Shoe for simulating exercising on natural granular matertial

A shoe for simulating exercising on natural granular material, comprising:

• a shoe upper;
• a shoe outsole;
• a chamber located between the shoe upper and the outsole;
• at least one bladder located in the chamber and attached to the shoe upper, wherein the bladder includes synthetic granular material having a simulation distribution of synthetic granular material for simulating exercising on natural granular material wherein a size of the bladder is compressed by the shoe upper during exercise to displace the synthetic granular material and wherein the size of the bladder is subsequently expanded by upward movement of the shoe upper during exercise to redistribute the synthetic granular material and again form a simulation distribution of synthetic granular material,
• wherein a rear portion of the shoe includes an aperture that provides access to the chamber to enable insertion of the bladder into the chamber via the aperture;
• further including a flap that is moveable between an open position wherein the flap extends from the shoe to open the aperture and enables insertion of the bladder and a closed position wherein the flap is folded over the aperture to close the aperture.