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.
摘要：
本研究旨在阐明6至12岁儿童的运动单位（MU）放电特性的发展以及这些神经特性与力稳定性（FS）/神经系统测试之间的关联。58名学龄儿童进行了最大的自愿膝关节伸展收缩，在最大自愿性膝关节伸展收缩的10％时进行次最大FS测试，对光线刺激测试的膝盖伸展反应时间，和单腿站立测试，对38名通过标准的儿童的数据进行分析.在FS测试期间，从股外侧肌记录高密度表面肌电图，以确定单个MU放电活动。FS随着年龄的增加而改善（r=-.540，P<.001）。MU放电率（MUFR）随着年龄的增加而显着降低（r=-.343，P=.035）。MUFR变异性与年龄无关。尽管FS和MUFR之间没有显著的相关性,即使调整了年龄的影响，FS也与MUFR变异性显着相关（r=.551，P=.002）。反应时间和单腿站立测试均不与任何MU点火性能相关。这些发现表明，MUFR变异性对儿童的精确力控制做出了重要贡献，但不会随着年龄的增长而自然发展。
