Noninvasive measurement of muscle high-energy phosphates and glycogen concentrations in elite soccer players by P-31- and C-13-MRS

Purpose: The purpose of this study was to measure noninvasively the absolut e concentrations of muscle adenosine triphosphate [ATP], phosphocreatine [P Cr], inorganic phosphate (Pi), and glycogen [Gly] of elite soccer players. Methods: Magnetic resonance spectroscopy (P-31-,d C-13-MRS) was used to mea sure the concentrations of metabolites in the calf muscles of 18 young male players [age = 17.5 +/- 1.0 (SD) yr]. Results: Average muscle [PCr] and [A TP] were 17.8 +/- 3.3 and 6.0 +/- 1.2 mmol . (kg wet weight)(-1), respectiv ely. The ratios of Pi/PCr and PCr/ATP were 0.15 +/- 0.05 and 3.00 +/- 0.26, respectively. The muscle [Gly] was 144 +/- 54 mmol(kg wet weight)(-1). The re was a high correlation (r = 0.93, P < 0.0001) between muscle ATP and PCr concentrations, but there was no correlation between [Gly] and [PCr] or [A TP]. The concentrations of the different metabolites determined in the pres ent study with noninvasive MRS methods were within the ranges of values rep orted in human muscle from biochemical analysis of muscle biopsies. Conclus ion: MRS methods can be utilized to assess noninvasively the muscle energet ic status of elite soccer players during a soccer season. The high correlat ion between ATP and PCr might be indicative of fiber type differences in th e content of these two metabolites.