular strength; however, if incorporated into a programme, training to failure should be performed sparingly to limit the risks of injuries and overtraining.
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