Exercise muscle metabolism measured by magnetic resonance spectroscopy.

Nuclear magnetic resonance imaging (MRI) is a technique which gives body images in much the same way as X-ray tomography. Most images are produced from signals of mobile hydrogen atoms in the tissues. Since bone contains few such atoms the images do not show bone material but allow marrow to be observed. Recently the technique has been extended to include spectroscopy of atoms of 31P, 13C and several others important in cell and tissue metabolism. The technique which uses a radiofrequency surface coil placed over the tissue of interest, is called topical magnetic resonance spectroscopy (MRS). Magnetic resonance spectroscopy which measures phosphorus nuclei can be used to study phosphorus in muscle. The same instrument can be used to study hydrogen density distribution. It can monitor muscle metabolism during exercise and muscle energetics can thus be evaluated. MRS gives a more accurate picture of the in vivo proportions of high energy phosphates than conventional biochemical analysis, which requires muscle biopsy, it can be used to monitor living tissue in a non-destructive way.