Abstract: The portable exercise mat enables the user to exercise his or her gluteus maximus muscles by permitting the user to lift his or her thigh above a planar exercise mat face or surface. The mat includes a forward and a rearward mat section. The rearward planar mat section is joined by a hinge mechanism to the forward planar mat section. Both sections form a flat, enlarged mat system when it is open. The rearward mat section includes a reinforcement plate which, in a preferred embodiment, is located between upper and lower foam layers. The reinforcement plate spans at least thirty percent of the entire rear mat section and, in a preferred embodiment at least eighty percent of the lateral aspect of the rearward mat section. This plate permits the user to place his or her knee on a region atop the reinforcement plate and keep the exercise mat flat as he or she lifts his or her thigh above the exercise plane defined by the enlarged mat system.