Too many jiggly bits jostling, jangling, bouncing and banging around. Damage was being done to tissues. Irreparable damage. Even if you have very small parts, it is wise to protect what you have :) And if things are more sizeable... well, do you really want to look like this....
because that's what's going to happen if you don't take precautions.
What everyone chooses for their support garments is purely individual. Some people focus on the comfort of the garment at the expense of how it performs. Soft and stretchy.... mmmmm... nice :) Until you are out there hurting yourself!
Personally, I prefer no movement whatsoever in the chest region while I am running. This is very challenging for me to achieve. I am not flat-chested. I have tried so many different types and configurations of running bras over the years. What I have found works the best for my skinny frame and "healthy girls" is a bra that has an absolute minimum of stretchy parts. NO stretchy straps. NO stretchy cups. A band with some give to it but not soft, loose and stretchy. There are so many bras out there that tout their functionality for D, DD and larger. Most of them are lying.
One place that has a HUGE selection of sports bras is Title Nine. They use a barbell ranking system... more barbells = more support. And like most online shops, they have reviews that are sometimes but not always helpful. Athleta also has a large selection, grouped according to impact level... high, medium or low.
I am getting a little worried, though. My running bras are 9 years old and will need to be replaced soon. Will I be able to find such a winning support-combo? I wear two different styles at the same time to achieve the feeling I need to be comfortable running.
the bluish-looking one on the right goes on first...
They are total granny bras. They have seams that show through my clothing. And I don't care. I would rather make my favorable fashion statement in a situation where functionality isn't as important to me!