Muscle interstitial potassium kinetics during intense exhaustive exercise: effect of previous arm exercise

Am J Physiol Regul Integr Comp Physiol. 2003 Jul;285(1):R143-8. doi: 10.1152/ajpregu.00029.2003. Epub 2003 Mar 27.


Interstitial K+ ([K+]i) was measured in human skeletal muscle by microdialysis during exhaustive leg exercise, with (AL) and without (L) previous intense arm exercise. In addition, the reproducibility of the [K+]i determinations was examined. Possible microdialysis-induced rupture of the sarcolemma was assessed by measurement of carnosine in the dialysate, because carnosine is only expected to be found intracellularly. Changes in [K+]i could be reproduced, when exhaustive leg exercise was performed on two different days, with a between-day difference of approximately 0.5 mM at rest and 1.5 mM at exhaustion. The time to exhaustion was shorter in AL than in L (2.7 +/- 0.3 vs. 4.0 +/- 0.3 min; P < 0.05). Furthermore, [K+]i was higher from 0 to 1.5 min of the intense leg exercise period in AL compared with L (9.2 +/- 0.7 vs. 6.4 +/- 0.9 mM; P < 0.001) and at exhaustion (11.9 +/- 0.5 vs. 10.3 +/- 0.6 mM; P < 0.05). The dialysate content of carnosine was elevated by exercise, but low-intensity exercise resulted in higher dialysate carnosine concentrations than subsequent intense exercise. Furthermore, no relationship was found between carnosine concentrations and [K+]i. Thus the present data suggest that microdialysis can be used to determine muscle [K+]i kinetics during intense exercise, when low-intensity exercise is performed before the intense exercise. The high [K+]i levels reached at exhaustion can be expected to cause fatigue, which is supported by the finding that a faster accumulation of interstitial K+, induced by prior arm exercise, was associated with a reduced time to fatigue.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Acidosis / metabolism
  • Adult
  • Arm / physiology
  • Carnosine / metabolism
  • Extracellular Space / metabolism
  • Humans
  • Hydrogen-Ion Concentration
  • Kinetics
  • Leg / physiology
  • Male
  • Microdialysis
  • Muscle Fatigue / physiology
  • Muscle, Skeletal / metabolism*
  • Physical Endurance / physiology*
  • Potassium / metabolism*


  • Carnosine
  • Potassium