Sorry I don't have the answer but was wondering the same thing. Seems odd the Vivosmart 3 would get this useful feature but the high-end F5 and FR935 wouldn't.
What would be the use of such a feature? In case you forget how many reps you have done on the current exericise? Or will the reps be converted to steps? I know I definitely would not be looking at my watch during a session of bench presses.
