Abstract: A rectangularly-shaped exercise apparatus (20) having an endless frame (22) formed by angular elements (24) joined together at their adjacent corners (25) that include shoulders (45) and gussets (46). A bed (29) of fabric is disposed within frame (20) and joined to it by coiled springs (31) attaching the bed's grommets (33) to pins (38) extending from horizontally-oriented flanges (26) of angular elements (24), being held to pins (38) by washer-nuts 41/42). A socket (29) is securely mounted at the corners (25) to the undersides (39) of flanges (26) and into which deep-stroked leg assemblies (52) having springs (56) are slip fit. The leg assemblies (52) include an additional stroke displacement over the spring's stroke displacement by a plunger (53) over which the spring's tubular cylinder (54) displaces.