"She always joked around with me because I love Justin Bieber," Crain said.
Anything to make Martin smile.
The Cedar Hills native and Lone Peak High School graduate suffered severe injuries, including a lacerated liver and collapsed lung, during a crash on her last day of training in Chula Vista, Calif., on Wednesday. It knocked the 27-year-old out of what would have been her first Olympic Games.
According to a post from her husband on Martin's Facebook page, she is expected to make a full recovery.
Crain, 19, was the alternate on the U.S. BMX team and replaced Martin. Before leaving, she said, she left the card on Martin's bed.
"I just told her to keep her head up and this race is for her," Crain said.
The BMX begins seeding runs on Wednesday, and the five-person American team's focus is on competition. But Martin still weighs heavily on her teammates' minds.
"It still stings a little bit to talk about it," USA Cycling BMX program director Mike King said, "just because I know she worked so hard."
It was the second devastating blow to Martin in a quest for the Olympics, after she missed a spot in Beijing in 2008 due to a crash in the quarterfinal round of a qualifying event.
"It's heartbreaking to see that story," said Alise Post, the other woman on the U.S. team. "You never want anybody to go out that way. At the same time, we're all moving forward."
Crain was called into unexpected duty due to Martin's injury. As the alternate, she had planned a trip to London already, but said she had no nerves and planned to focus on qualifying for the Olympics in 2016.
She said the short notice actually was beneficial, but it will be strange to be there without Martin, one of the program's stalwarts.
"She's always been a leader to us," Crain said. "We've always all looked up to her because she's older, she has more experience. I know how much she wanted it and now how much of a heartbreak it is."
• Cedar Hills native Arielle Martin will not compete in BMX at the Olympics after suffering serious injuries during her final training session in Chula Vista, Calif.
• Martin was replaced by 19-year-old Californian Brooke Crain.
• Martin missed the 2008 Olympics, as well, after a qualifying run crash.