Laboratory of Neuromuscular Biomechanics, School of Health and Sport Sciences, Chukyo University, Toyota,Japan.
Faculty of Education, Iwate University, Morioka,Japan.
Pediatr Exerc Sci. 2023 Aug 8;36(1):23-29. doi: 10.1123/pes.2023-0002. Print 2024 Feb 1.
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.
本研究旨在阐明运动单位（MU）放电特性的发展，以及这些神经特性与力量稳定性（FS）/神经学测试之间的关系，研究对象为 6 至 12 岁的儿童。58 名学龄儿童进行了最大自主膝关节伸展收缩、最大自主膝关节伸展收缩的 10%的亚最大 FS 测试、膝关节伸展对光刺激反应时间测试和单腿站立测试，符合标准的 38 名儿童的数据被纳入分析。在 FS 测试中，从股外侧肌记录高密度表面肌电图以识别个体 MU 放电活动。FS 随年龄的增长而提高（r = -.540，P <.001）。MU 放电率（MUFR）随年龄的增长而显著降低（r = -.343，P =.035）。MUFR 变异性与年龄无关。尽管 FS 与 MUFR 之间没有显著相关性，但在调整年龄影响后，FS 与 MUFR 变异性显著相关（r =.551，P =.002）。反应时间和单腿站立测试与任何 MU 放电特性均无相关性。这些发现表明，MUFR 变异性对儿童精确力量控制有重要贡献，但不会随着年龄自然发展。
