This morning, putting on my sports bra, I managed to whack my left elbow against the nearby doorpost. Oh my fluffy elbow I shouted (or something like that). After a few minutes managed to forget about it. However, an hour or so later in the gym, realised I couldn't possibly do any exercise that involved holding a weight and bending my elbow. Also can't prop my head up at my desk because can't lean on my elbow.
Hopefully it won't affect my running, but now I know how dangerous sports bras really can be.