Hmmm... Guess I'm lucky. I'm an A-cup (but look more like the researcher (?) in the red top in that picture than the girl in the sports bra... but maybe I look smaller in a sports bra, not sure). I always wear a good supportive sports bra when I exercise due to vague fears of what might happen when I get older, but honestly, I think I'd be reasonably comfortable even running without a bra... I just don't move around that much (I don't THINK anyway!).

However, I really feel for women who move around more. I often see women running who have really big, robustly bouncing breasts and it DOES look painful, and I've certainly talked to women who have pain when running. I'm glad there's someone out there studying this and trying to find better solutions.