The Effect of Breathing Oxygen-Enriched Air During Exercise Upon Pulmonary Ventilation and Upon the Lactic Acid Content of Blood and Urine

Respiratory Regulation During Exercise in Unconditioned Subjects 1

“…The effect was greater the more severe the exercise, and for a given exercise rate the effect varied inversely with physical fitness. The finding has been confirmed abundantly (20,22,27,32,33). Conversely, it is known that ventilation for a given work rate is greater at high altitudes (13,34,35) or while breathing low-oxygen mixtures (15,27,36,37) than it is at normal oxygen tensions.…”

Historical Remarks on the Development of the Aerobic-Anaerobic Threshold up to 1966

“…Hewlett et a!. (52), Wilson et al (126,127), and Liljestrand et al (79) discovered large quantities of lactic acid and phosphoric acid in the urine. In 1925 Embden (35) provided evidence for an increase in anorganic phosphate in muscle during a series of muscular contractions.…”

“…In 1925 Schenk determined a venous lactate concentration of 150 mg% after a 400-rn race (119). A year later Hewlett et al observed a drop in the lactic acid concentration of the blood during oxygen respiration (52). In 1927 Douglas (29) ascertained that the degree to which lactic acid is formed in the working muscles is decisively influenced by the availability of oxygen in the same muscles.…”

Discussion

“…H i 11 (64) and his co-workers found that the fall in lactic acid concentration after exertion did not take p h e much more rapidly whether the subject breathed in pure oxygen or in atmospheric air. H e w 1 e t t, B a rn e t t and L e w i s (60) state however that the hyperlactacidsmia after muscular exertion was less when the quantity of oxygen in the air was increased. An increase of the oxygen tension in the alveolar air can hardly be supposed to play any important part in physical exertions.…”