Observation of intramyocellular lipids by means of H-1 magnetic resonance spectroscopy

Magnetic resonance imaging (MRI) and magnetic resonance spectroscopy (MRS) are being increasingly used for investigations of human muscle physiology. While MRI reveals the morphology of muscles in great detail (e.g. for the d etermination of muscle volumes),MRS provides information on the chemical co mposition of the tissue. Depending on the observed nucleus, MRS allows the monitoring of high-energy phosphates ((31)p MRS), glycogen (C-13 MRS), or i ntramyocellular lipids (H-1 MRS), to give only a few examples. The observat ion of intramyocellular lipids (IMCL) by means of H-1 MRS is non-invasive a nd, therefore, can be repeated many times and with a high temporal resoluti on. MRS has the potential to replace the biopsy for the monitoring of IMCL levels; however, the biopsy still has the advantage that other methods such as those used in molecular biology can be applied to the sample. The prese nt study describes variations in the IMCL levels (expressed in mmol/kg wet weight and ml/100 ml) in three different muscles before and after (0, 1, 2, and 5 d) marathon runs for a well-trained individual who followed two diff erent recovery protocols varying mainly in the diet. It was shown that the repletion of IMCL levels is strongly dependent on the diet post exercise. T he monitoring of IMCL levels by means of H-1 MRS is extremely promising, bu t several methodological limitations and pitfalls need to be considered, an d these are addressed in the present review.