Interrelationship between pH, plasma potassium concentration and ventilation during intense continuous exercise in man

Summary

During resting conditions plasma hydrogen ion concentration ([H⁺]_P) is known to influence ventilation$(\dot V_E )$, whereas the control of plasma potassium concentration ([K⁺]_P) at rest and of both [K⁺]_P and$\dot V_E$ during exercise are controversial issues. To obtain more information about these variables during muscular work, eight trained men performed two successive intense continuous cycle-ergometer tests, the first (test I) during metabolic acidosis, the second (test II) with an alkalotic pH. No correlation was found between [H⁺]_P and [K⁺]_P or$\dot V_E$ in the direction of change of these variables in test I. Furthermore, no correlation between [H⁺]_P and [K⁺]_P in test I and II was seen. Instead [K⁺]_P and$\dot V_E$ changed in relation to the exercise intensity. We suggest that the results confirm [K⁺]_P as an indicator of muscular stress. In addition, the similar behaviour of relative values of [K⁺]_P ande256-05 changes in test I (r=0.9,m=1.0, wherem is the slope of the regression curve) supports the hypothesis that extracellular potassium controlse256-06 and thereby [H⁺]_P also.