Muscular fatigue: effects of hydrogen ions and inorganic phosphate

Fed Proc. 1986 Dec;45(13):2921-3.


During muscular fatigue two metabolites, hydrogen ions (H+) and inorganic phosphate (Pi), increase in concentration. The effect of increase in [H+] has been modeled mathematically for a system containing creatine kinase (EC, adenylate kinase (EC, and the appropriate concentrations of their substrates. Assuming that no other equilibrium reactions are involved, the result of acidification should be a useful increase in the ratio [ATP]/[ADP]. It is also shown by a reanalysis of earlier 31P NMR studies that the observed combination of increased [H+] and increased [Pi] leads to an increase in the monobasic phosphate concentration [Pi-] that is inversely proportional to the force of contraction. This suggests that Pi- may be a direct inhibitor of the actomyosin ATPase system.

Publication types

  • Review

MeSH terms

  • Animals
  • Creatine Kinase / metabolism
  • Humans
  • Hydrogen-Ion Concentration
  • Lactates / metabolism
  • Lactic Acid
  • Magnetic Resonance Spectroscopy
  • Muscle Contraction
  • Muscles / physiology*
  • Phosphates / metabolism*


  • Lactates
  • Phosphates
  • Lactic Acid
  • Creatine Kinase