Origins of [H+] changes in exercising skeletal muscle

Can J Appl Physiol. 1995 Sep;20(3):357-68. doi: 10.1139/h95-028.


This brief review describes the main physicochemical factors that contribute to increases in intracellular hydrogen ion concentration ([H+]i) in mammalian skeletal muscle during high intensity exercise. High intensity exercise results in changes in the three main independent physicochemical variables: PCO2, the strong ion difference ([SID]), and total concentration of weak acids and bases ([Atot]), within the intracellular fluid compartment of contracting muscle that result in increased [H+]i. The decrease in [SID] contributes 62% to the increase in [H+]i, due to decreased [K+]i and increased [lactate]i; the decrease in phosphocreatine ([PCr2-]i) exerts an alkalinizing effect. The increase in [Atot], resulting primarily from increases in inorganic phosphate and creatine as a result of PCr2- breakdown, contributes 19% to the increase in [H+]i. An increase in the apparent proton dissociation constant (KA) for [Atot] contributes 7% to the increase in [H+]i. PCO2 is a relatively poor effector of changes in [H+]i, such that a 50-mmHg increase in PCO2 contributes only 12% to the increase in [H+]i during high intensity exercise.

Publication types

  • Research Support, Non-U.S. Gov't
  • Review

MeSH terms

  • Acid-Base Equilibrium / physiology*
  • Animals
  • Exercise / physiology*
  • Humans
  • Hydrogen-Ion Concentration
  • Intracellular Fluid / metabolism
  • Muscle Contraction / physiology*
  • Muscle, Skeletal / metabolism*