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Wang Z, Taniguchi M, Saeki J, Ichihashi N. Effects of High-Velocity Versus Low-Velocity Resistance Training on Muscle Echo Intensity in Healthy Young Women: A Randomized Controlled Trial. Sports Health 2024:19417381241257181. [PMID: 38864295 DOI: 10.1177/19417381241257181] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/13/2024] Open
Abstract
BACKGROUND Improving muscle quality to prevent and treat muscle dysfunction is critical. However, effective measures to improve muscle quality remain poorly understood. We investigated the effects of high- and low-velocity resistance training (RT) on muscle quality, mass, and function before and after an 8-week intervention. HYPOTHESIS High-velocity RT would improve muscle quality more effectively than low-velocity RT. STUDY DESIGN Randomized controlled trial. LEVEL OF EVIDENCE Level 1. METHODS A total of 33 healthy young women (23.1 ± 2.2 years) were assigned randomly to high-velocity (n = 16) or low-velocity (n = 17) groups. Both groups underwent concentric knee extension RT with a 60% 1-repetition maximum (1RM) load, performing 10 repetitions of 4 sets, 3 times per week for 8 weeks. The high-velocity group was instructed to complete each repetition as quickly as possible (mean repetition duration of 0.5 seconds), while the low-velocity group was required to execute each repetition in 3 seconds. Before and after the 8-week intervention, quadriceps femoris echo intensity (EI), muscle thickness (MT), isokinetic peak torque (60 and 300 deg/s), rate of velocity development (RVD) at 300 deg/s, and 1RM were assessed. Split-plot factorial design analysis of variance was used to compare the group × time interaction. RESULTS A group×time interaction was observed for EI (P < 0.01). Only the high-velocity group showed a significant reduction in EI after the intervention. MT revealed a main effect of time (P < 0.01), with both groups significantly increasing MT. RVD showed a group × time interaction (P < 0.05), with significant increase only in the high-velocity group. Isokinetic peak torque and 1RM showed main effects of time (P < 0.01), with significant increases in both groups. CONCLUSION High-velocity RT may be superior to low-velocity RT in enhancing muscle quality and RVD. CLINICAL RELEVANCE These results emphasize the importance of RT velocity for muscle quality improvement.
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Affiliation(s)
- Zimin Wang
- Human Health Sciences, Graduate School of Medicine, Kyoto University, Japan
- Japan Society for the Promotion of Science, Tokyo, Japan
| | - Masashi Taniguchi
- Human Health Sciences, Graduate School of Medicine, Kyoto University, Japan
| | - Junya Saeki
- Human Health Sciences, Graduate School of Medicine, Kyoto University, Japan
- Department of Rehabilitation, Osaka Kawasaki Rehabilitation University, Japan
| | - Noriaki Ichihashi
- Human Health Sciences, Graduate School of Medicine, Kyoto University, Japan
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Olmos AA, Montgomery TR, Sears KN, Dinyer TK, Hammer SM, Bergstrom HC, Hill EC, Succi PJ, Lawson J, Trevino MA. Blood flow restriction increases necessary muscle excitation of the elbow flexors during a single high-load contraction. Eur J Appl Physiol 2024; 124:1807-1820. [PMID: 38236301 DOI: 10.1007/s00421-023-05405-y] [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: 07/03/2023] [Accepted: 12/09/2023] [Indexed: 01/19/2024]
Abstract
PURPOSE To investigate the effects of blood flow restriction (BFR) on electromyographic amplitude (EMGRMS)-force relationships of the biceps brachii (BB) during a single high-load muscle action. METHODS Twelve recreationally active males and eleven recreationally active females performed maximal voluntary contractions (MVCs), followed by an isometric trapezoidal muscle action of the elbow flexors at 70% MVC. Surface EMG was recorded from the BB during BFR and control (CON) visits. For BFR, cuff pressure was 60% of the pressure required to completely occlude blood at rest. Individual b (slope) and a terms (gain) were calculated from the log-transformed EMGRMS-force relationships during the linearly increasing and decreasing segments of the trapezoid. EMGRMS during the steady force segment was normalized to MVC EMGRMS. RESULTS For BFR, the b terms were greater during the linearly increasing segment than the linearly decreasing segment (p < 0.001), and compared to the linearly increasing segment for CON (p < 0.001). The a terms for BFR were greater during the linearly decreasing than linearly increasing segment (p = 0.028). Steady force N-EMGRMS was greater for BFR than CON collapsed across sex (p = 0.041). CONCLUSION BFR likely elicited additional recruitment of higher threshold motor units during the linearly increasing- and steady force-segment. The differences between activation and deactivation strategies were only observed with BFR, such as the b terms decreased and the a terms increased for the linearly decreasing segment in comparison to the increasing segment. However, EMGRMS-force relationships during the linearly increasing- and decreasing-segments were not different between sexes during BFR and CON.
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Affiliation(s)
- Alex A Olmos
- Applied Neuromuscular Physiology Laboratory, Department of Health and Human Performance, Oklahoma State University, 191 CRC, Stillwater, OK, 74074, USA
| | - Tony R Montgomery
- Applied Neuromuscular Physiology Laboratory, Department of Health and Human Performance, Oklahoma State University, 191 CRC, Stillwater, OK, 74074, USA
| | - Kylie N Sears
- Applied Neuromuscular Physiology Laboratory, Department of Health and Human Performance, Oklahoma State University, 191 CRC, Stillwater, OK, 74074, USA
| | - Taylor K Dinyer
- Applied Neuromuscular Physiology Laboratory, Department of Health and Human Performance, Oklahoma State University, 191 CRC, Stillwater, OK, 74074, USA
| | - Shane M Hammer
- Applied Neuromuscular Physiology Laboratory, Department of Health and Human Performance, Oklahoma State University, 191 CRC, Stillwater, OK, 74074, USA
| | - Haley C Bergstrom
- Department of Kinesiology and Health Promotion, University of Kentucky, Lexington, KY, 40506, USA
| | - Ethan C Hill
- School of Kinesiology and Physical Therapy, University of Central Florida, Orlando, FL, 32816, USA
| | - Pasquale J Succi
- Department of Kinesiology and Health Promotion, University of Kentucky, Lexington, KY, 40506, USA
| | - John Lawson
- School of Kinesiology and Physical Therapy, University of Central Florida, Orlando, FL, 32816, USA
| | - Michael A Trevino
- Applied Neuromuscular Physiology Laboratory, Department of Health and Human Performance, Oklahoma State University, 191 CRC, Stillwater, OK, 74074, USA.
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Olmos AA, Sontag SA, Sterczala AJ, Parra ME, Dimmick HL, Miller JD, Deckert JA, Herda TJ, Trevino MA. High-Intensity Cycling Training Necessitates Increased Neuromuscular Demand of the Vastus Lateralis During a Fatiguing Contraction. RESEARCH QUARTERLY FOR EXERCISE AND SPORT 2024; 95:313-324. [PMID: 37369135 DOI: 10.1080/02701367.2023.2201311] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/13/2022] [Accepted: 04/05/2023] [Indexed: 06/29/2023]
Abstract
Purpose: To examine the effects of a 5-week continuous cycling training intervention on electromyographic amplitude (EMGRMS)- and mechanomyographic amplitude (MMGRMS)-torque relationships of the vastus lateralis (VL) during a prolonged contraction. Methods: Twenty-four sedentary, young adults performed maximal voluntary contractions (MVCs) and a prolonged isometric trapezoidal contraction at the same absolute 40% MVC for the knee extensors before (PRE) and after training (POSTABS). Individual b- (slopes) and a-terms (y-intercepts) were calculated from the log-transformed electromyographic amplitude (EMGRMS)- and mechanomyographic amplitude (MMGRMS)-torque relationships during the increasing and decreasing segments of the trapezoid. EMGRMS and MMGRMS was normalized for the 45-s steady torque segment. Results: At PRE, b-terms for the EMGRMS-torque relationships during the linearly decreasing segment were greater than the increasing segment (p < .001), and decreased from PRE to POSTABS (p = .027). a-terms were greater during the linearly increasing than decreasing segment at PRE, while the a-terms for the linearly decreasing segment increased from PRE to POSTABS (p = .027). For the MMGRMS-torque relationships, b-terms during the linearly decreasing segment decreased from PRE to POSTABS (p = .013), while a-terms increased from PRE to POSTABS when collapsed across segments (p = .022). Steady torque EMGRMS increased for POSTABS (p < .001). Conclusion: Although cycling training increased aerobic endurance, incorporating resistance training may benefit athletes/individuals as the alterations in neuromuscular parameters post-training suggest a greater neural cost (EMGRMS) and mechanical output (MMGRMS) to complete the same pre-training fatiguing contraction.
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Goreau V, Hug F, Jannou A, Dernoncourt F, Crouzier M, Cattagni T. Estimates of persistent inward currents in lower limb muscles are not different between inactive, resistance-trained, and endurance-trained young males. J Neurophysiol 2024; 131:166-175. [PMID: 38116611 DOI: 10.1152/jn.00278.2023] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/20/2023] [Revised: 11/20/2023] [Accepted: 12/17/2023] [Indexed: 12/21/2023] Open
Abstract
Persistent inward currents (PICs) increase the intrinsic excitability of α-motoneurons. The main objective of this study was to compare estimates of α-motoneuronal PICs between inactive, chronic resistance-trained, and chronic endurance-trained young individuals. We also aimed to investigate whether there is a relationship in the estimates of α-motoneuronal PIC magnitude between muscles. Estimates of PIC magnitude were obtained in three groups of young individuals: resistance-trained (n = 12), endurance-trained (n = 12), and inactive (n = 13). We recorded high-density surface electromyography (HDsEMG) signals from tibialis anterior (TA), gastrocnemius medialis (GM), soleus (SOL), vastus medialis (VM), and vastus lateralis (VL). Then, signals were decomposed with convolutive blind source separation to identify motor unit (MU) spike trains. Participants performed triangular isometric contractions to a peak of 20% of their maximum voluntary contraction. A paired-motor-unit analysis was used to calculate ΔF, which is assumed to be proportional to PIC magnitude. Despite the substantial differences in physical training experience between groups, we found no differences in ΔF, regardless of the muscle. Significant correlations of estimates of PIC magnitude were found between muscles of the same group (VL-VM, SOL-GM). Only two correlations (out of 8) between muscles of different groups were found (TA-GM and VL-GM). Overall, our findings suggest that estimates of PIC magnitude from lower-threshold MUs at low contraction intensities in the lower limb muscles are not influenced by physical training experience in healthy young individuals. They also suggest muscle-specific and muscle group-specific regulations of the estimates of PIC magnitude.NEW & NOTEWORTHY Chronic resistance and endurance training can lead to specific adaptations in motor unit activity. The contribution of α-motoneuronal persistent inward currents (PICs) to these adaptations is currently unknown in healthy young individuals. Therefore, we studied whether estimates of α-motoneuronal PIC magnitude are higher in chronically trained endurance- and resistance-trained individuals. We also studied whether there is a relationship between the estimates of α-motoneuronal PIC magnitude of different lower limb muscles.
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Affiliation(s)
- Valentin Goreau
- Movement - Interactions - Performance (MIP, UR 4334), Nantes Université, Nantes, France
| | | | - Anthony Jannou
- Movement - Interactions - Performance (MIP, UR 4334), Nantes Université, Nantes, France
| | - François Dernoncourt
- Movement - Interactions - Performance (MIP, UR 4334), Nantes Université, Nantes, France
- LAMHESS, Université Côte d'Azur, Nice, France
| | - Marion Crouzier
- Movement - Interactions - Performance (MIP, UR 4334), Nantes Université, Nantes, France
- Department of Movement Science, Human Movement Biomechanics Research Group, KU Leuven, Leuven, Belgium
| | - Thomas Cattagni
- Movement - Interactions - Performance (MIP, UR 4334), Nantes Université, Nantes, France
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Olmos AA, Sterczala AJ, Parra ME, Dimmick HL, Miller JD, Deckert JA, Sontag SA, Gallagher PM, Fry AC, Herda TJ, Trevino MA. Sex-related differences in motor unit behavior are influenced by myosin heavy chain during high- but not moderate-intensity contractions. Acta Physiol (Oxf) 2023; 239:e14024. [PMID: 37551144 DOI: 10.1111/apha.14024] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/03/2022] [Revised: 07/18/2023] [Accepted: 07/19/2023] [Indexed: 08/09/2023]
Abstract
AIMS Motor unit recruitment and firing rate patterns of the vastus lateralis (VL) have not been compared between sexes during moderate- and high-intensity contraction intensities. Additionally, the influence of fiber composition on potential sex-related differences remains unquantified. METHODS Eleven males and 11 females performed 40% and 70% maximal voluntary contractions (MVCs). Surface electromyographic (EMG) signals recorded from the VL were decomposed. Recruitment thresholds (RTs), MU action potential amplitudes (MUAPAMP ), initial firing rates (IFRs), mean firing rates (MFRs), and normalized EMG amplitude (N-EMGRMS ) at steady torque were analyzed. Y-intercepts and slopes were calculated for MUAPAMP , IFR, and MFR versus RT relationships. Type I myosin heavy chain isoform (MHC) was determined with muscle biopsies. RESULTS There were no sex-related differences in MU characteristics at 40% MVC. At 70% MVC, males exhibited greater slopes (p = 0.002) for the MUAPAMP , whereas females displayed greater slopes (p = 0.001-0.007) for the IFR and MFR versus RT relationships. N-EMGRMS at 70% MVC was greater for females (p < 0.001). Type I %MHC was greater for females (p = 0.006), and was correlated (p = 0.018-0.031) with the slopes for the MUAPAMP , IFR, and MFR versus RT relationships at 70% MVC (r = -0.599-0.585). CONCLUSION Both sexes exhibited an inverse relationship between MU firing rates and recruitment thresholds. However, the sex-related differences in MU recruitment and firing rate patterns and N-EMGRMS at 70% MVC were likely due to greater type I% MHC and smaller twitch forces of the higher threshold MUs for the females. Evidence is provided that muscle fiber composition may explain divergent MU behavior between sexes.
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Affiliation(s)
- Alex A Olmos
- Applied Neuromuscular Physiology Lab, Department of Kinesiology, Applied Health, and Recreation, Oklahoma State University, Stillwater, Oklahoma, USA
| | - Adam J Sterczala
- Neuromuscular Research Laboratory, Department of Sports Medicine and Nutrition, University of Pittsburgh, Pittsburgh, Pennsylvania, USA
| | - Mandy E Parra
- School of Exercise and Sport Science, University of Mary Hardin-Baylor, Belton, Texas, USA
| | - Hannah L Dimmick
- Faculty of Kinesiology, University of Calgary, Calgary, Alberta, Canada
| | - Jonathan D Miller
- Department of Chemical and Petroleum Engineering, University of Kansas, Lawrence, Kansas, USA
| | - Jake A Deckert
- Department of Human Physiology, Gonzaga University, Spokane, Washington, USA
| | - Stephanie A Sontag
- Applied Neuromuscular Physiology Lab, Department of Kinesiology, Applied Health, and Recreation, Oklahoma State University, Stillwater, Oklahoma, USA
| | - Philip M Gallagher
- Applied Physiology Laboratory, Department of Health, Sport, and Exercise Sciences, University of Kansas, Lawrence, Kansas, USA
| | - Andrew C Fry
- Jayhawk Athletic Performance Laboratory - Wu Tsai Human Performance Alliance, University of Kansas, Lawrence, Kansas, USA
| | - Trent J Herda
- Neuromechanics Laboratory, Department of Health, Sport, and Exercise Sciences, University of Kansas, Lawrence, Kansas, USA
| | - Michael A Trevino
- Applied Neuromuscular Physiology Lab, Department of Kinesiology, Applied Health, and Recreation, Oklahoma State University, Stillwater, Oklahoma, USA
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Trevino M, Perez S, Sontag S, Olmos A, Jeon S, Richardson L. Influence of Pennation Angle and Muscle Thickness on Mechanomyographic Amplitude-Torque Relationships and Sex-Related Differences in the Vastus Lateralis. J Funct Morphol Kinesiol 2023; 8:jfmk8020053. [PMID: 37218849 DOI: 10.3390/jfmk8020053] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/25/2023] [Revised: 04/17/2023] [Accepted: 04/27/2023] [Indexed: 05/24/2023] Open
Abstract
This study examined potential sex-related differences and correlations among the pennation angle (PA), muscle thickness (MT), and mechanomyographic amplitude (MMGRMS)-torque relationships of the vastus lateralis (VL) in 11 healthy males and 12 healthy females. The PA and MT of the VL were quantified with ultrasound. Participants performed an isometric muscle action of the knee extensors that linearly increased to 70% of maximal strength followed by a 12 s plateau. MMG was recorded from the VL. Linear regression models were fit to the log-transformed MMGRMS-torque relationships to calculate b terms (slopes) for the linearly increasing segment. MMGRMS was averaged during the plateau. Males exhibited greater PA (p < 0.001), MT (p = 0.027), b terms (p = 0.005), and MMGRMS (p = 0.016). The b terms were strongly (p < 0.001, r = 0.772) and moderately correlated (p = 0.004, r = 0.571) with PA and MT, respectively, while MMGRMS was moderately correlated with PA (p = 0.018, r = 0.500) and MT (p = 0.014, r = 0.515). The greater mechanical behavior of individuals possessing a larger PA and MT of the VL may reflect increased cross-bridge activity within the muscle fibers. Additionally, PA may help explain sex-related differences in MMGRMS between sexes.
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Affiliation(s)
- Michael Trevino
- Applied Neuromuscular Physiology Laboratory, Department of Kinesiology, Applied Health, and Recreation, Oklahoma State University, Stillwater, OK 74078, USA
| | - Sergio Perez
- Applied Neuromuscular Physiology Laboratory, Department of Kinesiology, Applied Health, and Recreation, Oklahoma State University, Stillwater, OK 74078, USA
| | - Stephanie Sontag
- Applied Neuromuscular Physiology Laboratory, Department of Kinesiology, Applied Health, and Recreation, Oklahoma State University, Stillwater, OK 74078, USA
| | - Alex Olmos
- Applied Neuromuscular Physiology Laboratory, Department of Kinesiology, Applied Health, and Recreation, Oklahoma State University, Stillwater, OK 74078, USA
| | - Sunggun Jeon
- Applied Neuromuscular Physiology Laboratory, Department of Kinesiology, Applied Health, and Recreation, Oklahoma State University, Stillwater, OK 74078, USA
| | - Lyric Richardson
- Applied Neuromuscular Physiology Laboratory, Department of Kinesiology, Applied Health, and Recreation, Oklahoma State University, Stillwater, OK 74078, USA
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Jeon S, Sontag SA, Herda TJ, Trevino MA. Chronic training status affects muscle excitation of the vastus lateralis during repeated contractions. SPORTS MEDICINE AND HEALTH SCIENCE 2023; 5:42-49. [PMID: 36994174 PMCID: PMC10040376 DOI: 10.1016/j.smhs.2022.12.005] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/19/2022] [Revised: 11/23/2022] [Accepted: 12/31/2022] [Indexed: 01/03/2023] Open
Abstract
This study examined electromyographic amplitude (EMGRMS)-force relationships during repeated submaximal knee extensor muscle actions among chronic aerobically-(AT), resistance-trained (RT), and sedentary (SED) individuals. Fifteen adults (5/group) attempted 20 isometric trapezoidal muscle actions at 50% of maximal strength. Surface electromyography (EMG) was recorded from vastus lateralis (VL) during the muscle actions. For the first and last successfully completed contractions, linear regression models were fit to the log-transformed EMGRMS-force relationships during the linearly increasing and decreasing segments, and the b terms (slope) and a terms (antilog of y-intercept) were calculated. EMGRMS was averaged during steady force. Only the AT completed all 20 muscle actions. During the first contraction, the b terms for RT (1.301 ± 0.197) were greater than AT (0.910 ± 0.123; p = 0.008) and SED (0.912 ± 0.162; p = 0.008) during the linearly increasing segment, and in comparison to the linearly decreasing segment (1.018 ± 0.139; p = 0.014), respectively. For the last contraction, the b terms for RT were greater than AT during the linearly increasing (RT = 1.373 ± 0.353; AT = 0.883 ± 0.129; p = 0.018) and decreasing (RT = 1.526 ± 0.328; AT = 0.970 ± 0.223; p = 0.010) segments. In addition, the b terms for SED increased from the linearly increasing (0.968 ± 0.144) to decreasing segment (1.268 ± 0.126; p = 0.015). There were no training, segment, or contraction differences for the a terms. EMGRMS during steady force increased from the first- ([64.08 ± 51.68] μV) to last-contraction ([86.73 ± 49.55] μV; p = 0.001) collapsed across training statuses. The b terms differentiated the rate of change for EMGRMS with increments in force among training groups, indicating greater muscle excitation to the motoneuron pool was necessary for the RT than AT during the linearly increasing and decreasing segments of a repetitive task.
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Reece TM, Hatcher ML, Emerson DM, Herda TJ. The effects of passive dehydration on motor unit firing rates of the vastus lateralis in males. SPORT SCIENCES FOR HEALTH 2022. [DOI: 10.1007/s11332-022-01006-y] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
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Trevino MA, Dimmick HL, Parra ME, Sterczala AJ, Miller JD, Deckert JA, Gallagher PM, Fry AC, Weir JP, Herda TJ. Effects of continuous cycling training on motor unit firing rates, input excitation, and myosin heavy chain of the vastus lateralis in sedentary females. Exp Brain Res 2022; 240:825-839. [DOI: 10.1007/s00221-021-06278-3] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/18/2021] [Accepted: 11/13/2021] [Indexed: 11/25/2022]
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Parra ME, Miller JD, Sterczala AJ, Kelly MR, Herda TJ. The reliability of the slopes and y-intercepts of the motor unit firing times and action potential waveforms versus recruitment threshold relationships derived from surface electromyography signal decomposition. Eur J Appl Physiol 2021; 121:3389-3398. [PMID: 34477930 DOI: 10.1007/s00421-021-04790-6] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/10/2021] [Accepted: 08/12/2021] [Indexed: 11/24/2022]
Abstract
PURPOSE Changes in motor unit (MU) activity pre- to post-interventions is of high interest. However, there is minimal information regarding day-to-day changes or the reliability of measuring MU activity. This study examined the reliability of relationships calculated via the MU action potential (AP) trains derived from surface electromyography signal decomposition. A comparison between reliability statistics was made between MUAP trains verified with only the reconstruct-and-test versus verification including reconstruct-and-test with spike trigger average (STA) procedures. METHODS Twenty-one individuals performed isometric muscle actions at 50% of maximal voluntary contraction of the first dorsal interosseous on two separate visits. MUs included for reliability analyses initially met the > 90% accuracy from the reconstruct-and-test. STA was applied as an additional exclusionary procedure. Linear regressions were applied to the firing rate and AP amplitude versus recruitment threshold relationships with and without MUs that met the STA criteria. Reliability statistics were also performed on relationships that met a strict range of recruitment thresholds. Reliability was established with intraclass correlation coefficients (ICC) along with other traditional parameters. RESULTS The firing rate versus recruitment threshold relationships were reliable (ICC > 0.56) and improved (ICC > 0.84) when recruitment ranges were controlled. The slopes of the MUAP amplitude versus recruitment threshold relationships were reliable (ICC > 0.78) while the y-intercepts were reliable (ICC > 0.81) once corrections were made to combat negative scores. CONCLUSIONS Electromyographic signal decomposition without the secondary STA verification procedures can be used to detect intervention-related changes in neural drive with confidence when recorded MU recruitment thresholds are similar across days.
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Affiliation(s)
- Mandy E Parra
- School of Exercise and Sport Science, University of Mary Hardin-Baylor, Belton, TX, USA
| | - Jonathan D Miller
- Neuromechanics Laboratory, Department of Health, Sport and Exercise Sciences, University of Kansas, 1301 Sunnyside Avenue, Room 101BE, Lawrence, KS, 66045, USA
| | - Adam J Sterczala
- Neuromuscular Research Laboratory, Department of Sports Medicine and Nutrition, University of Pittsburg, Pittsburgh, PA, USA
| | - Melani R Kelly
- Human Performance Research Laboratory, Department of Exercise Science and Pre-Health Professions, Creighton University, Omaha, NE, USA
| | - Trent J Herda
- Neuromechanics Laboratory, Department of Health, Sport and Exercise Sciences, University of Kansas, 1301 Sunnyside Avenue, Room 101BE, Lawrence, KS, 66045, USA.
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Reece TM, Herda TJ. An examination of a potential organized motor unit firing rate and recruitment scheme of an antagonist muscle during isometric contractions. J Neurophysiol 2021; 125:2094-2106. [PMID: 33909509 DOI: 10.1152/jn.00034.2021] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
The primary purpose of the present study is to determine if an organized control scheme exists for the antagonist muscle during steady isometric torque. A secondary focus is to better understand how firing rates of the antagonist muscle change from a moderate- to higher-contraction intensity. Fourteen subjects performed two submaximal isometric trapezoid muscle actions of the forearm flexors that included a linearly increasing, steady force at both 40% and 70% maximum voluntary contraction, and linearly decreasing segments. Surface electromyographic signals of the biceps and triceps brachii were collected and decomposed into constituent motor unit action potential trains. Motor unit firing rate versus recruitment threshold, motor unit action potential amplitude versus recruitment threshold, and motor unit firing rate versus action potential amplitude relationships of the biceps brachii (agonist) and triceps brachii (antagonist) muscles were analyzed. Moderate- to-strong relationships (|r| ≥ 0.69) were present for the agonist and antagonist muscles for each relationship with no differences between muscles (P = 0.716, 0.428, 0.182). The y-intercepts of the motor unit firing rate versus recruitment threshold relationship of the antagonist did not increase from 40% to 70% maximal voluntary contractions (P = 0.96), unlike for the agonist (P = 0.009). The antagonist muscle exhibits a similar motor unit control scheme to the agonist. Unlike the agonist, however, the firing rates of the antagonist did not increase with increasing intensity. Future research should investigate how antagonist firing rates adapt to resistance training and changes in antagonist firing rates in the absence of peripheral feedback.NEW & NOTEWORTHY This is the first study to explore a potential motor unit control scheme and quantify changes in firing rates with increasing intensity of an antagonist muscle during isometric contractions. We demonstrate that the antagonist muscle possesses an organized motor unit firing rate and recruitment scheme similar to the agonist muscle during isometric forearm flexion, but unlike the agonist muscle, there was no significant increase in firing rates from a moderate- to higher-intensity isometric contraction.
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Affiliation(s)
- Tanner M Reece
- Neuromechanics Laboratory, Department of Health, Sport and Exercise Sciences, University of Kansas, Lawrence, Kansas
| | - Trent J Herda
- Neuromechanics Laboratory, Department of Health, Sport and Exercise Sciences, University of Kansas, Lawrence, Kansas
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Parra ME, Miller JD, Sterczala AJ, Trevino MA, Dimmick HL, Herda TJ. Differences in the firing rate versus recruitment threshold relationships of the vastus lateralis in children ages 7-10 years and adults. Hum Mov Sci 2020; 72:102650. [PMID: 32721368 DOI: 10.1016/j.humov.2020.102650] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/13/2019] [Revised: 03/18/2020] [Accepted: 05/25/2020] [Indexed: 11/17/2022]
Abstract
Motor unit (MU) firing rates of the vastus lateralis in children and adults were examined. Seven healthy adult males (mean ± SD, age = 21 ± 2.6 yrs) and six healthy male children (mean ± SD age = 8.8 ± 1.7) volunteered. Surface electromyography (EMG) signals were recorded from 20% and 60% maximal voluntary contractions (MVC). Surface EMG signals were decomposed into firing events of individual MUs and slopes and y-intercepts were calculated for the mean firing rate (MFR, pps) at steady torque vs. recruitment thresholds (RT) relationships for each subject. Muscle cross-sectional area (mCSA) was measured, via ultrasonography, with specific torque calculated (MVC/mCSA). Adults possessed greater mCSA (p = .002; children = 11.5 ± 2.1 cm2; adults = 31.80 ± 12.15 cm2) and greater specific torque (p = .018; children = 4.63 ± 1.4 Nm/cm2; adults = 7.1 ± 1.8 Nm/cm2) compared to children. The y-intercepts were significantly (p < .001) greater during the 60% (28.91 ± 4.56 pps) than the 20% MVC (23.5 ± 4.9 pps) collapsed across groups while the children had significantly (p = .036) lower y-intercepts (23.9 ± 5.4 pps) than the adults (28.2 ± 4.8 pps) when collapsed across intensities. Slopes of the MFR vs RT relationships were greater for the 60% (-0.342 ± 0.127 pps/%MVC) contraction than the 20% (-0.50 ± 0.159 pps/%MVC) MVC when collapsed across groups. Adults had greater firing rates regardless of recruitment threshold than children. This may be due to lower recruitment potential and overall excitation to the motoneuron pool of children as indicated with differences in specific torque and/or differences in antagonist co-activation.
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Affiliation(s)
- Mandy E Parra
- Neuromechanics Laboratory, Department of Health, Sport and Exercise Sciences, University of Kansas, Lawrence, KS, USA
| | - Jonathan D Miller
- Neuromechanics Laboratory, Department of Health, Sport and Exercise Sciences, University of Kansas, Lawrence, KS, USA
| | - Adam J Sterczala
- Neuromuscular Research Laboratory, Department of Sports Medicine and Nutrition, University of Pittsburgh, Pittsburgh, PA, USA
| | - Michael A Trevino
- Applied Neuromuscular Physiology Laboratory Department of Health and Human Performance, Oklahoma State University, Stillwater, OK 74078, USA
| | - Hannah L Dimmick
- Neuromechanics Laboratory, Department of Health, Sport and Exercise Sciences, University of Kansas, Lawrence, KS, USA
| | - Trent J Herda
- Neuromechanics Laboratory, Department of Health, Sport and Exercise Sciences, University of Kansas, Lawrence, KS, USA.
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Skeletal Muscle Composition and Glucose Levels in Children Who Are Overweight and Obese. Pediatr Exerc Sci 2020; 32:157-164. [PMID: 32454457 DOI: 10.1123/pes.2020-0018] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/27/2020] [Revised: 04/15/2020] [Accepted: 04/17/2020] [Indexed: 11/18/2022]
Abstract
BACKGROUND Skeletal muscle is overlooked in the realm of insulin resistance in children who are overweight and obese despite the fact that it accounts for the most glucose disposal. OBJECTIVES Therefore, this study examined fasted glucose levels and muscle cross-sectional area and echo intensity (EI) via ultrasound images of the first dorsal interosseous, vastus lateralis, and rectus femoris in children who are normal weight and overweight and obese aged 8-10 years. METHODS In total, 13 males (age = 9.0 [0.7] y) and 7 females (age = 9.0 [0.8] y) volunteered for this study. Independent samples t tests and effect sizes (ESs) were used to examine potential differences in skeletal muscle composition and glucose concentrations. RESULTS There were no significant differences between groups for glucose concentration (P = .07, ES = 0.86); however, the children who were overweight and obese had significantly greater EI (P < .01, ES = 0.98-1.63) for the first dorsal interosseous, vastus lateralis, and rectus femoris and lower cross-sectional area when normalized to EI when collapsed across muscles (P < .04, ES = 0.92). Glucose concentrations correlated with EI and cross-sectional area/EI for the vastus lateralis (r = .514 to -.593) and rectus femoris (r = .551 to -.513), but not the first dorsal interosseous. DISCUSSION There is evidence that adiposity-related pathways leading to insulin resistance and skeletal muscle degradation are active in young children who are overweight and obese.
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Herda TJ, Parra ME, Miller JD, Sterczala AJ, Kelly MR. Measuring the accuracies of motor unit firing times and action potential waveforms derived from surface electromyographic decomposition. J Electromyogr Kinesiol 2020; 52:102421. [PMID: 32353708 DOI: 10.1016/j.jelekin.2020.102421] [Citation(s) in RCA: 16] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/23/2019] [Revised: 04/09/2020] [Accepted: 04/09/2020] [Indexed: 11/25/2022] Open
Abstract
This study included spike trigger averaging (STA) procedures to examine the acceptability of the Precision Decomposition (PD) III derived motor unit action potential (MUAP) trains that met the >90% accuracy criteria from the reconstruct-and-test. MUs met the >90% accuracy criteria from the reconstruct-and-test with STA procedures then applied. Y-intercepts and slopes were calculated for the firing rate- and MUAP amplitude-recruitment threshold relationships. Gaussian noise (1% of the SD of the mean interspike interval) was added to the firing times with the changes in MUAPs quantified. A total of 455 MUs were decomposed with 155 MUs removed as a result of the reconstruct-and-test. Five additional MUs were excluded via the STA criteria. The MUAP waveforms deteriorated with the inclusion of Gaussian noise. There were differences in the derived action potentials amplitudes of higher-threshold MUs between the PD III algorithm and the STA procedure. There was excellent agreement among the slopes and y-intercepts between the relationships that included or excluded MUs that did not meet the STA criteria. There was good agreement between the MUAP amplitude-recruitment threshold relationships derived from the PD III and STA procedure. The addition of the STA procedures did not alter the MU-derived relationships.
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Affiliation(s)
- Trent J Herda
- Neuromechanics Laboratory, Department of Health, Sport and Exercise Sciences, University of Kansas, Lawrence, USA.
| | - Mandy E Parra
- Neuromechanics Laboratory, Department of Health, Sport and Exercise Sciences, University of Kansas, Lawrence, USA
| | - Jonathan D Miller
- Neuromechanics Laboratory, Department of Health, Sport and Exercise Sciences, University of Kansas, Lawrence, USA
| | - Adam J Sterczala
- Neuromuscular Research Laboratory, Department of Sports Medicine and Nutrition, University of Pittsburg, Pittsburgh, PA, USA
| | - Melani R Kelly
- Neuromechanics Laboratory, Department of Health, Sport and Exercise Sciences, University of Kansas, Lawrence, USA
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Herda TJ, Ryan ED, Kohlmeier M, Trevino MA, Gerstner GR, Roelofs EJ, Miller JD. Muscle cross‐sectional area and motor unit properties of the medial gastrocnemius and vastus lateralis in normal weight and overfat children. Exp Physiol 2020; 105:335-346. [DOI: 10.1113/ep088181] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/17/2019] [Accepted: 11/27/2019] [Indexed: 11/08/2022]
Affiliation(s)
- Trent J. Herda
- Neuromechanics LaboratoryUniversity of Kansas Lawrence KS USA
| | - Eric D. Ryan
- Neuromuscular Research LaboratoryDepartment of Exercise Science and Sport ScienceUniversity of North Carolina at Chapel Hill Chapel Hill NC USA
- Human Movement Science CurriculumUniversity of North Carolina at Chapel Hill Chapel Hill NC USA
| | - Martin Kohlmeier
- Department of Nutrition, School of MedicineUniversity of North Carolina at Chapel Hill Chapel Hill NC USA
- Nutrigenetics LaboratoryUniversity of North Carolina at Chapel Hill Kannapolis NC USA
| | - Michael A. Trevino
- Applied Neuromuscular Physiology LaboratoryDepartment of Health and Human PerformanceOklahoma State University Stillwater OK USA
| | - Gena R. Gerstner
- Department of Human Movement SciencesOld Dominion University Norfolk VA USA
| | - Erica J. Roelofs
- School of KinesiologyUniversity of Minnesota Twin Cities Minneapolis MN USA
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Sterczala AJ, Miller JD, Dimmick HL, Wray ME, Trevino MA, Herda TJ. Eight weeks of resistance training increases strength, muscle cross-sectional area and motor unit size, but does not alter firing rates in the vastus lateralis. Eur J Appl Physiol 2019; 120:281-294. [DOI: 10.1007/s00421-019-04273-9] [Citation(s) in RCA: 17] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/30/2019] [Accepted: 11/23/2019] [Indexed: 12/11/2022]
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Harmon KK, Girts RM, MacLennan RJ, Stock MS. Is the motor unit mean firing rate versus recruitment threshold relationship linear? Physiol Meas 2019; 40:095002. [PMID: 31470424 DOI: 10.1088/1361-6579/ab4025] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Abstract
Advances in surface electromyographic (EMG) signal decomposition allow researchers to analyze data for 20-50 motor units per contraction. To simplify interpretation, some investigators rely on group mean analysis of the mean firing rate versus recruitment threshold relationship, but it is unclear if this association is linear. OBJECTIVE To determine whether this relationship is strongest when analyzed via linear, quadratic, or cubic regression. APPROACH Twenty-one men (mean ± SD age = 24 ± 4 years) and 16 women (21 ± 2 years) performed isometric contractions of the knee extensors at 50% of maximal force while bipolar surface EMG signals were recorded from the vastus lateralis. A decomposition algorithm was used to calculate the mean firing rate and recruitment threshold of each motor unit at accuracy levels ranging from 90.0%-93.0%. Polynominal regression was used to determine if each relationship was best fit with a linear, quadratic, or cubic model. We examined individual contractions and grouped data. MAIN RESULTS Overall, 80% of the relationships were best fit with a linear model. Quadratic and cubic relationships were more appropriate for 16% and 2% of the contractions, respectively. Selecting varying accuracy levels within a range of 90.0%-93.0% had little influence on whether a given dataset was best fit with a linear, quadratic, or cubic model. Grouping of data provided different relationships than otherwise found on a contraction-by-contraction basis. SIGNIFICANCE The mean firing rate versus recruitment threshold relationship is typically best fit with a linear model. These relationships should be examined on an individual contraction basis.
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Affiliation(s)
- Kylie K Harmon
- Neuromuscular Plasticity Laboratory, School of Kinesiology and Physical Therapy, University of Central Florida, 12354 Research Parkway, Orlando, FL, 32826, United States of America
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Laurin JL, Reid JJ, Lawrence MM, Miller BF. Long-term aerobic exercise preserves muscle mass and function with age. CURRENT OPINION IN PHYSIOLOGY 2019. [DOI: 10.1016/j.cophys.2019.04.019] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
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Muscular strength and power are correlated with motor unit action potential amplitudes, but not myosin heavy chain isoforms in sedentary males and females. J Biomech 2019; 86:251-255. [DOI: 10.1016/j.jbiomech.2019.01.050] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/04/2018] [Revised: 01/11/2019] [Accepted: 01/30/2019] [Indexed: 12/26/2022]
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Colquhoun RJ, Tomko PM, Magrini MA, Muddle TWD, Jenkins NDM. The influence of input excitation on the inter- and intra-day reliability of the motor unit firing rate versus recruitment threshold relationship. J Neurophysiol 2018; 120:3131-3139. [PMID: 30355024 DOI: 10.1152/jn.00490.2018] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022] Open
Abstract
Decomposition of the surface electromyographic (sEMG) signal is commonly used to examine motor unit (MU) firing behavior. However, the intra- and inter-day reliability of these measurements has yet to be quantified or reported. This investigation 1) examined the effect of input excitation on the mean firing rate (MFR) vs. recruitment threshold (RT) relationship and 2) determined the inter- and intra-day reliability of the MFR vs. RT relationship at 30%, 50%, and 70% of maximum voluntary isometric strength (MVIC). Twenty-eight healthy males (23 ± 3 yr) completed two experimental visits, during which they performed MVIC testing and isometric ramp contractions at 30%, 50%, and 70% MVIC. sEMG signals were recorded from the vastus lateralis during the ramp contractions and decomposed to establish the MFR vs. RT relationship for the detected MUs. Intra- and inter-day reliability was then established for the slopes and y-intercepts of the MFR vs. RT relationship at each contraction intensity. All participants displayed significant MFR vs. RT relationships ( r range: -0.662 to -0.999; P ≤ 0.001-0.006). Intra- and inter-day intraclass correlation coefficients (ICCs) ranged from 0.766-0.824 and 0.867-0.919 for the slopes and from 0.780-0.915 and 0.804-0.927 for the y-intercepts, respectively. Furthermore, the slope coefficient was significantly greater at 70% than at 30% MVIC, and the y-intercepts increased with increasing contraction intensities. Changes in input excitation to the MU pool alter the magnitude, but not the reliability, of the slopes and y-intercepts of the MFR vs. RT relationship. NEW & NOTEWORTHY The firing behavior of the motor unit (MU) pool is often characterized using the mean firing rate vs. recruitment threshold relationship of the active MUs. Although this relationship has been widely used, this is the first study to report the effects of input excitation (contraction intensity) on the intra- and inter-day reliability of this relationship. The criteria used for MU analysis and the model utilized in this study allow for generalization to outside investigators and laboratories.
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Affiliation(s)
- Ryan J Colquhoun
- Applied Neuromuscular Physiology Laboratory, Oklahoma State University , Stillwater, Oklahoma
| | - Patrick M Tomko
- Applied Neuromuscular Physiology Laboratory, Oklahoma State University , Stillwater, Oklahoma
| | - Mitchel A Magrini
- Applied Neuromuscular Physiology Laboratory, Oklahoma State University , Stillwater, Oklahoma
| | - Tyler W D Muddle
- Applied Neuromuscular Physiology Laboratory, Oklahoma State University , Stillwater, Oklahoma
| | - Nathaniel D M Jenkins
- Applied Neuromuscular Physiology Laboratory, Oklahoma State University , Stillwater, Oklahoma
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