Abstract: An improved treadmill control system which adjusts the speed of a moving tread belt to follow user motions. Equipment includes a tread base supporting a moving tread belt upon which a user can run or walk, a motor assembly and motor driver to move the tread belt, a plurality of foot sensors, a tread belt motion sensor, a measurement system to estimate user motion based on foot and tread belt sensor signals, and a motor controller to adjust motor assembly speed based on estimates of user motion. The system is capable of making improved user motion estimates and of using them to provide improved belt speed control. In one embodiment, user position, speed, and acceleration are estimated at each user footfall while estimates are continually revised between footfalls. In one embodiment, foot sensors are capacitive proximity sensors which are effective, fully concealable, and economical.