Fig 1. Typical transversal slice obtained by MRI of a rat lower hindlimb (A), ³¹P-MRS spectra obtained from a single WT rat gastrocnemius muscle at rest (B) and at the end of 6-min of in vivo electrostimulation protocol (C).

Abbreviations for signal assignments (in p.p.m.) are PME (phosphomonoester), P_i (inorganic phosphate), PCr (phosphocreatine), and γ-, α-, and β-resonances of ATP.