Demi Lovato, Kate Hudson collaborate on workout clothes

Demi Lovato, left, and Kate Hudson arrive at the launch of Demi Lovato and Fabletics Collaboration Collection in Beverly Hill, Calif. on Wednesday, May 10, 2017. (Jordan Strauss/Invision/AP)

BEVERLY HILLS, Calif. -- Kate Hudson and Demi Lovato went from working out at the gym together to working on a fashion-line collaboration.

Hudson, who co-founded activewear brand Fabletics in 2013, says she instantly hit it off with the "ConfidMarcela Isazaent" singer when the two ran into each other at the gym. They were celebrating together Wednesday at the Demi Lovato for Fabletics Collaboration launch event.

"Because she is fierce. It was perfect," said Hudson, 38. "Her values and what she stands for is a big part of what our brand is really pushing out there for women. Body positivity, strength, taking control of your life and things. She's been a very open communicator about things in her own life, which I think is really important for women to feel like they can come out and be really open about things that are going on in their life and finding happiness."

Lovato, 24, says she has bipolar disorder and has been an advocate for mental health awareness. The pop singer says the fashion line reflects her story.

"It's come forward through the confidence that you get when you wear the clothing and the cuts are great, the compression in the pants are great. It's all about feeling comfortable while you're working out and while you are going about your day," said Lovato. She trains regularly with mixed martial arts fighters and says she also enjoys workouts "with weights, like strength and conditioning."

The new limited-edition capsule collection is youthful with leggings in pink and yellow flowered prints, black-and-white shorts and long-sleeved grey shirts. A long, hot-pink tank top is emblazoned with "CONFIDENT" in capital letters at the bottom.

Lovato says she was very hands-on during the design process, "down to colour swatches, what the tag looks like."

"I didn't draw. That's the only thing that I didn't do is draw the sketches ... I love what we've come up with," she said.

The athletic collections will be available in sizes ranging from XXS to 3XL when it goes on sale on the Fabletics site on May 17.

Lovato recently announced a YouTube series and said she's planning to release a new studio album later this year.