Relationships of intracellular pH to oxygenated hemoglobin/myoglobin and to phosphate compounds in active muscle during forearm exercise.
- VernacularTitle:前腕の運動時における活動筋の酸素化ヘモグロビン・ミオグロビン濃度およびリン酸化合物濃度と細胞内ｐＨとの関係
- Author:
MASASUKE KUWAMORI
;
HISAO IWANE
;
TAKAFUMI HAMAOKA
;
NORIO MURASE
;
YUKO KUROSAWA
- Publication Type:Journal Article
- Keywords:
31PNMR;
near-infrared spectroscopy;
grip;
wrist flexion;
intracellular pH
- From:Japanese Journal of Physical Fitness and Sports Medicine
1995;44(4):465-474
- CountryJapan
- Language:Japanese
-
Abstract:
The purpose of this study is to find a key to clarifying the mechanism of lactic acid production during exercise. Five healthy men performed the grip and wrist flexion exercises at different occasions. Exercise intensities were increased by 5% MVC (maximum voluntary contraction force) per minute from 10% MVC. Intracellular pH, oxygenated hemoglobin/myoglobin (Oxy-Hb/Mb), inorganic phosphate (Pi), and phosphocreatin (PCr) in forearm flexor muscles were measured by 31P-MRS and NIRS. The lowest Oxy-Hb/Mb concentrations during the grip and wrist flexion exercises were 40.7± 8.86% (average±SE) and 15.4 ± 2.26%, respectively. These results suggest that oxygen remain sufficient in the muscles at least during the grip exercise. Intracellular pH dropped as exercise intensity rose above 25% MVC for the grip and above 10% MVC for the wrist flexion exercise. These results support the idea that oxygen deficiency is not the only cause for lactic acid production during exercise. On the other hand, intracellular pH fell with either negative or positive relations to Pi/PCr ratio, Pi, and PCr in each exercise. These results support the suggestion that the main causes of lactic acid production during exercise are the changes in ADP, Pi, and PCr.
