The self-powered, motorless Optimill flat treadmill has user-defined performance and is intended to simulate road jogging indoors. The Optimill provides unrestricted performance for both running and walking. Rehabilitation patients can walk at a speed and pattern that suit their current physical capacity because they are not constrained by the speed setting or programme of a motorised belt, but runners can sprint at speeds that most motorised treadmills couldn't match. The individual force-absorbing treads, or "slats," on the Optimill's flat surface reduce joint impact and require you to move forward for the belt to move. The Optimill is designed to stop when you stop running for added safety, providing a reassuring experience comparable to running on the ground.