Relationship between aging, muscle metabolisn and excercisp training by MRS

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To evaluate changes in muscle energetics following endurance training, we measured phosphorus -31 nuclear magnetic resonance ( ^<31>P NMR) spectra on rat muscle in vivo before and after training in the same animals. The endurance training was performed in the training group for 3 months. ^<31>P NMR spectra were obtained serially at rest, during exercise by electric stimulation, and during recovery. Intramuscular phosphocreatine (PCr), inorganic phosphate (Pi), ATP and pH were determined from the NMR spectra. The ratio of PCr/ (PCr+Pi) at rest showed no difference between the training and control group even after 3 months of training. During exercise, however, this ratio was significantly higher in the training group than in the control group. The ratio also recovered more rapidly after exercise in the training group. The muscular pH slightly decreased - 0.1 pH unit during exercise, but did not show significant difference in both groups. These results indicate that the endurance training of 3 months improves the ATP supply system in the muscle without significant change in the muscular fiber types. It is also demonstrated that ^<31>P NMR is a potent method to evaluate the training effects on the same individuals consecutively.