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Su L, Zhao C, Sun B, Dou L, Wang C, Yang Z, Li T, Jin Y. Effects of exercise on muscle fiber conversion, muscle development and meat quality of Sunit sheep. Meat Sci 2024; 211:109440. [PMID: 38324956 DOI: 10.1016/j.meatsci.2024.109440] [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: 09/04/2023] [Revised: 01/22/2024] [Accepted: 01/26/2024] [Indexed: 02/09/2024]
Abstract
This study aimed to investigate the effects of exercise on muscle fiber conversion, muscle development and meat quality in the biceps femoris (BF) muscle of Sunit sheep. Twelve Sunit sheep with similar body weight were divided into two groups: control group (C group) and exercise group (E group), E group lambs underwent 6 km of exercise training per day for 90 d. The findings revealed that compared with the C group, exercise training enhanced the expression of MyHC IIa mRNA, decreased the number ratio of type IIB muscle fibers and the expression of MyHC IIb mRNA (P < 0.05). Furthermore, the E group lamb displayed higher creatine kinase (CK) activity, and lactic acid levels (P < 0.05), while glycogen content and lactic dehydrogenase (LDH) activity showed opposite trends (P < 0.05). Exercise significantly up-regulated the mRNA expression of AMP-activated protein kinase α1 (AMPKα1), sirtuin1 (SIRT1), peroxisome proliferator-activated receptor gamma coactivator 1-α (PGC-1α), cytochrome c oxidase IV (COX IV), protein kinase B (Akt), mammalian target of rapamycin (mTOR) and p70 Ribosomal S6 Kinase 1 (p70s6k1) (P < 0.05), suggesting exercise promoted muscle fiber conversion by mediating AMPK/PGC-1α pathway, and improved skeletal muscle development via Akt/mTOR pathway. Besides, backfat thickness and pH45min value in the E group decreased significantly, while the pH24, a*, and shear force value increased significantly (P < 0.05). To conclude, this study suggested that exercise training can be used to alter muscle fiber characteristics and muscle development in lamb production.
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Affiliation(s)
- Lin Su
- Department of Food Science, College of Food Science and Engineering, Inner Mongolia Agricultural University, Hohhot 010018, China; Integrative Research Base of Beef and Lamb Processing Technology, Inner Mongolia Agricultural University, Hohhot, 010018, China
| | - Congying Zhao
- Department of Food Science, College of Food Science and Engineering, Inner Mongolia Agricultural University, Hohhot 010018, China; Integrative Research Base of Beef and Lamb Processing Technology, Inner Mongolia Agricultural University, Hohhot, 010018, China
| | - Bing Sun
- Saihan District Center for Disease Control and Prevention, Hohhot 010010, China
| | - Lu Dou
- Department of Food Science, College of Food Science and Engineering, Inner Mongolia Agricultural University, Hohhot 010018, China; Integrative Research Base of Beef and Lamb Processing Technology, Inner Mongolia Agricultural University, Hohhot, 010018, China
| | - Chenlei Wang
- Department of Food Science, College of Food Science and Engineering, Inner Mongolia Agricultural University, Hohhot 010018, China; Integrative Research Base of Beef and Lamb Processing Technology, Inner Mongolia Agricultural University, Hohhot, 010018, China
| | - Zhihao Yang
- Department of Food Science, College of Food Science and Engineering, Inner Mongolia Agricultural University, Hohhot 010018, China; Integrative Research Base of Beef and Lamb Processing Technology, Inner Mongolia Agricultural University, Hohhot, 010018, China
| | - Tianle Li
- Department of Food Science, College of Food Science and Engineering, Inner Mongolia Agricultural University, Hohhot 010018, China; Integrative Research Base of Beef and Lamb Processing Technology, Inner Mongolia Agricultural University, Hohhot, 010018, China
| | - Ye Jin
- Department of Food Science, College of Food Science and Engineering, Inner Mongolia Agricultural University, Hohhot 010018, China; Integrative Research Base of Beef and Lamb Processing Technology, Inner Mongolia Agricultural University, Hohhot, 010018, China.
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Dotan R, Woods S, Langille J, Falk B. Boys-men mean-power-frequency differences in progressive exercise to exhaustion, confounded by variability and adiposity. Eur J Appl Physiol 2024; 124:491-505. [PMID: 37553549 DOI: 10.1007/s00421-023-05292-3] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/02/2023] [Accepted: 07/26/2023] [Indexed: 08/10/2023]
Abstract
BACKGROUND Only scant research has compared children's mean power frequency (MPF) to adults', with a clear overview still lacking. A significant obstacle has been MPF's high variability, which this study aimed to overcome by elucidating the MPF characteristics distinguishing boys from men in progressive exhaustive exercise. METHODS Electromyographic (EMG) data of 20 men (23.5 ± 2.5yrs) and 17 boys (10.2 ± 1.0 yrs), who performed progressively exhausting, intermittent isometric knee extensions, were subjected to secondary MPF analysis. Participants' vastus lateralis MPF data series were transformed to third-order polynomial regressions and expressed as percentages of the peak polynomial MPF values (%MPFpeak). The resulting curves were compared at 5-% time-to-exhaustion (TTE) intervals, using repeated-measures ANOVA. Raw MPFpeak values were adiposity corrected to 0% fat and used to convert the %MPFpeak data back to absolute MPF values (Hz) for estimating muscle-level MPF. RESULTS No overall interaction or group effects could be shown between the %MPFpeak plots, but pairwise comparisons revealed significantly higher men's values at 50-70%TTE and lower at 100%TTE, i.e. boys' shallower MPF rise and decline. The adiposity-corrected boys' and men's composite MPF values peaked at 125.7 ± 2.5 and 166.0 ± 2.4 Hz, respectively (110.7 ± 1.7 and 122.5 ± 2.1 Hz, uncorrected), with a significant group effect (p < 0.05) and pairwise differences at all %TTE points. CONCLUSIONS The boys were lower than the men in both the observed and, more so, in the adiposity-corrected MPF values that presumably estimate muscle-level MPF. The boys' shallower MPF rise and decline conform to children's claimed type-II motor-unit activation and/or compositional deficits and their related known advantage in muscular endurance.
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Affiliation(s)
- Raffy Dotan
- Kinesiology Department, Faculty of Applied Health Sciences, Brock University, St Catharines, ON, Canada.
| | - Stacey Woods
- Kinesiology Department, Faculty of Applied Health Sciences, Brock University, St Catharines, ON, Canada
| | - Jordan Langille
- Kinesiology Department, Faculty of Applied Health Sciences, Brock University, St Catharines, ON, Canada
| | - Bareket Falk
- Kinesiology Department, Faculty of Applied Health Sciences, Brock University, St Catharines, ON, Canada
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3
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Brouwer NP, Tabasi A, Kingma I, Stegeman DF, van Dijk W, Moya-Esteban A, Sartori M, van Dieën JH. Trunk extensor muscle endurance and its relationship to action potential conduction velocity and spectral parameters estimated using high-density electromyography. J Electromyogr Kinesiol 2023; 73:102830. [PMID: 37862925 DOI: 10.1016/j.jelekin.2023.102830] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/16/2023] [Revised: 08/23/2023] [Accepted: 10/10/2023] [Indexed: 10/22/2023] Open
Abstract
Trunk extensor muscle fatigue typically manifests as a decline in spectral content of surface electromyography. However, previous research on the relationship of this decline with trunk extensor muscle endurance have shown inconsistent results. The decline of spectral content mainly reflects the decrease in average motor unit action potential conduction velocity (CV). We evaluated whether the rate of change in CV, as well as two approaches employing the change in spectral content, are related to trunk extensor muscle endurance. Fourteen healthy male participants without a low-back pain history performed a non-strictly controlled static forward trunk bending trial until exhaustion while standing. For 13 participants, physiologically plausible CV estimates were obtained from high-density surface electromyography bilaterally from T6 to L5. Laterally between L1 and L2, the linear rate of CV change was strongly correlated to endurance time (R2 = 0.79), whereas analyses involving the linear rate of change in spectral measures showed a lower (R2 = 0.38) or no correlation. For medial electrode locations, estimating CV and its relationship with endurance time was less successful, while the linear rate of change in spectral measures correlated moderately to endurance time (R2 = 0.44; R2 = 0.56). This study provides guidance on monitoring trunk extensor muscle fatigue development using electromyography.
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Affiliation(s)
- Niels P Brouwer
- Department of Human Movement Sciences, Vrije Universiteit Amsterdam, Amsterdam Movement Sciences, Amsterdam, The Netherlands
| | - Ali Tabasi
- Department of Human Movement Sciences, Vrije Universiteit Amsterdam, Amsterdam Movement Sciences, Amsterdam, The Netherlands
| | - Idsart Kingma
- Department of Human Movement Sciences, Vrije Universiteit Amsterdam, Amsterdam Movement Sciences, Amsterdam, The Netherlands
| | - Dick F Stegeman
- Department of Human Movement Sciences, Vrije Universiteit Amsterdam, Amsterdam Movement Sciences, Amsterdam, The Netherlands
| | | | - Alejandro Moya-Esteban
- Department of Biomechanical Engineering, University of Twente, Enschede, The Netherlands
| | - Massimo Sartori
- Department of Biomechanical Engineering, University of Twente, Enschede, The Netherlands
| | - Jaap H van Dieën
- Department of Human Movement Sciences, Vrije Universiteit Amsterdam, Amsterdam Movement Sciences, Amsterdam, The Netherlands.
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4
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Gabriel DA. Teaching Essential EMG Theory to Kinesiologists and Physical Therapists Using Analogies Visual Descriptions, and Qualitative Analysis of Biophysical Concepts. SENSORS (BASEL, SWITZERLAND) 2022; 22:6555. [PMID: 36081014 PMCID: PMC9460425 DOI: 10.3390/s22176555] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 08/01/2022] [Revised: 08/24/2022] [Accepted: 08/28/2022] [Indexed: 06/15/2023]
Abstract
Electromyography (EMG) is a multidisciplinary field that brings together allied health (kinesiology and physical therapy) and the engineering sciences (biomedical and electrical). Since the physical sciences are used in the measurement of a biological process, the presentation of the theoretical foundations of EMG is most conveniently conducted using math and physics. However, given the multidisciplinary nature of EMG, a course will most likely include students from diverse backgrounds, with varying levels of math and physics. This is a pedagogical paper that outlines an approach for teaching foundational concepts in EMG to kinesiologists and physical therapists that uses a combination of analogies, visual descriptions, and qualitative analysis of biophysical concepts to develop an intuitive understanding for those who are new to surface EMG. The approach focuses on muscle fiber action potentials (MFAPs), motor unit action potentials (MUAPs), and compound muscle action potentials (CMAPs) because changes in these waveforms are much easier to identify and describe in comparison to the surface EMG interference pattern (IP).
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Affiliation(s)
- David A Gabriel
- Electromyographic Kinesiology Laboratory, Faculty of Applied Health Sciences, Brock University, 1812 Sir Isaac Brock Way, St. Catharines, ON L2S 3A1, Canada
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5
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Brouwer NP, Tabasi A, Kingma I, Stegeman DF, van Dijk W, Moya-Esteban A, Sartori M, van Dieën JH. Low back muscle action potential conduction velocity estimated using high-density electromyography. J Electromyogr Kinesiol 2022; 66:102679. [DOI: 10.1016/j.jelekin.2022.102679] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/17/2022] [Revised: 06/03/2022] [Accepted: 06/23/2022] [Indexed: 10/17/2022] Open
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Zhu S, Zhao J, Wu Y, She Q. Intermuscular coupling network analysis of upper limbs based on R-vine copula transfer entropy. MATHEMATICAL BIOSCIENCES AND ENGINEERING : MBE 2022; 19:9437-9456. [PMID: 35942767 DOI: 10.3934/mbe.2022439] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/15/2023]
Abstract
In the field of neuroscience, it is very important to evaluate the causal coupling characteristics between bioelectrical signals accurately and effectively. Transfer entropy is commonly used to analyze complex data, especially the causal relationship between data with non-linear, multidimensional characteristics. However, traditional transfer entropy needs to estimate the probability density function of the variable, which is computationally complex and unstable. In this paper, a new and effective method for entropy transfer is proposed, by means of applying R-vine copula function estimation. The effectiveness of R-vine copula transfer entropy is first verified on several simulations, and then applied to intermuscular coupling analysis to explore the characteristics of the intermuscular coupling network of muscles in non-fatigue and fatigue conditions. The experiment results show that as the muscle group enters the fatigue state, the community structure can be adjusted and the muscle nodes participating in the exercise are fully activated, enabling the two-way interaction between different communities. Finally, it comes to the conclusion that the proposed method can make accurate inferences about complex causal coupling. Moreover, the characteristics of the intermuscular coupling network in both non-fatigue and fatigue states can provide a new theoretical perspective for the diagnosis of neuromuscular fatigue and sports rehabilitation, which has good application value.
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Affiliation(s)
- Shaojun Zhu
- Hangzhou Xinyizhen Technology Company Limited, Hangzhou 310018, China
| | - Jinhui Zhao
- College of Electrical Engineering, Zhejiang University of Water Resources and Electric Power, Hangzhou 310018, China
| | - Yating Wu
- College of Automation, Hangzhou Dianzi University, Hangzhou 310018, China
| | - Qingshan She
- College of Automation, Hangzhou Dianzi University, Hangzhou 310018, China
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7
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Costa-García Á, Iáñez E, Yokoyama M, Ueda S, Okajima S, Shimoda S. Quantification of high and low sEMG spectral components during sustained isometric contraction. Physiol Rep 2022; 10:e15296. [PMID: 35614546 PMCID: PMC9133435 DOI: 10.14814/phy2.15296] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/01/2022] [Accepted: 04/19/2022] [Indexed: 11/24/2022] Open
Abstract
Superficial Electromyography (sEMG) spectrum contains aggregated information from several underlying physiological processes. Due to technological limitations, the isolation of these processes is challenging, and therefore, the interpretation of changes in muscle activity frequency is still controversial. Recent studies showed that the spectrum of sEMG signals recorded from isotonic and short-term isometric contractions can be decomposed into independent components whose spectral features recall those of motor unit action potentials. In this paper sEMG spectral decomposition is tested during muscle fatigue induced by long-term isometric contraction where sEMG spectral changes have been widely studied. The main goals of this work are to validate spectral component extraction during long-term isometric muscle activation and the quantification of energy exchange between the low- and high-frequency bands of sEMG signals during muscle fatigue.
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Affiliation(s)
- Álvaro Costa-García
- CBS-TOYOTA Collaboration Center in the Nagoya Science Park Research and Development Center, Intelligent Behaviour Control Unit (RIKEN), Nagoya, Aichi, Japan
| | - Eduardo Iáñez
- Brain Machine Interface Systems Lab from Miguel Hernández University (UMH), Parque Cientifico UMH, Edificio Innova, Elche, Alicante, Spain
| | - Moeka Yokoyama
- CBS-TOYOTA Collaboration Center in the Nagoya Science Park Research and Development Center, Intelligent Behaviour Control Unit (RIKEN), Nagoya, Aichi, Japan
| | - Sayako Ueda
- CBS-TOYOTA Collaboration Center in the Nagoya Science Park Research and Development Center, Intelligent Behaviour Control Unit (RIKEN), Nagoya, Aichi, Japan
| | - Shotaro Okajima
- CBS-TOYOTA Collaboration Center in the Nagoya Science Park Research and Development Center, Intelligent Behaviour Control Unit (RIKEN), Nagoya, Aichi, Japan
| | - Shingo Shimoda
- CBS-TOYOTA Collaboration Center in the Nagoya Science Park Research and Development Center, Intelligent Behaviour Control Unit (RIKEN), Nagoya, Aichi, Japan
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8
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Rakshit R, Xiang Y, Yang J. Functional muscle group- and sex-specific parameters for a three-compartment controller muscle fatigue model applied to isometric contractions. J Biomech 2021; 127:110695. [PMID: 34454329 DOI: 10.1016/j.jbiomech.2021.110695] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/07/2021] [Revised: 08/10/2021] [Accepted: 08/12/2021] [Indexed: 02/06/2023]
Abstract
The three-compartment controller with enhanced recovery (3CC-r) model of muscle fatigue has previously been validated separately for both sustained (SIC) and intermittent isometric contractions (IIC) using different objective functions, but its performance has not yet been tested against both contraction types simultaneously using a common objective function. Additionally, prior validation has been performed using common parameters at the joint level, whereas applications to many real-world tasks will require the model to be applied to agonistic and synergistic muscle groups. Lastly, parameters for the model have previously been derived for a mixed-sex cohort not considering the differece in fatigabilities between the sexes. In this work we validate the 3CC-r model using a comprehensive isometric contraction database drawn from 172 publications segregated by functional muscle group (FMG) and sex. We find that prediction errors are reduced by 19% on average when segregating the dataset by FMG alone, and by 34% when segregating by both sex and FMG. However, minimum prediction errors are found to be higher when validated against both SIC and IIC data together using torque decline as the outcome variable than when validated sequentially against hypothesized SIC intensity-endurance time curves with endurance time as the outcome variable and against raw IIC data with torque decline as the outcome variable.
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Affiliation(s)
- Ritwik Rakshit
- Human-Centric Design Research Lab, Department of Mechanical Engineering, Texas Tech University, Lubbock, TX 79409, USA
| | - Yujiang Xiang
- School of Mechanical and Aerospace Engineering, Oklahoma State University, Stillwater, OK 74078, USA
| | - James Yang
- Human-Centric Design Research Lab, Department of Mechanical Engineering, Texas Tech University, Lubbock, TX 79409, USA.
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9
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Chronic fatigue syndrome: Abnormally fast muscle fiber conduction in the membranes of motor units at low static force load. Clin Neurophysiol 2021; 132:967-974. [PMID: 33639451 DOI: 10.1016/j.clinph.2020.11.043] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/12/2019] [Revised: 10/29/2020] [Accepted: 11/25/2020] [Indexed: 11/23/2022]
Abstract
OBJECTIVE Chronic fatigue syndrome (CFS) and fibromyalgia (FM) are disorders of unknown etiology and unclear pathophysiology, with overlapping symptoms of - especially muscular -fatigue and pain. Studies have shown increased muscle fiber conduction velocity (CV) in the non-painful muscles of FM patients. We investigated whether CFS patients also show CV abnormalities. METHODS Females with CFS (n = 25), with FM (n = 22), and healthy controls (n = 21) underwent surface electromyography of the biceps brachii, loaded up to 20% of maximum strength, during short static contractions. The mean CV and motor unit potential (MUP) velocities with their statistical distribution were measured. RESULTS The CV changes with force differed between CFS-group and both FM-group and controls (P = 0.01). The CV of the CFS-group increased excessively with force (P < 0.001), whereas that of the controls increased only slightly and non-significantly, and that of the FM-group did not increase at all. In the CFS-group, the number of MUPs conveying very high conduction velocities increased abundantly with force and the MUPs narrowed. CONCLUSION Our results suggest disturbed muscle membrane function in CFS patients, in their motor units involved in low force generation. Central neural deregulation may contribute to this disturbance. SIGNIFICANCE These findings help to detangle the underlying mechanisms of CFS.
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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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11
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Wernbom M, Aagaard P. Muscle fibre activation and fatigue with low-load blood flow restricted resistance exercise-An integrative physiology review. Acta Physiol (Oxf) 2020; 228:e13302. [PMID: 31108025 DOI: 10.1111/apha.13302] [Citation(s) in RCA: 42] [Impact Index Per Article: 10.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/10/2019] [Revised: 05/12/2019] [Accepted: 05/17/2019] [Indexed: 12/13/2022]
Abstract
Blood flow-restricted resistance exercise (BFRRE) has been shown to induce increases in muscle size and strength, and continues to generate interest from both clinical and basic research points of view. The low loads employed, typically 20%-50% of the one repetition maximum, make BFRRE an attractive training modality for individuals who may not tolerate high musculoskeletal forces (eg, selected clinical patient groups such as frail old adults and patients recovering from sports injury) and/or for highly trained athletes who have reached a plateau in muscle mass and strength. It has been proposed that achieving a high degree of muscle fibre recruitment is important for inducing muscle hypertrophy with BFRRE, and the available evidence suggest that fatiguing low-load exercise during ischemic conditions can recruit both slow (type I) and fast (type II) muscle fibres. Nevertheless, closer scrutiny reveals that type II fibre activation in BFRRE has to date largely been inferred using indirect methods such as electromyography and magnetic resonance spectroscopy, while only rarely addressed using more direct methods such as measurements of glycogen stores and phosphocreatine levels in muscle fibres. Hence, considerable uncertainity exists about the specific pattern of muscle fibre activation during BFRRE. Therefore, the purpose of this narrative review was (1) to summarize the evidence on muscle fibre recruitment during BFRRE as revealed by various methods employed for determining muscle fibre usage during exercise, and (2) to discuss reported findings in light of the specific advantages and limitations associated with these methods.
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Affiliation(s)
- Mathias Wernbom
- Center for Health and Performance, Department of Food and Nutrition and Sport Science University of Gothenburg Gothenburg Sweden
- Department of Health and Rehabilitation, Institute of Neuroscience and Physiology, Sahlgrenska Academy University of Gothenburg Gothenburg Sweden
| | - Per Aagaard
- Department of Sports Sciences and Clinical Biomechanics, SDU Muscle Research Cluster (SMRC) University of Southern Denmark Odense M Denmark
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12
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Cholewa JM, Newmire DE, Zanchi NE. Carbohydrate restriction: Friend or foe of resistance-based exercise performance? Nutrition 2018; 60:136-146. [PMID: 30586657 DOI: 10.1016/j.nut.2018.09.026] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/25/2018] [Accepted: 09/29/2018] [Indexed: 12/17/2022]
Abstract
It is commonly accepted that adequate carbohydrate availability is necessary for optimal endurance performance. However, for strength- and physique-based athletes, sports nutrition research and recommendations have focused on protein ingestion, with far less attention given to carbohydrates. Varying resistance exercise protocols, such as differences in intensity, volume, and intraset rest prescriptions between strength-training and physique-training goals elicit different metabolic responses, which may necessitate different carbohydrate needs. The results of several acute and chronic training studies suggest that although severe carbohydrate restriction may not impair strength adaptations during a resistance training program, consuming an adequate amount of carbohydrate in the days leading up to testing may enhance maximal strength and strength-endurance performance. Although several molecular studies demonstrate no additive increases in postexercise mammalian target of rapamycin 1 phosphorylation with carbohydrate and protein compared with protein ingestion alone, the effects of chronic resistance training with carbohydrate restriction on muscle hypertrophy are conflicting and require further research to determine a minimal carbohydrate threshold necessary to optimize muscle hypertrophy. This review summarizes the current knowledge regarding carbohydrate availability and resistance training outcomes and poses new research questions that will better help guide carbohydrate recommendations for strength and physique athletes. In addition, given that success in physique sports is based on subjective appearance, and not objective physical performance, we also review the effects of subchronic carbohydrate ingestion during contest preparation on aesthetic appearance.
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Affiliation(s)
- Jason M Cholewa
- Department of Kinesiology, Coastal Carolina University, Conway, South Carolina, USA.
| | - Daniel E Newmire
- Department of Kinesiology and Military Science, University of Texas A&M, Corpus Christi, Texas, USA
| | - Nelo Eidy Zanchi
- Department of Physical Education, Federal University of Maranhão, São Luís, Brazil; Laboratory of Cellular and Molecular Biology of Skeletal Muscle (LABCEMME), São Luís, Brazil
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Sleutjes BT, Drenthen J, Boskovic E, van Schelven LJ, Kovalchuk MO, Lumens PG, van den Berg LH, Franssen H. Excitability tests using high-density surface-EMG: A novel approach to studying single motor units. Clin Neurophysiol 2018; 129:1634-1641. [DOI: 10.1016/j.clinph.2018.04.754] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/04/2017] [Revised: 04/19/2018] [Accepted: 04/29/2018] [Indexed: 12/13/2022]
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14
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Martinez-Valdes E, Negro F, Falla D, De Nunzio AM, Farina D. Surface electromyographic amplitude does not identify differences in neural drive to synergistic muscles. J Appl Physiol (1985) 2018; 124:1071-1079. [DOI: 10.1152/japplphysiol.01115.2017] [Citation(s) in RCA: 69] [Impact Index Per Article: 11.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023] Open
Abstract
Surface electromyographic (EMG) signal amplitude is typically used to compare the neural drive to muscles. We experimentally investigated this association by studying the motor unit (MU) behavior and action potentials in the vastus medialis (VM) and vastus lateralis (VL) muscles. Eighteen participants performed isometric knee extensions at four target torques [10, 30, 50, and 70% of the maximum torque (MVC)] while high-density EMG signals were recorded from the VM and VL. The absolute EMG amplitude was greater for VM than VL ( P < 0.001), whereas the EMG amplitude normalized with respect to MVC was greater for VL than VM ( P < 0.04). Because differences in EMG amplitude can be due to both differences in the neural drive and in the size of the MU action potentials, we indirectly inferred the neural drives received by the two muscles by estimating the synaptic inputs received by the corresponding motor neuron pools. For this purpose, we analyzed the increase in discharge rate from recruitment to target torque for motor units matched by recruitment threshold in the two muscles. This analysis indicated that the two muscles received similar levels of neural drive. Nonetheless, the size of the MU action potentials was greater for VM than VL ( P < 0.001), and this difference explained most of the differences in EMG amplitude between the two muscles (~63% of explained variance). These results indicate that EMG amplitude, even following normalization, does not reflect the neural drive to synergistic muscles. Moreover, absolute EMG amplitude is mainly explained by the size of MU action potentials. NEW & NOTEWORTHY Electromyographic (EMG) amplitude is widely used to compare indirectly the strength of neural drive received by synergistic muscles. However, there are no studies validating this approach with motor unit data. Here, we compared between-muscles differences in surface EMG amplitude and motor unit behavior. The results clarify the limitations of surface EMG to interpret differences in neural drive between muscles.
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Affiliation(s)
- Eduardo Martinez-Valdes
- Centre of Precision Rehabilitation for Spinal Pain, School of Sport, Exercise and Rehabilitation Sciences, College of Life and Environmental Sciences, University of Birmingham, Birmingham, United Kingdom
- Department of Sports Medicine and Sports Orthopaedics, University of Potsdam, Potsdam, Germany
- Centro de Investigación en Fisiología del Ejercicio, Universidad Mayor, Santiago, Chile
| | - Francesco Negro
- Department of Clinical and Experimental Sciences, Università degli Studi di Brescia, Brescia, Italy
| | - Deborah Falla
- Centre of Precision Rehabilitation for Spinal Pain, School of Sport, Exercise and Rehabilitation Sciences, College of Life and Environmental Sciences, University of Birmingham, Birmingham, United Kingdom
| | - Alessandro Marco De Nunzio
- Centre of Precision Rehabilitation for Spinal Pain, School of Sport, Exercise and Rehabilitation Sciences, College of Life and Environmental Sciences, University of Birmingham, Birmingham, United Kingdom
| | - Dario Farina
- Department of Bioengineering, Imperial College London, Royal School of Mines, London, United Kingdom
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Del Vecchio A, Negro F, Felici F, Farina D. Distribution of muscle fibre conduction velocity for representative samples of motor units in the full recruitment range of the tibialis anterior muscle. Acta Physiol (Oxf) 2018; 222. [PMID: 28763156 DOI: 10.1111/apha.12930] [Citation(s) in RCA: 45] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/04/2017] [Revised: 05/17/2017] [Accepted: 07/26/2017] [Indexed: 01/11/2023]
Abstract
AIM Motor units are recruited in an orderly manner according to the size of motor neurones. Moreover, because larger motor neurones innervate fibres with larger diameters than smaller motor neurones, motor units should be recruited orderly according to their conduction velocity (MUCV). Because of technical limitations, these relations have been previously tested either indirectly or in small motor unit samples that revealed weak associations between motor unit recruitment threshold (RT) and MUCV. Here, we analyse the relation between MUCV and RT for large samples of motor units. METHODS Ten healthy volunteers completed a series of isometric ankle dorsiflexions at forces up to 70% of the maximum. Multi-channel surface electromyographic signals recorded from the tibialis anterior muscle were decomposed into single motor unit action potentials, from which the corresponding motor unit RT, MUCV and action potential amplitude were estimated. Established relations between muscle fibre diameter and CV were used to estimate the fibre size. RESULTS Within individual subjects, the distributions of MUCV and fibre diameters were unimodal and did not show distinct populations. MUCV was strongly correlated with RT (mean (SD) R2 = 0.7 (0.09), P < 0.001; 406 motor units), which supported the hypothesis that fibre diameter is associated with RT. CONCLUSION The results provide further evidence for the relations between motor neurone and muscle fibre properties for large samples of motor units. The proposed methodology for motor unit analysis has also the potential to open new perspectives in the study of chronic and acute neuromuscular adaptations to ageing, training and pathology.
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Affiliation(s)
- A. Del Vecchio
- Department of Movement, Human and Health Sciences; University of Rome “Foro Italico”; Rome Italy
- Department of Bioengineering; Imperial College London; London UK
| | - F. Negro
- Department of Clinical and Experimental Sciences; University of Brescia; Brescia Italy
| | - F. Felici
- Department of Movement, Human and Health Sciences; University of Rome “Foro Italico”; Rome Italy
| | - D. Farina
- Department of Bioengineering; Imperial College London; London UK
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16
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The effects of local forearm muscle cooling on motor unit properties. Eur J Appl Physiol 2017; 118:401-410. [DOI: 10.1007/s00421-017-3782-y] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/06/2017] [Accepted: 12/03/2017] [Indexed: 10/18/2022]
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17
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McManus L, Hu X, Rymer WZ, Suresh NL, Lowery MM. Motor Unit Activity during Fatiguing Isometric Muscle Contraction in Hemispheric Stroke Survivors. Front Hum Neurosci 2017; 11:569. [PMID: 29225574 PMCID: PMC5705653 DOI: 10.3389/fnhum.2017.00569] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/04/2017] [Accepted: 11/09/2017] [Indexed: 12/03/2022] Open
Abstract
Enhanced muscle weakness is commonly experienced following stroke and may be accompanied by increased susceptibility to fatigue. To examine the contributions of central and peripheral factors to isometric muscle fatigue in stroke survivors, this study investigates changes in motor unit (MU) mean firing rate, and action potential duration during, and directly following, a sustained submaximal fatiguing contraction at 30% maximum voluntary contraction (MVC). A series of short contractions of the first dorsal interosseous muscle were performed pre- and post-fatigue at 20% MVC, and again following a 10-min recovery period, by 12 chronic stroke survivors. Individual MU firing times were extracted using surface EMG decomposition and used to obtain the spike-triggered average MU action potential waveforms. During the sustained fatiguing contraction, the mean rate of change in firing rate across all detected MUs was greater on the affected side (-0.02 ± 0.03 Hz/s) than on the less-affected side (-0.004 ± 0.003 Hz/s, p = 0.045). The change in firing rate immediately post-fatigue was also greater on the affected side than less-affected side (-13.5 ± 20 and 0.1 ± 19%, p = 0.04). Mean MU firing rates increased following the recovery period on the less-affected side when compared to the affected side (19.3 ± 17 and 0.5 ± 20%, respectively, p = 0.03). MU action potential duration increased post-fatigue on both sides (10.3 ± 1.2 to 11.2 ± 1.3 ms on the affected side and 9.9 ± 1.7 to 11.2 ± 1.9 ms on the less-affected side, p = 0.001 and p = 0.02, respectively), and changes in action potential duration tended to be smaller in subjects with greater impairment (p = 0.04). This study presents evidence of both central and peripheral fatigue at the MU level during isometric fatiguing contraction for the first time in stroke survivors. Together, these preliminary observations indicate that the response to an isometric fatiguing contraction differs between the affected and less-affected side post-stroke, and may suggest that central mechanisms observed here as changes in firing rate are the dominant processes leading to task failure on the affected side.
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Affiliation(s)
- Lara McManus
- Neuromuscular Systems Lab, School of Electrical and Electronic Engineering, University College Dublin, Belfield, Ireland
| | - Xiaogang Hu
- Joint Department of Biomedical Engineering, University of North Carolina at Chapel Hill and North Carolina State University, Chapel Hill, NC, United States
| | - William Z Rymer
- Shirley Ryan AbilityLab, Chicago, IL, United States.,Department of Physical Medicine and Rehabilitation, Northwestern University, Chicago, IL, United States
| | - Nina L Suresh
- Shirley Ryan AbilityLab, Chicago, IL, United States.,Department of Physical Medicine and Rehabilitation, Northwestern University, Chicago, IL, United States
| | - Madeleine M Lowery
- Neuromuscular Systems Lab, School of Electrical and Electronic Engineering, University College Dublin, Belfield, Ireland
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18
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Lopes CR, Aoki MS, Crisp AH, de Mattos RS, Lins MA, da Mota GR, Schoenfeld BJ, Marchetti PH. The Effect of Different Resistance Training Load Schemes on Strength and Body Composition in Trained Men. J Hum Kinet 2017; 58:177-186. [PMID: 28828088 PMCID: PMC5548165 DOI: 10.1515/hukin-2017-0081] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022] Open
Abstract
The purpose of this study was to evaluate the impact of moderate-load (10 RM) and low-load (20 RM) resistance training schemes on maximal strength and body composition. Sixteen resistance-trained men were randomly assigned to 1 of 2 groups: a moderate-load group (n = 8) or a low-load group (n = 8). The resistance training schemes consisted of 8 exercises performed 4 times per week for 6 weeks. In order to equate the number of repetitions performed by each group, the moderate load group performed 6 sets of 10 RM, while the low load group performed 3 sets of 20 RM. Between-group differences were evaluated using a 2-way ANOVA and independent t-tests. There was no difference in the weekly total load lifted (sets × reps × kg) between the 2 groups. Both groups equally improved maximal strength and measures of body composition after 6 weeks of resistance training, with no significant between-group differences detected. In conclusion, both moderate-load and low-load resistance training schemes, similar for the total load lifted, induced a similar improvement in maximal strength and body composition in resistance-trained men.
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Affiliation(s)
- Charles Ricardo Lopes
- Human Performance Research Group - MethodistUniversity of Piracicaba (UNIMEP) Piracicaba, Sao Paulo, Brazil.,Adventist Faculty of Hortolandia (UNASP), Hortolandia, Sao Paulo, Brazil
| | - Marcelo Saldanha Aoki
- School of Arts, Sciences and Humanities, University of Sao Paulo (USP), Sao Paulo, Brazil
| | - Alex Harley Crisp
- Human Performance Research Group - MethodistUniversity of Piracicaba (UNIMEP) Piracicaba, Sao Paulo, Brazil
| | | | - Miguel Alves Lins
- School of Arts, Sciences and Humanities, University of Sao Paulo (USP), Sao Paulo, Brazil
| | - Gustavo Ribeiro da Mota
- Department of Sports Sciences - Post-Graduation Program in Physical Education (UFTM), Uberaba, Minas Gerais, Brazil
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19
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Weakley JJS, Till K, Read DB, Roe GAB, Darrall-Jones J, Phibbs PJ, Jones B. The effects of traditional, superset, and tri-set resistance training structures on perceived intensity and physiological responses. Eur J Appl Physiol 2017; 117:1877-1889. [PMID: 28698987 PMCID: PMC5556132 DOI: 10.1007/s00421-017-3680-3] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/17/2017] [Accepted: 07/05/2017] [Indexed: 12/31/2022]
Abstract
Purpose Investigate the acute and short-term (i.e., 24 h) effects of traditional (TRAD), superset (SS), and tri-set (TRI) resistance training protocols on perceptions of intensity and physiological responses. Methods Fourteen male participants completed a familiarisation session and three resistance training protocols (i.e., TRAD, SS, and TRI) in a randomised-crossover design. Rating of perceived exertion, lactate concentration ([Lac]), creatine kinase concentration ([CK]), countermovement jump (CMJ), testosterone, and cortisol concentrations was measured pre, immediately, and 24-h post the resistance training sessions with magnitude-based inferences assessing changes/differences within/between protocols. Results TRI reported possible to almost certainly greater efficiency and rate of perceived exertion, although session perceived load was very likely lower. SS and TRI had very likely to almost certainly greater lactate responses during the protocols, with changes in [CK] being very likely and likely increased at 24 h, respectively. At 24-h post-training, CMJ variables in the TRAD protocol had returned to baseline; however, SS and TRI were still possibly to likely reduced. Possible increases in testosterone immediately post SS and TRI protocols were reported, with SS showing possible increases at 24-h post-training. TRAD and SS showed almost certain and likely decreases in cortisol immediately post, respectively, with TRAD reporting likely decreases at 24-h post-training. Conclusions SS and TRI can enhance training efficiency and reduce training time. However, acute and short-term physiological responses differ between protocols. Athletes can utilise SS and TRI resistance training, but may require additional recovery post-training to minimise effects of fatigue.
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Affiliation(s)
- Jonathon J S Weakley
- Room G03, Macaulay Hall, Institute for Sport, Physical Activity and Leisure, Centre for Sports Performance, Headingley Campus, Leeds Beckett University, West Yorkshire, LS6 3GZ, UK. .,Yorkshire Carnegie Rugby Union Club, Kirkstall Training Ground, Leeds Rugby Academy, Leeds, West Yorkshire, UK.
| | - Kevin Till
- Room G03, Macaulay Hall, Institute for Sport, Physical Activity and Leisure, Centre for Sports Performance, Headingley Campus, Leeds Beckett University, West Yorkshire, LS6 3GZ, UK.,Yorkshire Carnegie Rugby Union Club, Kirkstall Training Ground, Leeds Rugby Academy, Leeds, West Yorkshire, UK
| | - Dale B Read
- Room G03, Macaulay Hall, Institute for Sport, Physical Activity and Leisure, Centre for Sports Performance, Headingley Campus, Leeds Beckett University, West Yorkshire, LS6 3GZ, UK.,Yorkshire Carnegie Rugby Union Club, Kirkstall Training Ground, Leeds Rugby Academy, Leeds, West Yorkshire, UK
| | - Gregory A B Roe
- Room G03, Macaulay Hall, Institute for Sport, Physical Activity and Leisure, Centre for Sports Performance, Headingley Campus, Leeds Beckett University, West Yorkshire, LS6 3GZ, UK.,Yorkshire Carnegie Rugby Union Club, Kirkstall Training Ground, Leeds Rugby Academy, Leeds, West Yorkshire, UK
| | - Joshua Darrall-Jones
- Room G03, Macaulay Hall, Institute for Sport, Physical Activity and Leisure, Centre for Sports Performance, Headingley Campus, Leeds Beckett University, West Yorkshire, LS6 3GZ, UK.,Yorkshire Carnegie Rugby Union Club, Kirkstall Training Ground, Leeds Rugby Academy, Leeds, West Yorkshire, UK
| | - Padraic J Phibbs
- Room G03, Macaulay Hall, Institute for Sport, Physical Activity and Leisure, Centre for Sports Performance, Headingley Campus, Leeds Beckett University, West Yorkshire, LS6 3GZ, UK.,Yorkshire Carnegie Rugby Union Club, Kirkstall Training Ground, Leeds Rugby Academy, Leeds, West Yorkshire, UK
| | - Ben Jones
- Room G03, Macaulay Hall, Institute for Sport, Physical Activity and Leisure, Centre for Sports Performance, Headingley Campus, Leeds Beckett University, West Yorkshire, LS6 3GZ, UK.,Yorkshire Carnegie Rugby Union Club, Kirkstall Training Ground, Leeds Rugby Academy, Leeds, West Yorkshire, UK.,The Rugby Football League, Leeds, West Yorkshire, UK
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20
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Marco G, Alberto B, Taian V. Surface EMG and muscle fatigue: multi-channel approaches to the study of myoelectric manifestations of muscle fatigue. Physiol Meas 2017; 38:R27-R60. [DOI: 10.1088/1361-6579/aa60b9] [Citation(s) in RCA: 44] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
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21
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A new optical flow model for motor unit conduction velocity estimation in multichannel surface EMG. Comput Biol Med 2017; 83:59-68. [PMID: 28237905 DOI: 10.1016/j.compbiomed.2017.02.006] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/21/2016] [Revised: 01/30/2017] [Accepted: 02/17/2017] [Indexed: 11/22/2022]
Abstract
Many studies have demonstrated the feasibility and benefits of Conduction Velocity (CV) estimation from surface electromyograms (EMGs) in various experimental conditions. Among them, a method based on optical flow was proposed recently, demonstrating relatively accurate CV estimation for EMG signals acquired in monopolar mode. We extended this method by a new data model that compensates more realistically for the spatial Motor Unit Action Potential (MUAP) shape variability and enables accurate CV estimation also in single-differential acquisition mode. The proposed modification was validated on 5000 synthetic Motor Units (MUs) with known CV and direction of fibres. It was shown that, in the noiseless case, the mean CV estimation error was significantly lower for our proposed modification compared to the original CV estimation procedure by up to 2% in the case of monopolar EMG signals and by up to 18.6% for single-differential EMG signals. When estimating fibre directions, the mean error was lower by up to 2.4° (for monopolar EMG signals) and 9.6° (for single-differential EMG signals). The results of tests with 10dB and 20dB noise further demonstrated the robustness of the proposed algorithm to noise in MUAP estimation.
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22
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Suda EY, Madeleine P, Hirata RP, Samani A, Kawamura TT, Sacco ICN. Reduced complexity of force and muscle activity during low level isometric contractions of the ankle in diabetic individuals. Clin Biomech (Bristol, Avon) 2017; 42:38-46. [PMID: 28088014 DOI: 10.1016/j.clinbiomech.2017.01.001] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/24/2016] [Revised: 12/19/2016] [Accepted: 01/03/2017] [Indexed: 02/07/2023]
Abstract
BACKGROUND This study evaluated the structure and amount of variability of surface electromyography (sEMG) patterns and ankle force data during low-level isometric contractions in diabetic subjects with different degrees of neuropathy. METHODS We assessed 10 control subjects and 38 diabetic patients, classified as absent, mild, moderate, or severe neuropathy, by a fuzzy system based on clinical variables. Multichannel sEMG (64-electrode matrix) of tibialis anterior and gastrocnemius medialis muscles were acquired during isometric contractions at 10%, 20%, and 30% of the maximum voluntary contraction, and force levels during dorsi- and plantarflexion were recorded. Standard deviation and sample entropy of force signals were calculated and root mean square and sample entropy were calculated from sEMG signals. Differences among groups of force and sEMG variables were verified using a multivariate analysis of variance. FINDINGS Overall, during dorsiflexion contractions, moderate and severe subjects had higher force standard deviation and moderate subjects had lower force sample entropy. During plantarflexion, moderate subjects had higher force standard deviation and all diabetic subjects had lower entropy. Tibialis anterior presented higher root mean square in absent group and lower entropy in mild subjects. For gastrocnemius medialis, entropy was higher in severe and lower in moderate subjects. INTERPRETATION Diabetic neuropathy affects the complexity of the neuromuscular system during low-level isometric contractions, reducing the system's capacity to adapt to challenging mechanical demands. The observed patterns of neuromuscular complexity were not associated with disease severity, with the majority of alterations recorded in moderate subject.
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Affiliation(s)
- E Y Suda
- Laboratory of Biomechanics of Human Movement, Dept. Physical Therapy, Speech and Occupational Therapy, School of Medicine, University of Sao Paulo, Sao Paulo, Brazil
| | - P Madeleine
- SMI, Department of Health Science and Technology, Faculty of Medicine, Aalborg University, Denmark
| | - R P Hirata
- SMI, Department of Health Science and Technology, Faculty of Medicine, Aalborg University, Denmark
| | - A Samani
- SMI, Department of Health Science and Technology, Faculty of Medicine, Aalborg University, Denmark
| | - T T Kawamura
- Laboratory of Biomechanics of Human Movement, Dept. Physical Therapy, Speech and Occupational Therapy, School of Medicine, University of Sao Paulo, Sao Paulo, Brazil
| | - I C N Sacco
- Laboratory of Biomechanics of Human Movement, Dept. Physical Therapy, Speech and Occupational Therapy, School of Medicine, University of Sao Paulo, Sao Paulo, Brazil.
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23
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Teles FS, Pereira MC, Rocha-Júnior VDA, Carmo JCD, Andrade MMD. Parâmetros eletromiográficos em exercícios fatigantes realizados com diferentes tipos de resistência. FISIOTERAPIA E PESQUISA 2016. [DOI: 10.1590/1809-2950/15008423032016] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
RESUMO Buscou-se investigar os parâmetros eletromiográficos da fadiga muscular durante exercício dinâmico realizado com resistência variável (elástica) e resistência fixa (polia). Dez homens treinados participaram voluntariamente do estudo. Foram realizadas duas contrações voluntárias isométricas máximas (CVIM) de flexão do cotovelo com 5 segundos de duração cada e 2 minutos de intervalo entre as mesmas. Em seguida, os voluntários realizaram a flexão unilateral do cotovelo até a exaustão, utilizando resistência fixa e elástica com ritmo pré-estabelecido de 2 segundos para cada fase do movimento. A resistência constante foi realizada na polia a 30% da CVIM. Para a resistência elástica, o controle de carga era baseado na percepção subjetiva de esforço do participante. A ordem do exercício foi randomizada, e o sinal de eletromiografia do músculo bíceps braquial foi registrado durante as contrações. A partir do sinal eletromiográfico referente a cada execução de movimento, foram traçadas retas de regressão linear para as variáveis RMS e frequência de potência mediana (FPM). As inclinações das retas normalizadas pelo coeficiente linear das equações de regressão foram comparadas por meio do teste t pareado. Não foram observadas diferenças significativas entre os tipos de resistência (elástica e polia). Os parâmetros eletromiográficos de fadiga não foram diferentes durante o exercício de flexão do cotovelo realizado com resistência elástica e polia. A percepção de esforço durante o exercício com implemento elástico não influencia no padrão do sinal eletromiográfico (RMS e FPM).
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Schoenfeld BJ, Contreras B, Vigotsky AD, Ogborn D, Fontana F, Tiryaki-Sonmez G. Upper body muscle activation during low-versus high-load resistance exercise in the bench press. ISOKINET EXERC SCI 2016. [DOI: 10.3233/ies-160620] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Affiliation(s)
- Brad J. Schoenfeld
- Department of Health Sciences, Program of Exercise Science, CUNY Lehman College, Bronx, NY, USA
| | - Bret Contreras
- Sport Performance Research Institute New Zealand, Auckland University of Technology, Auckland, New Zealand
| | | | - Dan Ogborn
- School of Rehabilitation Science, McMaster University, Hamilton, ON, Canada
| | - Fabio Fontana
- School of Health, Physical Education, and Leisure Services, University of Northern Iowa, Cedar Falls, IA, USA
| | - Gul Tiryaki-Sonmez
- Department of Health Sciences, Program of Exercise Science, CUNY Lehman College, Bronx, NY, USA
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Nicholson G, Ispoglou T, Bissas A. The impact of repetition mechanics on the adaptations resulting from strength-, hypertrophy- and cluster-type resistance training. Eur J Appl Physiol 2016; 116:1875-88. [PMID: 27473446 PMCID: PMC5020128 DOI: 10.1007/s00421-016-3439-2] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/28/2015] [Accepted: 07/21/2016] [Indexed: 01/05/2023]
Abstract
Purpose The purpose of this study was to examine the acute and chronic training responses to strength-, hypertrophy- and cluster-type resistance training. Methods Thirty-four trained males were assigned to a strength [STR: 4 × 6 repetitions, 85 % of one repetition maximum, (1RM), 900 s total rest], hypertrophy (HYP: 5 × 10 repetitions, 70 % 1RM, 360 s total rest), cluster 1 (CL-1: 4 × 6/1 repetitions, 85 % 1RM, 1400 s total rest), and cluster 2 (CL-2: 4 × 6/1 repetitions, 90 % 1RM, 1400 s total rest) regimens which were performed twice weekly for a 6-week period. Measurements were taken before, during and following the four workouts to investigate the acute training stimulus, whilst similar measurements were employed to examine the training effects before and after the intervention. Results The improvements in 1RM strength were significantly greater for the STR (12.09 ± 2.75 %; p < 0.05, d = 1.106) and CL-2 (13.20 ± 2.18 %; p < 0.001, d = 0.816) regimens than the HYP regimen (8.13 ± 2.54 %, d = 0.453). In terms of the acute responses, the STR and CL-2 workouts resulted in greater time under tension (TUT) and impulse generation in individual repetitions than the HYP workout (p < 0.05). Furthermore, the STR (+3.65 ± 2.54 mmol/L−1) and HYP (+6.02 ± 2.97 mmol/L−1) workouts resulted in significantly greater elevations in blood lactate concentration (p < 0.001) than the CL-1 and CL-2 workouts. Conclusion CL regimens produced similar strength improvements to STR regimens even when volume load was elevated (CL-2). The effectiveness of the STR and CL-2 regimens underlines the importance of high loads and impulse generation for strength development.
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Affiliation(s)
- G Nicholson
- Carnegie School of Sport, Institute for Sport, Physical Activity and Leisure, Leeds Beckett University, Fairfax Room 107, Headingley Campus, Leeds, LS6 3QT, UK.
| | - T Ispoglou
- Carnegie School of Sport, Institute for Sport, Physical Activity and Leisure, Leeds Beckett University, Fairfax Room 107, Headingley Campus, Leeds, LS6 3QT, UK
| | - A Bissas
- Carnegie School of Sport, Institute for Sport, Physical Activity and Leisure, Leeds Beckett University, Fairfax Room 107, Headingley Campus, Leeds, LS6 3QT, UK
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26
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Schoenfeld BJ, Peterson MD, Ogborn D, Contreras B, Sonmez GT. Effects of Low- vs. High-Load Resistance Training on Muscle Strength and Hypertrophy in Well-Trained Men. J Strength Cond Res 2016; 29:2954-63. [PMID: 25853914 DOI: 10.1519/jsc.0000000000000958] [Citation(s) in RCA: 238] [Impact Index Per Article: 29.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
The purpose of this study was to compare the effect of low- versus high-load resistance training (RT) on muscular adaptations in well-trained subjects. Eighteen young men experienced in RT were matched according to baseline strength and then randomly assigned to 1 of 2 experimental groups: a low-load RT routine (LL) where 25-35 repetitions were performed per set per exercise (n = 9) or a high-load RT routine (HL) where 8-12 repetitions were performed per set per exercise (n = 9). During each session, subjects in both groups performed 3 sets of 7 different exercises representing all major muscles. Training was performed 3 times per week on nonconsecutive days, for a total of 8 weeks. Both HL and LL conditions produced significant increases in thickness of the elbow flexors (5.3 vs. 8.6%, respectively), elbow extensors (6.0 vs. 5.2%, respectively), and quadriceps femoris (9.3 vs. 9.5%, respectively), with no significant differences noted between groups. Improvements in back squat strength were significantly greater for HL compared with LL (19.6 vs. 8.8%, respectively), and there was a trend for greater increases in 1 repetition maximum (1RM) bench press (6.5 vs. 2.0%, respectively). Upper body muscle endurance (assessed by the bench press at 50% 1RM to failure) improved to a greater extent in LL compared with HL (16.6 vs. -1.2%, respectively). These findings indicate that both HL and LL training to failure can elicit significant increases in muscle hypertrophy among well-trained young men; however, HL training is superior for maximizing strength adaptations.
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Affiliation(s)
- Brad J Schoenfeld
- 1Department of Health Sciences, CUNY Lehman College, Bronx, New York; 2Department of Physical Medicine and Rehabilitation, University of Michigan, Ann Arbor, Michigan; 3Neuromuscular and Neurometabolic Unit, McMaster University Medical Center, Hamilton, Ontario, Canada; and 4Sport Performance Research Institute New Zealand, AUT University, Auckland, New Zealand
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27
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Martín López LM, Miller PJO, Aguilar de Soto N, Johnson M. Gait switches in deep-diving beaked whales: biomechanical strategies for long-duration dives. J Exp Biol 2015; 218:1325-38. [DOI: 10.1242/jeb.106013] [Citation(s) in RCA: 40] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
ABSTRACT
Diving animals modulate their swimming gaits to promote locomotor efficiency and so enable longer, more productive dives. Beaked whales perform extremely long and deep foraging dives that probably exceed aerobic capacities for some species. Here, we use biomechanical data from suction-cup tags attached to three species of beaked whales (Mesoplodon densirostris, N=10; Ziphius cavirostris, N=9; and Hyperoodon ampullatus, N=2) to characterize their swimming gaits. In addition to continuous stroking and stroke-and-glide gaits described for other diving mammals, all whales produced occasional fluke-strokes with distinctly larger dorso-ventral acceleration, which we termed ‘type-B’ strokes. These high-power strokes occurred almost exclusively during deep dive ascents as part of a novel mixed gait. To quantify body rotations and specific acceleration generated during strokes we adapted a kinematic method combining data from two sensors in the tag. Body rotations estimated with high-rate magnetometer data were subtracted from accelerometer data to estimate the resulting surge and heave accelerations. Using this method, we show that stroke duration, rotation angle and acceleration were bi-modal for these species, with B-strokes having 76% of the duration, 52% larger body rotation and four times more surge than normal strokes. The additional acceleration of B-strokes did not lead to faster ascents, but rather enabled brief glides, which may improve the overall efficiency of this gait. Their occurrence towards the end of long dives leads us to propose that B-strokes may recruit fast-twitch fibres that comprise ∼80% of swimming muscles in Blainville's beaked whales, thus prolonging foraging time at depth.
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Affiliation(s)
| | - Patrick J. O. Miller
- SMRU (Sea Mammal Research Unit), University of St Andrews, St Andrews, Fife KY16 8LB, UK
| | - Natacha Aguilar de Soto
- SMRU (Sea Mammal Research Unit), University of St Andrews, St Andrews, Fife KY16 8LB, UK
- BIOECOMAC (Biodiversidad, Ecología Marina y Conservación), University of La Laguna, La Laguna, 38206, Spain
| | - Mark Johnson
- SMRU (Sea Mammal Research Unit), University of St Andrews, St Andrews, Fife KY16 8LB, UK
- Department of Bioscience, Aarhus University, 8000 Aarhus C, Denmark
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Ota N, Soga S, Hase T, Shimotoyodome A. Daily consumption of milk fat globule membrane plus habitual exercise improves physical performance in healthy middle-aged adults. SPRINGERPLUS 2015; 4:120. [PMID: 25810952 PMCID: PMC4369537 DOI: 10.1186/s40064-015-0896-8] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Subscribe] [Scholar Register] [Received: 10/13/2014] [Accepted: 02/20/2015] [Indexed: 11/10/2022]
Abstract
Our recent studies demonstrated that habitual exercise plus dietary supplementation with milk fat globule membrane (MFGM) improved endurance capacity and muscle function by stimulating neuromuscular development in mice. The aim of this study was to investigate the efficacy of dietary MFGM supplementation plus habitual exercise on the physical performance of middle-aged Japanese adults in a pilot randomized, double-blind, placebo-controlled trial. Forty-four subjects (men, n = 22; women, n = 22) were randomly assigned into two groups: one received placebo tablets (placebo group, n = 22 [men, n = 11; women, n = 11]), while the other received MFGM tablets (MFGM group, n = 22 [men, n = 11; women, n = 11]). The subjects ingested either MFGM (1 g/day) or placebo (1 g/day of whole milk powder) tablets every day for the 10-week study period and engaged in an exercise training program twice per week. A physical function test was performed at baseline and at 5 and 10 weeks. A significant group-by-time interaction was found for the side step test, muscle cross-sectional area (CSA), and muscle fiber conduction velocity (MFCV). In the placebo group, there were no significant intragroup differences. In the MFGM group, side step score and muscle CSA were significantly greater at 10 weeks compared to the baseline, and MFCV was significantly higher than that in the placebo group at 10 weeks. The changes in percentage of the side step score, muscle CSA, and MFCV in the MFGM group were significantly higher than in the placebo group at 10 weeks. These results suggest that daily MFGM ingestion combined with regular exercise might enhance physical performance such as agility in middle-aged adults.
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Affiliation(s)
- Noriyasu Ota
- Biological Science Research Laboratories, Kao Corporation, 2606 Akabane, Ichikai-machi, Haga-gun, Tochigi, 321-3497 Japan
| | - Satoko Soga
- Biological Science Research Laboratories, Kao Corporation, 2606 Akabane, Ichikai-machi, Haga-gun, Tochigi, 321-3497 Japan
| | - Tadashi Hase
- Biological Science Research Laboratories, Kao Corporation, 2606 Akabane, Ichikai-machi, Haga-gun, Tochigi, 321-3497 Japan
| | - Akira Shimotoyodome
- Biological Science Research Laboratories, Kao Corporation, 2606 Akabane, Ichikai-machi, Haga-gun, Tochigi, 321-3497 Japan
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On the nature of the electromyographic signals recorded during vibration exercise. Eur J Appl Physiol 2015; 115:1095-106. [DOI: 10.1007/s00421-014-3091-7] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/10/2014] [Accepted: 12/19/2014] [Indexed: 11/27/2022]
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30
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Hassanlouei H, Falla D, Arendt-Nielsen L, Kersting U. The effect of six weeks endurance training on dynamic muscular control of the knee following fatiguing exercise. J Electromyogr Kinesiol 2014; 24:682-8. [DOI: 10.1016/j.jelekin.2014.06.004] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/26/2013] [Revised: 05/23/2014] [Accepted: 06/10/2014] [Indexed: 12/26/2022] Open
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Electromyogram features during linear torque decrement and their changes with fatigue. Eur J Appl Physiol 2014; 114:2105-17. [DOI: 10.1007/s00421-014-2928-4] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/14/2013] [Accepted: 05/30/2014] [Indexed: 10/25/2022]
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32
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Concurrent repeated-sprint and resistance training with superimposed vibrations in rugby players. Int J Sports Physiol Perform 2013; 9:667-73. [PMID: 24231555 DOI: 10.1123/ijspp.2013-0238] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
PURPOSE To examine the effect of repeated-sprint training (RST) vs combined RST and resistance training with superimposed vibrations on repeated-sprint ability (RSA) and lower-body power output in male rugby players. METHODS Players were divided into 2 training groups. One group performed RST (n = 10) 2 d/wk and the other performed RST 1 d/wk and squat resistance training with superimposed vibrations on the second day (RS+ST; n = 10). The squat training was carried out with a volume similar (ie, number of sets and repetitions) to that of the RST. The training period lasted 6 wk, and it was carried out as a supplement to the regular rugby training sessions. RESULTS Substantial improvements in RSA mean time (RSA(mean); +2.3%/ES: 0.77 vs +4.1%/ES: 0.91), RSA percent decrement (%Dec; -25.6%/ES: 1.70 vs -23.2%/ES: 0.99), and squat absolute power output (+5.0%/ES:0.36 vs +17.2%/ES: 0.93) were obtained in RST and RS+ST, respectively. Substantial improvements in RSA best time (RSA(best); +2.6%/ES: 0.61) and squat power output normalized to body mass (+18.6%/ES: 0.76) only occurred in RS+ST. Both pretest and posttest RSA(mean) were largely correlated with the RSA(best). However, there were only unclear, small to moderate correlations between individual changes in squat power output and either RSA(mean) or RSA(best). CONCLUSION Combined RST and resistance training induced improvements of greater magnitude in both repeated-sprint performance and muscle power output than the RST alone. The lack of substantial correlations between individual changes in repeated-sprint and muscle-power performance suggests that the same subjects were not systematically low or high responders to both RST and strength training.
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Schoenfeld BJ. Potential mechanisms for a role of metabolic stress in hypertrophic adaptations to resistance training. Sports Med 2013; 43:179-94. [PMID: 23338987 DOI: 10.1007/s40279-013-0017-1] [Citation(s) in RCA: 260] [Impact Index Per Article: 23.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
It is well established that regimented resistance training can promote increases in muscle hypertrophy. The prevailing body of research indicates that mechanical stress is the primary impetus for this adaptive response and studies show that mechanical stress alone can initiate anabolic signalling. Given the dominant role of mechanical stress in muscle growth, the question arises as to whether other factors may enhance the post-exercise hypertrophic response. Several researchers have proposed that exercise-induced metabolic stress may in fact confer such an anabolic effect and some have even suggested that metabolite accumulation may be more important than high force development in optimizing muscle growth. Metabolic stress pursuant to traditional resistance training manifests as a result of exercise that relies on anaerobic glycolysis for adenosine triphosphate production. This, in turn, causes the subsequent accumulation of metabolites, particularly lactate and H(+). Acute muscle hypoxia associated with such training methods may further heighten metabolic buildup. Therefore, the purpose of this paper will be to review the emerging body of research suggesting a role for exercise-induced metabolic stress in maximizing muscle development and present insights as to the potential mechanisms by which these hypertrophic adaptations may occur. These mechanisms include increased fibre recruitment, elevated systemic hormonal production, alterations in local myokines, heightened production of reactive oxygen species and cell swelling. Recommendations are provided for potential areas of future research on the subject.
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Affiliation(s)
- Brad J Schoenfeld
- Department of Health Sciences, Program of Exercise Science, APEX Building, Room # 265, Lehman College, CUNY, 250 Bedford Park Blvd West, Bronx, NY 10468, USA.
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Patients with temporomandibular disorders have increased fatigability of the cervical extensor muscles. Clin J Pain 2012; 28:55-64. [PMID: 21677569 DOI: 10.1097/ajp.0b013e31822019f2] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
Abstract
OBJECTIVES To determine whether patients with myogenous and mixed temporomandibular disorders (TMD) have greater fatigability of the cervical extensor muscles while performing a neck extensor muscle endurance test (NEMET) when compared with healthy controls. METHODS A total of 151 individuals participated in this study. Of these 47 were healthy controls, 57 patients had myogenous TMD, and 47 patients had mixed TMD. All patients performed the NEMET. The patients were instructed to maintain a prone lying position with the neck unsupported as long as possible, stopping at signs of fatigue or any discomfort. Electromyographic activity of the cervical extensor muscles during the NEMET and the holding time were collected for all patients and were compared across groups. A 1-way analysis of variance was used to evaluate the differences in holding time between patients with TMD and healthy controls. A mixed model analysis was used to evaluate the differences in normalized median frequency at different times (fatigue index) for the cervical extensor muscles while performing the NEMET between patients with TMD and controls. RESULTS There were statistically significant differences (P<0.05) in the slopes of the normalized median frequency between patients with TMD and healthy controls at 10, 30, 40, 50, 60, 70, 80, 90, and 100 seconds of the NEMET. Holding time was significantly reduced in both patients with myogenous TMD and mixed TMD when compared with healthy controls (P<0.05). DISCUSSION These results highlight the fact that alterations of endurance capacity of the extensor cervical muscles could be implicated in the neck-shoulder disturbances presented in patients with TMD.
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35
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Evidence of neuroaxonal degeneration in myofascial pain syndrome: A study of neuromuscular jitter by axonal microstimulation. Eur J Pain 2012; 12:1026-30. [DOI: 10.1016/j.ejpain.2008.01.012] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/17/2007] [Revised: 01/06/2008] [Accepted: 01/25/2008] [Indexed: 11/21/2022]
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36
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Ishii N, Ogasawara R, Kobayashi K, Nakazato K. Roles played by protein metabolism and myogenic progenitor cells in exercise-induced muscle hypertrophy and their relation to resistance training regimens. JOURNAL OF PHYSICAL FITNESS AND SPORTS MEDICINE 2012. [DOI: 10.7600/jpfsm.1.83] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
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Dick F. S, Bert U. K, Bernd G. L, Johannes P. VD. High-density Surface EMG: Techniques and Applications at a Motor Unit Level. Biocybern Biomed Eng 2012. [DOI: 10.1016/s0208-5216(12)70039-6] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
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38
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Schmitz JPJ, van Dijk JP, Hilbers PAJ, Nicolay K, Jeneson JAL, Stegeman DF. Unchanged muscle fiber conduction velocity relates to mild acidosis during exhaustive bicycling. Eur J Appl Physiol 2011; 112:1593-602. [PMID: 21861110 PMCID: PMC3324688 DOI: 10.1007/s00421-011-2119-5] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/23/2011] [Accepted: 08/05/2011] [Indexed: 11/27/2022]
Abstract
Muscle fiber conduction velocity (MFCV) has often been shown to decrease during standardized fatiguing isometric contractions. However, several studies have indicated that the MFCV may remain constant during fatiguing dynamic exercise. It was investigated if these observations can be related to the absence of a large decrease in pH and if MFCV can be considered as a good indicator of acidosis, also during dynamic bicycle exercise. High-density surface electromyography (HDsEMG) was combined with read-outs of muscle energetics recorded by in vivo 31P magnetic resonance spectroscopy (MRS). Measurements were performed during serial exhausting bouts of bicycle exercise at three different workloads. The HDsEMG recordings revealed a small and incoherent variation of MFCV during all high-intensity exercise bouts. 31P MRS spectra revealed a moderate decrease in pH at the end of exercise (~0.3 units down to 6.8) and a rapid ancillary drop to pH 6.5 during recovery 30 s post-exercise. This additional degree of acidification caused a significant decrease in MFCV during cycling immediately after the rest period. From the data a significant correlation between MFCV and [H+] ([H+] = 10−pH) was calculated (p < 0.001, Pearson’s R = −0.87). Our results confirmed the previous observations of MFCV remaining constant during fatiguing dynamic exercise. A constant MFCV is in line with a low degree of acidification, considering the presence of a correlation between pH and MFCV after further increasing acidification.
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Affiliation(s)
- J P J Schmitz
- Biomedical NMR, Department of Biomedical Engineering, Eindhoven University of Technology, PO box 513, 5600MB Eindhoven, The Netherlands.
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Kinugasa R, Kawakami Y, Sinha S, Fukunaga T. Unique spatial distribution ofin vivohuman muscle activation. Exp Physiol 2011; 96:938-48. [DOI: 10.1113/expphysiol.2011.057562] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
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40
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Dideriksen JL, Enoka RM, Farina D. Neuromuscular adjustments that constrain submaximal EMG amplitude at task failure of sustained isometric contractions. J Appl Physiol (1985) 2011; 111:485-94. [PMID: 21596915 DOI: 10.1152/japplphysiol.00186.2011] [Citation(s) in RCA: 70] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
The amplitude of the surface EMG does not reach the level achieved during a maximal voluntary contraction force at the end of a sustained, submaximal contraction, despite near-maximal levels of voluntary effort. The depression of EMG amplitude may be explained by several neural and muscular adjustments during fatiguing contractions, including decreased net neural drive to the muscle, changes in the shape of the motor unit action potentials, and EMG amplitude cancellation. The changes in these parameters for the entire motor unit pool, however, cannot be measured experimentally. The present study used a computational model to simulate the adjustments during sustained isometric contractions and thereby determine the relative importance of these factors in explaining the submaximal levels of EMG amplitude at task failure. The simulation results indicated that the amount of amplitude cancellation in the simulated EMG (∼ 40%) exhibited a negligible change during the fatiguing contractions. Instead, the main determinant of the submaximal EMG amplitude at task failure was a decrease in muscle activation (number of muscle fiber action potentials), due to a reduction in the net synaptic input to motor neurons, with a lesser contribution from changes in the shape of the motor unit action potentials. Despite the association between the submaximal EMG amplitude and reduced muscle activation, the deficit in EMG amplitude at task failure was not consistently associated with the decrease in neural drive (number of motor unit action potentials) to the muscle. This indicates that the EMG amplitude cannot be used as an index of neural drive.
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Affiliation(s)
- Jakob L Dideriksen
- Center for Sensory-Motor Interaction (SMI), Department of Health Science and Technology, Aalborg University, Aalborg, Denmark
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41
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Edmondston S, Björnsdóttir G, Pálsson T, Solgård H, Ussing K, Allison G. Endurance and fatigue characteristics of the neck flexor and extensor muscles during isometric tests in patients with postural neck pain. ACTA ACUST UNITED AC 2011; 16:332-8. [PMID: 21256071 DOI: 10.1016/j.math.2010.12.005] [Citation(s) in RCA: 56] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/03/2010] [Revised: 12/02/2010] [Accepted: 12/14/2010] [Indexed: 11/26/2022]
Abstract
Sustained postural loading of the cervical spine during work or recreational tasks may contribute to the development of neck pain. The aim of this study was to compare neck muscle endurance and fatigue characteristics during sub-maximal isometric endurance tests in patients with postural neck pain, with asymptomatic subjects. Thirteen female patients with postural neck pain and 12 asymptomatic female control subjects completed timed sub-maximal muscle endurance tests for the neck flexor and extensor muscles. Muscle fatigue, defined as the time-dependent decrease in median frequency electromyography (EMG), was examined using surface EMG analysis during the tests. The median extensor test holding time was lower but not significantly different in the neck pain group (165 s) that the control group (228 s) (p = 0.17). There was no difference between groups in the flexor test holding time (neck pain = 36 s, controls = 38 s) (p = 0.96). The neck pain group was characterised by greater variability in neck flexor (p = 0.03) and extensor (p = 0.006) muscle endurance. For both tests, the rate of decrease in median frequency EMG was highly variable within and between groups with no significant difference between groups for the flexor or extensor test (p = 0.05-0.82). Patients with postural neck pain did not have significant impairment of neck muscle endurance or accelerated fatigue compared to control subjects. However, the greater variability in these indices of muscle function may reflect patient-specific changes in muscle function associated with neck pain disorder.
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Affiliation(s)
- Stephen Edmondston
- School of Physiotherapy & Curtin Health Innovation Research Institute, Curtin University of Technology, Perth, Western Australia, Australia.
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42
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Avin KG, Naughton MR, Ford BW, Moore HE, Monitto-Webber MN, Stark AM, Gentile AJ, Law LAF. Sex differences in fatigue resistance are muscle group dependent. Med Sci Sports Exerc 2011; 42:1943-50. [PMID: 20195184 DOI: 10.1249/mss.0b013e3181d8f8fa] [Citation(s) in RCA: 51] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
PURPOSE Women are often reported to be generally more resistant to fatigue than men for relative-intensity tasks. This has been observed repeatedly for elbow flexors, whereas at the ankle, sex differences appear less robust, suggesting localized rather than systemic influences. Thus, the purpose of this study was to examine sex differences in fatigue resistance at muscle groups in a single cohort and which factors, if any, predict endurance time. METHODS Thirty-two young adults (age = 19-44 yr, 16 women) performed sustained isometric contractions at 50% maximum voluntary isometric contraction to failure for elbow flexion and ankle dorsiflexion. Pain, exertion, and muscle EMG were assessed throughout. Self-reported baseline activity was measured using the International Physical Activity Questionnaire. RESULTS Women were significantly more resistant to fatigue than men at the elbow (112.3 ± 6.2 vs 80.3 ± 5.8 s, P = 0.001) but not at the ankle (140.6 ± 10.7 vs 129.2 ± 10.5 s, P = 0.45). Peak torque was greater in men than that in women (P < 0.0001) at the ankle (45.0 ± 1.7 vs 30.1 ± 1.0 N·m) and at the elbow (75.7 ± 3.1 vs 34.4 ± 2.2 N·m). Peak torque was significantly related to endurance time at the elbow (R2= 0.30) but not at the ankle (R2 = 0.03). Peak pain, rate of pain increase, peak exertion, EMG, and baseline physical activity did not differ between sexes. CONCLUSIONS Sex differences in fatigue resistance are muscle group specific. Women were more fatigue resistant at the elbow but not at the ankle during a sustained isometric contraction. Further, factors that may contribute to fatigue resistance for one muscle group (e.g., sex, peak torque) may not be critical at another.
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Affiliation(s)
- Keith G Avin
- Graduate Program in Physical Therapy and Rehabilitation Science, The University of Iowa, Iowa City, IA 52242-1190, USA
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Distribution of motor unit potential velocities in the biceps brachii muscle of sprinters and endurance athletes during prolonged dynamic exercises at low force levels. J Electromyogr Kinesiol 2010; 20:1115-24. [DOI: 10.1016/j.jelekin.2010.05.007] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/09/2009] [Revised: 05/19/2010] [Accepted: 05/19/2010] [Indexed: 11/19/2022] Open
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Distribution of motor unit potential velocities in the biceps brachii muscle of sprinters and endurance athletes during short static contractions at low force levels. J Electromyogr Kinesiol 2010; 20:1107-14. [DOI: 10.1016/j.jelekin.2010.05.008] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/09/2009] [Revised: 05/19/2010] [Accepted: 05/19/2010] [Indexed: 11/22/2022] Open
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45
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Physiological Attributes of Vocal Fatigue and Their Acoustic Effects: A Synthesis of Findings for a Criterion-Based Prevention of Acquired Voice Disorders. J Voice 2010; 24:324-36. [DOI: 10.1016/j.jvoice.2008.10.001] [Citation(s) in RCA: 39] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/06/2008] [Accepted: 10/02/2008] [Indexed: 11/19/2022]
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46
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Law LAF, Avin KG. Endurance time is joint-specific: a modelling and meta-analysis investigation. ERGONOMICS 2010; 53:109-29. [PMID: 20069487 PMCID: PMC2891087 DOI: 10.1080/00140130903389068] [Citation(s) in RCA: 68] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/04/2023]
Abstract
Static task intensity-endurance time (ET) relationships (e.g. Rohmert's curve) were first reported decades ago. However, a comprehensive meta-analysis to compare experimentally-observed ETs across bodily regions has not been reported. We performed a systematic literature review of ETs for static contractions, developed joint-specific power and exponential models of the intensity-ET relationships, and compared these models between each joint (ankle, trunk, hand/grip, elbow, knee, and shoulder) and the pooled data (generalised curve). 194 publications were found, representing a total of 369 data points. The power model provided the best fit to the experimental data. Significant intensity-dependent ET differences were predicted between each pair of joints. Overall, the ankle was most fatigue-resistant, followed by the trunk, hand/grip, elbow, knee and finally the shoulder was most fatigable. We conclude ET varies systematically between joints, in some cases with large effect sizes. Thus, a single generalised ET model does not adequately represent fatigue across joints. STATEMENT OF RELEVANCE: Rohmert curves have been used in ergonomic analyses of fatigue, as there are limited tools available to accurately predict force decrements. This study provides updated endurance time-intensity curves using a large meta-analysis of fatigue data. Specific models derived for five distinct joint regions should further increase prediction accuracy.
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Rabotti C, Mischi M, Beulen L, Oei G, Bergmans JWM. Modeling and identification of the electrohysterographic volume conductor by high-density electrodes. IEEE Trans Biomed Eng 2009; 57:519-27. [PMID: 19884073 DOI: 10.1109/tbme.2009.2035440] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
The surface electrohysterographic (EHG) signal represents the bioelectrical activity that triggers the mechanical contraction of the uterine muscle. Previous work demonstrated the relevance of the EHG signal analysis for fetal and maternal monitoring as well as for prognosis of preterm labor. However, for the introduction in the clinical practice of diagnostic and prognostic EHG techniques, further insights are needed on the properties of the uterine electrical activation and its propagation through biological tissues. An important contribution for studying these phenomena in humans can be provided by mathematical modeling. A five-parameter analytical model of the EHG volume conductor and the cellular action potential (AP) is proposed here and tested on EHG signals recorded by a grid of 64 high-density electrodes. The model parameters are identified by a least-squares optimization method that uses a subset of electrodes. The parameters representing fat and abdominal muscle thickness are also measured by echography. The mean correlation coefficient and standard deviation of the difference between the echographic and EHG estimates were 0.94 and 1.9 mm, respectively. No bias was present. These results suggest that the model provides an accurate description of the EHG AP and the volume conductor, with promising perspectives for future applications.
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Affiliation(s)
- Chiara Rabotti
- Department of Electrical Engineering, Eindhoven University of Technology, Eindhoven, The Netherlands.
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48
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Rabotti C, Mischi M, van Laar JOEH, Oei GS, Bergmans JWM. Inter-electrode delay estimators for electrohysterographic propagation analysis. Physiol Meas 2009; 30:745-61. [DOI: 10.1088/0967-3334/30/8/002] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
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49
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Hwang IS, Yang ZR, Huang CT, Guo MC. Reorganization of multidigit physiological tremors after repetitive contractions of a single finger. J Appl Physiol (1985) 2009; 106:966-74. [PMID: 19150860 DOI: 10.1152/japplphysiol.90851.2008] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
In light of the interplay among physiological finger tremors, this study was undertaken to investigate the transfer effect of fatigue on coordinative strategies of multiple fingers. Fourteen volunteers performed prolonged position tracking with a loaded middle finger while measures of neuromuscular function, including electromyographic activities of the extensor digitorum (ED)/flexor digitorum superficialis (FDS) and physiological tremors of the index, middle, ring, and little fingers, were monitored. The subjects exhibited inferior tracking congruence and an increase in ED activity at the end of the tracking. Fatigue spread was manifested in a remarkable increase in tremor across fingers, in association with enhanced involuntary tremor coupling among fingers that was topologically organized in relation to the distance of the digits from the middle finger. Principal component analysis suggested that an enhanced 8- to 12-Hz central rhythm contributed primarily to the tremor restructure following fatigue spread. The observed tremor reorganization validated the hypothesis that the effect of fatigue was not limited to the instructed finger and that fatigue functionally decreased independence of the digits. The spreading of fatigue weakens neural inputs that diverge to motor units acting on various digits because of fatigue-related enhancement of common drive at the supraspinal level.
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50
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Karlsson JS, Roeleveld K, Grönlund C, Holtermann A, Ostlund N. Signal processing of the surface electromyogram to gain insight into neuromuscular physiology. PHILOSOPHICAL TRANSACTIONS. SERIES A, MATHEMATICAL, PHYSICAL, AND ENGINEERING SCIENCES 2009; 367:337-356. [PMID: 18974034 DOI: 10.1098/rsta.2008.0214] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/27/2023]
Abstract
A surface electromyogram (sEMG) contains information about physiological and morphological characteristics of the active muscle and its neural strategies. Because the electrodes are situated on the skin above the muscle, the sEMG is an easily obtainable source of information. However, different combinations of physiological and morphological characteristics can lead to similar sEMG signals and sEMG recordings contain noise and other artefacts. Therefore, many sEMG signal processing methods have been developed and applied to allow insight into neuromuscular physiology. This paper gives an overview of important advances in the development and applications of sEMG signal processing methods, including spectral estimation, higher order statistics and spatio-temporal processing. These methods provide information about muscle activation dynamics and muscle fatigue, as well as characteristics and control of single motor units (conduction velocity, firing rate, amplitude distribution and synchronization).
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Affiliation(s)
- J Stefan Karlsson
- Department of Biomedical Engineering & Informatics, University Hospital, 901 85 Umeå, Sweden.
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