Hi There....whoa......slow the horses....you cannot drive any motor with a simple bridge rectifier for longer than say.....a few seconds for the diodes to fry. As someone pointed out....POWER is huge in the motor world.
Your treadmill motor and controller are from what brand? I can maybe help you but you will need to throw away what "someone told you" and read a bit on motors.....
Here is a simple way to understand your treadmill or any motor controlled device.....
Max motor rating appear on all motors, voltage, current, power, spin-rate(RPM)
These factors now need a drive circuit to drive the motor which is a DC motor using "Brushes"
First we take a Large ugly unruly "Bulk Voltage" of say 165vdc.....rectified and filtered
NEXT ... we add a switch that allows superfast pulses of 165vdc to pass to the motor, enabling it to spin
NEXT ... we add regulation to keep that "spin" at a constant rate(by varying that pulse-width)
NEXT ... we add an "isolated human interface"(switches and buttons) board for users settings
NEXT .... we supply feedbacks for spin rate (RPM), motor voltage & current back to interface
NEXT .... we MUST be sure to design the switching FET and kick-back diode circuit critically or we fail~!
please see inductive kickback for an explanation of this electrical condition and how it relates to inductive loads
Now, that superfast pulse of 165v shooting thru the motor brushes, then windings, builds a magnetic FLUX which "pulls" magnets inside the motor to one direction or another, with unbelievable force(3-5x internal combustion power)
If we stretch that "superfast" pulse to the motor a bit longer, the motor spins faster, eats more power......if we reduce that superfast pulse we slow that motor....the voltage applied to the motor leads is always 165vdc but your meter will not read that.....you're meter will read an RMS value of that pulse at a certain frequency(root-mean-square = RMS), so a servicer may see 55vdc on the motor leads with the unit running.....and 75vdc when it's running faster....
but in reality....the applied voltage is always a sliced section of an available "bulk drive voltage" simply selected for how much power, spin, speed, or pressure we need or want..... have a super day!!
;o)