低酸素環境の運動時エネルギー代謝への影響 : 血中pHと血中乳酸濃度の変化

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Since it was found that metabolic alkalosis induced by sodium bicarbonate ingestion enhances lactate diffusion from muscle, we attempted to examine the effect of an hypoxic environment which causes respiratory alkalosis on the changes in blood pH and lactate accumulation by high intensity exercise. Six young male adult were employed. Each subject performed 3 exercise tests (Max, Hypoxia and Submax) on a bicycle ergometer. In the Max test, subjects performed incremental exercise until exhaustion under air. In the Hypoxia test, a similar test was carried out under low oxygen gas. In the Submax test, the work load was the same as in the Hypoxia test but under air. Blood sample were obtained before, immediately after and at , 1, 3, 5, 7, 10, 15, 20 and 30 min. after exercise. In the Hypoxia test subjects breathed 12% oxygen gas from 60min. before exercise until 30min. after exercise and additional samples were obtained before exercise. Mean power output in the Hypoxia test and Submax test was about 67% of the Max test. In the Max test, blood pH rapidly fell after exercise and rose towards the initial level thereafter, but it did not reach the initial level 30 min. after exercise. In the Hypoxia test, blood pH elevated slightly by breathing low oxygen gas before exercise , but fell sharply by exercise and returned to the pre-exercise level 30min. after exercise. In the Submax test, the fall and its recovery were slower than in the other tests. Plasma lactate concentration rose after exercise and fell thereafter similarly in both Max and Hypoxia tests without significant differences at any point. Changes in the Submax test were far less than in the other 2. Blood bicarbonate ion concentration declined significantly by exercise and elevated thereafter in each test, though changes in the Submax test were much smaller than in the other 2. In the Hypoxia test, bicarbonate concentration elevated before exercise and pre-exercise value and the value immediately after exercise were significantly higher than those in Max test. Difference of bicarbonate ion before and after exercise, i.e., Δ bicarbonate, tended to be greater in Hypoxia test than in the Max test, indicating greater H^+ efflux in the Hypoxia test. From these results, it may be concluded that under 12% oxygen inhalation maximal power output decreased to 67% of that under air, yet almost a similar blood lactate concentration was reached by this lessened exercise ; moreover, recovery from exercise-induced metabolic acidosis is facilitated by respiratory alkalosis due to low oxygen inhalatoin.
中京大学の論文
1998-03-17

低酸素環境の運動時エネルギー代謝への影響 : 血中pHと血中乳酸濃度の変化

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