Increase in the maximal oxygen intake

Oxygen Intake

The practical advantage to the subject is that a greater proportion of the oxygen requirement for a given task is obtained without the accumulation of lactic acid and the acquisition of an oxygen debt. The average individual with a resting oxygen consumption of 250 ml. per minute may increase this to about 1500 ml. per minute during work, an increase of 600 per cent. In the athlete this margin may be raised to 3 or 4 liters per minute, an increase of 1200 to 1600 per cent.

Oxygen Debt

The maximal oxygen debt which can be tolerated by a subject is usually increased by training. This means, primarily, that the trained individual is able to buffer a larger amount of lactic acid since there is no evidence of any difference in ability to tolerate a higher degree of actual tissue acidity. It might be expected, then, that training would increase the body's supply of buffer alkali, and this seems to be true. An average alkali reserve or 72.12 volumes per cent in highly trained athletes as compared with 65.15 volumes per cent in normal but untrained men. A steady rise in the alkali reserve of dogs subjected to regular exercise on a treadmill for a period of 7 to 9 weeks.

It is probable, however, that an increase in the alkali reserve does not invariably occur. Thus, normal alkali reserves in five young athletes of international renown in distance running. Apparently, then, the ability to accumulate a large oxygen debt must depend partly on other factors as yet unidentified.