Muscle pain after exercise is linked with an inorganic phosphate increase as shown by 31P NMR.

@article{Aldridge1986MusclePA,
  title={Muscle pain after exercise is linked with an inorganic phosphate increase as shown by 31P NMR.},
  author={R. Aldridge and Ernest Cady and D A Jones and G Obletter},
  journal={Bioscience reports},
  year={1986},
  volume={6 7},
  pages={663-7}
}
31P nuclear magnetic resonance (NMR) spectra were obtained from the forearm muscles of 5 subjects before and after performing a muscle stretching (eccentric) exercise routine. Spectra collected before and immediately after exercise showed normal resting phosphorylated metabolite levels and unchanged intracellular pH (pHi). Measurements made on the day following exercise, when muscular pain was apparent, revealed an elevated inorganic phosphate level. No significant changes in other metabolites… CONTINUE READING