The Acid-Base Equilibrium of the Blood in Exercise

Intracellular pH and distribution of weak acids across cell membranes. A study of D‐ and L‐lactate and of DMO in rat diaphragm.

“…Bock, Dill, Hurxthal, Lawrence, Coolidge, Dailey & Henderson (1927) also observed this displacement. Both seem to have felt (Hill et al 1924;Henderson, 1928) that all of the accumulated lactate ions in the blood had reached it as lactic acid from the active muscle fibres; this was later confirmed (Turrell & Robinson, 1942). These and subsequent workers conceived of the transmembrane movement of lactic acid as diffusion of its ionic components, rather than of the undissociated molecule.…”

Respiratory Regulation During Exercise in Unconditioned Subjects 1

“…With subjects in better training, exercise rates of this degree or much higher may be maintained without the accumulation of large amounts of lactic acid and without a decline in pH (8,22). However, with exercise which is severe for the subject, fall in arterial pH and serum CO2 content of this general magnitude have been reported (14,21,23). Our experience is similar to Barr's and Himwich's (23) in the finding that resting pH and CO content may not be restored for many minutes after exercise.…”

“…A large change had occurred by the time of the first sample, and the decline was continued in the second sample. Decreases of arterial pH and CO2 content during exercise are a reflection of the accumulation of lactic acid (8,21), and changes of this magnitude indicate that the rate of exercise was severe for the group as a whole. With subjects in better training, exercise rates of this degree or much higher may be maintained without the accumulation of large amounts of lactic acid and without a decline in pH (8,22).…”

Homeostatic Adjustments After Exercise

“…Since with decreasing pH less base is bound by the proteins of the blood, the decrease in bicarbonate observed is less than the actual addition of fixed acid (15). By utilizing the buffer value of whole blood and correcting all observed values of (BHCO3)b to pH 7.40, the true increase in fixed acid in the blood could be calculated.…”