Curved manual treadmills use no electricity at all and can be placed anywhere, since they need no outlet. The Best Treadmills of 20261. Sole F80 Folding Treadmill: Best OverallThe Sole F80 is the machine most home gyms should buy. IN10CT Health Runner Curved Manual: Best for Using No ElectricityThe IN10CT Health Runner has no motor and no power cord, so it can go anywhere and costs nothing to run. This is also where a curved manual machine has an edge, since the curve itself creates the resistance.