Thoracoabdominal motion. Improvement in abdominal
motion was evaluated by means of a reduction in the amplitude
of the rib cage to abdominal motion ratio (RC/ABD ratio)
recorded using a computer-assisted respiratory inductive plethysmography
system (Respitrace).a Teflon-coated inductance
bandsa of appropriate size were placed around the rib cage and
abdomen and connected to an oscillator module and calibration
unit.25 Each subject was measured in a quiet, private room, and
data acquisition was performed in a supine position26 for a total
period of 9 minutes, equally distributed as follows: (1) at
rest— basal NB; (2) during DB exercise—voluntary DB; and
(3) post-DB exercise. Pulse oximetry was continuously monitored,
and dyspnea sensations were evaluated every minute
using the modified Borg scale.27 Rib cage and abdominal wall
movement waveforms were digitized, and the RC/ABD ratio
was calculated from the absolute changes in the circumference
of these compartments.22