Would this kind of mat be good for placement under a heavy piece of aerobic equipment like an ARC trainer (404 lbs) or similarly heavy treadmill?

Our 3/4" Shock Mats were meant to be placed in areas where heavy Olympic lifting would occur. Typically this is in an area where a squat rack would be placed, so placing a piece of equipment over the mats won't harm it in any way. You can place any type of fitness equipment on our Shock Mats like treadmills, ellipticals, and much more.