AN INTERLEAVED HETERONUCLEAR NMRI-NMRS APPROACH TO NONINVASIVE INVESTIGATION OF EXERCISING HUMAN SKELETAL-MUSCLE

Novel tools are presented that aim at more comprehensive NMR investiga tions of human skeletal muscle metabolism, in particular during exerci se protocols. They integrate imaging (NMRI) and spectroscopy (NMRS) ex periments in a single dynamic examination. The first. sequence that we propose combines NMR-plethysmography, H-1-NMRS of deoxymyoglobin and P-31-NMRS. This allows simultaneous determination of skeletal muscle p erfusion, oxygenation and high-energy phosphates status. It is very we ll suited to the study of interplay between blood supply and energy me tabolism during the recovery period from aerobic or anaerobic exercise s. In a second sequence, the same spectroscopic measurements are assoc iated to a H-1 double quantum coherence (DQC) edition of lactate. It i s, this time, possible to estimate muscle lactate production concurren tly with oxygen content, high-energy phosphates distribution and intra cellular pH. This sequence is intended mainly for metabolic investigat ions of ischemic bouts. Examples are given of the use of these sequenc es in normal adult volunteers. They demonstrate the technical feasibil ity of these new approaches and illustrate their potential for future applications, particularly non-invasive investigations of regulatory m echanisms of muscle metabolism in situ.