A system for a treadmill including a tread that rotates around a front axle and a rear axle and side rails on opposing sides of the tread, comprises a brake configured to slow rotation of at least one of the front axle or the rear axle, a controller, and a first presence sensor in communication with the controller, the first presence sensor positioned on a side rail and configured to detect the user on the side rail. The brake is not engaged during operation of the treadmill when the tread is moving and the first presence sensor does not detect the user on the side rail. The controller is configured to, in response to the first presence sensor subsequently detecting the user on the side rail, engage the brake.