The HIITAXLE is a HIIT trainer designed to work the upper body and core in a unique way. It works by moving the wheels with the handles while the wheels are on the ground or on the roller cradle. When on the ground, you can place your feet on the HIITAXLE skate to move with the wheel or use your feet to move. When used with the roller cradle, the wheel stays stationary when you spin it and using the skate in this configuration makes your core work harder. But even without the wheels it can still give you an intense workout. Whether with the cradle or without it's like doing planks with movement in the upper body.