A portable trampoline exercise system, including a foldable trampoline with long-lasting rigidity in the frame and a specifically adapted carrying case for transporting the folded trampoline. The trampoline is made foldable by using hinges to connect sections of the frame of the trampoline. The hinges are configured to provide lateral flexibility in the frame, thereby reducing the damage caused by stresses applied to the hinges (and therefore increasing the life of the hinges) when the trampoline is folded.