A height-adjustable DAP exercise system is provided having a support platform, an inflatable enclosure secured to the support platform at a base opening through the enclosure and extending vertically therefrom when inflated, and a top frame attached to the enclosure at an enclosure top opening. The DAP system further includes adjustable lift restraints each having a restraint length between first and second ends and configured for adjustment between a first restraint length and at least one second restraint length, in which each first end of each lift restraint is attached to a middle portion of the enclosure and each second end is attached to the top frame or the base. The enclosure height is adjustable between a first and second enclosure height responsive to adjustments for lift restraint lengths. The system also includes a low height safety harness for the top frame and related methods.