Figure 2: Treadmill walking sessions: lower body positive pressure (LBPP) exercise. A patient wore neoprene shorts with a kayak-type skirt attached at the waist. Then, he/she stepped into the lower body positive pressure (LBPP) chamber and the compliance properties of the skirt were such that a subject was able to walk comfortably on an electronically controlled treadmill without leaning on the seal for support. Seal height was adjusted to the level at each subject’s iliac crest, so that the seal itself exerted little or no vertical force when at ambient pressure.