Exercise Physiology: Theory and Application to Fitness and Performance 9th Edition by Scott Powers, Edward Howley

Exercise 6

Because many subjects do not exhibit a plateau in oxygen consumption in the last stages of a maximal GXT, what other criteria could be used to show that the person was exercising maximally when the highest  was measured?

Step 1 of 2

VO2 max is the maximal capacity of the heart, lungs, and blood to transport oxygen to the working muscles during exercise, and its utilization. Graded exercise tests (GXT) are generally used to measure VO2 max. VO2 increases with increasing loads of GXT until the maximal cardiorespiratory system capacity is reached. The true VO2 max achievement is the point at which the VO2 fails to increase with further increase in the workload, that is, a plateau is achieved.

However, VO2 max is reached only in 50% of healthy adults. Therefore, several alternative criteria are used as evidence that VO2 max is achieved. Important of them are the following:

• Measurement of post-exercise blood lactate concentration

• A respiratory quotient exceeding 1.15