Abstract: Exercise treadmill with motor driven tread belt and means for varying the tread belt speed by a speed control system which makes available to the treadmill user a plurality of nominal speeds and also a plurality of rates of restoration of the tread belt speed upon the occurrence of a change in load on the moving tread belt resulting from the user's foot plant impact on the tread belt. By selection by the user of one of the plurality of available rates of restoration of tread belt speed, the user through the user operated speed control can select a desired "stiffness" or "softness", otherwise known as "feel", to reduce user foot plant induced stress or trauma. The preferred speed control system involves a variable speed DC motor with a microprocessor controlled SCR phase control power module, the microprocessor including program memory with plural sets of program values, each with respective delta gain, loop gain and maximum power values.