Katie Ledecky & Simone Biles' Inspiring Friendship

Two of Rio's biggest stars have a lot of qualities in common. They both dominate in their respective sports, which they have been training for since the age of 6. And they're both impressed with and have shown support for one another. They've both won their share of gold medals in Rio — and leading into the 2016 Olympic Games — and will likely continue to snag a few more golds before the Games are over. Team USA's stars, female swimmer and female gymnast, Katie Ledecky and Simone Biles exemplify girl power through their mutual support for one another.

The two Olympic stars have won a combined 19 world gold medals — 10 for the gymnast, and nine for the swimmer, according to Daily Mail. The two 19-year-old athletes have also won a combined five Olympic gold medals in Rio so far, and they've been encouraging each other. NBC Olympics reported that the two first met in New York in 2015 after they were both nominated for the Sullivan Award. While neither won the award in the end, they exchanged brief words and then later met again in Los Angeles during "pre-Olympic media shoots," NBC Olympics reported.

Since then, the two have exchanged jokes on Twitter, including a post by Biles, who tagged Ledecky in a tweet where the gymnast is seen practicing her form on a diving block at an indoor pool. Biles' tweeted, "Watch out, I'm coming for ya" and Ledecky responded with, "Yes @Simone_Biles! Great technique! You are more than welcome on the @USASwimming team!"

Together (and separately), the two female Olympians are basically unstoppable, and both have made history in their respective sport. Biles has been named as the best gymnast in the world, with her complicated routines and her ability to crush the competition in virtually every event. Ledecky, on the other hand, was described by the Washington Post as "better at swimming than anyone is at anything else." Basically, they're top-notch competitors.

Aimee Boorman, Biles' coach, said the two female athletes are so good that they're challenging their male counterparts, NBC Olympics reported. Boorman told NBC Olympics she heard a female swimmer saying that Ledecky "needs to train with the guys just to have someone to push her, someone to challenge her." Boorman added, "So that says how dominant she is. It's funny, because I've heard male gymnasts talk about Simone that way. They get upset that she can tumble and vault better than they can."

Biles and Ledecky are two young women who are carving spots for themselves in sports history and showing us what girl power really looks like.