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Hum Mov Sci. 2014 Oct;37:69-86. doi: 10.1016/j.humov.2014.07.001. Epub 2014 Aug 12.

Relationship between improvements in motor performance and changes in anticipatory postural adjustments during whole-body reaching training.

Author information

1
Department of Rehabilitation Science, Faculty of Health Sciences, Hokkaido University, West 5, North 12, Sapporo 060-0812, Japan. Electronic address: saitoh@hs.hokudai.ac.jp.
2
Department of Rehabilitation Science, Faculty of Health Sciences, Hokkaido University, West 5, North 12, Sapporo 060-0812, Japan. Electronic address: yamanaka@hs.hokudai.ac.jp.
3
Department of Rehabilitation Science, Faculty of Health Sciences, Hokkaido University, West 5, North 12, Sapporo 060-0812, Japan. Electronic address: kasahara@hs.hokudai.ac.jp.
4
Department of Rehabilitation Science, Faculty of Health Sciences, Hokkaido University, West 5, North 12, Sapporo 060-0812, Japan. Electronic address: jf002@cme.hokudai.ac.jp.

Abstract

Anticipatory postural adjustments (APAs) provide postural stability and play an important role in ensuring appropriate motor performance. APAs also change in various situations. However, it is unknown whether changes in APAs during repetitive movement training contribute to improvement in motor performance. This study aimed to investigate the relationship between improvement in motor performance and changes in APAs during repeated reaching training, as well as the learning effects on APA changes. Sixteen healthy subjects (23 ± 2 years of age) stood barefoot on a force platform and reached as quickly and accurately as possible to a target placed at their maximum reach distance immediately following a beep signal in a reaction time condition. Whole-body reaching training with the right arm was repeated 100 times for three consecutive days. Motor performance and APAs were evaluated on the first day, after discontinuation of training for one day, and again at three months. In addition, reaching with the left arm (untrained limb) was tested on the first and the fifth training day. Body position segments were measured using three-dimensional motion analysis. Surface electromyography of eight postural muscles in both lower limbs was recorded. Kinetics data were recorded using the force platform. Whole-body reaching training induced not only improvements in motor performance (e.g., increased peak hand velocity), but also changes in APAs (e.g., earlier APA onset and increased amplitude). These changes were strongly correlated with and occurred earlier than improvements in motor performance. The learning effects on APAs were retained after the discontinuation of training and were generalized to the untrained limb. These results suggest that change in APAs contributes to improvement in motor performance; that is, the central nervous system may be able to adapt APAs for improvement in motor performance.

KEYWORDS:

Anticipatory postural adjustment; Focal learning; Motor performance; Muscle activity; Reaching movement

PMID:
25108269
DOI:
10.1016/j.humov.2014.07.001
[Indexed for MEDLINE]
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