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Hirono T, Okudaira M, Takeda R, Ueda S, Nishikawa T, Igawa K, Kunugi S, Yoshimura A, Watanabe K. Association between physical fitness tests and neuromuscular properties. Eur J Appl Physiol 2024; 124:1703-1717. [PMID: 38193907 DOI: 10.1007/s00421-023-05394-y] [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: 07/12/2023] [Accepted: 12/07/2023] [Indexed: 01/10/2024]
Abstract
PURPOSE While various fitness tests have been developed to assess physical performances, it is unclear how these tests are affected by differences, such as, in morphological and neural factors. This study was aimed to investigate associations between individual differences in physical fitness tests and neuromuscular properties. METHODS One hundred and thirty-three young adults participated in various general physical fitness tests and neuromuscular measurements. The appendicular skeletal muscle mass (ASM) was estimated by bioelectrical impedance analysis. Echo intensity (EI) was evaluated from the vastus lateralis. During submaximal knee extension force, high-density surface electromyography of the vastus lateralis was recorded and individual motor unit firings were detected. Y-intercept (i-MU) and slope (s-MU) from the regression line between the recruitment threshold and motor unit firing rate were calculated. RESULTS Stepwise multiple regression analyses revealed that knee extension strength could be explained (adjusted R2 = 0.712) by ASM (β = 0.723), i-MU (0.317), EI (- 0.177), and s-MU (0.210). Five-sec stepping could be explained by ASM (adjusted R2 = 0.212). Grip strength, side-stepping, and standing broad jump could be explained by ASM and echo intensity (adjusted R2 = 0.686, 0.354, and 0.627, respectively). Squat jump could be explained by EI (adjusted R2 = 0.640). Counter-movement jump could be explained by EI and s-MU (adjusted R2 = 0.631). On the other hand, i-MU and s-MU could be explained by five-sec stepping and counter-movement jump, respectively, but the coefficients of determination were low (adjusted R2 = 0.100 and 0.045). CONCLUSION Generally developed physical fitness tests were mainly explained by morphological factors, but were weakly affected by neural factors involved in performance.
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Affiliation(s)
- Tetsuya Hirono
- Laboratory of Neuromuscular Biomechanics, School of Health and Sport Science, Chukyo University, 101 Tokodachi, Kaizu-cho, Toyota, Aichi, 470-0393, Japan.
- Human Health Sciences, Graduate School of Medicine, Kyoto University, Kyoto, Japan.
| | - Masamichi Okudaira
- Laboratory of Neuromuscular Biomechanics, School of Health and Sport Science, Chukyo University, 101 Tokodachi, Kaizu-cho, Toyota, Aichi, 470-0393, Japan
- Faculty of Education, Iwate University, Morioka, Japan
| | - Ryosuke Takeda
- Laboratory of Neuromuscular Biomechanics, School of Health and Sport Science, Chukyo University, 101 Tokodachi, Kaizu-cho, Toyota, Aichi, 470-0393, Japan
| | - Saeko Ueda
- Department of Human Nutrition, School of Life Studies, Sugiyama Jogakuen University, Nagoya, Japan
| | - Taichi Nishikawa
- Laboratory of Neuromuscular Biomechanics, School of Health and Sport Science, Chukyo University, 101 Tokodachi, Kaizu-cho, Toyota, Aichi, 470-0393, Japan
| | - Kaito Igawa
- Laboratory of Neuromuscular Biomechanics, School of Health and Sport Science, Chukyo University, 101 Tokodachi, Kaizu-cho, Toyota, Aichi, 470-0393, Japan
| | - Shun Kunugi
- Laboratory of Neuromuscular Biomechanics, School of Health and Sport Science, Chukyo University, 101 Tokodachi, Kaizu-cho, Toyota, Aichi, 470-0393, Japan
- Center for General Education, Aichi Institute of Technology, Toyota, Japan
| | - Akane Yoshimura
- Laboratory of Neuromuscular Biomechanics, School of Health and Sport Science, Chukyo University, 101 Tokodachi, Kaizu-cho, Toyota, Aichi, 470-0393, Japan
- Faculty of Education and Integrated Arts and Sciences, Waseda University, Tokyo, Japan
| | - Kohei Watanabe
- Laboratory of Neuromuscular Biomechanics, School of Health and Sport Science, Chukyo University, 101 Tokodachi, Kaizu-cho, Toyota, Aichi, 470-0393, Japan
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Herda TJ, Holmes EA, Cleary CJ, Minor KT, Thyfault JP, Shook RP, Herda AA. Motor unit firing rates increase in prepubescent youth following linear periodization resistance exercise training. Eur J Appl Physiol 2024:10.1007/s00421-024-05455-w. [PMID: 38634901 DOI: 10.1007/s00421-024-05455-w] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/11/2023] [Accepted: 02/29/2024] [Indexed: 04/19/2024]
Abstract
PURPOSE The purpose was to examine the effects of 8-weeks (3 days/week) of linear periodization resistance exercise training (RET) on neuromuscular function in prepubescent youth. METHODS Twenty-five healthy prepubescent youth (11 males, 14 females, age = 9.1 ± 0.8 years) completed the RET (n = 17) or served as controls (CON, n = 8). Isometric maximal voluntary contractions (MVCs) and trapezoidal submaximal contractions at 35 and 60% MVC of the right leg extensors were performed with surface electromyography (EMG) recorded from the leg extensors [vastus lateralis (VL), rectus femoris, and vastus medialis] and flexors (biceps femoris and semitendinosus). EMG amplitude of the leg extensors and flexors were calculated during the MVCs. Motor unit (MU) action potential trains were decomposed from the surface EMG of the VL for the 35 and 60% MVCs. MU firing rates and action potential amplitudes were regressed against recruitment threshold with the y-intercepts and slopes calculated for each contraction. Total leg extensor muscle cross-sectional area (CSA) was collected using ultrasound images. ANOVA models were used to examine potential differences. RESULTS Isometric strength increased post-RET (P = 0.006) with no changes in leg extensor and flexor EMG amplitude. Furthermore, there were no changes in total CSA or the MU action potential amplitude vs. recruitment threshold relationships. However, there were increases in the firing rates of the higher-threshold MUs post-RET as indicated with greater y-intercepts (P = 0.003) from the 60% MVC and less negative slope (P = 0.004) of the firing rates vs. recruitment threshold relationships at 35% MVC. CONCLUSIONS MU adaptations contribute to strength increases following RET in prepubescent youth.
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Affiliation(s)
- Trent J Herda
- Department of Health, Sport, and Exercise Science, University of Kansas, 1301 Sunnyside Avenue, Room 101BE, Lawrence, 66045, KS, USA.
- Center for Children's Healthy Lifestyle and Nutrition, Kansas City, MO, USA.
| | - Elizabeth A Holmes
- Department of Health, Sport, and Exercise Science, University of Kansas, 1301 Sunnyside Avenue, Room 101BE, Lawrence, 66045, KS, USA
| | - Christopher J Cleary
- Department of Health, Sport, and Exercise Science, University of Kansas-Edwards Campus, Overland Park, KS, USA
| | - Kelsey T Minor
- Department of Health, Sport, and Exercise Science, University of Kansas, 1301 Sunnyside Avenue, Room 101BE, Lawrence, 66045, KS, USA
| | - John P Thyfault
- Department of Cell Biology and Physiology and Internal Medicine, University of Kansas Medical Center, Kansas City, KS, USA
- Center for Children's Healthy Lifestyle and Nutrition, Kansas City, MO, USA
| | - Robin P Shook
- Department of Pediatrics, Children's Mercy Hospital, Kansas City, MO, USA
- Center for Children's Healthy Lifestyle and Nutrition, Kansas City, MO, USA
| | - Ashley A Herda
- Department of Health, Sport, and Exercise Science, University of Kansas-Edwards Campus, Overland Park, KS, USA
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Beausejour JP, Bohlen P, Harmon KK, Girts RM, Pagan JI, Hahs-Vaughn DL, Herda TJ, Stock MS. A comparison of techniques for verifying the accuracy of precision decomposition-derived relationships between motor unit firing rates and recruitment thresholds from surface EMG signals. Exp Brain Res 2023; 241:2547-2560. [PMID: 37707570 DOI: 10.1007/s00221-023-06694-7] [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: 03/15/2023] [Accepted: 08/21/2023] [Indexed: 09/15/2023]
Abstract
Approaches for validating motor unit firing times following surface electromyographic (EMG) signal decomposition with the precision decomposition III (PDIII) algorithm have not been agreed upon. Two approaches have been common: (1) "reconstruct-and-test" and (2) spike-triggered averaging (STA). We sought to compare motor unit results following the application of these approaches. Surface EMG signals were recorded from the vastus lateralis of 13 young males performing trapezoidal, isometric knee extensions at 50% and 80% of maximum voluntary contraction (MVC) force. The PDIII algorithm was used to quantify motor unit firing rates. Motor units were excluded using eight combinations of the reconstruct-and-test approach with accuracy thresholds of 0, 90, 91, and 92% with and without STA. The mean firing rate versus recruitment threshold relationship was minimally affected by STA. At 80% MVC, slopes acquired at the 0% accuracy threshold were significantly greater (i.e., less negative) than when 91% (p = .010) and 92% (p = .030) accuracy thresholds were applied. The application of STA has minimal influence on surface EMG signal decomposition results. Stringent reconstruct-and-test accuracy thresholds influence motor unit-derived relationships at high forces, perhaps explained through the increased presence of large motor unit action potentials. Investigators using the PDIII algorithm can expect negligible changes in motor unit-derived linear regression relationships with the application of secondary validation procedures.
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Affiliation(s)
- Jonathan P Beausejour
- Neuromuscular Plasticity Laboratory, Institute of Exercise Physiology and Rehabilitation Science, University of Central Florida, 4000 Central Florida Blvd, Orlando, FL, 32816-2205, USA
- School of Kinesiology and Rehabilitation Sciences, University of Central Florida, Orlando, FL, USA
| | - Paul Bohlen
- Neuromuscular Plasticity Laboratory, Institute of Exercise Physiology and Rehabilitation Science, University of Central Florida, 4000 Central Florida Blvd, Orlando, FL, 32816-2205, USA
- School of Kinesiology and Rehabilitation Sciences, University of Central Florida, Orlando, FL, USA
| | - Kylie K Harmon
- Department of Exercise Science, Syracuse University, Syracuse, NY, USA
| | - Ryan M Girts
- Department of Natural and Health Sciences, Pfeiffer University, Misenheimer, NC, USA
| | - Jason I Pagan
- Neuromuscular Plasticity Laboratory, Institute of Exercise Physiology and Rehabilitation Science, University of Central Florida, 4000 Central Florida Blvd, Orlando, FL, 32816-2205, USA
- School of Kinesiology and Rehabilitation Sciences, University of Central Florida, Orlando, FL, USA
| | - Debbie L Hahs-Vaughn
- College of Community Innovation and Education, University of Central Florida, Orlando, FL, USA
| | - Trent J Herda
- Neuromechanics Laboratory, Department of Health, Sport and Exercise Sciences, University of Kansas, Lawrence, USA
| | - Matt S Stock
- Neuromuscular Plasticity Laboratory, Institute of Exercise Physiology and Rehabilitation Science, University of Central Florida, 4000 Central Florida Blvd, Orlando, FL, 32816-2205, USA.
- School of Kinesiology and Rehabilitation Sciences, University of Central Florida, Orlando, FL, USA.
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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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Watanabe K, Yoshimura A, Holobar A, Yamashita D, Kunugi S, Hirono T. Neuromuscular characteristics of front and back legs in junior fencers. Exp Brain Res 2022; 240:2085-2096. [PMID: 35771284 PMCID: PMC9288367 DOI: 10.1007/s00221-022-06403-w] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/20/2022] [Accepted: 06/16/2022] [Indexed: 11/19/2022]
Abstract
In elite fencers, muscle strength and muscle mass of the front leg (FL) are greater than those of the back leg (BL) due to characteristic physiological and biomechanical demands placed on each leg during fencing. However, the development of laterality in their neural and muscular components is not well-understood. The present study investigated neuromuscular characteristics of FL and BL in junior fencers. Nineteen junior fencers performed neuromuscular performance tests for FL and BL, separately. There were no significant differences in the isometric knee extension strength (MVC), unilateral vertical jump (UVJ), vastus lateralis muscle thickness (MT), or motor unit firing rate of the vastus lateralis muscle (MUFR) between FL and BL (p > 0.05). In subgroup analyses, a significantly greater MUFR in FL than BL was noted only in fencers with > 3 years of fencing experience, and significantly greater UVJ in FL than BL was observed solely in fencers with < 3 years of fencing experience (p < 0.05). Strong positive correlations between FL and BL were identified in MVC, MT, and MUFR in fencers with > 3 years of fencing experience, but not in those with < 3 years of experience. These findings suggest that in junior fencers, laterality in neuromuscular performance has not manifested, whereas longer fencing experience induces fencing-dependent laterality in neural components, and laterality in dynamic muscle strength is decreased with fencing experience.
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Affiliation(s)
- Kohei Watanabe
- Laboratory of Neuromuscular Biomechanics, School of Health and Sport Sciences, Chukyo University, Tokodachi, Kaizu-cho, Toyota, 470-0093, Japan.
| | - Akane Yoshimura
- Laboratory of Neuromuscular Biomechanics, School of Health and Sport Sciences, Chukyo University, Tokodachi, Kaizu-cho, Toyota, 470-0093, Japan. .,Faculty of Education and Integrated Arts and Sciences, Waseda University, Tokyo, Japan.
| | - Aleš Holobar
- Faculty of Electrical Engineering and Computer Science, University of Maribor, Maribor, Slovenia
| | - Daichi Yamashita
- Department of Sport Science, Japan Institute of Sport Sciences, Kita-ku, Tokyo, Japan
| | - Shun Kunugi
- Laboratory of Neuromuscular Biomechanics, School of Health and Sport Sciences, Chukyo University, Tokodachi, Kaizu-cho, Toyota, 470-0093, Japan.,Center for General Education, Aichi Institute of Technology, Toyota, Japan
| | - Tetsuya Hirono
- Laboratory of Neuromuscular Biomechanics, School of Health and Sport Sciences, Chukyo University, Tokodachi, Kaizu-cho, Toyota, 470-0093, Japan.,Research Fellow of Japan Society for the Promotion of Science, Tokyo, Japan
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Resistance exercise training and the motor unit. Eur J Appl Physiol 2022; 122:2019-2035. [PMID: 35751668 DOI: 10.1007/s00421-022-04983-7] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2022] [Accepted: 06/06/2022] [Indexed: 11/03/2022]
Abstract
Resistance exercise training (RET) is a key modality to enhance sports performance, injury prevention and rehabilitation, and improving overall health via increases in muscular strength. Yet, the contribution of neural mechanisms to increases in muscular strength are highly debated. This is particularly true for the involvement of the motor unit, which is the link between neural (activation) and mechanical (muscle fiber twitch forces) mechanisms. A plethora of literature that examines the effects of RET on skeletal muscle speculate the role of motor units, such as increases in firing rates partially explains muscular strength gains. Results, however, are mixed regarding changes in firing rates in studies that utilize single motor unit recordings. The lack of clarity could be related to vast or subtle differences in RET programs, methods to record motor units, muscles tested, types of contractions and intensities used to record motor units, etc. Yet to be discussed, mixed findings could be the result of non-uniform MU behavior that is not typically accounted for in RET research. The purpose of this narration is to discuss the effects of acute resistance exercise training studies on MU behavior and to provide guidance for future research.
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Reece TM, Arnold CE, Herda TJ. An examination of motor unit firing rates during steady torque of maximal efforts with either an explosive or slower rate of torque development. Exp Physiol 2021; 106:2517-2530. [PMID: 34676609 DOI: 10.1113/ep089808] [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: 06/03/2021] [Accepted: 10/11/2021] [Indexed: 12/29/2022]
Abstract
NEW FINDINGS What is the central question of this study? The aim was to explore agonist and antagonist motor unit firing rates during maximal efforts performed with either an explosive or a slower rate of torque development. What is the main finding and its importance? The antagonist muscle presented a motor unit firing rate relationship similar to the agonist muscle. Additionally, the motor units of both muscles exhibited higher firing rates during explosive maximal contractions than during maximal contractions performed at a slower rate of torque development. These results could prove useful to future research analysing the effects of age, disease, resistance training and/or fatigue-related alterations to motor unit firing rates. ABSTRACT The primary purpose of the present study was to examine motor unit (MU) firing rates in agonist and antagonist muscles during periods of steady, maximal efforts using explosive and slower rates of torque development. A secondary purpose was to analyse the MU firing rate versus action potential amplitude relationships of the agonist and antagonist muscles during maximal efforts. Thirteen subjects (mean ± SD; age, 21.2 ± 3.6 years; mass 81.1 ± 21.3 kg; and stature, 177.1±9.9 cm) performed two maximal isometric trapezoid muscle actions of the elbow flexors that included either an explosive or a slower, linearly increasing rate (ramp) of torque development. Surface EMG signals of the biceps brachii (BB) and triceps brachii (TB) muscles were collected and decomposed into their constituent MU action potential trains. The MU firing rate versus action potential amplitude relationships of the BB (agonist) and TB (antagonist) muscles were analysed. Moderate to strong relationships (|r| ≥ 0.65) were present for the explosive and ramp contractions in the agonist and antagonist muscles. Firing rates of smaller and larger MUs were higher during the explosive [mean ± SD; agonist = 18.1 ± 6.9 pulses per second (pps), antagonist = 22.0±3.9 pps] than the ramp (agonist = 14.0 ± 5.1 pps, antagonist = 18.3 ± 4.4 pps) contractions for the agonist (P = 0.013) and antagonist muscles (P = 0.007). The antagonist muscle exhibits a similar MU firing rate versus action potential amplitude relationship to the agonist muscle at maximal efforts. Future research should investigate the effects of short-term resistance training on antagonist firing rates and the involvement of peripheral feedback on firing rates during maximal efforts performed at various rates of torque development.
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Affiliation(s)
- Tanner M Reece
- Neuromechanics Laboratory, Department of Health, Sport and Exercise Sciences, University of Kansas, Lawrence, Kansas, USA
| | - Catherine E Arnold
- Neuromechanics Laboratory, Department of Health, Sport and Exercise Sciences, University of Kansas, Lawrence, Kansas, USA
| | - Trent J Herda
- Neuromechanics Laboratory, Department of Health, Sport and Exercise Sciences, University of Kansas, Lawrence, Kansas, USA
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