A treadmill system includes a deck, an endless tread belt covering at least a portion of the deck, and a motion transducer positioned to detect movement of the tread belt. The treadmill system also includes a processor and memory where the memory includes instructions executable by the processor to receive an output of the motion transducer, determine an exercise type performed on the tread belt, and calculate an amount of work performed by a user on the tread belt based on the output of the motion transducer and the determined type of exercise.