Yes I know I've posted this treadmill question to death, but I'm all about
ressurection.

I never did get a chance to go and get some oak to replace that treadmill
deck, but I got all this poplar sitting around from my table mock up.

Would poplar split and break in an environment like a treadmill? I seem to
remember that it isn't very bendy strong but overall is quite stable. I'm
thinking to myself, "Hmm, I'll get this 13/16th poplar deck installed and it
will feel solid as a rock. Then running on it will cause it to crack and
split because it's bending - better stick to my original plan and use white
oak." Am I being uncharitable here? I think I estimated it was about a 4
foot span between supports.