Caitlyn Jenner: 'Now I Know Why Girls Need a Sports Bra'

— -- Caitlyn Jenner may have a closet full of designer dresses, but she's investing in new undergarments too.

The reality TV star makes a discovery about her body during a tennis match in a scene from her new E! series, "I Am Cait."

"Now I know why girls need a sports bra!" Jenner remarks in the scene.

The show, to premiere on July 26, documents Jenner's life since her transition, and her new look will play a role. In one scene, she and her former step-daughter Kim Kardashian look at dresses, and Kardashian laughs that Jenner chooses a dress that her mother, Kris, also has.

"All of a sudden, I am the authority on hair and makeup!" Jenner tells the camera.

There are more poignant moments too. In the preview, Jenner has a heart-to-heart talk with her mother, and tells her, "I'm still the same person." When her mother suggests that her soul is the same, Jenner agrees.

"That's your soul," she says. "That's exactly right."