EMG SPECTRAL SHIFT-NMR AND P-31-NMR - DETERMINED INTRACELLULAR PH IN FATIGUED HUMAN BICEPS BRACHII MUSCLE

We have simultaneously recorded human biceps brachii intracellular pH, estimated by P-31-NMR, and EMG spectral shift, during isometric contraction and recovery in six subjects. This method allows us to concurrently study several components of muscle fatigue. The results show a clear dissociation between the recovery of intracellular pH, force-generating capacity, and the shift to low frequency of the EMG power spectrum induced by fatiguing exercise.