The Rate of Phosphocreatine Hydrolysis and Resynthesis in Exercising Muscle in Humans using ^31P-MRS

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Time-resolved 31-phosphorus nuclear magnetic resonance spectroscopy (^31P-MRS) of the biceps femoris muscles was performed during exercise and recovery in six healthy sedentary male subjects (maximal oxygen uptake; 46.6±1.7 (SEM) ml・kg^-1・min^-1), 5 male sprinters (56.2±2.5), and 5 male long-distance runners (73.6±2.2) Each performed 4min of knee fiexion exercises at absolute values of 1.63W and 4.90W, followed by 5min of recovery in a prone position in a 2.1T superconducting magnet with a 67cm bore. ^31P-MRS spectra were recorded every 12.8s during the rest-exercise-recovery sequence. Computer-aided contour analysis and pixel imaging of phosphocreatine peaks (PCr) and inorganic phosphate (Pi) were performed. The work loads in the present study were selected as mild exercise (1.63W) and heavy exercise (4.90W), corresponding to 18-23% and 54-70% of maximal exercise intensity. Long-distance runners showed a significantly smaller decrement in PCr and less acidification at a given exercise intensity compared to those shown by sedentary subjects. The transient responses of PCr and Pi during recovery were characterized by first-order kinetics. After exercise, the recovery rates of PCr and Pi were significantly faster in long-distance runners than in sedentary subjects (P<0.05). Since it is postulated that PCr resynthesis is controlled by aerobic metabolism and mitochondrial creatine kinase, it is suggested that the faster PCr and Pi recovery rates and decreased acidification seen in long-distance runners during and after exercise might be attributed to their greater capacity for aerobic metabolism. J Physiol Anthropol 21 (5): 247-255, 2002 http://www.jstage.jst.go.jp/en/
日本生理人類学会の論文

The Rate of Phosphocreatine Hydrolysis and Resynthesis in Exercising Muscle in Humans using ^31P-MRS

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