Having worked as a Track Coach in Southern CA for over 15 years its not necessarily the case that they cant run it is support. I has team mom's all but bound their daughter so they could compete. It does make it difficult and it is in many ways unfair. Nike, New Balance all athletic wear companies should address.
As to the drastic measures of reduction this is not something I feel a Track Coach or someone other than the family should decide. I am an Italian American, my father was the youngest of 15 and my mother the oldest of 13 and unfortunately I watched all my cousins deal with having large breast at a early age. Society unfairly labels or suggest what these woman are. Another sign of how men should decide what women do to their bodies (like birth control or abortion).
Again although difficult there are women with large breast that do compete and yes it is difficult but athletics in general can be.
As If Running Weren’t Challenging Enough, Large Breasts Can Make It a Full-on Contact Sport