Development of motor programming capacity during lifting a task with a precision grip in infants

这项研究调查了婴儿(N=49，年龄=10个月-6岁)在使用精密握把举起不同物体重量时产生程序化等长力的能力。记录握力、垂直提升力和物体的垂直位置。受试者在5天内每天举起不同重量(200g和400g)的物体20-30次。对象权重以随机方式改变。研究发现，在第一天的数据中，与成人相比，年龄在5岁以下的儿童在任务排序上明显缓慢，而且他们的握力更高。0岁和1岁婴儿的握力比(DGF/DT)曲线呈多峰型，而2岁婴儿则呈单峰型。5岁以下婴幼儿握力、提升力耦合作用差。对于第5天的数据，也发现与第1天的数据相似，但与第1天的结果相比，运动时间和力量大小的表现都有改善，特别是2-4岁的婴儿。在体重意外变化的数据中，检查了运动编程能力与物体重量的关系。研究发现，随着婴儿年龄的增长，意外体重变化的影响更加明显；随着婴儿年龄的增加，时间和力量大小的修正表现出更长的时间和力量大小的修正。经过五天的举重练习，即使是10个月大的婴儿，意外体重变化的影响也变得更加明显。在2-4岁的婴儿中，改善相当明显，这表明这些时期在获得编程能力方面很重要。

This study investigated the capacity to generate programmed isometric forces in infants (N = 49, age = 10 month old - 6 years) during lifting varied object weights using a precision grip. Grip force and the vertical lifting force, and vertical position of the object were recorded. The subjects lifted the object of varied weights (200 g and 400 g) 20 - 30 times per day over 5 days. Object weight was changed in a random manner. It was found that for the 1st day data regardless of the object weight younger children below 5 years compared to adults were significantly slow in sequencing the task, and their grip forces were higher. Grip force rate (dGF/dt) curves in 0 and 1 year old infants contained multiple peaks, while the curves with a unimodal peak were revealed from 2 year old infants. Grip force lifting force coupling action was poor in infants below 5 years old. For the 5th day data, similar results to the 1st day data were also found, but compared to the 1st day results, there was improvement of the performance in both movement time and force magnitude particularly in infants aged 2 - 4 years old. Motor programming capacity in relation to object weight was examined in the data of unexpected weight change. It was found that with an increase in age the effect of unexpected weight change became more evident; longer timing and force magnitude correction were revealed as age of the infants increased. After five days of lifting practice, the effect of unexpected weight change became more clear even in 10 month old infants. Improvement was quite evident in 2 - 4 year old infants, suggesting that these periods were important in the acquisition of programming capacity.