Abdominal binding. The binder incorporated a semirigid neoprene back
panel with six plastic stays (100% neoprene rubber), flexible sidepanels
(90% nylon, 10% Lycra), and a flexible neoprene front panel
with double Velcro fastening. The binder was individually sized and
fitted in the upright position with the upper edge just beneath the
costal margin so that the binder interfered minimally with rib cage
movement. An inflatable rubber reservoir with a known volume of air was connected to a digital manometer and placed between the binder and the anterior abdominal wall. The
binder tightness was adjusted until end-expiratory gastric pressure
was approximately twice that in the unbound condition; this level of
binding has been shown to optimize resting cardiopulmonary function
and improve field-based endurance performance . The corresponding
abdominal-wall pressure was used to set the binder tightness
for the maximal exercise test