Laura's actually wearing more than usual.

Well the entire point of design is that they don't impede any movement during physical activity fan service cliches be damned. But even with the best ones available a girl as big as Laura or Chun it would take well more then even a single sports bra to make you look about petite, realistically they'd only be down like 1-2 cups because they're already that big, picture just makes it look more like they got full on reductions or actually look more like realistic female athletes.
Doesn't matter because tits are life anyway.