there's special bra for you to wear for exercise,

check any sports store.



example of sports bra:

http://www2.victoriassecret.com/collection/?cgname=OSBRPSPTZZZ&cgnbr=OSBRPSPTZZZ&rfnbr=1801

还是直接穿sport bra比较好，平常的bra很多有wire,我觉得锻炼的时候压迫。