I can only speak personally on this one, but I had one sports bra that gave me a plugged duct every time I wore it. It took me a few weeks of suffering, getting it unplugged only to have it happen again, then having vasospasms (my son doesn't have the greatest latch), to realize what was doing it. The bra is in the garbage now, I continue to run, and I haven't had a single plug since then.
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