For valid users, the Varibike offers you both an arm-and-leg propulsion two-wheeler. You can use your whole body to reach top speeds. Research has shown that the maximum power output can be increased by over 30% using combined arm-and-leg cranking compared with normal cycling at the same heart rate. Cycling with the Varibike is a full body workout. Aside from your legs, you have to use your arms, chest, back, and core to ride this innovative bicycle.