After 12 weeks of training, there were further
increases in exercise performance determined from
the training sessions and from treadmill testing. At
this point in time, treated subjects had an increase in
peak Vo2, possibly reflecting either an increase in
muscle oxygen delivery or an improvement in muscle
oxidative metabolism. These changes in peak Vo2
could not be inferred from the treadmill work load
alone because patients with cardiovascular disease
have less of an increase in Vo2 per increment in work
load than normal subjects.4 Thus, changes in peak
work capacity with training must be evaluated by
direct measurements of Vo2.