Reigning Olympic all-around champion Sunisa Lee will not compete at the world gymnastics championships next month after declining an invitation to the selection camp.

USA Gymnastics did not say why Lee "opted not to participate" at next week's camp in Texas, where 19 gymnasts will be competing for spots on the five-woman team. But Lee's training has been limited the last six months because of a kidney issue that forced her to end her final NCAA season early, and she only did balance beam and vault at last month's national championships.

Longtime coach Jess Graba said then Lee was training all for four events and planned to do the all-around at selection camp. But he also said her training schedule depended on how she was reacting that day to the medication she's taking.

"She's training pretty good when we can train," Graba said. "It's more of a balancing act. They're still monkeying with the medication to try to get it so she reacts the same way each day. As they're adjusting the medication, then some days aren't very good so we have to adjust our training and sometimes we don't train that day."

Lee has not competed internationally since winning the all-around gold in Tokyo, opting instead to go to Auburn after Tokyo and compete there for two years. She announced earlier this year she'd be leaving school at the end of the season to train for next summer's Paris Games, and the expectation was her comeback program would include the world championships.

Instead, she'll be watching from home as her fellow Americans try to win a record seventh consecutive title at the world championships, which begin Sept. 30 in Antwerp, Belgium.

The team is likely to be led by four-time Olympic champion Simone Biles, who won a record eighth national title after returning to competition last month for the first time since Tokyo. Fellow Olympians Jade Carey and Jordan Chiles are also vying for spots as is Shilese Jones, the silver all-around medalist at last year's world championships.

Skye Blakely and Leanne Wong, members of last year's world team, will also be at the Sept. 19-20 selection camp.

The other gymnasts invited to the camp are: Kayla DiCello, Amelia Disidore, Addison Fatta, Madray Johnson, Katelyn Jong, Kaliya Lincoln, Eveylynn Lowe, Nola Matthews, Zoe Miller, Joscelyn Roberson, Tiana Sumanasekera, Lexie Zeiss and Alicia Zhou.

This article originally appeared on USA TODAY: Sunisa Lee won't be on US team for world gymnastics championships