Historically, the achievement of maximal oxygen uptake (VO2max) has be
en based on objective criteria such as a leveling off of oxygen uptake
with an increase in work rate, high levels of lactic acid in the bloo
d in the minutes following the exercise test, elevated respiratory exc
hange ratio, and achievement of some percentage of an age-adjusted est
imate of maximal heart rate. These criteria are reviewed relative to t
heir history, the degree to which they have been achieved in published
research, and how investigators and reviewers follow them in current
practice. The majority of the criteria were based on discontinuous pro
tocols, often carried out over several days. Questions are raised abou
t the applicability of these criteria to modern continuous graded exer
cise test protocols, and our lack of consistency in the terminology we
use relative to the measurement of maximal oxygen uptake.