Teenage swimming star Rikako Ikee has resumed light exercise while she continues to battle leukemia, her coach said Saturday.

The 18-year-old Ikee, who revealed her diagnosis in February, has started training on a stationary bike that she brought to her hospital room about three weeks ago. She is increasing or decreasing her workout load depending on her condition, coach Jiro Miki told reporters.

"She is getting better day by day. She is really battling it with a positive mindset, so sometimes she even gives me energy. I'm really impressed," Miki said, without elaborating on Ikee's status.

Ikee, who holds several national records, has put all swimming-related activities on hold to focus on treatment, but she said in March she will not give up on competing at next summer's Tokyo Olympics.

The news of Ikee's diagnosis shocked Japan, as she was considered likely to be one of the faces of the Olympics. She enrolled at Nihon University's College of Sports Sciences in Tokyo in April while undergoing treatment.

Miki took up a coaching position at the university swimming club and said he will coach Ikee when she returns to competition.

"I want to improve as a coach for when she comes back," he said.

Ikee set a Japanese record in the women's 100-meter butterfly in her first Olympic final at the 2016 Rio de Janeiro Games, placing sixth.

At last summer's Asian Games in Jakarta, she was named the first female MVP after becoming the first swimmer to win six gold medals, all in games-record times.