2000 Fiscal Year Final Research Report Summary
Motor unit activation patterns during the alternate activity in the synergistic muscles
| Project/Area Number |
10680043
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| Research Category |
Grant-in-Aid for Scientific Research (C)
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| Allocation Type | Single-year Grants |
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| Section | 一般 |
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| Research Field |
体育学
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| Research Institution | National Institute of Fitness and Sports in Kanoya |
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Principal Investigator |
KURATA Hiroshi National Institute of Fitness and Sports in Kanoya Vice-president, 副学長 (80056895)
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| Co-Investigator(Kenkyū-buntansha) |
TAMAKI Hiroyuki Faculty of Physical Education, National Institute of Fitness and Sports in Kanoya Research Associate, 体育学部, 助手 (40253926)
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| Project Period (FY) |
1998 – 2000
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| Keywords | rotational activity / motor unit / triceps surae muscle |
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| Research Abstract |
This study has focused on five points to investigate the alternate activity in the triceps surae muscles ;
(1) controlling the emergence of alternate muscular activity, (2) functional interrelationships between joint angle, force output and electromyographic (EMG) activity, (3) characteristics of EMG patterns during alternate muscular activity, (4) single motor unit activity during alternate activity in the synergistic muscles and (5) significance of alternate activity in the static muscle work.
EMG-angle relationships showed direct and inverse proportion in gastrocnemius (MG, LG) and soleus (SOL) muscle respectively. There was a quasi-linear relationship between force and EMG in SOL, but MG and LG took on a curvilinear relationship. It was found that prolonged isometric contractions at 110 degrees of ankle joint angle under relatively low level workload (10% maximal voluntary contraction) resulted in the frequent occurrence of alternate muscular activity. Moreover, quantitative analysis revealed the existence of the EMG overlap not only in time but also in magnitude during the alternate activity among synergistic three muscles. In the overlap periods, on the other hands, there is no hysteresis in activation patterns of single motor units during recruitment and derecruitment. Therefore, the reverse pattern of synaptic input to a-motoneurons during recruitment would not be applied to that during derecruitment. Finally, it is suggested that the type of alternate activity in the synergistic muscles reduce the development of muscle fatigue and keep the functional ability for muscle endurance and maximal force output on the next day.
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