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3.2 運動時の筋交感神経活動に及ぼすレジスタンストレーニングの効果
斉藤 満，蜂矢 鉄心，岩瀬 敏
Effect of resistance training on the muscle sympathetic nerve activity
during handgrip exercise
った．
6 週以下の短期間の RT に伴う筋力向上は筋収縮に 動 員 さ れ る 運 動 単 位 数 の 増 加 が 主 要 因 と さ れ る
（Sale 1988）．今回は 4 週間の最大努力 HG 運動を用 いたことから，中枢指令を含めた運動神経機能の向 上が筋力増加の主要因と考えられる．トレーニング 停止後も高い張力が持続した背景には，高い運動神 経機能が維持されたためと考えられる．
2）運動時の生理反応
Fig. III.3.2-1 に 33 ％ MVC 張力が維持できなくな るまで持続する HG 運動とそれに続く動脈阻血時の MSNA 反応の結果を示す．運動時の MSNA 反応はト レーニング後有意に増加し，トレーニング停止 4 週後 にはトレーニング前値に戻った．しかし，代謝受容 器反射が反映される運動後阻血時の MSNA 反応は研 究期間を通して一定であり，トレーニング効果は認 められなかった．対照群の MSNA 反応は運動時およ び運動後阻血時ともに研究期間を通してほぼ一定で あった．トレーニング群，対照群ともに運動時，運 動後阻血時の心拍数，血圧反応は研究期間を通して
変化は認められなかった．
筋反射が反映される運動後阻血時の MSNA 反応が トレーニング期間を通して一定であったことから，
運動時の MSNA 反応の増大には中枢指令の効果が大 き く 関 与 し た 可 能 性 が 推 察 さ れ る ． 本 結 果 は ， MSNA 反応は RT の影響を受けないか低下するとされ るこれまでの結果（斉藤 2004）とは異なった．おそ らくこの背景にはトレーニングに用いた運動強度の 違いが影響したと考えられる．これまでの RT 研究で は 30 ％ MVC 程度の負荷を用いているが，本研究で はより高強度の最大努力筋収縮を用いた．このこと が，中枢指令に対する効果を有意にしたと推察され る．
本結果から，高強度レジスタンス運動は運動時の 中枢指令に影響を及ぼすが，代謝受容器反射への効 果は小さいことが明らかとなった．
●文 献
斉藤 満 : 運動および安静時の交感神経活動に対する身 体トレーニングの効果− Microneurography による 研究−. 東海保健体育科学, 26: 1-8, 2004.
Sale DG : Neural adaptation to resistance training.
Med Sci Sports Exerc, 20: S135-S145, 1988.
70
Fig. III.3.2-1 Comparison of the changes in burst frequency (dBF) during fatiguing handgrip exercise (HG) and post exercise forearm occlusion (PEFO) at pre-training (B), 1 week post-training (A) and 4 weeks post-training (D) in the trained (left panel) and control group (right panel). * p < 0.05 compared to the pre-training or 4 weeks post-training values.
4 Effects of Different Exercise Modalities on S k e l e t a l M u s c l e a n d P r e f r o n t a l C o r t e x Oxygenation Monitored by Near Infrared Spectroscopy
Valentina Quaresima
1）■
Co-worker（本課題の共同研究者）Marco Ferrari1）
1）Department of Health Sciences, University of L’Aquila
4.1 Metabolic pattern of the leg skeletal muscle groups during very short and intense isometric exercise
4.2 Acute effects of whole body vibration exercise (an alternative exercise intervention) on gastroc-nemius medialis and vastus lateralis oxygenation
4.3 Biceps brachii myoelectric and oxygenation changes during static and sinusoidal isometric exer-cises
4.4 Auxiliary muscles oxygenation during a rowing exercise 4.5 Effects of handgrip exercise on frontal cortex oxygenation
The purpose of the study was to assess on heavy-resistance strength trained and untrained subjects the vastus lateralis (VL) muscle O2 satura- tion (TOI) time course in response to a brief maxi-mal voluntary isometric contraction.
●Methods
Trained (n = 10) and untrained (n = 10) sub-jects performed a trial consisting of: 1) a 1-min rest period, 2) a leg press exercise of about 3 s, and 3) a 2-min recovery period. The leg press exercise consisted of a static maximal voluntary contraction using only the dominant leg. The leg press strength was recorded using a load cell. The TOI was measured by NIRS (NIRO-300; 0.17 s sampling time).
●Results
Fig. III.4.1-1 left panel shows the VL oxygena-tion pattern observed in a athlete. TOI was unchanged over the 3-s exercise and started to
drop immediately after the exercise end. Fig.
III.4.1-1 right panel shows the typical TOI pattern of a sedentary subject. TOI was stable only over the first 1.5-2.0 s of the exercise; thereafter, TOI started to decline. The time to the onset of TOI decrease was consistently shorter in the untrained than in the trained subjects. In all the trained sub-jects, TOI started to decrease 0.5-1.0 s after the end of the contraction. After the end of the exer-cise, TOI transiently decreased reaching its mini-mum value in about 15 and 10 s in the trained and untrained subjects, respectively.
In conclusion, the results of this in vivo study demonstrated that the aerobic oxidative metabolic system occurs earlier in untrained than in strength power trained subjects upon a very short isometric high-intensity exercise. From this point of view, NIRS could be employed to: 1) profile in each muscle group the aerobic and, indirectly, anaerobic energy system contribution during even single brief maximal exercise, and 2) follow the
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Effects of Different Exercise Modalities on Skeletal Muscle and Prefrontal Cortex Oxygenation Monitored by Near
Infrared Spectroscopy
Valentina Quaresima
Abstract
The research activity has mainly been focused on the study of the vascular and metabolic mecha- nism regulating the cerebral and muscular oxygenation and metabolism by using near infrared spec-troscopy (NIRS) and functional NIRS with a multidisciplinary approach. In particular, the results want to give a contribution for: 1) understanding the mechanism of the muscle fatigue during exercise and the kinetics of the transition rest-exercise, and 2) supporting the hypothesis that prefrontal/frontal lobe plays a role in maintaining strength of the forearm muscles and ensuring a correct execution of motor tasks which require a fine motor control and coordination.