2006 Fiscal Year Final Research Report Summary
The effects of low-intensity resistance exercise combined with vascular occlusion on the central nervous activity : fMRI study
| Project/Area Number |
16500425
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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 |
Sports science
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| Research Institution | Waseda University |
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Principal Investigator |
TAKARADA Yudai Waseda University, Faculty of Sport Sciences, Associate professor., スポーツ科学学術院, 助教授 (70367093)
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| Co-Investigator(Kenkyū-buntansha) |
TAIRA Masato Nihon University, Advanced Research Institute for the Sciences and Humanities, Professor., 大学院総合科学研究科, 教授 (50179397)
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| Project Period (FY) |
2004 – 2006
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| Keywords | fMRI / force perception / the primary motor cortex / ischaemia / neuronal correlates |
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| Research Abstract |
We have previously shown that low-intensity resistance exercise combined with vascular occlusion induced a marked hypertrophy and concomitant increase in muscular strength in elbow flexor muscles of order women ; even if the load of exercise was much lower than expected to induce muscular hypertrophy. The processes related to such an effect of externally applied occlusive stimulus have been interpreted as follows : (a) additional recruitment of fast-twitch fibers in a hypoxic condition, (b) moderate production of reactive oxygen species (ROS) promoting the tissue growth, and (c) stimulated secretions of catecholamine and growth hormone by intramuscular accumulation of metabolic subproducts. However, the mechanism has been unclear. Thus we examined the effects of the low-intensity resistance exercise with occlusion on the central nervous activity, in order to elucidate the neuronal mechanism.
We measured the brain activity with functional magnetic resonance imaging (fMRI) during unilater
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al isometric handgrip contractions at the predetermined target level of muscular force [20%, 40%, 60%, and 80% of maximal voluntary contraction (MVC)] with or without the arterial occlusion applied by a tourniquet at the right arm proximal to the axilla. The arterial occlusion significantly increased the primary motor cortex (Mi) with no changes of muscular force exertion [F _<(1, 6)> = 381.5, p < 0.01], whereas such a significant change of neuronal activity was never observed in the somatosensory cortex (SI). The occlusion-induced rise of neuronal activity in the section of the MI will be one of strong factor to induce the above mentioned effect of the low-intensity exercise with occlusion.
In addition, this fMRI experiment showed that neuronal activity in MI is also closely correlated with the perceive magnitude of muscular force. Further studies are being carried out with trans cranial magnetic stimulation (TMS), in order to examine whether additionally neuronal excitability of the MI enhances force perception. Less
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