Crown Princess Masako played tennis and attended a lecture with her husband, Crown Prince Naruhito, in the past week, but her ailing health has not improved, the Imperial Household Agency said Friday.

They were the Crown Princess' first activities since taking a break from her official duties in December, when she was hospitalized for shingles. The agency suspended her official duties shortly afterward.

The Crown Princess "has not shown any signs of a positive change in her condition, and playing tennis and attending the lecture are part of her treatment," Hideki Hayashida, grand master of the Crown Prince's Household, told a regular news briefing.

Hayashida said the 40-year-old Crown Princess played tennis briefly on Saturday with her husband and took a walk with him and their 2-year-old daughter, Princess Aiko, in the palace grounds.

She also attended a one-hour lecture on current international issues Tuesday with her husband at the palace.

In May, the Crown Prince -- in a highly unusual move -- spoke publicly about what he saw as the causes of her ill health, saying, "There were developments that denied Masako's career as a diplomat as well as her personality."