The acid base equilibrium of the blood following vigorous muscular exercise

Abstract

Immediately following short periods of vigorous muscular work, there is a marked reduction in the bicarbonate content of the blood, a phenomenon observed by Christianson, Douglass and Haldane in 1914. 1 The initial purpose of the present investigation has been to discover what changes in the reaction and the CO₂ tension of arterial blood accompany the diminution in bicarbonate. For this purpose, four individuals without demonstrable organic defects but of varying grades of apparent fitness were selected for experiment. Each did on a Krogh bicycle ergometer a standard amount of exercise which consisted of the performance of approximately 3,500 kilogrammeters of work in three and a half minutes. The method employed upon the blood is that introduced by Henderson and Haggard 2 and consists in the simultaneous determination of the carbon dioxide absorption curve of blood at body temperature and the carbon dioxide content of the arterial blood as it occurs in the body. The reaction of the arterial blood is calculated from the H₂CO₃/BHCO₃ ratio after the formula of Hasselbalch. Arterial blood was drawn from the brachial or radial artery immediately before the exercise while the patient was resting and three minutes after the exercise had ceased. In one individual a third sample was taken eight minutes after the work was stopped.

In all cases there was a striking reduction in the bicarbonate content of the blood, varying in the different individuals from 10.5 to 18.8 volumes per cent. of CO₂. The C0₂ tension of the arterial blood was always lower after exercise. The diminution varied from 1.5 to 12.0 mm. The reaction of the blood was always less alkaline, in one instance assuming the very low figure of P_H 7.02, practical neutrality.