長さ4mの直線走行路を作成, 条件づけにより雄ラットに1日12回, 14週間にわたるスプリント (疾走) トレーニングを負荷した.その後, 前脛骨筋, ヒラメ筋線維ならびに支配運動ニューロンの総数, 組織化学的特性の変化について検討した.
1.筋線維, 支配運動ニューロンの総数, ならびにそれらの組織化学的特性には, トレーニングによる影響はみられなかった.
2.前脛骨筋のFOG線維, FG線維において, トレーニングによる横断面積の増大が認められた.
したがって, スプリントトレーニングでは, 負荷強度は高いが十分な運動量が得られないため, 速筋線維の肥大は認められたものの, 運動単位の組織化学的特性を変化させるまでには至らなかったものと推察される.

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In order to evaluate the effect of muscle pump on blood circulation at the start and end of exercise, cardiac responses to pedaling exercise at 75 watt in the supine position were investigated under lower body negative pressure (LBNP) of -60mmHg. Six healthy male college students volunteered for subjects. Cardiac output (Q), stroke volume (SV), thoracic impedance (ZO) and heart rate (HR) were determined by using ensemble-averaged impedance cardiogram and ECG.
The results obtained were as follows.
1) By the initiation of exercise under LBNP, SV and Q promptly and more markedly increased and ZO decreased than the control experiment which were done under normal pressure. These changes were suggested to be caused by mobilization of previously pooled blood in the legs by muscle pump. Effects of muscle pump arrived to a plateau within about 30 sec after the start of exercise. And these effects were immediately disappeard by the cessation of exercise.
2) By the release of LBNP during resting condition, the same changes were observed in SV, Q and ZO as in the start of exercise under LBNP. However HR decreased in the case while it increased in the case of exercise in LBNP. This difference in HR might be the result of the chronotropic effects by the exercise.
3) In the very early phase of exercise in the control exercise, SV decreased and ZO increased. These changes were probably caused by superiority of chronotropic action by the exercise to increase in venous return in this position.
These results led us to a conclusion that the effect of muscle pump appeares immediately by the start of the exercise and it arrives at plateau within about 30 sec. This effect is immediately disappeared by the cessation of exercise.

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The purpose of this study was to investigate the effects of contraction force and the pooled blood volume in the calf on the pumping action of calf muscle contraction. Calf blood volume was controlled by lower body negative pressure (LBNP) and isometric contraction of calf extensor muscle was performed using a handmade dynamometer in recumbent position. The relative volume changes (ΔV/V%) of calf were determined using rubber straingage, when isometric contractions (5, 10, 20, 40 and 60 kg) of the calf muscle were repeated under LBNP of 0, -20, -40, and -60 mmHg.
During resting condition, Δ V/V was increased by 1.04% under -20 mmHg LBNP, 1.88% under -40 mmHg, and 2.54% under -60 mmHg. These increases of ΔV/V were due to the increased blood pooling in the calf. It was shown that the increased blood volume was almost expelled by several bouts of muscle contractions of proper force. The optimum force of contractions for expelling pooled blood was 20 kg under -20mmHg LBNP, and 40 kg under -40 and -60 mmHg LBNP. And it was apparent that the effectiveness of muscle pump was accumulated with repeating contractions, arriving to a plateau after several bouts.
It was shown that the effect of muscle pump in the given contraction force was more effective under the condition with more amount of blood contained in the calf, but the muscle pumping action by light contraction forces couldn't overcome the effect of severe LBNP.

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本研究は, 身体トレーニングの内容の差異が赤血球性状, 特に赤血球2, 3-DPGに及ぼす影響について検討し, 同時に有酸素的作業能力との関連について考察した.
1) 有酸素的作業能力 (VO₂max/w, O₂ pulse max) は3グループ間で有意に異なっていた (Group1>Group2>Control) .
2) 赤血球性状では, Group1, 2のRBC, Hb及びHctはControl群に比べ低い傾向にあった.また赤血球恒数ではGroup1が他の2グループに比べ低値を示し, MCH, MCHCにおいてその差は有意であった.赤血球2, 3-DPGはGroup1, 2がControl群に比べ有意に高い値であった.
3) 赤血球容積の分布曲線において, Group1の曲線はGroup2, Control群のそれに比べ全体的に左方へ移行し, Group1には容積の小さい小赤血球が多く存在していた.
4) 赤血球2, 3-DPGとVO₂max/wとの間には, 3グループを合せた全体において有意な正の相関関係が見られた.またGroup1だけにおいても有意な相関関係が認められた.

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Previous research has demonstrated that the VO₂max is a strong predictor of performance time in distance running. Collecting data from previous studies and from their laboratory, the authors have developed a set of normative tables for predicting times for serious runners competing in the 5, 10 km and marathon races. Recognizing individual differences in psychological and biomechanical factors, as well as environmental influences, five categories ranging from“poor”to“super excellent”have been developed for each value from 55 to 85 ml·kg^-1·min^-1. By periodically assessing their VO₂max values, runners can aspire to reach the top category and achieve his/her peak performance.

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