- 著者
- Yudai Takarada
- 出版者
- 一般社団法人日本体力医学会
- 雑誌
- The Journal of Physical Fitness and Sports Medicine (ISSN:21868131)
- 巻号頁・発行日
- vol.5, no.2, pp.123-130, 2016-03-25 (Released:2016-05-14)
- 参考文献数
- 29
- 被引用文献数
- 3
Low-to-moderate intensity resistance exercise with vascular occlusion induces increased muscle mass and strength, comparable to that after conventional heavy resistance training. Also, participants feel as if they require greater force (effort) to lift a weight when undergoing resistance exercise following vascular occlusion. Vascular occlusion of the proximal upper arm increased perceived magnitude of exerted hand-grip force without causing any accompanying changes either in electromyographic or efferent/afferent activity of the median nerve. There was also no effect on motor evoked potentials in the hand following resting-state transcranial magnetic stimulation (TMS) over the primary motor cortex (M1). Moreover, low-frequency, repetitive transcranial magnetic stimulation (lf-rTMS) over the left primary somatosensory cortex did not significantly affect estimations of right-hand grip force exertion. Thus, the primary factor responsible for the overestimation of force exertion with increased voluntary effort (“sense of effort”) during occlusion was the central signal related to motor command size. Brain imaging studies show that vascular occlusion increases M1 activity during force exertion, which may be related to functions of motor-related cortical areas, e.g., supplementary motor area, as sources of excitatory input to M1. M1 suppression by lf-rTMS during force exertion causes participants’ sense of effort and force perception to increase. This mechanism may also operate during muscular contraction with vascular occlusion. It is easy to imagine perceiving maximal effort when we consciously try to produce maximal force; however, does M1 activity become maximal at that point in time? In this study, the liberation of potential muscular strength, focusing on the motor system state before awareness of motor intention, is looked at.
- 著者
- Yudai Takarada Tomomi Tsuruta Naokata Ishii
- 出版者
- 日本生理学会
- 雑誌
- The Japanese Journal of Physiology (ISSN:0021521X)
- 巻号頁・発行日
- vol.54, no.6, pp.585-592, 2004 (Released:2005-03-12)
- 参考文献数
- 36
- 被引用文献数
- 56 120
To obtain insight into the relative contributions of exercise and occlusive stimuli to these muscular adaptations, the present study investigated the short- and long-term effects of varied combinations of low- intensity exercise and vascular occlusion. The subjects were separated into 3 groups (n = 6 for each group): low- intensity with vascular occlusion (LIO), low-intensity without vascular occlusion (LI), and vascular occlusion without exercise (VO). LIO and LI groups performed bilateral knee extension exercises in seated positions with an isotonic extension machine. In the LIO group, both sides of the thigh were pressure-occluded at the proximal end by means of a tourniquet during the entire session of exercise (˜10 min), whereas only the occlusion with the same pressure and duration was given in the VO group. The mean occlusion pressure was 218 ± 8.1 mmHg (mean ± SE). The exercise session consisted of five sets of exercise at an intensity of 10-20% 1RM and was performed twice a week for 8 wk. After the period of exercise training, isometric and isokinetic strengths at all velocities examined increased significantly in the LIO group (p < 0.05), whereas no significant change in strength was seen in the LI and VO groups. The increase in muscular strength in LIO was associated with a significant increase in the cross-sectional area of knee extensor muscles by 10.3 ± 1.6%. The plasma growth hormone concentration measured 15 min after the session of exercise showed a marked increase only in LIO. The results showed that the low-intensity exercise and occlusive stimuli have cooperative effects in the long-term adaptation of muscle and an acute response to growth hormone.