Treadmill test
Prior to the treadmill test, subjects were provided a warm-up
period on the treadmill. This warm up protocol was individualized
and selected by the subject. Next, MFV loops were obtained while
in the standing position and then subjects rested while seated on a
stool for 5 min. During this time all metabolic and ventilatory data
was continuously collected (see below). (IC) maneuvers were performed
twice every minute to aid in the placement of the tidal flow
volume loop within the MFV loop as previously reported (Chapman
et al., 1998; Johnson et al., 1992). After 5 min of rest the treadmill
speed was gradually increased from a walking speed (∼4.8 km h−1)
to a comfortable running speed that could be maintained throughout
the test (9.6–12.9 km h−1). For the first 2 min of the test, the
grade of the treadmill was set to 0%. For the second 2 min, the
grade was increased to 4% and then raised by 2% every 2 min thereafter
until the subject could no longer continue. Within a 2–3 min
following the exercise test afinal series ofMFVloops were obtained.