DALY CITY, Calif. – Na Yeon Choi’s nearly yearlong hiatus from golf to heal her mind, body and spirit didn’t include a total escape from the game.

After climbing on to the leaderboard Friday at the Mediheal Championship, she revealed that she earned a master’s degree in biomechanics while away last year.

“It was hard,” Choi said. “Sometimes, I’d go to bed at 3 or 4 in the morning after studying.”

Choi, whose nine LPGA titles include the 2012 U.S. Women’s Open, once climbed as high as No. 2 in the Rolex Women’s World Rankings. A back injury, however, led to driver yips, which precipitated a slow spiral down the world rankings. In April of 2018, she decided to leave the LPGA to give her ailing back the time it needed to fully heal. She visited castles in Eastern Europe, read books she never had time to read and also wrote a 50-page thesis. It was on the biomechanics of the golf swing. It earned her a master’s degree from the University of Kunkok last December.

“I learned a lot about my swing,” Choi said.

Choi, 31, returned to the LPGA at the Bank of Hope Founders Cup in March feeling healthy again but unsure what to expect. She had plummeted to No. 486 in the world.

“It was like I was a rookie again,” she said. “I was really nervous, my hands almost shaking.”

Choi didn’t look like a rookie. She shot 65 in her first round back at the Founders Cup before slipping to a tie for 27^th. Her finish almost didn’t matter, she said. 

“I felt so happy, excited just being back on the course,” Choi said. “This is where I belong.”

Choi is playing on a medical extension. She has eight events left, including this week, to see how much money she can make and where that would rank her on the final 2018 money list. She will be reshuffled into this year’s priority rankings based on that medical extension tally.

In four starts so far this year, Choi has missed two cuts, with that T-27 finish her best effort. She has earned $22,097 when combined with her limited starts in 2018. She’s looking poised to boost that in a big way this weekend. A 5-under-par 67 Friday at Lake Merced Golf Club left her tied for fourth, two shots behind fellow South Korean So Yeon Ryu.

“I just want to keep doing what I’ve been doing the first two days,” Choi said.

Choi said her back was a little sore in the damp, cold air here this week, but she’s feeling just fine.