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Hirono T, Takeda R, Nishikawa T, Watanabe K. Prediction of 1-year change in knee extension strength by neuromuscular properties in older adults. GeroScience 2024; 46:2561-2569. [PMID: 38093024 PMCID: PMC10828468 DOI: 10.1007/s11357-023-01035-6] [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: 10/23/2023] [Accepted: 12/04/2023] [Indexed: 02/01/2024] Open
Abstract
Improving muscle strength and preventing muscle weakness are important for older adults. The change in strength can be effectively explained by skeletal muscle mass and neural factors. Neural factors are important for older adults because the variation of neural components is greater in older than in young adults, and any decline in strength cannot solely be explained by a decrease in skeletal muscle mass. The purpose of the present study was to investigate whether skeletal muscle mass or motor unit firing properties could explain the change in muscle strength after 1 year. Thirty-eight older adults (75.0 ± 4.7 years, 156.6 ± 7.7 cm, 55.5 ± 9.4 kg, 26 women) performed maximum voluntary knee extension and their skeletal muscle mass was measured using a bioimpedance device. During a submaximal contraction task, high-density surface electromyography was recorded and the signals were decomposed into individual motor unit firing. As an index of motor unit firing properties, the slope and y-intercept (MU intercept) were calculated from the regression line between recruitment thresholds and firing rates in each participant. After 1 year, their maximum knee extension torque was evaluated again. A stepwise multiple regression linear model with sex and age as covariates indicated that MU intercept was a significant explanation with a negative association for the 1-year change in muscle strength (β = - 0.493, p = 0.004), but not skeletal muscle mass (p = 0.364). The results suggest that neural components might be predictors of increasing and decreasing muscle strength rather than skeletal muscle mass.
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Affiliation(s)
- Tetsuya Hirono
- Laboratory of Neuromuscular Biomechanics, School of Health and Sport Sciences, Chukyo University, 101 Tokodachi, Kaizu-Cho, Toyota, Aichi, Japan.
- Human Health Sciences, Graduate School of Medicine, Kyoto University, 53 Kawahara-Cho, Shogoin, Sakyo-Ku, Kyoto, Japan.
| | - Ryosuke Takeda
- Laboratory of Neuromuscular Biomechanics, School of Health and Sport Sciences, Chukyo University, 101 Tokodachi, Kaizu-Cho, Toyota, Aichi, Japan
| | - Taichi Nishikawa
- Laboratory of Neuromuscular Biomechanics, School of Health and Sport Sciences, Chukyo University, 101 Tokodachi, Kaizu-Cho, Toyota, Aichi, Japan
- Graduate School of Health and Sport Sciences, Chukyo University, 101 Tokodachi, Kaizu-Cho, Toyota, Aichi, Japan
| | - Kohei Watanabe
- Laboratory of Neuromuscular Biomechanics, School of Health and Sport Sciences, Chukyo University, 101 Tokodachi, Kaizu-Cho, Toyota, Aichi, Japan
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Okudaira M, Takeda R, Hirono T, Nishikawa T, Kunugi S, Watanabe K. Motor Unit Firing Properties During Force Control Task and Associations With Neurological Tests in Children. Pediatr Exerc Sci 2024; 36:23-29. [PMID: 37553109 DOI: 10.1123/pes.2023-0002] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/09/2023] [Revised: 03/14/2023] [Accepted: 05/11/2023] [Indexed: 08/10/2023]
Abstract
The present study aimed to clarify the development of motor unit (MU) firing properties and the association between those neural properties and force steadiness (FS)/neurological tests in 6- to 12-year-old children. Fifty-eight school-aged children performed maximal voluntary knee extension contraction, a submaximal FS test at 10% of maximal voluntary knee extension contraction, knee extension reaction time to light stimulus test, and single-leg standing test, and data from 38 children who passed the criteria were subject to analysis. During the FS test, high-density surface electromyography was recorded from the vastus lateralis muscle to identify individual MU firing activity. FS was improved with an increase in age (r = -.540, P < .001). The MU firing rate (MUFR) was significantly decreased with an increase in age (r = -.343, P = .035). MUFR variability was not associated with age. Although there was no significant correlation between FS and MUFR, FS was significantly correlated with MUFR variability even after adjustment for the effect of age (r = .551, P = .002). Neither the reaction time nor the single-leg standing test was correlated with any MU firing properties. These findings suggest that MUFR variability makes an important contribution to precise force control in children but does not naturally develop with age.
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Affiliation(s)
- Masamichi Okudaira
- Laboratory of Neuromuscular Biomechanics, School of Health and Sport Sciences, Chukyo University, Toyota,Japan
- Faculty of Education, Iwate University, Morioka,Japan
| | - Ryosuke Takeda
- Laboratory of Neuromuscular Biomechanics, School of Health and Sport Sciences, Chukyo University, Toyota,Japan
| | - Tetsuya Hirono
- Laboratory of Neuromuscular Biomechanics, School of Health and Sport Sciences, Chukyo University, Toyota,Japan
- Japan Society for the Promotion of Science, Tokyo,Japan
| | - Taichi Nishikawa
- Graduate School of Health and Sport Sciences, Chukyo University, Toyota,Japan
| | - Shun Kunugi
- Center for General Education, Aichi Institute of Technology, Toyota,Japan
| | - Kohei Watanabe
- Laboratory of Neuromuscular Biomechanics, School of Health and Sport Sciences, Chukyo University, Toyota,Japan
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Mickevicius M, Satkunskiene D, Sipaviciene S, Kamandulis S. Riding a Mechanical Scooter from the Inconvenient Side Promotes Muscular Balance Development in Children. CHILDREN (BASEL, SWITZERLAND) 2023; 10:1064. [PMID: 37371295 DOI: 10.3390/children10061064] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/17/2023] [Revised: 06/09/2023] [Accepted: 06/13/2023] [Indexed: 06/29/2023]
Abstract
Mechanical scooter riding is a popular physical activity among children, but little is known about the differences in muscle loading between the dominant and non-dominant sides during this activity. The objective of this study was to identify the muscle activation patterns in children's dominant and non-dominant legs as they rode scooters on the convenient and inconvenient sides. The study included nine healthy children aged 6-8. The participants rode 20 m on a mechanical scooter at a self-selected pace using both the convenient and inconvenient sides. Electromyography was used to measure the muscle activity in the dominant and non-dominant legs during the pushing and gliding phases. A 20 m sprint run was used as a control exercise to estimate the typical differences in muscle activation between the dominant and non-dominant legs. In the pushing phase, the symmetry index for five of the eight analyzed muscles exceeded 50% (p < 0.05); four of these muscles were more active in the pushing leg, and one was more active in the standing leg. In the gliding phase, four muscles were more active in the standing leg, and one was more active in the pushing leg (p < 0.05). Upon observing children who changed sides while riding a scooter, it was found that the pattern of muscle activation displayed a reverse trend that resembled the initial pattern. Our study indicated notable differences in muscle activity patterns between the dominant and non-dominant sides of individual leg muscles during children's scooter riding. These patterns were reversed when children switched sides on the scooter. These findings suggest that using both legs and switching sides while riding a scooter may be a viable strategy for promoting balanced muscular development.
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Affiliation(s)
- Mantas Mickevicius
- Institute of Sports Science and Innovations, Lithuanian Sports University, 44221 Kaunas, Lithuania
| | - Danguole Satkunskiene
- Institute of Sports Science and Innovations, Lithuanian Sports University, 44221 Kaunas, Lithuania
| | - Saule Sipaviciene
- Department of Health Promotion and Rehabilitation, Lithuanian Sports University, 44221 Kaunas, Lithuania
| | - Sigitas Kamandulis
- Institute of Sports Science and Innovations, Lithuanian Sports University, 44221 Kaunas, Lithuania
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Okudaira M, Hirono T, Takeda R, Nishikawa T, Ueda S, Mita Y, Holobar A, Yoshimura A, Watanabe K. Longitudinal development of muscle strength and relationship with motor unit activity and muscle morphological characteristics in youth athletes. Exp Brain Res 2023; 241:1009-1019. [PMID: 36905448 DOI: 10.1007/s00221-023-06590-0] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/13/2022] [Accepted: 02/28/2023] [Indexed: 03/12/2023]
Abstract
Neural and morphological adaptations determine gains of muscle strength. For youth athletes, the importance of morphological adaptation is typically highlighted based on the change in maturity status. However, the long-term development of neural components in youth athletes remains unclear. The present study investigated the longitudinal development of muscle strength, muscle thickness (MT), and motor unit firing activity of the knee extensor and their relationships in youth athletes. Seventy male youth soccer players (mean ± SD age = 16.3 ± 0.6 years) performed neuromuscular, maximal voluntary isometric contraction (MVC), and submaximal ramp contraction (at 30 and 50% MVC) tests with knee extensors, two times with a 10-month measurement interval. High-density surface electromyography was recorded from the vastus lateralis and decomposed to identify each individual motor unit activity. MT was evaluated by the sum of the vastus lateralis and vastus intermedius thicknesses. Finally, sixty-four participants were employed to compare MVC and MT, and 26 participants were employed to analyze motor unit activity. MVC and MT were increased from pre to post (p < 0.05, 6.9 and 1.7% for MVC and MT, respectively). Y-intercept of the regression line between median firing rate vs. recruitment threshold was also increased (p < 0.05, 13.3%). Multiple regression analysis demonstrated that the gains of both MT and Y-intercept were explanatory variables for the gain of strength. These findings suggest that the neural adaptation could also make the important contribution to the strength gain for the youth athletes over a 10-month training period.
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Affiliation(s)
- Masamichi Okudaira
- Laboratory of Neuromuscular Biomechanics, School of Health and Sport Sciences, Chukyo University, 101, Tokodachi, Kaizu, Toyota, 470-0393, Japan.
| | - Tetsuya Hirono
- Laboratory of Neuromuscular Biomechanics, School of Health and Sport Sciences, Chukyo University, 101, Tokodachi, Kaizu, Toyota, 470-0393, Japan.,Japan Society for the Promotion of Science, Toyota, Japan
| | - Ryosuke Takeda
- Laboratory of Neuromuscular Biomechanics, School of Health and Sport Sciences, Chukyo University, 101, Tokodachi, Kaizu, Toyota, 470-0393, Japan
| | - Taichi Nishikawa
- Laboratory of Neuromuscular Biomechanics, School of Health and Sport Sciences, Chukyo University, 101, Tokodachi, Kaizu, Toyota, 470-0393, Japan.,Graduate School of Health and Sport Sciences, Chukyo University, Toyota, Japan
| | - Saeko Ueda
- Graduate School of Life Studies, Sugiyama Jogakuen University, Nagoya, Japan
| | - Yukiko Mita
- Graduate School of Life Studies, Sugiyama Jogakuen University, Nagoya, Japan
| | - Aleš Holobar
- Faculty of Electrical Engineering and Computer Science, University of Maribor, Maribor, Slovenia
| | - Akane Yoshimura
- Faculty of Education and Integrated Arts and Sciences, Waseda University, Tokyo, Japan
| | - Kohei Watanabe
- Laboratory of Neuromuscular Biomechanics, School of Health and Sport Sciences, Chukyo University, 101, Tokodachi, Kaizu, Toyota, 470-0393, Japan
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