[Drew]

"Was looking at sports bras at Walmart, getting a noticable bounce when running."

Then don't try skipping as that can really frigging hurt, or running up or down stairs or jumping from high places. Done that recently!
Just a weird thought/experience.
But seriously now, always thought my sport bras were kinda okay, but a quality, underwired, padded very well fitting ....kinda sexy bra offered me way more support and kept me in place and stopped me from bouncing all over the place to some extent. Well a bit. Seriously! Only drawback, your tits look HUGE....no hiding them. Just a cold winter thing that you can only do under a padded top to sorta hide them a bit. But when they get to a certain size you can think you are fooling everybody but, well they talk behind your back