The ruling today related to XY individuals with DSD and applies to races between 400m and 1 mile so shorter and longer races are not subject to this ruling.
People affected by this are required to reduce their testosterone levels to something approximating 3 times that of the highest level usually measured in XX people, for 6 months prior to competing
So it's an XX race, but if you are XY and DSD, you can train as hard as you like, build muscle, stamina, heart and lung capacity and then if you reduce your testosterone to three times that of an XX person, you can compete.
Taking how we feel about the individual out of the picture and putting the feelings of all XX women into the frame, this is still very difficult to see how this reflects fairness in sport towards XX people.
Coe said, “Athletics has two classifications: it has age, it has gender. We are fiercely protective about both.''' The problem with this statement, with gender having been redefined is that he has left it up to interpretation what this means for other XY people who identify as female gender.